Method for monitoring intravascular pressure and flow rate

Abstract

To provide methods for monitoring the intravascular pressure and flow.SOLUTION: An intravascular pressure and flow monitoring method includes: measuring multiple intravascular blood flow values, multiple proximal pressure values and multiple distal pressure values using one or more sensors during each of multiple cardiac cycles; determining multiple flow thresholds including a flow threshold for each of the multiple cardiac cycles using the multiple intravascular blood flow values; determining a proximal pressure value (Pa) and a distal pressure value (Pd) at the time of each flow threshold; calculating a first diagnostic parameter based upon the Pa and Pd values at the time of each flow threshold; displaying, on a user display, the diagnostic parameter for the multiple cardiac cycles.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 61 / 975,424, filed on April 4, 2014, and U.S. Provisional Patent Application No. 62 / 073,284, filed on October 31, 2014, the disclosures of which are incorporated herein by reference in their entirety.

[0002] This disclosure relates, in general, to methods and apparatus for intravascular measurements such as pressure measurement, temperature measurement, and flow rate measurement, and related diagnostics. [Background technology]

[0003] By using a sensor and guidewire assembly, intravascular data can be collected by a measuring sensor positioned at or near the distal end of the assembly. These devices are typically used in applications to measure the internal properties of tissues and fluids, such as blood pressure. The sensor and guidewire assembly can be introduced into an artery, vein, or other body organ, either independently or through a catheter already placed in the patient. These assemblies can be used to measure pressure and other parameters.

[0004] For example, by using such an assembly with one or more pressure sensing devices, such as a delivery catheter, it is possible to measure the fractional flow reserve (FFR) using pressure data. Furthermore, coronary flow reserve (CFR) can be measured using a thermodilution-based method. In such a method, the CFR value is obtained by injecting a cold saline solution into the coronary artery of interest and using a temperature sensor to measure the time from the start of injection of cold saline into the artery until the temperature returns to a specific level.

[0005] The thermodilution method has several limitations. Its specified accuracy is as low as ±30%. Furthermore, the procedure is cumbersome and time-consuming, requiring several injections of saline solution with specific characteristics to generate sufficient data for the system software to calculate the CFR value. FFR and CFR measurements are performed using two separate methods, taking into account the required thermodilution system, saline delivery, and the nature of the subsequent measurements.

[0006] FFR is used to measure the severity of coronary artery stenosis. A typical method for determining FFR is to measure the pressure drop in the coronary arteries during hyperemia. By injecting a substance that causes hyperemia, an increase in blood flow in the coronary artery system is induced over a controlled period. The pressure drop during this period is measured and used as input when determining FFR.

[0007] This disclosure relates, in part, to methods, systems, and apparatus suitable for measuring FFR values, CFR values, and other values ​​and for generating diagnostic outputs that overcome some of the challenges in existing methods. [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention aims to solve the problems of the background technology. [Means for solving the problem]

[0009] This disclosure relates in part to methods, systems, and apparatus for simultaneously measuring intravascular pressure while measuring blood flow values ​​or parameters associated with such flow. These embodiments may be based on hot film velocity measurement or hot wire velocity measurement. Hot film velocity measurement or hot wire velocity measurement is a method for measuring the cooling effect of a fluid (or gas) flowing over a heated surface. When a sensor is used as a hot film anemometer, the sensor is heated by an electric current, and the cooling effect of the blood flow is measured by sampling the voltage across a resistor. The voltage across the resistor may be measured together with other resistances, currents, electrical parameters, and electrical signals. These measurements can be correlated with flow parameters. In one embodiment, the voltage can be used for two related velocity measurement methods, namely constant temperature velocity measurement (CTA) and constant excitation voltage (CVEX) velocity measurement.

[0010] In one embodiment, a semiconductor-based sensor including a first temperature-sensitive resistor and a second temperature-sensitive resistor is used as part of a pressure-sensing intravascular device. Furthermore, at least one of the first and second resistors is also pressure-sensitive. The sensor may be delivered via a guidewire, and the sensor can be used to measure pressure before and after a stenosis candidate while simultaneously acquiring flow rate data, pressure data, or temperature data based on changes in excitation voltage, current, temperature, or other sensor parameters. Various control systems and calibration methods may be used to support such pressure and flow rate measurements.

[0011] In one embodiment, this disclosure relates to the use of a digital control system while performing simultaneous measurement of pressure and flow rate using a semiconductor-based pressure sensor. The digital control system overcomes several shortcomings of analog control systems. Specifically, some advantages of the digital control system include calibration functionality and user-specified temperature selection functionality. The digital system can also be used to improve the signal level relative to the noise level. The calibration functionality includes reading digitally encoded information on a memory device associated with a given sensing probe and adjusting each stage of the control system in response to this reading. The memory device is attachable to the probe and is, for example, a PROM, EEPROM, RFID, or other suitable memory storage device.

[0012] The temperature selection function involves automatically acquiring the temperature of a blood vessel using one or more sensors and then modifying the electrical characteristics of the sensing system. This modification of current, voltage, impedance, or other parameters is made in response to a user-specified temperature (e.g., overtemperature or sensing temperature range) higher than the temperature of the flowing blood. The overtemperature or sensing temperature range provides a range or value that can be reduced by cooling. This temperature reduction is measurable as a result of blood flow. Alternatively, it is possible to measure how much the electrical characteristics, such as voltage or current, need to be increased to maintain a constant overtemperature or sensing temperature range, and correlate this with blood flow. Thus, the overtemperature can be constant or a range that changes in response to cooling.

[0013] In one embodiment, the disclosure relates to a graphical user interface and probe interface or processing system or display system or integrated cardiac disease display system (ICD) (each separate or integrated and collectively referred to as the “measurement system”) that electronically communicates with a guidewire probe that simultaneously relays pressure data and flow rate data associated with the pressure data. In one embodiment, suitable measurement systems such as ICDs may include, but are not limited to, the RadiAnalyzer system, the RadiAnalyzer Xpress system, the Quantien system, the Aeris system, the Prestige guidewire probe system, the ComboMap® pressure and flow system, and other devices and systems that detect intravascular pressure or determine FFR. In one embodiment, the measurement system and the probe interface or processing system and display system are the same device or device assembly.

[0014] In one embodiment, the interface device receives signals from a guidewire probe representing flow rate and pressure at one or more locations along the blood vessel. The guidewire probe sensor is placed inside the catheter before being introduced into the blood vessel. Furthermore, the system acquires a zero flow rate reference value from inside the catheter before being introduced into the lumen of the blood vessel. This zero flow rate reference value may be used as an input during calibration of the guidewire probe. Atmospheric pressure may also be used as the zero point during sensor calibration.

[0015] The timing of data collection and selection in the controlled environment where data is collected determines the zero point or origin that serves as the basis for evaluating other flow and / or pressure measurements. By using the zero point or calibration point in conjunction with other parameters and transfer functions, guidewire probe signal data can be converted into flow data suitable for display and analysis using one or more processors within the measurement system.

[0016] In one embodiment, the transfer function T(x) is of the form T(x) = a + b × ln(x), and T(x) gives a temperature value as a response to a flow rate value x. In one embodiment, the transfer function T(x) is of the form T(x) = a + b × ln(x), and T(x) gives an excitation voltage or power value as a response to a flow rate value x. In one embodiment, the flow rate value x is the flow velocity. In another embodiment, the flow rate value x is the flow rate. In one embodiment, the transfer function T(x) is of the form T(x) = a + b × x^c.

[0017] In one embodiment, the transfer function is determined based on data fitting. Specifically, the data used for such fitting may include flow rate versus temperature, flow rate versus excitation voltage, velocity versus temperature, velocity versus excitation voltage, etc. One or more sensor-specific parameters available through the transfer function are stored in the memory storage of the guidewire probe. In one embodiment, the transfer function is determined based solely on the model, constraints, and other formulas, or a combination of formulas and data.

[0018] The time range for collecting data from blood vessels and displaying pressure and flow rate information based on the collected data is approximately 0 seconds to approximately 1 second. In one embodiment, the data includes a time-varying electrical signal correlated with resistance changes. In another embodiment, the data includes a time-varying electrical signal correlated with current changes.

[0019] In one embodiment, the range of potential difference applied to one or more resistors located within the sensing portion of the guidewire probe is from approximately 0.1 volts to approximately 15 volts. In one embodiment, the range of temperature changes measured in a blood vessel using the temperature (P), flow rate (Q), or temperature (T) sensing portion of the guidewire probe is from approximately 0°C to approximately 5°C. In one embodiment, the excitation voltage required to generate a sufficient excess temperature (i.e., sensitivity to flow rate changes) is approximately 4 volts. This excitation voltage range applies to the CVEX and CTA embodiments in one embodiment.

[0020] This disclosure relates in part to a method for collecting vascular-related data. The method includes the steps of: storing data from a guidewire probe in one or more memory devices; measuring first electrical signals associated with first and second resistors placed in a blood vessel; measuring second electrical signals associated with second resistors placed in a blood vessel; determining a transfer function with flow parameters as its output using the guidewire probe data; determining blood pressure values ​​in a blood vessel using one or more of the first and second electrical signals; determining blood temperature values ​​in a blood vessel using one or more of the first and second electrical signals; determining blood flow values ​​in a blood vessel using one or more of the first and second electrical signals and the transfer function; and displaying a pressure-to-flow curve of a blood vessel. In one embodiment, the transfer function relates to flow parameters and excitation voltage. In one embodiment, the transfer function relates to flow values ​​and the temperature of one or more of the first and second resistors. In one embodiment, the method further includes the steps of identifying the occurrence of one or more of the maximum flow rate, minimum flow rate, and relative extreme values ​​of the flow rate, and relating such occurrences to an intravascular event or a cardiac event.

[0021] This disclosure relates in part to an intravascular pressure and flow monitoring system. The system includes one or more memory devices and a computing device communicating with the memory devices, the memory devices include instructions that the computing device can execute to cause the computing device to perform the following steps: to determine one or more intravascular pressure values ​​in response to a first electrical signal from a measurement circuit formed from a guidewire probe and interface device; to determine one or more intravascular flow values ​​using a transfer function in response to a second electrical signal from a measurement circuit formed from a guidewire probe and interface device; and to display a pressure-vs-flow curve that changes with respect to time, generated based on one or more intravascular pressure and intravascular flow values.

[0022] In one embodiment, the pressure-flow curve is displayed in near real-time. In one embodiment, the transfer function T(x) is of the form T(x) = a + b × ln(x), where x is the flow rate and a and b are constants. In one embodiment, the transfer function T(x) is T(x) = a + b × x c The format is such that x is the flow rate and a, b, and c are constants. In one embodiment, the system further includes instructions for displaying one or more cardiovascular-related values ​​acquired between one or more time points.

[0023] In one embodiment, the one or more cardiovascular-related values ​​are selected from the group consisting of flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme value of flow rate, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values.

[0024] In one embodiment, the system further includes commands to display one or more trajectories or signatures generated in response to intravascular probe data relating to one or more locations within an artery. In one embodiment, the system further includes commands to display a user interface including flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme values ​​of flow, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, or one or more myocardial resistance index (IMR) values ​​generated using pressure and flow data from an intravascular probe.

[0025] In one embodiment, the system further includes instructions for determining one or more temperature values ​​using a linear function or other function in response to a second electrical signal from a measuring circuit formed from a guidewire probe and interface device.

[0026] This disclosure relates in part to an intravascular pressure and flow monitoring adapter kit. The kit includes a power supply, which includes a first intravascular pressure measurement system output connector and a second intravascular pressure measurement system output connector, the power output range of the power supply being greater than about 0.2 volts and less than about 12 volts, and the size of the power supply is determined to electrically connect to the intravascular pressure measurement system. The kit may include one or more electrical components that are in electrical communication with the power supply. In one embodiment of the kit, one or more electrical components are selected from the group consisting of filters, amplifiers, current sources, voltage sources, and control system connectors.

[0027] In one embodiment of this kit, the power output range is from approximately 0.3 volts to less than approximately 30 volts. In one embodiment of this kit, the kit further includes a non-transient storage medium, which includes instructions to cause the computing device of the intravascular pressure monitoring system to perform the following steps: storing in memory a transfer function that outputs intravascular flow values ​​as a response to an excitation voltage or temperature; and generating intravascular flow values ​​as a response to (i) an excitation voltage from the power supply and the transfer function, or (ii) a difference between a fixed voltage and the voltage across a temperature-dependent resistor.

[0028] This disclosure relates in part to a method for calibrating a flow monitoring device. The method includes the steps of: selecting an excitation voltage for a pressure sensor such that the temperature of the pressure sensor substantially matches the temperature of the blood in which the pressure sensor is located; determining the absolute temperature of the blood in a vessel of interest; and measuring the flow rate in the vessel using the pressure sensor. In one embodiment, the step of determining the absolute temperature of the blood in a vessel of interest, as included in the method, includes the step of acquiring the measurement value during a change in the switch configuration in the interface system.

[0029] This disclosure relates in part to an integrated cardiac system. The system includes a display system, a pressure and flow measurement system electrically connected to the display system, a processor located in either the display system or the pressure and flow measurement system, and one or more panels generated using the processor and drawn on the display, which include flow rate and pressure values ​​acquired using an intravascular probe including pressure and flow sensors. In one embodiment, the one or more panels include a pressure-vs-flow curve, the pressure-vs-flow curve includes one or more trajectories generated using intravascular pressure and flow data, and further includes an input for receiving data signals from an intravascular probe, the intravascular probe including a temperature sensor for measuring temperature changes correlated with flow rate values.

[0030] In one embodiment, the trajectory may include a graphical representation of transitions between states related to the cardiac cycle, which may change in response to stenosis, changes in intraarterial pressure, and changes in flow due to contraction or other arterial or cardiac conditions. In one embodiment, one or more panels may include a signature, trajectory, slope, maximum point, minimum point, ratio of measured values, ratio of measured values ​​to derived values, ratio of primary derived values ​​to secondary derived values, range, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) values, coronary velocity reserve (CFVR) values, instantaneous flow reserve (IFR) values, and one or more myocardial resistance index (IMR) values.

[0031] This disclosure relates in part to an intravascular pressure and flow monitoring system. The system includes an intravascular pressure and flow interface system including a wired or wireless interface for receiving data from an intravascular probe; a display system electrically connected to the intravascular pressure and flow interface system; one or more memory storage devices including instructions for outputting a user interface on the display, which includes one or more panels having fields for one or more flow measurement values; and a processor electrically connected to the intravascular pressure and flow interface system, the display system, and the one or more memory storage devices, which responds to instructions so that the user interface is output on the display system.

[0032] In one embodiment, the system includes a calibration system configured to convert either a measured temperature signal or an excitation voltage into a flow velocity using a transfer function. In one embodiment, the transfer function is a+b×lnx and / or a+b×x c This is the format. In one embodiment, the display system simultaneously outputs pressure and flow velocity measurements. In one embodiment, the display system simultaneously outputs pressure and absolute temperature measurements. In one embodiment, the display system outputs one or more parameters or indices corresponding to one or more signals acquired at the measurement position of the probe sensor.

[0033] In one embodiment, the one or more parameters or indices are selected from the group consisting of signature, trajectory, slope, maximum point, minimum point, ratio of measured values, ratio of measured values ​​to derived values, ratio of primary derived values ​​to secondary derived values, range, ratio of flow reserve (FFR) value, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values. In one embodiment, the wired interface includes an excitation voltage source, a first resistor, a second resistor, a first switch, and a second switch. In one embodiment, the wireless interface includes a plurality of current sources, a plurality of switches, a first resistor, and a second resistor, each current source in series with one of the switches. Features and embodiments related to coronary blood flow reserve

[0034] This disclosure relates, in part, to methods and systems suitable for determining one or more coronary flow reserve (CFR) values ​​and fractional flow reserve (FFR) values ​​separately or simultaneously using thermal convection devices, such as intravascular pressure and flow sensors and intravascular data acquisition and processing systems. Furthermore, this disclosure also relates, in part, to determining CFR values ​​using an intravascular probe having a pressure sensor and constant temperature velocity measurement (CTA) or constant excitation voltage (CVEX) velocity measurement.

[0035] This disclosure also relates to a method for determining coronary flow reserve data using an intravascular pressure or flow sensor. The method includes the steps of: sampling an intravascular data acquisition probe to obtain one or more distal pressure values ​​(Pd) from the distal region of a vessel and one or more thermal convection data values; receiving one or more aortic pressure values ​​(Pa) obtained from the proximal region of a vessel in an intravascular data processing system; determining one or more fractional flow reserve (FFR) values ​​from one or more distal pressure values ​​and one or more aortic pressure values; determining one or more coronary flow reserve (CFR) values ​​from one or more thermal convection data values; and displaying one or more FFR values ​​and one or more CFR values ​​on a display device.

[0036] In one embodiment, each CFR value is determined using a transfer function. In one embodiment, the transfer function is of the form T = a + c × lnQ, where T is the measured temperature of the temperature variable resistor of the thermal convection device, Q is the flow rate, and a and c are constants. In one embodiment, the above step of determining one or more coronary flow reserve (CFR) values ​​is performed by measuring the temperature T at the time of hyperemia flow. hyp and the measured temperature T at baseline flow rate bas The process includes the step of determining the following: In one embodiment, each CFR value is of form b

number

[0037] This disclosure relates in part to a data acquisition method and / or a diagnostic method using the acquired data, for example, measured pressure, temperature, or flow rate values. The method includes the steps of: setting a zero value for a distal pressure signal measured by an intravascular thermal convection device; positioning the intravascular thermal convection device at the opening of a delivery catheter; setting a zero value for a temperature signal measured by the intravascular thermal convection device before advancing it through the vascular system; advancing the intravascular thermal convection device to a position distal to the catheter opening; equalizing the intravascular thermal convection device pressure (Pd) signal against an aortic pressure (Pa) signal; adjusting or optimizing the intravascular thermal convection device temperature signal when the intravascular thermal convection device is at the measurement location of interest; sampling the intravascular thermal convection device to obtain a baseline thermal convection signal value; and sampling the intravascular thermal convection device to obtain Pd and thermal convection device values ​​for performing FFR and CFR calculations. In one embodiment, the method further includes the step of confirming that the pressure has been equalized and the flow signal has returned to a baseline level. In one embodiment, the method further includes the step of displaying one or more FFR values ​​and one or more CFR values ​​relative to a graphical user interface including one or more axes and one or more operating inputs. In one embodiment, the operating inputs and user interface are performed using a touchscreen.

[0038] This disclosure relates in part to an intravascular data monitoring system. The system includes an intravascular data acquisition system including an interface for receiving data from an intravascular probe; a display system electrically connected to the intravascular data acquisition system; one or more memory storage devices including instructions for outputting a user interface on the display system, the user interface including one or more areas for displaying one or more CFR values ​​or plots thereof; and a processor electrically connected to the intravascular data acquisition system, the display system, and the one or more memory storage devices, the processor being programmed to sample a plurality of proximal pressure values ​​(Pa), a plurality of distal pressure values ​​(Pd), a plurality of thermal convection data values, and to determine one or more CFR values ​​and one or more FFR values ​​using the sampled Pa values, Pd values, and thermal convection data values.

[0039] This disclosure relates in part to a method for calibrating an intravascular data acquisition system. The method includes the steps of: setting a baseline value for a distal pressure signal measured by an intravascular thermal convection device; positioning the intravascular thermal convection device at the opening of a delivery catheter; setting a baseline value for a temperature signal measured by the intravascular thermal convection device before advancing it through the vascular system; advancing the intravascular thermal convection device to a position distal to the catheter opening; equalizing the intravascular thermal convection device pressure (Pd) signal against an aortic pressure (Pa) signal; calibrating the temperature signal of the intravascular thermal convection device when the intravascular thermal convection device is at the measurement location of interest; and sampling the intravascular thermal convection device to obtain a Pd value and a thermal convection device value. Measurement embodiment guided by stenosis evaluation and flow threshold / flow peak

[0040] This disclosure relates in part to an intravascular pressure monitoring system and data acquisition device suitable for analyzing pressure drops in non-congestive or congestive states, identifying one or more flow thresholds, and collecting or otherwise generating diagnostic data based on data collected at such selected time points. In one embodiment, pressure ratios, such as distal-to-proximal ratios, or pressure differences are collected over time at one or more different flow thresholds. Using the pressure and flow values ​​measured at each flow threshold, it is possible to calculate the arithmetic mean of the pressure ratio / pressure difference over several heartbeats.

[0041] This disclosure relates in part to a method for evaluating blood vessels. The method includes the steps of: measuring multiple intravascular blood flow values ​​and multiple blood pressure values ​​over one or more heartbeats using one or more sensors; determining a flow threshold over one or more heartbeats using one or more of the multiple intravascular blood flow values; determining proximal pressure values ​​(Pa) and distal pressure values ​​(Pd) between the flow thresholds; calculating a first diagnostic parameter based on the Pa and Pd values ​​at the flow thresholds over one or more heartbeats; and displaying the first diagnostic parameter over one or more heartbeats, or a second diagnostic parameter determined using the first diagnostic parameter, on a user display. In one embodiment, the first diagnostic parameter is a pressure difference Pa-Pd or a pressure ratio Pd / Pa. In one embodiment, the multiple blood pressure values ​​include one or more proximal pressure values ​​measured relative to stenosis and one or more aortic pressure values.

[0042] In one embodiment, the first and second diagnostic parameters are selected from the group consisting of Pa, Pd, Pd / Pa, Pa-Pd, flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme value of flow rate, ratio of flow reserve (FFR) value, coronary flow reserve (CFR) value, coronary flow velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values. In one embodiment, the flow threshold is selected from the group consisting of the maximum flow rate during a cardiac cycle, the relative extreme value of flow rate during a cardiac cycle, a fraction of the maximum flow rate during a cardiac cycle, the maximum flow rate during hyperemia, and the flow rate during non-hypertensive conditions.

[0043] In one embodiment, the steps of measuring a plurality of intravascular blood flow values ​​and a plurality of blood pressure values ​​further include: measuring a first electrical signal associated with a first resistance and a second resistance placed in the blood vessel; measuring a second electrical signal associated with a second resistance placed in the blood vessel; determining one or more blood pressure values ​​from a plurality of intravascular blood pressure values ​​using one or more of the first and second electrical signals; determining one or more blood temperature values ​​of the blood vessel using one or more of the first and second electrical signals; and determining a plurality of intravascular blood flow values ​​of the blood vessel using one or more of the first and second electrical signals.

[0044] In one embodiment, one or more blood pressure values ​​are aortic pressure values ​​or proximal pressure values. In one embodiment, the first diagnostic parameter is a plot of values ​​against time. In one embodiment, the step of calculating the first diagnostic parameter includes the step of calculating the average value of the pressure ratio or pressure difference over multiple cardiac cycles according to a flow threshold determined for each cardiac cycle. In one embodiment, the first diagnostic parameter is the average value of the pressure ratio over multiple cardiac cycles, or the average value of the pressure difference over multiple cardiac cycles.

[0045] This disclosure relates in part to a method for evaluating blood vessels. The method includes receiving intravascular blood flow data and blood pressure data acquired during one or more cardiac cycles, wherein the intravascular blood flow data includes a peak blood flow value; determining a flow threshold including the peak blood flow value; determining a first intravascular blood pressure (Pa) and a second intravascular blood pressure (Pd) at the peak blood flow in each of one or more heartbeats; calculating one or more pressure differences between Pa and Pd, or one or more pressure ratios Pd / Pa, in each of one or more cardiac cycles; and displaying diagnostic information about blood vessels on a user display, wherein the diagnostic information includes one or more of a pressure ratio, a pressure difference, or a plot thereof. In one embodiment, the step of calculating the pressure difference includes calculating the average of the pressure differences over multiple heartbeats.

[0046] In one embodiment, the method further includes receiving an electrical signal correlated with a temperature change in an intravascular thermal convection device that is thermally communicating with a blood vessel, wherein the temperature change correlates with a change in flow rate over one or more cardiac cycles, and intravascular blood flow data includes this electrical signal; and determining a peak blood flow value from the electrical signal correlated with the temperature change.

[0047] In one embodiment, the method further includes receiving an electrical signal correlated with a temperature change in an intravascular thermal convection device that is thermally communicating with a blood vessel, wherein the temperature change correlates with a change in flow rate over one or more cardiac cycles, and intravascular blood flow data includes this electrical signal; and determining a peak blood flow value from the electrical signal correlated with the temperature change. Other embodiments and embodiments

[0048] This disclosure relates in part to an intravascular pressure and flow monitoring system. The system includes one or more memory devices and a computing device communicating with the memory devices, the memory devices being executable by the computing device and including instructions to cause the computing device to perform the following steps: to determine one or more intravascular pressure values ​​in response to a first electrical signal from a measurement circuit formed from a guidewire probe and an interface device; to determine one or more intravascular flow values ​​using a transfer function in response to a second electrical signal from a measurement circuit formed from the guidewire probe and the interface device; and to display a time-varying pressure-vary-flow curve generated based on one or more intravascular pressure and intravascular flow values. In one embodiment, the pressure-vary-flow curve is displayed in near real time. In one embodiment, the transfer function T(x) is of the form T(x) = a + b × ln(x), where x is the flow rate and a and b are constants. In one embodiment, the transfer function T(x) is T(x) = a + b × x c This is the format, where x is the flow rate and a, b, and c are constants.

[0049] In one embodiment, the system further includes instructions for displaying one or more cardiovascular-related values ​​acquired between one or more time points. In one embodiment, the one or more cardiovascular-related values ​​are selected from the group consisting of flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme values ​​of flow, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values.

[0050] In one embodiment, the system further includes commands to display one or more trajectories or signatures generated in response to intravascular probe data relating to one or more locations within an artery. In one embodiment, the system further includes commands to display a user interface including flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme values ​​of flow, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, or one or more myocardial resistance index (IMR) values ​​generated using pressure and flow data from an intravascular probe.

[0051] In one embodiment, the system further includes commands to determine one or more temperature values ​​using a linear function or other function in response to a second electrical signal from a measurement circuit formed from a guidewire probe and an interface device. In one embodiment, the system further includes commands to calibrate the guidewire probe by the following calibration method steps: selecting an excitation voltage for a pressure sensor such that the temperature of the pressure sensor substantially matches the temperature of the blood in which the pressure sensor is located; determining the absolute temperature of the blood in the vessel of interest; and measuring the flow rate in the vessel using the pressure sensor. In one embodiment, the step of determining the absolute temperature of the blood in the vessel of interest includes taking the measurement value during a change in the switch configuration in the interface system.

[0052] In one embodiment, the intravascular pressure and flow monitoring system further includes a display system, a pressure and flow measurement system electrically connected to the display system and including a computing device, the computing device located in either the display system or the pressure and flow measurement system, and one or more panels generated using the computing device and displayed on the display, including flow rate and pressure values ​​acquired using an intravascular probe including pressure and flow sensors.

[0053] In one embodiment, one or more panels include a pressure-versus-flow curve that includes one or more trajectories generated using intravascular pressure and flow data, and further includes an input for receiving a data signal from an intravascular probe, the intravascular probe including a temperature sensor that measures a temperature change correlated with a flow value. In one embodiment, one or more panels include a signature, a trajectory, a slope, a maximum point, a minimum point, a ratio of measured values, a ratio of a measured value to a derived value, a ratio of a first derivative value to a second derivative value, a range, one or more fractional flow reserve (FFR) values, a coronary flow reserve (CFR) value, a coronary flow velocity reserve (CFVR) value, an instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values.

[0054] In one embodiment, the intravascular pressure and flow monitoring system further includes instructions for processing coronary flow reserve data using an intravascular pressure or flow sensor, the instructions including sampling an intravascular data collection probe to obtain one or more distal pressure values (Pd) from a distal region of a blood vessel and one or more heat convection data values, receiving one or more aortic pressure values (Pa) obtained from a proximal region of the blood vessel in an intravascular data processing system, determining one or more fractional flow reserve (FFR) values from the one or more distal pressure values and the one or more aortic pressure values, determining one or more coronary flow reserve (CFR) values from the one or more heat convection data values, and displaying the one or more FFR values and the one or more CFR values on a display device, wherein each CFR value is determined using a transfer function. In one embodiment, the transfer function is in the form T = a + c × lnQ, where T is the measured temperature of the temperature variable resistor of the heat convection device, Q is the flow rate, and a and c are constants. In one embodiment, each CFR value is determined using the relationship between T of the form b

Number

[0055] This disclosure relates in part to a method for monitoring intravascular pressure and flow. The method includes the steps of: measuring multiple intravascular blood flow values ​​and multiple blood pressure values ​​over one or more heartbeats using one or more sensors; determining a flow threshold over one or more heartbeats using one or more of the multiple intravascular blood flow values; determining proximal pressure values ​​(Pa) and distal pressure values ​​(Pd) between the flow thresholds; calculating a first diagnostic parameter based on the Pa and Pd values ​​at the flow thresholds over one or more heartbeats; and displaying the first diagnostic parameter over one or more heartbeats, or a second diagnostic parameter determined using the first diagnostic parameter, on a user display. In one embodiment, the first diagnostic parameter may be a pressure difference Pa-Pd or a pressure ratio Pd / Pa. In one embodiment, the multiple blood pressure values ​​include one or more proximal pressure values ​​measured relative to stenosis and one or more aortic pressure values.

[0056] In one embodiment, the first and second diagnostic parameters are selected from the group consisting of Pa, Pd, Pd / Pa, Pa-Pd, flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme value of flow rate, ratio of flow reserve (FFR) value, coronary flow reserve (CFR) value, coronary flow velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values. In one embodiment, the flow threshold is selected from the group consisting of the maximum flow rate during a cardiac cycle, the relative extreme value of flow rate during a cardiac cycle, a fraction of the maximum flow rate during a cardiac cycle, the maximum flow rate during hyperemia, and the flow rate during non-hypertensive conditions. In one embodiment, the steps of measuring a plurality of intravascular blood flow values ​​and a plurality of blood pressure values ​​further include: measuring a first electrical signal associated with a first resistance and a second resistance placed in the blood vessel; measuring a second electrical signal associated with a second resistance placed in the blood vessel; determining one or more blood pressure values ​​from a plurality of intravascular blood pressure values ​​using one or more of the first and second electrical signals; determining one or more blood temperature values ​​of the blood vessel using one or more of the first and second electrical signals; and determining a plurality of intravascular blood flow values ​​of the blood vessel using one or more of the first and second electrical signals.

[0057] In one embodiment, the step of calculating a first diagnostic parameter includes the step of calculating the average value of a pressure ratio or pressure difference over multiple cardiac cycles according to a flow threshold determined for each cardiac cycle. In one embodiment, the first diagnostic parameter is the average value of a pressure ratio over multiple cardiac cycles, or the average value of a pressure difference over multiple cardiac cycles. In one embodiment, the method includes the step of receiving an electrical signal correlated with a temperature change of an intravascular thermal convection device that is thermally communicating with a blood vessel, wherein the temperature change correlates with a flow change over one or more cardiac cycles, and intravascular blood flow data includes this electrical signal; and the step of determining a peak blood flow value from the electrical signal correlated with the temperature change.

[0058] In one embodiment, the method further includes steps of calibrating an intravascular data acquisition system, which include setting a baseline value for a distal pressure signal measured by an intravascular thermal convection device; positioning the intravascular thermal convection device at the opening of a delivery catheter; setting a baseline value for a temperature signal measured by the intravascular thermal convection device before advancing it through the vascular system; advancing the intravascular thermal convection device to a position distal to the catheter opening; equalizing the intravascular thermal convection device pressure (Pd) signal against the aortic pressure (Pa) signal; calibrating the temperature signal of the intravascular thermal convection device when the intravascular thermal convection device is at the measurement location of interest; and sampling the intravascular thermal convection device to obtain Pd values ​​and thermal convection device values.

[0059] The drawings are not necessarily drawn to the correct scale, and rather, in general, the focus is on illustrating the principles. The drawings should be considered illustrative in all respects and are not intended to limit the disclosure, and the scope of the disclosure is defined solely by the claims. [Brief explanation of the drawing]

[0060] [Figure 1A] This is a schematic diagram of an intravascular probe suitable for measuring pressure, flow parameters, and other parameters of interest in a configuration wired to one or more measurement systems. [Figure 1B] This is a schematic diagram of an intravascular probe suitable for measuring pressure, flow rate, and other parameters of interest in a configuration wirelessly connected to one or more measurement systems. [Figure 2A] This is a schematic diagram of a blood vessel in which a guidewire probe for detecting pressure and flow rate is positioned, according to an exemplary embodiment of the present disclosure. [Figure 2B] This is a schematic diagram of the detection area and related components of an exemplary embodiment of a guidewire probe suitable for simultaneously measuring pressure and flow rate, according to an exemplary embodiment of the present disclosure. [Figure 2C]This is an illustrative image of a part of the semiconductor substrate of a guidewire probe, including active and passive resistors for detecting pressure and flow rate, according to an exemplary embodiment of the present disclosure. [Figure 2D] This is a perspective view of a guidewire probe showing a capsule surrounding a sensor array according to an exemplary embodiment of the present disclosure. [Figure 3] This is a schematic diagram, including various resistors and nodes, representing components of a probe, connector, and associated contact pad according to an exemplary embodiment of the present disclosure. [Figure 4A] This is a schematic diagram including various resistors and nodes as a representation of components of an intravascular probe and interface system or processing system that is a bridge configuration, according to an exemplary embodiment of the present disclosure. [Figure 4B] This is a schematic diagram including various resistors and nodes as a representation of components of an intravascular probe and interface system or processing system that is a bridge configuration, according to an exemplary embodiment of the present disclosure. [Figure 5A] This is a schematic diagram of a signal sampling system used in combination with an intravascular probe and a measurement bridge as shown in Figure 4A. [Figure 5B] This is a schematic diagram of a control system for an embodiment of constant temperature flow measurement (CTA) using a guidewire probe, according to an exemplary embodiment of the present disclosure. [Figure 5C] This is a schematic diagram of a constant temperature control system for monitoring changes in excitation voltage, according to an exemplary embodiment of the present disclosure. [Figure 5D] This is a schematic diagram of a flow rate calculation system implemented using constant excitation voltage (CVEX) according to an exemplary embodiment of the present disclosure. [Figure 5E] This is a schematic diagram of software signal processing for simultaneously measuring pressure and flow rate using CVEX, according to an exemplary embodiment of the present disclosure. [Figure 6A] Plots and representations of transfer functions for CTA and CVEX embodiments of pressure and flow rate monitoring using an intravascular probe, respectively, according to an exemplary embodiment of the present disclosure. [Figure 6B] Plots and representations of transfer functions for CTA and CVEX embodiments of pressure and flow rate monitoring using an intravascular probe, respectively, according to an exemplary embodiment of the present disclosure. [Figure 7A] This figure shows a comparison between a flow rate signal (blue) and a reference flow rate signal (red) measured in one embodiment of the present disclosure. The measurement was performed using a hypothetical flow rate. [Figure 7B] This figure plots the flow velocity against the pullback from the distal LAD to the proximal LAD. Recordings were made in a beating, extracted pig heart. [Figure 8A] This figure shows a plot of pressure and flow rate against time obtained by using a pressure and flow rate sensing probe according to an exemplary embodiment of the present disclosure, with the sensor placed in the proximal RCA of a pig's heart. [Figure 8B] This figure shows a plot of pressure and flow rate against time obtained by using a pressure and flow rate sensing probe according to an exemplary embodiment of the present disclosure, with the sensor placed in the proximal LAD of a pig's heart. [Figure 8C] Figure 8D shows a pressure-to-flow plot obtained using a pressure and flow detection probe according to an exemplary embodiment of the present disclosure, and is a figure having a loop or trajectory obtained with respect to the RCA. Points corresponding to the markings are shown in Figure 8D. [Figure 8D] This figure shows a plot of pressure and flow rate against time of a velocity profile acquired with respect to the RCA using pressure and flow rate sensing probes according to an exemplary embodiment of the present disclosure. Points corresponding to the markings are shown in Figure 8C. [Figure 8E] Figure 8F shows a pressure-to-flow plot obtained using a pressure and flow detection probe according to an exemplary embodiment of the present disclosure, and is a figure having a loop or trajectory obtained with respect to LCA. Points corresponding to the markings are shown in Figure 8F. [Figure 8F]This figure shows a plot of pressure and flow rate against time for a velocity profile obtained with respect to LCA according to an exemplary embodiment of the present disclosure. Points corresponding to the markings are shown in Figure 8E. [Figure 9A] This figure shows a plot of pressure and flow rate over time in the proximal left anterior descending coronary artery, according to an exemplary embodiment of the present disclosure. [Figure 9B] This figure shows a plot of myocardial resistance against time according to an exemplary embodiment of the present disclosure. The plot in Figure 9B was obtained by dividing the pressure in Figure 9A by the flow signal. [Figure 10A] This figure shows the pressure-to-flow rate plot (upper) and the time-to-pressure plot (lower) in an exemplary embodiment of the present disclosure for a normal scenario (Figure 10A) and an abnormal scenario (Figure 10B). The abnormal scenario shown in Figure 10B was created by an occluded balloon that caused a myocardial infarction. [Figure 10B] This figure shows the pressure-to-flow rate plot (upper) and the time-to-pressure plot (lower) in an exemplary embodiment of the present disclosure for a normal scenario (Figure 10A) and an abnormal scenario (Figure 10B). The abnormal scenario shown in Figure 10B was created by an occluded balloon that caused a myocardial infarction. [Figure 11] This is a schematic diagram of an intravascular data acquisition and display system suitable for measuring CFR using an intravascular detection device, according to an exemplary embodiment of the present disclosure. [Figure 12A] This is a flowchart of an exemplary method for intravascular data analysis and display according to an exemplary embodiment of the present disclosure. [Figure 12B] This is a flowchart of an exemplary method for intravascular data analysis and display according to an exemplary embodiment of the present disclosure. [Figure 13A] This is a screenshot of the exemplary user interface and data display in review mode, according to an exemplary embodiment of the present disclosure. [Figure 13B] This is a screenshot of the exemplary user interface and data display in review mode, according to an exemplary embodiment of the present disclosure. [Figure 13C] This is a screenshot of the exemplary user interface and data display in review mode, according to an exemplary embodiment of the present disclosure. [Figure 13D] This is a screenshot of the exemplary user interface and data display in review mode, according to an exemplary embodiment of the present disclosure. [Figure 14] This graph shows the results of one system according to an exemplary embodiment of the present disclosure, and is used to determine the CFR value by comparing it with a reference CFR value. [Figure 15A] These are screenshots of exemplary user interfaces and data displays according to exemplary embodiments of the present disclosure. [Figure 15B] These are screenshots of exemplary user interfaces and data displays according to exemplary embodiments of the present disclosure. [Figure 15C] These are screenshots of exemplary user interfaces and data displays according to exemplary embodiments of the present disclosure. [Figure 15D] These are screenshots of exemplary user interfaces and data displays according to exemplary embodiments of the present disclosure. [Figure 16] This figure shows a diagnostic method related to flow threshold detection according to an exemplary embodiment of the present disclosure. [Figure 17A] This flowchart shows an exemplary embodiment of a method relating to intravascular data collection, analysis, and display of diagnostic information of interest, according to an exemplary embodiment of the present disclosure. [Figure 17B] This flowchart shows an exemplary embodiment of a method relating to intravascular data collection, analysis, and display of diagnostic information of interest, according to an exemplary embodiment of the present disclosure. [Figure 18] This is a plot of pressure ratios and pressure differences obtained at multiple flow thresholds acquired at various time points using a detection device according to an exemplary embodiment of the present disclosure, with respect to pressure measurements (upper) and flow measurement values ​​correlated with flow values ​​(lower). [Modes for carrying out the invention]

[0061] Various data acquisition and analysis systems are available to obtain information about the coronary artery system. By analyzing or displaying data acquired from blood vessels using these devices, or data derived from related intravascular or extravascular measurements, it is possible to perform correlations and extrapolations that are useful to researchers and clinicians. For example, various measurement systems and intravascular probes are available to determine the fractional flow reserve (FFR) for blood vessels using pressure sensor devices. Intravascular ultrasound (IVUS) is an imaging modality that uses sound waves to image a portion of a blood vessel. Optical coherence tomography (OCT), on the other hand, is an imaging modality that uses an interferometer to acquire relative distance measurements to blood vessels or objects placed inside blood vessels.

[0062] By using an intravascular data acquisition device within a blood vessel, it is possible to generate and receive signals containing diagnostic information relative to that vessel. Such devices include, but are not limited to, imaging devices such as optical probes and ultrasound probes, pressure sensors, flow sensors, temperature sensors, chemical sensors such as ion sensors, and other devices suitable for acquiring data on blood vessels or other components of the cardiovascular system. Furthermore, for example, as shown in Figures 1A and 1B, it is possible to image a patient using an angiography system 95 in a catheterization room and other external sensors 97, and provide the data to the measurement system along with data from other devices and systems 10, 20 described herein.

[0063] Using such devices and systems, coronary flow reserve (CFR) and fractional flow reserve (FFR) values ​​can be determined separately or simultaneously, as will be detailed herein. Furthermore, it is possible to selectively measure pressure ratios and pressure differences at specific time points or a set of specific time points. These time points may correspond to flow thresholds, which are correlated with or derived from flow values ​​at time points corresponding to, for example, peak flow, or other extreme flow values, or periodic events in the cardiac cycle. An example of such periodic events is the repeated peak or maximum flow points that occur as the heart expands and contracts, although these do not necessarily represent the same flow level.

[0064] This disclosure relates, in part, to methods, systems, and apparatus that enable the acquisition of intravascular blood flow and pressure measurements and the use of these to generate diagnostic feedback about a patient. In this specification, references to acquiring blood flow measurements, references to measuring blood flow values ​​or blood flow parameters, and similar references to blood flow refer to velocity values ​​or correlated values, not absolute flow values. Specifically, various embodiments of the disclosure described herein simultaneously perform intravascular pressure measurements while acquiring blood flow information or parameters correlated with such blood flow. By employing methods based on CTA and CVEX flow velocity measurement in one or more embodiments, it is possible to simultaneously perform flow and pressure measurements about a blood vessel using a single guidewire probe comprising one or more optical or electrical sensors. The probe may include other sensors such as OCT, IVUS, and other data acquisition sensors.

[0065] In the CTA embodiment, a constant temperature is maintained for the temperature sensor. A control system is used to maintain the temperature, and the control system is capable of detecting when the voltage required to maintain the temperature changes. As a result, the cooling effect of the fluid flowing to the temperature sensor can be converted into a time-varying voltage corresponding to the flow rate parameter. In contrast, in the CVEX embodiment, the excitation voltage of the temperature sensor is maintained constant, and changes in resistance, impedance, and other voltage, current, or time-varying parameters are measured as indicating the flow rate parameter.

[0066] By using intravascular blood flow measurements alone or in combination with other measurements, it is possible to display diagnostic information of interest in real time or near real time (e.g., within a time frame of approximately 0 to 5 seconds). An integrated cardiac disease display system (ICD), which may include one or more measurement systems, can be used to display various types of patient-related data acquired using intravascular probes and other catheterization laboratory measurement devices (e.g., angiography systems), integrated with room temperature, blood oxygen levels, etc. These functions are further described herein.

[0067] Figures 1A and 1B show systems 10 and 20, which are different types of guidewire devices, suitable for use in a catheterization room environment or other environments that enable the acquisition and display of intravascular blood flow measurements. Figure 1A shows an intravascular probe 20 including a wired connection 90 to an interface system 80. In contrast, Figure 1B shows an intravascular probe 35 including a wireless connection 91 to an interface system 82. Each device shown in Figures 1A and 1B includes a guidewire 40 and one or more sensors located at the distal end of the guidewire, which constitute the components of the intravascular probe. The distal end of the guidewire is sized to be inserted into a blood vessel such as a coronary artery. One or more of these sensors define a detection area suitable for detecting or measuring one or more of the following: pressure value P, flow rate value Q, values ​​correlated with flow rate, temperature value T, and changes related to any of these. The PQT detection area 45 may correspond to the tip of the intravascular probe. The pressure sensor may be electrical, mechanical, or optical, as appropriate for the given embodiment.

[0068] Furthermore, Figures 1A and 1B show magnified views of the probe tip of each type of intravascular probe, respectively. As shown in the magnified views, the guidewire 40 is adjacent to a jacket or capsule 50, or other support structure, that defines the cavity above the sensor array 43. The jacket or capsule may be a metal tube in one embodiment. The sensor array may include one or more sensors. In one embodiment, the sensor array 43 includes a pressure-sensitive resistor and a temperature-sensitive resistor. In another embodiment, the sensor array includes an optical pressure sensor, for example, an optical fiber pressure sensor. The sensor array may include an optical flow sensor, a mechanical flow sensor, and other flow sensors. Depending on the type of pressure sensor and flow sensor, an electrical or optical connection extends from the sensor array through the guidewire to the proximal connector. The probe tip may include one or more coils 55, which are for detecting passability or angiography, for example, as shown in Figure 2D.

[0069] As shown in Figures 1A and 1B, the proximal connectors 70 and 72 differ depending on the two types of probes 30 and 35. In Figure 1A, the proximal connector 70 has its distal end communicating with the probe tip and is connected to the guidewire at the proximal end of the probe. As shown in Figure 1A, the proximal connector 70 is connected to the probe interface / processing system 80 via a detachable wired connection 90. In contrast, in Figure 1B, the intravascular probe 35 has a guidewire extending to the proximal connector 72, which includes a transmitter 75.

[0070] Referring to the wireless embodiment in Figure 1B, the transmitter wirelessly transmits a signal from the probe to the probe interface / processing system 82. In contrast, in the embodiment of Figure 1A, a wired connection 90 is used. The proximal connector and transmitter also include a power source, such as a battery, in one embodiment. Both of these proximal connectors include an electrical or optical connection to a sensor array located at the tip of the probe. The proximal connector may also include an interface circuit that forms a wired or wireless bridge to a measurement system, such as the probe interface / processing system.

[0071] In a wired connector system using an electric pressure sensor, an interface electronic circuit, such as that shown in Figure 4A, is incorporated in one embodiment into the display system 87 or another measurement system. The display system, interface / processing system, and other systems having inputs for receiving intravascular probe signals may be separate systems or may be combined at various levels as one or more systems, such as an ICD. In one or more of the systems described herein that directly or indirectly receive probe signals, or data including data generated from probe signals, or data received from a given intravascular probe, analog-to-digital conversion, signal processing and conversion from raw signal data to calibrated data, and a graphical user interface for presenting pressure, flow rate, and temperature data in real time may be implemented.

[0072] These interfaces or interface devices are connected to one or more circuits, signal processing elements, or control elements. These circuits, elements, and other components of a given intravascular measurement system are used to convert time-varying electrical signals from a guidewire probe into flow rate and pressure data. These time-varying electrical signals may be current, voltage, resistance changes, temperature changes, or other data correlated with intravascular flow or pressure. These interfaces and displays are formatted and programmed to display one or more panels. The panels may include multiple display sections, for example, display sections used in the measurement system for pressure data, ultrasound images, angiographic images, OCT images, and other intravascular images and data. One or more such panels, for example, D1, D2, and D3, may be controlled and programmed using a display system or other measurement system to display flow rate data as a time-domain real-time curve. Pressure data may be displayed simultaneously with flow rate data. FFR values ​​based on pressure data may also be displayed. In addition, various trajectories and loops described herein may be displayed along with the point of interest.

[0073] The display system includes various panels, displays, or GUIs, such as D1, D2, and D3. These panels may present appropriate intravascular measurement data, such as imaging data, pressure data, or other data, such as angiography data, ultrasound data, or OCT data. For example, D1, D2, or D3 can display pressure-to-flow curves and real-time FFR data acquired using pressure measurements instead of other measurements. D1, D2, or D3 can also display intravascular data of other areas of interest, such as imaging data, relative extremes, maximum flow rate, minimum flow rate, maximum pressure, minimum pressure, myocardial resistance, flow rate data, and stent placement images.

[0074] In one embodiment, flow rate data is displayed in the same format as pressure data, or in a format that coexists with or is synchronized with pressure data. For example, additional panels such as D1, D2, or D3 may be added to the existing user interface or data display screen of a measurement system, such as an FFR system or a complex or multimode intravascular data acquisition system. Two or more of these additional panels can display pressure and flow rate information simultaneously, for example, by a pressure-flow rate curve, or by other representations integrated with the FFR results. These displays or interfaces may be part of an interface device for a guidewire probe, OCT, FFR, IVUS, or other intravascular data acquisition system, or may be electrically connected to such an interface device by wireless communication or the like. In one embodiment, a transfer function or calibration function is used to calibrate a guidewire probe, and these functions use parameters stored in memory as input as part of a calibration system 93. In one embodiment, the calibration system 93 may be part of a control system 92.

[0075] D1, D2, and D3 may provide user interfaces for operating the flow rate and pressure measurement system. Furthermore, information panels or graphical user interface panels such as D1, D2, and D3 can be used to display one or more of the plots or parameters depicted in Figures 7A to 10B. D1, D2, and D3 are shown, but these are examples and not limitations. Accordingly, displays, panels, or subpanels may be added or removed in various ways for one or more types of real-time data, stored data, and user interfaces described herein.

[0076] In a wireless probe system, in one embodiment, the proximal connector and transmitter incorporate interface electronic circuits. In one embodiment, analog-to-digital conversion of signal data acquired regarding blood flowing through the blood vessels is performed within the proximal connector. Furthermore, the raw data may be converted to calibrated data by circuit elements or processors within the proximal connector and transmitter, or within the display system. A graphical user interface (GUI) that displays pressure, flow rate, and temperature data in real time may be implemented within the display system in one embodiment.

[0077] Embodiments of this disclosure relate, in part, to various features of pressure sensing devices, measurement systems, and associated software suitable for pressure monitoring and flow rate monitoring. Pressure monitoring and flow rate monitoring may be performed using a guidewire probe having a semiconductor element that includes a component that generates an electrical change in response to changes in flow rate and pressure. For some clinical measurements, such as coronary flow reserve (CFR), coronary velocity reserve (CFVR), fractional flow reserve (FFR), and myocardial resistance index (IMR), it is desirable to perform pressure and flow rate measurements simultaneously. In one embodiment, a maximum flow rate value or other flow rate value of interest (e.g., in a region of a PQ plot) is identified using any of the embodiments described herein such that one or more of CFR, CFVR, FFR, or IMR can be performed in response to such value. Embodiments described herein support methods for performing the above-described procedures and measurements using a measurement system, a guidewire probe, and associated software and electrical components.

[0078] By using a guidewire probe in combination with the measurement platform and software methods described herein, it is possible to simultaneously measure pressure and flow rate based on changes in electrical signals. These components provide diagnostic tools and various interface types that are useful for displaying data in real time. Given that such data can be obtained from the electrical signals from the guidewire probe, it is possible to display pressure and flow rate data while the probe is in the patient. The pressure and flow rate data can then be plotted together in real time as a pressure-for-flow rate, or PQ plot, and can be used to trigger events or as a diagnostic tool as described herein. A stent can be deployed along the probe's guidewire or using other catheter-layout wires or devices at a location identified by an angiography system or other imaging system and its output data that is commonly aligned with the pressure and flow rate probe position in the patient.

[0079] As shown in Figure 2A, a blood vessel 100 is illustrated, which may be, for example, a portion of a coronary artery. Blood flows within the blood vessel 100 and throughout the rest of the artery, and when the blood encounters a narrowing in the flow path, such as the illustrated stenosis 120, changes in flow rate and a decrease in pressure occur. The wall 150 of the blood vessel 100 surrounds the lumen 200 through which the blood flows. To acquire data on the blood vessel 100, a pressure sensor device 250, such as a guidewire probe, may be inserted into the lumen 200 of the blood vessel 100. The sensing area 300 of the device 250, where flow rate and pressure are detected, is exposed to the blood but may be surrounded by a capsule, jacket, or other structural support or other structure. The capsule, jacket, or other elongated support area or support member provides structural support while allowing the sensing area to be exposed.

[0080] As shown in Figure 2A, a guidewire 320 containing an electrical conductor communicating with a circuit element in region 300 can be used to introduce the device 250 into the lumen 200 of a blood vessel. In one embodiment, the guidewire 320 is part of a guidewire probe. The pressure sensor device 250 is typically placed inside a catheter (not shown). Measurements can be taken inside the catheter, during which the flow is suppressed or substantially zero, providing a reference or calibration value for the flow. In one embodiment, the guidewire may extend into a wireless proximal connector PC.

[0081] In one embodiment, the guidewire and the electrical conductors located within the guidewire probe extend to a connector or wireless device, and the data may be relayed to a probe interface system 340, also referred to as an interface device. The probe interface system or device 340 may perform calculations of the measurement values ​​based on the signals from the probe. Alternatively, the system 340 may receive a signal encoding the result of calculations performed using circuits or processing elements located within the probe (e.g., within the proximal connector of the probe). In one embodiment, the interface device 340 is a component or subsystem of the measuring device. In one embodiment, the interface device 340 communicates with a measuring system 390, which may include a display device or an ICD. Systems 340 and 390 may include power supplies and other adapter components for supplying or controlling overtemperature or excitation voltage, as described herein. The adapter components can be used to retrofit existing pressure monitoring systems.

[0082] The measuring device or interface device 340 may include circuit elements selected to harmonize with or operate in conjunction with those positioned within a guidewire probe. The interface device may also include software, a control system, and a data analysis / display device and processor suitable for graphing and displaying pressure, flow rate, and associated relative extreme values. In one embodiment, the control system is programmed to trigger pressure measurement, flow rate measurement, or otherwise perform FFR, CFR, CFVR, or other action or calculation when any of the maximum flow rate, maximum pressure, relative maximum flow rate, relative maximum pressure, or other values ​​or thresholds occur.

[0083] Figure 2B shows further details regarding the sensing region 300 of the guidewire probe shown in Figure 2A. The guidewire 320 typically includes the sensing region 300, which may be partially covered by a capsule exposed to the blood flow or supported in another manner. The sensing region can be cooled directly or indirectly by the blood flow. The temperature of the sensing region may be raised to a temperature equal to or higher than that of the blood flow. Without being limited to a specific mechanism, in one embodiment, the blood flow comes into contact with the sensing region 300, causing heat transfer from the sensing region 300. In another embodiment, the blood flow causes heat transfer from the capsule and other materials of the guidewire or other support structures that are positioned around the sensing region 300 and are in thermal communication with the sensing region 300. Thus, the sensing region, capsule, and surrounding materials may be sized and made of suitable thermally conductive materials to improve the ability to detect blood flow parameters by increasing the amount of heat transfer.

[0084] In one embodiment, as shown in Figure 2B, the sensing region 300 of the guidewire probe is in fluid communication with the surrounding blood. This sensing region is bounded by a capsule or other barrier positioned around it. In one embodiment, the sensing region is directly cooled by the blood flow. In another embodiment, the amount of heat transferred through the capsule or other probe component supporting the sensing region correlates with one or more blood flow parameters. Efficient heat transfer to the sensing region, whether in direct contact with the surrounding blood or not, improves thermal responsiveness and the accuracy of flow measurement. In one embodiment, no capsule is present.

[0085] In one embodiment, a piezoelectric membrane 350 is placed on a semiconductor substrate 400. The membrane 350 moves in response to pressure changes and has an active resistance R A It operates as such. On the other hand, on the semiconductor substrate 400, there is a passive resistor R P A reference resistor, also known as a reference resistor, is also provided or formed. The pressure sensor and the reference (passive) resistor may be electrically connected to one or more electrical wires or other electrical components in various configurations for various embodiments of the probe.

[0086] For example, the electrical wires L1 and L2 shown in the diagram have resistances R P and R A It is electrically connected to the semiconductor substrate. As an alternative embodiment, Figure 2C shows the semiconductor chip portion 128 of a guidewire type probe device, which is connected to the semiconductor substrate and the active resistor R A and passive resistance R P This includes, in one embodiment, one or more electrical conductors, such as conductors L1 and L2, are connected to the measurement system 340 through a coupler or terminal end of a guidewire incorporated as part of a guidewire probe. As shown in Figure 2B, the grounding connection may also be another connection from the guidewire probe. A pressure sensor using an optical sensor, such as an optical fiber etalon, may also be implemented. This optical sensor may be integrated with other thermal velocity measuring devices. Data collection of temperature, pressure, and flow rate.

[0087] A pressure sensor device, as described herein, includes a small pressure sensor mounted on the tip of a guidewire. The pressure sensor is typically disposed on or formed from a semiconductor substrate, as shown in Figures 2B and 2C. As shown in Figures 1A and 1B, the pressure sensor is part of a sensor array connected to the guidewire, with a portion supported by a capsule. In one embodiment, the sensor array includes a single sensor suitable for performing flow measurement, pressure measurement, or both. Figure 2D shows an illustrative representation of an intravascular probe 220 having a sensing device, e.g., a capsule 50 and a sensor array 43. The guidewire probe 220 includes two or more measuring resistances as part of the sensor array, e.g., R A and R P It may include. The pressure sensor is R in Figure 2C. A It has a membrane having tensile resistance that communicates with the membrane shown. When the pressure changes, this affects the sensor membrane and the active resistance R A The resistance value of the tensile strength, also known as the resistance, changes.

[0088] R A Typically, it is temperature-sensitive. A similar reference resistance, i.e., passive resistance R, P A reference resistor is placed on the substrate 400 and is temperature-sensitive only. This reference resistor facilitates compensation for temperature changes that may alter the pressure signal or act as noise. As a result, in one embodiment, one resistor of the guidewire probe is pressure and temperature-sensitive (R A ), the other resistance of the guidewire probe is sensitive only to temperature (R P ).

[0089] These resistors are connected to a measuring electronic circuit, which may be located within an interface device or measuring system, or may be electrically connected to the interface device or measuring system by a microcable. The selected cable is sized to fit the guide wire. Because the cable is thin, r a , rp , and r g The resistance is quite high, typically ranging from about 40 ohms to about 70 ohms depending on the length. The microcable is also temperature-sensitive. An electrical equivalent model is shown in Figure 3. The sensor array is connected to a schematicly shown elongated guidewire, which extends to a proximal connector. As shown in Figures 1A and 1B, the proximal connector may include a transmitter in a wireless embodiment, or, in an alternative embodiment, a wired connection may be used for data signal transmission. Guidewire probe capsule and flow direction determination component

[0090] Figure 2D shows the tip 220 of a guidewire probe, with a sensor array 43, as shown in Figures 1A, 1B, 2A, 2B, and 2C, exposed through an opening in the capsule 50. The capsule or jacket may be a tube with an opening on its side, which contacts the guidewire portion as shown and defines an opening through which one or more components of the sensor array are visible. The role of the capsule is to structurally support the guidewire probe while allowing blood flow to pass through the sensing area and remain in contact with the tip of the probe, thereby cooling the tip of the probe. In one embodiment, the capsule can be made thinner or eliminated, V TOFFS -V P The signal sensitivity increases. Therefore, it is possible to use a probe that integrates pressure and flow rate measurements, whether or not it has a capsule. Electrical interface components

[0091] R A and R PWhen measuring pressure and flow rate using a guidewire probe, the probe transmits data to an interface system or display system. Such systems include, for example, the RadiAnalyzer, RadiAnalyzer Xpress, Quantien, or Aeris systems. In one embodiment, the arrangement of the guidewire probe device and its own circuit elements is shown in Figure 3, which form a bridge. This is a Wheatstone bridge when connected to the electronic circuitry of the measuring system, for example, as shown in Figure 4A.

[0092] As shown in the circuit diagram in Figure 3, R A and R P This represents the resistance on the semiconductor substrate 40, and r a , r g , and r p This corresponds to a microcable including the bond and connector of a given guidewire probe. The resistance of the grounded cable is r g Therefore, the active resistance R A and passive resistance R P R may be in the range of about 2200 ohms to about 3200 ohms, and is typically 2700 ohms. In one embodiment, R A The pressure sensitivity is at least about 7.9 ppm / mmHg, and typically about 10 ppm / mmHg. Therefore, for a typical guidewire probe sensor, the ratio of resistance to pressure sensitivity is approximately 2700 × 10 / 1,000,000 = 27 mΩ / mmHg. A and R P The temperature sensitivity is at least 400 ppm / °C, and typically 500 ppm / °C. That is, for a typical sensor, the ratio of resistance to temperature is approximately 2700 × 500 / 1,000,000 = approximately 1.35 Ω / °C. A change of 0.02°C corresponds to an active resistance R A This corresponds to a change of 1 mmHg.

[0093] Figure 4A shows the electronic components of an interface system or measurement system that interfaces with the electronic components of a guidewire probe. Resistance value r aThe active resistor and active resistor connection cable interface with node A of the interface system or measurement system. Node A then electronically communicates with resistor R1 when the guidewire probe is connected to the measuring device. In one embodiment, node A to V A The resistance value r is measured. p The passive resistor and passive resistor connection having interface with node P of the interface system or measurement system. Node P then electronically communicates with resistor R2 when the guidewire probe is connected to the measuring device. In one embodiment, from node P to V P This is measured.

[0094] Resistance value r g A grounding cable having is connected to ground G. Excitation voltage V EXC A voltage is applied to resistors R1 and R2. R1 and R2 are located in one or more systems, such as a probe interface system. In one embodiment, V EXC V is the excitation voltage of the Wheatstone bridge. In one embodiment, the bridge excitation voltage is in the range of about 1 volt to about 15 volts. R1 and R2 may be in the range of about 2000 ohms to about 3000 ohms in one embodiment. In one embodiment, the Wheatstone bridge is excited at the excitation voltage V EXC Excited by the interface of a guidewire probe using V A Gato V P The potential difference is measured, and the pressure is derived. The temperature is V TOFFS and V P It is measured between P. OFFS A 10% constraint is selected so that the bridge can be made horizontal. Voltage V TOFFS V at approximately 37°C P This corresponds to an offset voltage that is approximately equal to [this value].

[0095] Referring further to Figure 4A, the positive voltage V is shown in Figure 4A. POFFS + and negative voltage V POFFS - The applied voltage V POFFSThis corresponds to the offset voltage used to level, or balance, nodes A and P on the Wheatstone bridge. POFFS R A and R P This is an offset voltage used to balance the pressure channel in order to compensate for the resistance difference. POFFS Assuming a temperature of approximately 37°C and zero pressure at standard atmospheric pressure (760 mmHg), V A and V P The potential difference between them is adjusted to zero.

[0096] As shown in Figure 4A, the connection between the electrical components of the guidewire probe and the electrical components of the measurement system allows the excitation voltage applied in a bridge configuration, or for other current or voltage levels, to be maintained for as long as necessary to support the CTA or CVEX technique. Figure 5A shows how the voltage of the measurement bridge in Figure 4A is sampled, converted, and processed by the DSP. A and V P This signal may be amplified with a programmable gain before analog-to-digital conversion.

[0097] The wireless interface system shown in Figure 1B has an electrical signal interface, or an equivalent or similar interface, that forms a measurement bridge with the transmitter of the wireless intravascular probe when connecting a guidewire probe to a RadiAnalyzer, Xpress, Quantien, or ComboMap® Pressure and Flow System. The interface device or measurement system of the guidewire probe includes interface electronics that sample analog signals from bridges such as Wheatstone bridges or other balanced circuit configurations. An example of such interface electronics is shown in Figure 4B.

[0098] Specifically, Figure 4B is a circuit diagram showing an interface electronic circuit suitable for use with wireless intravascular flow and pressure sensors. The area enclosed by the dotted line corresponds to the electrical components within the intravascular probe. For example, the embodiment in Figure 1B is compatible with the interface circuit in Figure 4B. The right side of Figure 4B shows how the electronic components of a guidewire probe are connected to the constant current interface circuit. The constant current sources may be switched to contact the circuit by switches S1, S2, S3, and S4. These switches may be physical switches, multiplexers, or implemented as software control of the current sources. Resistors R1 and R2 are high-precision fixed resistors. In one embodiment, one or more current sources I are located in the proximal connector. Voltage V TOFFS In one embodiment, V P It is approximately equal to the voltage difference V. A -V P By measuring the voltage V, the pressure measurement can be derived. Temperature is the voltage V TOFFS -V P This can be derived from the constant current circuit, which causes current-induced heating of the guidewire probe tip, sufficient to measure flow rate using flow velocity measurement methods such as CVEX and CTA. By switching the current source, pressure and temperature values ​​(flow rate values) can be obtained, and these obtained values ​​can be transmitted wirelessly to the measurement system. Modification of the conventional system embodiment

[0099] In one embodiment, the disclosure relates to a system adapter for adapting to or retrofitting in another form to a measurement system, such as a pressure measurement interface device (e.g., a device originally designed solely for pressure monitoring). Thus, with the addition of the adapter, the sensing device can support simultaneous detection of pressure and flow rate by a guidewire probe. The adapter includes a power supply having a certain output power range. In one embodiment, the output power range is greater than approximately 5 volts. In one embodiment, the output power range is greater than approximately 10 volts. In one embodiment, the output power range is greater than approximately 12 volts. In one embodiment, the adapter is a circuit board sized to be installed within the measurement system.

[0100] In conventional systems for collecting pressure, FFR, and other intravascular data, one or more circuit elements in the interface device of a guidewire probe may be modified or replaced to achieve a higher excitation voltage for the guidewire probe. In one embodiment, power supply components may be added or modified so that the excitation voltage applied to the sensing region exceeds approximately 10 volts. In another embodiment, a filter having a passband configured to remove noise amplified to the level of the flow parameter measurement signal may be incorporated.

[0101] Each pressure sensor device has a memory storage device such as an EEPROM. In one embodiment, one or more parameters acquired with respect to the guidewire probe (for example, during the manufacture of the guidewire probe) are stored in the memory device. In one embodiment, the memory device is attached to the guidewire probe. The memory device may be an EEPROM, RFID, or other suitable memory storage device. By storing one or more sensor parameters in the memory device associated with the pressure probe, those parameters can be read out as needed. After being read out by a suitable scanner or interface device or its components, these parameters can be used to calibrate the guidewire probe before collecting pressure and flow rate information using the guidewire probe.

[0102] In one embodiment, parameters stored in the probe may include zero-level or baseline temperature, zero-level or baseline excitation voltage, and a sensitivity coefficient associated with excess temperature. A pressure-to-flow curve may also be output. This curve shows the changes in pressure and flow rate over time and with respect to location within the blood vessel. The stored memory parameters can be used to scale or calibrate the pressure-to-flow curve. Pressure and flow rate data may be displayed together with image data such as optical coherence tomography images, ultrasound images, and angiography images.

[0103] In one embodiment, a memory is located at the connector end to store individual, unique calibration parameters set during manufacturing. These stored parameters are used by the software of the guidewire probe interface device to convert the sampled "low" voltage into an accurate pressure value in mmHg. Specifically, the pressure sensor is measured at the final measurement station during the manufacturing process. Its purpose is R A Pressure sensitivity, R A and R P Temperature sensitivity, bridge and V POFFS and V TOFFS The objective is to measure the balance, sensor current, and temperature range. In one embodiment, the appropriate parameters are stored in a memory such as an RFID chip or EEPROM, or in other memory. In one embodiment, the memory is located within the connector of a guidewire probe. Flow rate measurement

[0104] When using a pressure sensor type thermofilm flowmeter, the sensor array, for example, the semiconductor sensor described herein, is heated by an electric current, and the cooling effect on blood flow is due to resistance R P It is measured by sampling the voltage across R. P The voltage across R can be measured. PA circuit showing the appropriate configuration, as well as other resistors and electrical connections, is shown in Figure 4A. This voltage may be used in two related flow velocity measurement methods, namely CTA and CVEX flow velocity measurements.

[0105] One consideration in relation to pressure-sensor-based thermofilm flow velocity measurement is the recognition that the electrical signal generated by the associated resistance does not distinguish between flow rate changes and blood temperature changes. If any unusual blood temperature changes occur, the system will interpret these as flow rate changes. Therefore, a feedback loop monitoring the environment in which the subject is located, as well as patient temperature readings, may be obtained using other temperature sensors. Despite the foregoing, typically, blood temperature may be considered constant given the time of the procedure and the time required for blood temperature changes. Constant temperature flow measurement (CTA)

[0106] As an example, the guidewire probes shown in Figures 1A, 1B, 2A, and 2C, and the components described herein, can be used as flow measuring devices and can be used as constant-temperature mode flow meters, also known as constant-temperature flow measurement (CTA). The temperature-sensitive resistor of the sensor tip of the guidewire probe is heated to a specific temperature higher than the ambient temperature by the application of a controlled excitation voltage. This resistor is exposed to the surrounding fluid or, in other forms, is in communication with other thermally conductive materials, which react to changes in flow to cause cooling, resulting in a corresponding cooling change within the sensor. On the other hand, the fluid flow has a variable cooling effect on the resistor. The cooling effect increases as the flow rate increases, and decreases as the flow rate decreases. P To ensure stability, the excitation voltage is controlled to a predetermined level by a digital system. Therefore, the excitation voltage becomes a measure of the flow rate.

[0107] Resistance R of the pressure sensor PThe temperature is maintained at a constant level, which is typically in the range of about 10°C to about 20°C higher than the blood temperature. This constant temperature is controlled by the bridge excitation voltage. The greater the blood flow rate, the higher the cooling effect and the higher the bridge excitation voltage. Conversely, the lower the flow rate, the lower the excitation voltage. Therefore, the excitation voltage serves as a measure of the flow rate. The software of the interface device of the guide wire type probe extracts the temperature from the voltage V TOFFS -V P to R P and uses this temperature as an input to the excitation voltage control system. This control system is also implemented within the software of the interface device of the guide wire type probe as a proportional (P) controller as shown in Figure 5B. Embodiment of the CTA control system

[0108] Figure 5A shows the principle of measuring the flow rate using the constant temperature flow velocity measurement (CTA) method with the measuring devices of Figures 1 to 4. As shown in Figure 5A, in the illustrated signal processing system 500, the difference V TOFFS -V P is measured, and by dividing this signal by the applied excitation voltage (VEX), a signal that depends only on the temperature change of R P and the microcable resistances r a of Figure 4, r p , and r g is obtained. This temperature-dependent signal, also referred to as the Temp signal in Figure 5B, is used as an input for the VEX control of the DSP software. The control system is designed to maintain a constant temperature signal by controlling VEX. The constant temperature signal is the same as the constant temperature of R P , which is the basic concept of CTA to cause and maintain a specific excess temperature on the surface exposed to the fluid flow (in this case R P ).

[0109] As shown in Figure 5A, in the case of pressure measurement, the voltage difference between V A and V P is sampled. V ASince it is temperature-sensitive and pressure-sensitive, it uses one or more signals to obtain a voltage difference V A -V P Ambient temperature changes acting on it are compensated. In one embodiment, the voltage difference V A -V P This uses a control system, control circuit, or signal processing device to control the voltage difference V A -V P Voltage difference V TOFFS -V P Temperature compensation is achieved through processing. TOFFS -V P This is a temperature-dependent signal.

[0110] As shown in Figure 5A, there are two signal channels, namely the pressure branch (V A and V P )505, and temperature branch (V TOFFS and V P )507 is measured. The pressure branch is V A and V P The difference between the two values ​​is measured. The pressure signal is amplified with a programmable gain 510. The gain value may be individually selected for each sensor of the guidewire probe and stored in the memory of a given pressure probe, or it may be generated from the information stored in that memory. In one embodiment, the programmable gain value is calibrated so that one analog-to-digital conversion unit (ADU) corresponds to approximately 0.1 mmHg. The analog-to-digital converter (ADC) 520 measures the pressure value V A -V P Sampling is performed in response to the amplified value, and a pressure value in ADU units is output. The gain value is read by the DSP530 signal processing software, which also loads this gain value into the gain circuit of the digital-to-analog converter (DAC), as shown in Figure 5A.

[0111] Figure 5C shows the control system 580 of the intravascular measurement system based on the operating principle of CTA. The control system is R P The control system is programmed to maintain a constant temperature. The control system is programmed to receive the signal V, as shown in Figure 5B. TOFFS -VP By dividing this by VEX and using this signal, labeled "Measured Temperature" in Figure 5C, as the input to the control system, R P The temperature change is measured. The control system uses this input signal to measure a specific R P Compare the setpoint value corresponding to the excess temperature. Setpoint temperature and measured R P The temperature difference is the system error, to which a coefficient k is multiplied. The result of this multiplication is added to the excitation voltage from the previous control iteration to generate a new excitation voltage, which is used to adjust the sensing circuit at the probe tip.

[0112] Before the control system is activated, a setpoint value based on the fluid temperature is determined. The setpoint is determined by converting the measured temperature signal to Celsius in a VEX range of approximately 0.5V to 2V using an ADU-to-Celsius conversion parameter stored in the guidewire probe's memory. A user-defined excess temperature is added to this measured fluid temperature to determine the setpoint in Celsius. Next, the temperature representation of the setpoint is converted to an ADU (Analog-to-Digital Conversion Unit) value and used as the setpoint for the control system. The conversion to the ADU setpoint is performed using an ADU-to-Celsius conversion parameter stored in the intravascular probe's memory or another memory location. In one embodiment, the user can set the excess temperature using the measurement system interface.

[0113] As shown in Figure 5C, the adder Σ585 adds the sign-inverted (-1) measured temperature 595 to the setpoint temperature 582 to generate an error 587 for the active control system. This error is multiplied by a coefficient k and then added to the previous excitation voltage (591), as shown in the processing step or stage 590. A new excitation voltage level is generated as a result of using this multiplied error. This new excitation voltage may be applied to the intravascular pressure and flow monitoring probe 592, which can then sample intravascular data and generate the measured temperature 594.

[0114] The measured temperature shown in Figure 5C is due to the voltage V TOFFS -V P This is obtained by dividing by the excitation voltage. By dividing by the excitation voltage in this way, a signal that depends only on temperature changes is obtained. The setpoint temperature is stored in the pressure sensor's memory. For example, if the memory setpoint parameter is 10, the system software or control system will be R P The temperature is kept 10°C higher than blood temperature. When the excess temperature is 10°C, the excitation voltage is in the range of approximately 5 volts to 7 volts. If the excess temperature is higher (above 10°C), in one embodiment, it may be necessary to use a higher voltage range, i.e., a voltage range above 7 volts. These changes in excitation voltage follow changes in flow rate. Constant excitation voltage

[0115] In one embodiment, flow rate and pressure are measured using a fixed excitation voltage (e.g., about 5 volts). In one embodiment, the CVEX method does not include a control system algorithm. This is a measure of flow rate measured in a blood vessel, using voltage V TOFFS -V P This is because it is used directly. Instead, for the control system in Figure 5C, instead of controlling based on changes in VEX as described above, a flow rate calculation algorithm is used. In contrast, R P The temperature changes with the flow rate. As the flow rate increases, R P The temperature of becomes lower. Conversely, if the flow rate decreases, R P The temperature increases. Figure 5D shows a flow measurement system 600 that processes signals from a guidewire probe while using a constant excitation voltage, i.e., CVEX.

[0116] As shown in Figure 5D, the DSP software embodiment of this disclosure receives the Temp signal (sampled V) from the analog-to-digital converter 630. TOFFS -V PThe signal (VEX) is received. VEX is constant, set by the DSP software, and converted to an analog signal by the digital-to-analog converter (DAC) 620. The flow rate calculation algorithm 615 can receive the Temp signal as input and generate a flow rate value from this signal.

[0117] Figure 5E is a schematic diagram of a software embodiment of the CVEX method pressure and flow rate simultaneous measurement system 650. As shown, the probe interface / measurement system software 660 receives the input voltage difference from the analog-to-digital converter 665. The difference signal V A -V P and difference signal V TOFFS -V P The signal is processed to generate a pressure value, which can be displayed as a value or plot on a console or other display as described herein. Meanwhile, the difference signal V TOFFS -V P The data is processed to generate flow rate values ​​or plots on the console or other display described herein. These values ​​may be displayed, plotted as pressure-to-flow curves, or otherwise used as input for FFR calculations by the measurement system or calculated by a circuit or processor built into the probe itself. Characteristics and Embodiments of Transfer Functions of CVEX and CTA

[0118] The applied excitation voltage (when using CTA) or the measured temperature (when using CVEX) can be converted to a flow rate value, or to a value correlated with the flow rate by a transfer function. In one embodiment, the transfer function is determined by exposing a pressure sensor to a known reference flow rate and plotting the measured signal against the reference flow rate. The reference flow rate can be generated using a fluid flowing in a closed-loop system, such as water flowing in a loop tank or a curved tank. Figures 6A and 6B show a typical relationship between the measured signal and the reference flow rate.

[0119] Figures 6A and 6B show the curve fittings performed to determine appropriate transfer functions relating flow rate x to temperature or excitation voltage T(x) for both CTA and CVEX, respectively. Calibration of pressure sensor devices is possible by exposing the device to several flow rate levels and then determining the constants a and b of the respective function T(x) = a + b × lnX by curve fitting or other methods. In the case of CTA, the output of T(x) is the excitation voltage, and in the case of CVEX, the output of T(x) is the temperature. Each constant (a and b) of this transfer function may be stored in the memory of the pressure sensor.

[0120] Furthermore, as part of the flow rate calculation algorithm, the reciprocal of the function a + b × lnX is used by the software of the guidewire probe interface device to calculate the flow rate value. By tracking the flow rate value over time, the point of maximum flow rate may be displayed. By using the point of maximum flow rate or relative extreme value generated using a pressure-vs-flow rate plot or other representation, it is possible to identify multiple time points or multiple locations along the vessel, between which images may be superimposed, and measurements (e.g., a series of FFR measurements) corresponding to multiple time points and flow rate levels spanning one or more of the maximum, minimum, or relative extreme values ​​may be obtained.

[0121] There are several differences to consider between the CTA method and the CVEX method. Figures 6A and 6B show that the same type of relationship (a + b × lnX) exists between the units of flow rate and the units of the measured quantity in both CTA and CVEX. Furthermore, both methods are equivalent in accuracy for measuring pulsating flow rates (in laboratory observations). Therefore, with respect to flow rate measurement, the CVEX method and the CTA method can be considered equivalent. In one embodiment, when measuring flow rate and pressure simultaneously, the CVEX method is considered to have advantages because pressure measurement is simplified. In the CTA method, pressure measurement becomes more complex due to fluctuations in the excitation voltage. In one embodiment, the hardware and software of the CTA pressure and flow rate measurement system are selected to accurately measure pressure while controlling the excitation voltage to stay within a narrow error limit. Adapting FFR and other measurement platforms to pressure and flow rate measurements.

[0122] A system that simultaneously measures pressure and flow rate may typically be implemented based on the CVEX principle. Implementing CVEX flow rate measurement in a pressure sensor-based measurement system is possible by using a circuit board or an adapter including the circuit and power supply, and by modifying some of the software and control flow.

[0123] From a device or hardware standpoint, it is useful to increase the maximum excitation voltage output to the Wheatstone bridge for pressure sensor measurements. As part of the process of retrofitting an intravascular measurement system (for example, a system that measures only pressure) for simultaneous monitoring of pressure and flow, a 12V output power supply (PSU) board may be mounted on the interface device board of a guidewire probe. Furthermore, one or more amplifiers within the interface device of the guidewire probe may be biased with +12V and -12V instead of the usual ±5V used for pressure sensing.

[0124] In one embodiment, the interface software for a guidewire probe uses a voltage VTOFFS -V P The signal is sampled at a sampling rate in the range of approximately 400 Hz to 600 Hz. The sampled signal is stored in memory. In one embodiment, this signal is stored in a specific location in the signal data array as a variable typically indicated as TEMP. In this CVEX embodiment, the voltage difference stored as the TEMP signal is converted into a flow rate value using the transfer function described herein. A software representation of this signal processing is shown in Figure 5E. These hardware and software features provide a system that enables simultaneous measurement of pressure and flow rate using a pressure sensor by the CVEX method.

[0125] The flow measurement systems described herein may be implemented with certain temperature-related design modifications, including one or more of the following: cable temperature compensation and flow-insensitive absolute temperature measurement. Embodiment of Cable Temperature Compensation Method

[0126] Switches S1 and S2 on the measuring bridge of the guidewire probe in Figure 4A (which are typically "on" during normal operation of the guidewire probe's interface device) allow either branch of the bridge to be switched off. When S2 is switched off, the resistance change (i.e., temperature change) of the microcables ra, rp, and rg is detected by the voltage (V TOFFS -V P This may be measured by sampling the V between the states of S2. TOFFS -V P By sampling, the temperature signal of the sensor array may be extracted as follows. Sensor temperature = (S2_ON_V) TOFFS -V P )-k×(S2_off_V TOFFS -V P ) However, (S2_on_V TOFFS -V P ) is the signal sampled while the S2 switching element is in the "on" state, and (S2_off_V TOFFS -V P ) is the signal sampled while the S2 switching element is in the "off" state, and k is a compensation constant associated with a particular probe interface device. The value of k may be stored in memory and may be accessible as needed by the sensor temperature determination method.

[0127] This cable temperature compensation method determines the sensor temperature and eliminates or minimizes the effect of cable temperature changes on the flow signal. Specifically, by compensating for the cable effect using a "switch-on" signal with a "switch-off" signal, a signal is generated that responds only to sensor temperature changes related to the sensor array within the intravascular probe tip. This is desirable because standard handling and clinical use of guidewire probes cause temperature changes within the microcable.

[0128] These resulting temperature changes can cause a change in cable resistance, potentially degrading the uncompensated signal (where switching element S2 is in the "on" state). In flow measurements, V TOFFS -V P Because a signal is used, the cable temperature compensation method described herein generates a signal that responds only to temperature changes of the probe tip sensor. Furthermore, when the blood temperature is stable, as is typically the case when a patient is resting in a constant temperature environment, only temperature changes to the sensor will correspond to changes in the flow parameter. In one embodiment, the flow parameter is flow velocity. In another embodiment, the flow parameter is flow rate. Embodiment of flow-insensitive absolute temperature measurement

[0129] By using the cable temperature compensation described herein and reducing the excitation voltage to approximately 0.5V, a system for measuring changes in blood temperature (or, whatever the temperature of the medium into which the probe is inserted) can be obtained. Selecting an excitation voltage in the range of approximately 0 volts to approximately 2 volts is advantageous because it ensures the sensor array temperature is approximately the same as the ambient blood temperature. As a result, by selecting the excitation voltage so that the sensor and fluid temperatures are approximately matched, the pressure and flow monitoring system becomes unresponsive to changes in flow rate. This is because flow measurement relies on generating sensor array temperature as a response to the excitation voltage, and the excitation voltage may be affected by cooling from the ambient fluid as it flows toward the probe tip. This makes it possible to measure blood flow rate, unlike simply measuring changes in blood temperature.

[0130] As defined above, the sensor temperature signal is measured with an excitation voltage of 0.5V in one embodiment. Next, the absolute temperature of the fluid (blood) may be calculated using the difference relationship between the product of the first constant, the second constant, and the sensor temperature, as follows. Absolute temperature = CD (sensor temperature) However, C and D are constants specific to the individual interface system or processing system, or associated integration system, that receives data from a given intravascular probe and its sensor array. The sensor temperature referred to in the absolute formula above is when the sensor temperature is (S2_on_V TOFFS -V P )-k×(S2_off_V TOFFS -V P These can be obtained using the above-mentioned relationship given by ). In one embodiment, the constants C and D are specific to each combination of intravascular probe and each interface system or processing system. In one embodiment, these constants C and D may be encoded in a memory attached to each probe.

[0131] Cable compensation measurement and absolute temperature measurement are useful features in flow measurement systems. This is partly because the signal influence from the resistance of the microcable is eliminated. Furthermore, monitoring blood temperature during flow measurement is useful because the flow measurement signal is sensitive to both flow rate changes and blood temperature changes. The user can manually switch between flow mode and absolute temperature mode through user operation of the measurement system. FFR measurement and its applications

[0132] In one embodiment, one or more pressure-to-flow plots are obtained after administration of an engorgement agent. In one embodiment, one or more pressure-to-flow plots are obtained without administration of an engorgement agent. In one embodiment, one or more cardiovascular measurements of FFR, pressure, flow rate, resistance, or other are obtained after administration of an engorgement agent. In one embodiment, one or more cardiovascular measurements of FFR, pressure, flow rate, resistance, or other are obtained without administration of an engorgement agent. In one embodiment, one or more cardiovascular measurements of FFR, pressure, flow rate, resistance, or other are obtained during periods of high or maximum flow rate identified by measurements from intravascular pressure and flow rate sensors.

[0133] In one embodiment, the FFR value or related value is obtained based on the ratio of distal pressure to proximal pressure in a blood vessel (P distal / P proximal). In another embodiment, the FFR value or related value is obtained based on the ratio of maximum occluded flow rate to maximum unoccluded flow rate. These various methods for obtaining flow data (e.g., flow velocity at multiple locations within the cardiovascular system) may be displayed individually, or together with other cardiovascular values, as a ratio, or through other relationships that represent the state of the subject.

[0134] In one embodiment, an intravascular probe is moved longitudinally along the artery, and a dataset of one or more of the following measurements—pressure, flow parameter, and position—is acquired over time. Each element of this dataset may be synchronized and aligned with data from IVUS, angiography, OCT, or other additional sensors. This dataset can be processed to calculate distal pressure measurements, such as distal coronary artery pressure, and proximal pressure measurements, such as aortic pressure. From these distal and proximal pressures, multiple FFRs can be calculated using the following relationships. i You may retrieve the value. FFR i =P 遠位I / P 近位I =maximum occlusion flow / maximum non-occlusion flow The i-value may be selected as an index for a set of elements obtained regarding the blood vessel (e.g., flow parameters, pressure values, maximum occluded flow rate / maximum unoccluded flow rate).

[0135] As described above, FFR may be evaluated as the maximum blood flow rate in the presence of stenosis (first flow rate) divided by the maximum blood flow rate in the absence of stenosis (second flow rate). The ratio of these occluded and unoccluded maximum flow rates gives the FFR value in terms of flow rate ratio. These flow rates can be obtained using the intravascular probes described herein.

[0136] In one embodiment, FFR values ​​acquired during periods of maximum or minimum flow rate are evaluated, and FFR values ​​are determined based on the events occurring during each of these measurement times and their locations on the blood vessel where they were acquired. In one embodiment, the acquired minimum FFR value, or the FFR value acquired for maximum flow rate or average maximum flow rate, is displayed as the FFR value. Plots and trajectories of pressure and flow rate

[0137] In one embodiment, the disclosure relates to performing pattern recognition on pressure-vs-flow plots or datasets generated using a CTA or CVEX method. This pattern recognition may be performed using a processor in a measuring device or another device that receives data generated by an intravascular pressure and flow probe. The pressure-vs-flow plot can be displayed in real time or near real time in response to simultaneous acquisition of pressure and flow data by a guidewire probe. The pattern recognition process can compare pressure-vs-flow trajectories or patterns, or subsets of such curves, and correlate them with a situation or patient condition of interest.

[0138] In one embodiment, patient data from a healthy population is used to establish a baseline signature, such as a PQ plot follow-up or trajectory, for comparison with individuals requiring diagnostic information. Individual follow-up records can also be obtained for each patient and compared with subsequent follow-up records to demonstrate the effectiveness of a given treatment plan or procedure. The quality and duration of recovery can also be evaluated using pressure-to-flow curves, as well as other plots and FFR values, obtained before and during the procedures described herein (e.g., stent placement).

[0139] The graphical user interface (GUI) of the measurement or display system displays flow rate data as a real-time curve in the time domain. It is possible to plot pressure and flow rate data together in real time to generate a PQ plot, which is shown in Figure 7A with further details regarding the pressure and flow rate ranges. To identify each curve, the symbols G for green, B for blue, and R for red are used, as described in the legend for each plot or as described herein. G is generally used to indicate curves related to the right side of the heart. R is generally used to indicate curves related to the left side of the heart. B is generally used to indicate curves related to time versus blood pressure.

[0140] In one embodiment, the pressure-to-flow curve includes relative extremes, inflection points, maximums, and minimums that are interrelated with one or more dynamic events, cardiac cycle events, cardiac status, degree of stenosis, pre-stent flow, post-stent flow, degree of recovery after cardiac events, comparison with historical data, and data acquired at various points in time. In one embodiment, the various points in time may be interrelated with the introduction of one or more drugs or treatment plans (e.g., stents).

[0141] In one embodiment, pressure-to-flow curves may be used to calibrate pacemaker function. This may be done by acquiring the patient's pressure-to-flow curves and monitoring how they change over time and converge to one or more trajectories or shapes. In one embodiment, pacemaker adjustment may be performed by using historical and current pressure-to-flow plots to make the trajectory follow that of a healthy heart. In this way, it is possible to adjust and calibrate the operating parameters of the pacemaker. Pressure-to-flow curves may also be used to determine pressure and flow readings before and after renal denervation to provide efficacy and diagnostic information. In one embodiment, a guidewire probe can be positioned at various locations within the artery (e.g., near major arteries or bifurcations) while collecting pressure and flow data. A given bifurcation can be classified as potentially occluded using locations where the flow rate changes from one bifurcation to another. These locations can be identified by IVUS, OCT, angiography, and other imaging modalities during the procedure.

[0142] The following describes in detail various exemplary curves that can be obtained using pressure and flow sensing probes. These curves are generated using sensor data acquired at one or more locations within an artery by an intravascular probe containing sensors suitable for simultaneously measuring pressure, temperature, and flow. Using this sensor data, it is possible to generate one or more of the values ​​and representations of information described herein, such as signatures, trajectories, slopes, maximum points, minimum points, ratios of measured values, ratios of measured values ​​to derived values, ratios of primary and secondary derived values, ranges, FFR values, CFR values, CFVR values, IFR values, IMR values, indices, patient status, and others.

[0143] Individual data elements and curves that unfold and change over time can be used for various diagnostic purposes as described herein. In one embodiment, the trajectory, shape, or range (or other features) of the pressure-to-flow curve can be fitted to historical data, such as the patient's age, weight, activity level, and one or more patient conditions (e.g., heart attack, valve injury, and other measurable patient parameters), which allows the pressure-to-flow curve of a new patient to be compared to a pressure-to-flow curve representing a specific patient condition, thus aiding in diagnosis.

[0144] Figure 7A shows a plot of flow rate over time, using a reference flow rate probe identified by R or red or other first mark, and a guidewire pressure and flow rate probe identified by B or blue or other second mark. Both embodiments of the reference flow rate probe and the guidewire pressure and flow rate probe were exposed to pulsating flow in a water circulation loop. The patterns of the reference flow rate and the measured flow rate clearly demonstrate a linear relationship between the applied flow rate and the measured signal.

[0145] Figure 7B shows how the plot of the measured temperature (flow rate) signal rises in response to the guidewire probe being withdrawn from the distal left anterior descending artery (dLAD) to the proximal left anterior descending artery (pLAD). The pressure signal remains nearly constant while the guidewire probe is withdrawn through the artery.

[0146] Figure 8A shows plots of pressure and flow rate against time, acquired using a pressure and flow rate sensing probe in a 40 kg pig. The proximal right coronary artery (pRCA) (right side) is the location monitored by the sensing probe. Pressure and flow rate are shown on the y-axis, with time on the x-axis. Small bumps at the bottom of the curves indicate small-scale regurgitation. The dotted line shows the pressure value, which generally rises and falls in a pattern correlated with the flow rate shown by the lower curve. The phases of the pressure and flow rate curves are aligned with the pRCA data shown in Figure 8A.

[0147] Figure 8B shows a plot of pressure and flow rate against time, acquired using a pressure and flow rate sensing probe in a 40 kg pig. pLAD indicates the location monitored by the sensing probe. Pressure and flow rate are shown on the y-axis, with time on the x-axis. Small bumps at the bottom of the curves represent small backflows. Unlike Figure 8A, the phases of the pressure and flow rate curves are shifted in Figure 8B, and the peak of the pressure signal appears to be shifted to the right relative to the flow rate signal. As shown in Figures 8A and 8B, the flow rate peak appears to the right during systole and to the left during diastole.

[0148] Figure 8C shows a pressure-to-flow plot obtained using a pressure and flow sensing probe in a 40 kg pig. The proximal right coronary artery (pRCA) is the location monitored by the sensing probe in Figure 8C. The loop direction is clockwise. Various points of interest A, B, C, and D are shown. Any point can be selected as the starting point, but it is possible to track the trajectory or loop from point A in the lower left. In one embodiment, it is possible to identify correlations by saving the shape or extent of a loop and comparing it with other loops. The shape or loop may be monitored for contraction, expansion, displacement, or other changes before, during, or after treatment.

[0149] For example, a loop-like path starting from point A, corresponding to low flow rate and low pressure conditions, can ascend along the loop to point B as pressure increases, and then move to the right along a nearly horizontal path, following the loop, to point C as flow rate increases. From point C, as pressure and flow rate decrease, it can reach point D along an angled path, and then the loop returns to point A. Point A corresponds to the low flow rate and low pressure conditions that characterize the start of contraction. Point B corresponds to the maximum pressure and minimum flow rate conditions that occur during contraction. Point C corresponds to the maximum pressure and maximum flow rate conditions that occur during contraction. Point D corresponds to the transient state between A and C, with a relative extremum corresponding to the second largest flow rate during diastole. The flow at point D is reverse flow.

[0150] Figure 8D shows a plot of pressure and flow rate against time, obtained using a pressure and flow rate sensing probe in a 40 kg pig. The proximal RCA is the location monitored by the sensing probe. Points A, B, C, and D in Figure 8C are also shown in Figure 8D. These points show how pressure and flow rate increase at the start of contraction and then decrease during diastole after cardiac contraction.

[0151] Figure 8E shows a pressure-to-flow plot obtained using a pressure and flow sensing probe in a 40 kg pig. Figure 8F shows a plot of pressure and flow against time, corresponding to the data in Figure 8E. The proximal left anterior descending coronary artery (pLAD) is the location monitored by the sensing probe. The loop direction is clockwise. Various points of interest A, B, C, D, E, and F are shown. Most of the selected points of interest, B, C, D, and E, occur during systole, while points A and F occur during diastole. Point A corresponds to the maximum flow in diastole after the systolic signal contraction. Point B corresponds to the minimum pressure value occurring at the start of contraction. Point C corresponds to the relative local increase in pressure before reaching the maximum pressure at point D. Point E corresponds to the closure of the aortic valve and the decrease in pressure within the left ventricle. Thus, as shown in Figure 8E, the decrease in pressure leads to an increase in blood flow within the left coronary artery again.

[0152] Figure 9A shows pressure and flow rate over time in the pLAD. Figure 9B shows myocardial resistance over time. The locations of maximum flow rate and minimum pressure are identified. The location where myocardial resistance is minimum at maximum flow rate is identified. Myocardial resistance at minimum pressure is also identified and plotted. These resistance values ​​can be used to determine the trajectory of change over time and may be displayed to the user in real time or near real time, along with FFR values ​​and other values ​​obtained using an intravascular pressure and flow rate probe that can simultaneously measure the parameters described above. These measurements were obtained for a 40 kg pig.

[0153] Figures 10A and 10B show plots of pressure and flow rate (top) along with a plot of flow rate against time (bottom). Figure 10A corresponds to a normal scenario, while Figure 10B corresponds to an abnormal flow rate scenario resulting from artificially induced partial occlusion of the marginal arteries. The illustrated pressure (P) versus flow rate (Q) trajectory resembles an inclined figure eight or infinity symbol, as plotted in the upper left corner of the pressure versus flow rate in Figure 10A. In the normal scenario in Figure 10A, the trajectory is nearly equal in both lobes. In contrast, in the corresponding plot in Figure 10B, an abnormal example after artificially induced occlusion, the trajectory is asymmetrical, with the left lobe contracting and the right lobe bulging. In one embodiment, these can be used as signatures to identify abnormal cardiac events. Similarly, the double-peak flow rate curve against time in Figure 10A becomes a rounder, larger amplitude curve in the abnormal scenario in Figure 10B. In one embodiment, abnormal cardiac events can be identified by using the amplitude shift, rounding, and transformation of a dual peak into a single peak as a signature. Furthermore, these plots can be tracked over time, along with other plots and parameter values ​​described herein, before, after, and during treatment, to provide information to clinicians and other interested users. System and method for diagnosing coronary blood flow reserve

[0154] This disclosure relates, in part, to a method and system suitable for determining coronary flow reserve as a response to one or more data from intravascular pressure and flow data or data correlated therewith in other forms. By using a sensing device (SD), such as a pressure sensor or flow sensor, it is possible to determine coronary flow reserve as a function of time using thermal convection data. By sampling the same sensing device in parallel with CFR measurement, it is possible to obtain a distal pressure value Pd, and by using the Pd value together with the reference pressure, it is possible to simultaneously determine the FFR value. Using various measurement systems described herein, such as ICDs, it is possible to process and display CFR, FFR, and other parameters described herein. This disclosure also relates to various user interfaces and associated live and review modes used for displaying and plotting CFR values ​​and other values.

[0155] An exemplary source of pressure data may be a pressure sensor, such as an electrical or optical pressure transducer. A suitable pressure sensor may be positioned on, in, or otherwise relative to a catheter (e.g., a delivery catheter), an intravascular data acquisition plot, a guidewire, and other suitable devices and systems. CFR and FFR values ​​may be simultaneously calculated and displayed over time as numerical values ​​or time-varying curves on a GUI, or may be used as input to generate other diagnostic data regarding the behavior of the cardiac system.

[0156] In one embodiment, the disclosure relates to an intravascular data acquisition method. The method enables the collection and generation of diagnostic data and diagnostic information. In one embodiment, the method includes the steps of: adjusting or optimizing the temperature signal of an intravascular thermal convection device when the intravascular thermal convection device is at the measurement site of interest; sampling the intravascular thermal convection device to obtain a baseline thermal convection signal value; and sampling the intravascular thermal convection device to obtain a Pd value and thermal convection device value for performing FFR and CFR calculations. The results of the FFR and CFR calculations may be output to a display on the device in the catheterization room or to another display (e.g., a touchscreen device).

[0157] This disclosure relates, in part, to a method and system suitable for simultaneously determining one or more coronary flow reserve (CFR) and fractional flow reserve (FFR) values ​​using thermal convection devices, such as intravascular pressure and flow sensors, and intravascular data acquisition and processing systems. Furthermore, this disclosure also relates, in part, to determining CFR values ​​using an intravascular probe having a pressure sensor and constant temperature velocity measurement (CTA) or constant excitation voltage (CVEX) velocity measurement.

[0158] In one embodiment, CFR is the ratio of the absolute hypertensive flow rate to the absolute baseline flow rate. Similarly, in one embodiment, CFVR is defined as the ratio of the hypertensive flow velocity to the baseline flow velocity. CFR and CFVR are equivalent in value. A reference to CFR may also be used to perform and display CFVR values. Accordingly, the use of the term CFR may be replaced with CFVR in this specification to describe embodiments and measurements of CFVR, and this is also within the scope of this disclosure.

[0159] Various data acquisition and analysis systems are available to obtain information about the coronary artery system. By analyzing or displaying data acquired from blood vessels using the device, or data derived from intravascular or extravascular measurements associated with blood vessels, it is possible to provide useful correlations and extrapolations for researchers and clinicians. For example, various measurement systems and intravascular probes are available to determine fractional flow reserve (FFR) and coronary flow reserve (CFR). As described herein, pressure sensor devices can be used to acquire one or more CFR measurements from a patient.

[0160] In one embodiment, pressure data (Pd) and thermal convection data are collected using an intravascular data acquisition probe placed in the patient's artery. Exemplary intravascular data acquisition probes include catheter-type or catheter-delivered probes, guidewire probes, imaging probes, resection probes, ultrasound probes, interferometer probes, and other suitable data acquisition probes described herein.

[0161] Specifically, by acquiring data using pressure sensors, it is possible to measure flow rate, thermal convection data, and other cardiac parameters described herein. The systems, methods, and apparatus described herein relate in part to thermal convection techniques and thermal film velocity measurement techniques, and, for example, depending on the embodiment, to constant temperature velocity measurement (CTA) and constant excitation voltage (CVEX) velocity measurement. As will be detailed later, pressure sensors enable sampling of intravascular data and generation of CFR measurements, which is superior to existing thermodilution methods.

[0162] In the background, coronary flow reserve may be measured using a pressure sensor, such as a pressure wire or other pressure sensor capable of operating as a thermodilution device. As part of the prior art, a CFR value is obtained by injecting a cold saline solution into the coronary artery of interest. The time it takes for the blood temperature to rise (from the start of cold saline injection into the artery until the temperature returns to a specific level) is then measured using the temperature-measuring function of an intravascular pressure sensor. This rise time can be converted into a CFR value.

[0163] Such conventional thermodilution methods have the drawback of insufficient accuracy and can be cumbersome to perform. For example, with the specified accuracy of a typical conventional thermodilution method, the accuracy of the resulting CFR value may be less than ±30%. The procedure is typically cumbersome and time-consuming, requiring multiple injections of saline solution with specific properties to generate enough data for the system software to calculate the CFR value.

[0164] By using the measurement systems, methods, and apparatus described and illustrated herein, it is possible to obtain signals that measure the temperature or power of a pressure sensor chip. The chip resistor is heated by the current, generating a specific excess temperature relative to the surrounding fluid (blood). The cooling effect of the blood flow on the chip resistor is measured directly (as a temperature value) or indirectly (as the power required to maintain the chip resistor temperature at a stable level).

[0165] Figure 11 shows an exemplary system 710 suitable for measuring CFR. Furthermore, it is also possible to measure CFR and FFR values ​​simultaneously using system 710. Some examples of intravascular data acquisition and analysis systems 710 or their components, which are not limited to these, may include RadiAnalyzer, RadiAnalyzer Xpress, Quantien, PressureWire systems (e.g., Aeris 1, Aeris 2, or Certus), Optis systems, multimode systems such as combined intravascular imaging and pressure monitoring systems, and hemodynamic displays with pressure data inputs.

[0166] In one embodiment, a system suitable for performing thermal convection CFR measurement alone or simultaneously with FFR measurement, such as the system 710 in Figure 11, may include multiple components, such as subsystems or devices. For example, such a system may include a thermal convection device 760. An example of such a thermal convection device may be a pressure sensor type device, such as the device described herein. Specifically, the thermal convection device may include a pressure sensor Aeris unit adapted to facilitate thermal convection measurement. Such an Aeris unit may be modified or programmed to use the measurement techniques described herein. In one embodiment, the thermal convection device may include a pressure sensor and be sized and configured to measure flow rate, CFR or FFR, or other cardiac parameters by measuring distal intravascular pressure and other parameters of interest.

[0167] As shown with respect to system 710 in Figure 11, the exemplary thermal convection CFR measurement system may include a reference pressure device 765. By using the reference pressure device, it is possible to measure a reference pressure (e.g., aortic pressure in one embodiment). The reference pressure device may include a pressure sensor on a guide catheter or delivery catheter. Such a reference pressure device also receives proximal pressure values ​​(Pa), such as aortic pressure values, and transmits them as inputs for FFR calculations, as shown in system 710.

[0168] The system may also include a signal processing and display device 730 (e.g., a Quantien system from St. Jude Medical) which receives pressure and thermal convection (flow rate) data from the thermal convection device wirelessly or via a wired connection. The device 730 also receives pressure data from a reference pressure device (e.g., an aortic pressure transducer). Embodiments of the present disclosure relate in part to various features of pressure sensing devices, measurement systems, and associated software suitable for determining ratios based on signals sampled from intravascular data acquisition probes such as those described and illustrated herein. The device 730 may include a display such as a touchscreen display or other display that outputs a GUI along with measured CFR, FFR, and other data of interest from the thermal convection device 760 and the reference pressure sensor 765 (e.g., an aortic pressure transducer). In one embodiment, the thermal convection data values ​​are temperature values. These values ​​may be generated based on electrical changes triggered within the thermal convection device. In one embodiment, the thermal convection data values ​​are given in temperature units such as °C.

[0169] An example of a sensing device that can be used for pressure monitoring, flow monitoring, sampling of intravascular data for CFR measurement, and sampling of intravascular data for FFR measurement is a guidewire probe having a semiconductor element that includes a component that generates an electrical change in response to a change in pressure. Embodiments described herein support a method for determining CFR values ​​using a thermal convection device, as well as various systems and methods for determining and measuring ratios using a guidewire probe and associated software and electrical components of a data acquisition and analysis system 710. It is possible to transmit Pd, Pa, and thermal convection data from a sensor associated with a given probe using a wired or wireless probe.

[0170] System 710 is capable of performing measurement calculations based on signals sampled from an intravascular probe. Alternatively, System 710 is capable of receiving a signal encoded with the results of calculations performed using circuits or processing elements located within the probe (e.g., within the proximal connector of the probe). System 710 may also include software, a control system, and data analysis and display devices and processors suitable for graphing and displaying pressure values, FFR values, CFR values, sampled Pa values, sampled Pd values, moving averages, and other related values.

[0171] The data acquisition and analysis system 710 may include a processor such as a microprocessor, memory, and one or more software modules, circuits, or hardware components (e.g., a CFR hardware component or a CFR software module 740). The system 710 may also include an FFR hardware component or an FFR software module 750. These components or software routines are configured to receive intravascular data and simultaneously determine CFR and FFR values ​​(if selected to display such information on an interface screen). The CFR hardware module or software module may include one or more of the methods described herein and related empirically determined functions or mathematical relationships with respect to determining CFR values ​​using data sampled from a sensing device (SD), such as a thermal convection device described with respect to a guidewire probe that senses temperature and flow rate.

[0172] In one embodiment, the thermal convection data is the relative temperature change of a heated measuring resistor, which is a measure of the flow rate change around the resistor / device. Further details regarding systems available for acquiring thermal convection data, and thermal convection devices based on pressure and flow rate sensing devices, are described and illustrated herein.

[0173] CFR measurement is performed in parallel with FFR measurement. For example, the CFR measurement software may be implemented as one or more software routines or methods as an extension of the pressure sensor signal processing software and / or one or more software components operating in the hardware components and apparatus of the system shown in Figure 11. Measurement procedure for FFR data and thermal convection CFR data

[0174] An exemplary set of steps for the simultaneous measurement of FFR and thermal convection CFR is described with reference to Figure 12B. These steps may be performed using the system in Figure 11 and the system described herein. Relevant screens of the graphical user interface associated with diagnostic data output are shown in Figures 13A-13D and 5A-5D.

[0175] Figure 12B shows an exemplary set of method steps that can be performed to determine one or more CFR values ​​and one or more FFR values ​​for a patient. Steps 10 through 55 may not all be performed depending on the embodiment. Furthermore, some steps may be performed in a different order, or may be performed simultaneously with other steps.

[0176] As part of this method, a step is performed to set a baseline value, or in another form, to set a zero value for the pressure signal of the sensing device (SD) (e.g., intravascular pressure in a tray, in saline or another buffer) (step 10). A step is performed to advance the SD and position it in the catheter opening (but not into the blood flow) (step 15). A step is performed to set a baseline value (zero value) for the SD temperature signal (step 20). A step is performed to advance the SD to a position distal to the catheter opening and make the SD pressure signal (Pd) equal to the aortic pressure (Pa) signal (step 25). A step is performed to advance the SD to a position where CFR and FFR can be evaluated (step 30). A step is performed to calibrate (adjust) the temperature signal to find the maximum level, minimum level, or other level by auditory and / or visual feedback (step 35). This calibration or adjustment step may be performed in the form of software, or the software may be facilitated to notify the operator by a visual or auditory cue when a calibrated state is reached while adjusting the control unit to find the temperature signal level. In one embodiment, adjustment or calibration means physically moving the intravascular device radially within the blood vessel to position the intravascular device at an optimal flow rate level or other desired flow rate level. The optimal flow rate is typically identified by the temperature signal settling at a maximum or minimum level. The temperature signal level is adjusted to achieve a relative maximum or minimum value or other threshold.

[0177] Continuing with the method shown in Figure 12B, the method may also include a step (step 40) of initiating a data recording session for SD values ​​and setting a CFR baseline. In one embodiment, once CFR measurements are obtained, a step of inducing hyperemia is performed (step 45). Thus, in step 45, for example, a hyperemetic such as adenosine is administered to the patient being monitored to determine CFR and FFR values. A step is performed to ensure that the pressure is equalized and the flow signal returns to baseline (step 50). Finally, in one embodiment, once a desired set of sampled probe values ​​has been obtained, or once parallel diagnosis or parallel treatment has been completed, a step of ending or stopping the data recording session is performed (step 55). In one embodiment, the baseline level is level 1 or another set baseline value.

[0178] The graphical user interface (GUI) of an FFR measurement system (e.g., the Quantien system or the system shown in Figure 11) may incorporate one or more processors or control systems that provide user controls for zeroing out the temperature signal from a pressure sensor. Furthermore, such user controls can be used to set a CFR baseline value and a new graph window for signal adjustment and CFR tracking. The system can also be extended with an audio interface / speaker for audio adjustment steps.

[0179] In various screenshots, one or more areas or panels of the GUI or other display outputs of the system in Figure 11 or other systems described and illustrated herein display the measured values ​​recorded to simultaneously evaluate FFR and CFR. For example, the simultaneous display of FFR and CFR data is indicated by Fv / Fv-B (flow rate / baseline flow rate ratio), which is the result of the CFR calculation, displayed along with the FFR value in review mode in various interface diagrams.

[0180] This disclosure includes, in part, various features that demonstrate to the user advancements and new diagnostic information and methodologies regarding CFR and FFR. One such feature is the process of determining the CFR value based on the relation CFR = b^((x_congestion - x_baseline) / c). Furthermore, this CFR relation may be evaluated based on the pressure sensor temperature or power signal measured by an intravascular pressure probe as described herein. As referred herein with respect to Figure 11, in order to facilitate the simultaneous measurement of FFR and CFR, and the subsequent simultaneous display of FFR and CFR values, it is advantageous to run the CFR software method or hardware component 740 in parallel with the pressure signal processing of the pressure sensor as part of the FFR software method or hardware component 50. Further features that provide the user with enhanced diagnostic information include the method steps described herein (for example, with respect to the processing flow in Figures 12A and 12B), the associated user interface and plotting of CFR data, and the simultaneous plotting of changes in FFR and CFR over time.

[0181] Figure 14 shows the results of CFR measurements performed using a St. Jude Medical PressureWire Generation 8 unit, using thermal convection flow rate measurements on the Aeris 2 platform against a reference CFR value that serves as a known CFR for comparison. The measurements were performed at three locations within a 3 mm tube (indicated in red (position 1), blue (position 2), and green (position 3)). In one embodiment, during measurement, the PressureWire was rotated before each CFR measurement to determine the maximum flow signal level. The results show that the maximum deviation at all locations was within 10%, which is better than the 30% tolerance specified for PressureWire CFR measurements using the thermal dilution method. Visual representation of intravascular data and other cardiac data

[0182] Various exemplary graphical user interfaces (GUIs) or display outputs are shown in Figures 13A–13D and 15A–15D, which include datasets generated using one or more intravascular measurements, such as pressure, temperature, flow rate measurements, or measurements derived therefrom, or correlated measurements. In one embodiment, there are multiple modes for the output of the intravascular data processing and display system. As an example, the live mode and review mode are described in detail below. Live Mode - GUI

[0183] Figure 13A shows an exemplary GUI 805 in live mode, where the displayed data is sampled by an intravascular probe and processed by a measurement system, e.g., system 710 or other ICD described herein. This GUI is typically displayed on a touchscreen, and various elements on the interface may be activated, deactivated, or otherwise interacted with to change the display, calibrate the system, and make other modifications. In the illustrated live mode, real-time data curves and numerical values ​​are displayed, which provide a real-time overview to the user reviewing such data, which may be done, for example, before, during, or after a diagnostic procedure for another treatment.

[0184] As shown in Figure 13A, various graphs and plots can be displayed for the measured cardiac system data. The upper graph window displays phase-dependent Pd (using one color such as green, or a second mark), Pa (using another color such as red, or a first mark), and their respective average values. The white phase curve 807 is thermal convection (flow rate) data, which is mapped to the current flow rate ratio value (see numerical information below). The average value of the phase curve coincides with the current flow rate ratio value (1.88). The lower graph window displays a colored line 808 (e.g., yellow line or another mark) representing the current Pd / Pa value (0.98). The right-hand panel displays the following numerical information from top to bottom. ·Average Pa value. The maximum Pa value and the minimum Pa value are also shown as small numbers. ·Average Pd value. The maximum Pd value and the minimum Pd value are also shown as small numbers. ·Pd / Pa value. Based on the average values of Pd and Pa. ·Fv / Fv-B (flow rate / flow rate baseline ratio). This is the result of the CFR calculation. In one embodiment, this value is not referred to as CFR in the live mode. This is because the definition of CFR is the ratio of the flow rate to the baseline flow rate at maximum hyperemia. These definitions may be modified and changed based on the expectations of the users of this system. In one embodiment, maximum hyperemia exists only for a very short period during the measurement cycle. In one embodiment, Pd / Pa is not identified as FFR in the live mode.

[0185] The GUI of FIG. 13A includes various user operation buttons, namely, each button and menu of "Record", "Equalize", "Patient", "Live", "Review", and "Archive". The exemplary GUI 805 of FIG. 13A also includes a new operation part and button for the "CFR Enable" operation interface. The "CFR Enable" operation part is adjustable by the user to enable or disable the FFR + CFR mode. That is, the user can select whether to set it to the FFR mode or the FFR + CFR mode. The GUI illustrated in this specification is implemented using a touch screen or other operation means and input devices in various embodiments.

[0186] Using the "baseline" operation unit (shown in FIG. 13A) enables the user to open a new menu where they can select "Adjustment" or "Baseline Setting". Then, using the "Adjustment" operation unit enables activating the adjustment of the heat convection signal, thereby giving the user the opportunity to optimize the heat convection signal using both visual information (graph) and auditory information (voice signal), i.e., the opportunity to place the device at the optimal position within the blood vessel. Using the "Baseline Setting" operation unit enables instructing the software to store the current average value of the heat convection signal as T for CFR calculation. bas It becomes possible to instruct the software to store it. Review mode

[0187] In the review mode shown in FIGS. 13B, 13C, and 13D, the measurement records are displayed. The screen shows that the pressure ratio and flow rate ratio start from 1 (baseline flow rate) and then shift to their respective hyperemia levels (i.e., in the case of FIG. 13B, the pressure ratio is around 0.8 and the flow rate ratio is 5.0) at the start of hyperemia. The scale of the flow rate ratio is shown on the right side of the upper graph window and ranges from 0.0 to 10.0. In the "Review" screen, each ratio is referred to as FFR and CFR, and the user is to identify the maximum hyperemia (where the two ratios become FFR and CFR) by sliding the cursor from end to end of the record. Determining CFR - Heat convection data

[0188] As described herein, several possible transfer functions from blood flow values ​​to measured pressure sensor signals are listed. In one embodiment, a transfer function of the form x = a + c × log b Q is used, where the base b of the logarithm is not specified, x is the measured pressure sensor temperature signal or chip power, a is the offset value, c is the gain coefficient, and Q is the blood flow value. Both a and c depend on the position of the pressure sensor chip in the blood vessel. The inverse function of this function, Q = b^((xa) / c), is used to calculate the flow value from the measured pressure sensor signal. CFR (Q_congestion / Q_baseline) may then be calculated as b^((x_congestion-x_baseline) / c), as further detailed herein. In one embodiment, the offset value (a) is not required for the calculation of CFR.

[0189] CFR calculation uses one of the transfer functions mentioned above, namely,

number

number

number

[0190] By inserting equation (2) into equation (3), we obtain the following equation.

number

[0191] However, T hyp This is the temperature measured during hyperemia, and T bas is the temperature measured at the baseline flow rate. For this to work, the thermal convection device must remain stable at a specific measurement location at both the baseline and hyperemia flow rates (otherwise, constants a and c will not be valid for both hyperemia and baseline). Hyperemia can be visualized in Figures 15A-15D as a negative flat region shown in the lower window of the FFR data plot, and as a positive flat region shown in the middle of the screen (see Figure 15A) for the Fv / Fv-B (flow rate / flow rate baseline ratio) plot. The vertical line shown in the left third of the screenshot of Figure 5A represents the onset of hyperemia. Simplifying equation (4) using the rule of logarithms, we obtain the following equation.

number

[0192] Further simplification yields the final CFR function (the following equation) used in CFR calculation software.

number

[0193] Note that the constant 'a' is not necessary for the calculation of CFR. However, the constant 'c' is very important, as it is specific to the thermal convection device and specific to the device's position within the blood vessel. Also, the CFR value is the ratio of the flow rate to the baseline flow rate, and this is between individual CFR calculations. bas The value means it behaves as a constant. bas The value is indirectly provided by the user. That is, when coronary blood flow is at resting levels and the operator places the thermal convection device in the optimal measurement position, the "Baseline Setting" button on the GUI is pressed, and the software sets the thermal convection value (average value) at that point in time. bas Remember it as such.

[0194] This function can be written in a more general form, such as the following equation, by using an arbitrary base (b) for the logarithm without using the base of the natural logarithm (e).

Number

[0195] By using an intravascular data collection device within a blood vessel, it is possible to generate or receive signals containing diagnostic information relative to that blood vessel. Such a device may include, without limitation, an imaging device, such as an optical or ultrasonic probe, a pressure sensor device, and other devices suitable for collecting data about blood vessels or other cardiovascular system components.

[0196] The present disclosure relates, in part, to an intravascular data collection system and related methods for use in converting or analyzing intravascular data collected by an intravascular probe in a processor-based system. The results of such analysis and conversion may be presented to an end user in various representations, such as, for example, by a display that communicates with or is part of a system such as a pressure monitoring system or an intravascular data collection system. Examples of such systems are shown, for example, in FIGS. 1A-2B, FIGS. 5A-5E, FIG. 11, FIGS. 13A-13D, FIGS. 15A-15D, and all or parts thereof are shown in other drawings in other forms.

[0197] In one embodiment, a display console is used to display a user interface, such as a touchscreen interface, and one or more of the following values: flow rate, maximum flow rate, minimum flow rate, flow threshold, relative extreme values ​​of flow, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values, on one or more panels, or in one embodiment, as values ​​on components of the system, or as plots or graphs. The display device, console, or cart or other housing to which they are mounted or electrically or wirelessly connected may include one or more microprocessors for performing one or more of the steps described herein and for processing intravascular signals from the probes described herein.

[0198] These drawings and user interface screens may be used as diagnostic tools in conjunction with intravascular or angiographic images to inform decisions regarding stent placement, identification of areas of interest from a diagnostic perspective, and decisions regarding other cardiac treatments.

[0199] In one embodiment, a user of the system, method, and display disclosed herein can review the display of given FFR and CFR values ​​over time before, during, or after treatment to diagnose the severity of stenosis, identify the location of stenosis, provide guidance on treatment strategies, evaluate the effectiveness of treatment, and assess the need for further treatment after treatment. Embodiments for measuring and evaluating flow peak / flow threshold

[0200] By using a pressure sensor, flow sensor, or other sensing device in combination with an integrated cardiac display system or other system, such as those described herein, it is possible to obtain one or more categories of intravascular data over time using thermal convection data or flow data acquired using a flow sensor, or from other measurements correlated with flow data. In addition to thermal convection sensors, mechanical, optical, or other flow sensors may be used. The system may include signal processing and display devices (e.g., RadiAnalyzer systems, RadiAnalyzer Xpress systems, Quantien systems, Aeris systems, Prestige guidewire probe systems, ComboMap® pressure and flow systems, and other devices and systems for detecting intravascular pressure or determining FFR). In one embodiment, a pressure sensor or flow sensor forming part of an intravascular probe is used. The system may also include, or communicate with, a reference pressure device, such as a catheter, suitable for measuring proximal or distal pressure values. By using a reference pressure device, it is possible to measure a reference pressure (e.g., aortic pressure in one embodiment). The reference pressure device may include a pressure sensor for the guide catheter or delivery catheter.

[0201] By sampling the same detection device, it is possible to obtain distal pressure values ​​Pd, and by using distal pressure values ​​Pd together with a reference pressure, it is possible to simultaneously determine the FFR value. Such a reference pressure device also receives proximal pressure values ​​(Pa), such as aortic pressure values, and transmits these to an appropriate system for subsequent analysis and calculation, for example, a system described herein and illustrated in the exemplary embodiments shown in Figures 1A-2B, 5A-5E, 11, 13A-13D, and 15A-15D.

[0202] In one embodiment, this disclosure relates to detecting a flow threshold using intravascular data acquired by one or more methods described herein. Non-limiting examples of flow thresholds during a cardiac cycle include flow peaks or other relative extremes, inflection points, primary derivations, or secondary derivations. The detected flow threshold, e.g., flow peak (or other value or time point), may be selected as an index for a measurement system and used, for example, in the calculation of pressure ratios or pressure differences. Exemplary processing steps will be described in further detail with reference to Figures 16, 17A, and 17B, and to exemplary pressure and flow curves and plots of Pa and Pd values ​​for each cardiac cycle.

[0203] Embodiments of this disclosure relate in part to various features of pressure sensing devices, measurement systems, and associated software suitable for determining ratios based on signals sampled from an intravascular data acquisition probe. These signals may be various values, for example, a pressure threshold or flow threshold used to select a time or period during a cardiac cycle (specified by the user via an interface or automatically identified by the measurement system). This time may be the maximum value among a series of flow values ​​acquired by the probe. The selected time or period is used to perform a measurement or to select a measurement already acquired, the measurement including distal pressure values ​​or other parameters, such as, but not limited to, flow velocity, maximum flow rate, minimum flow rate, flow threshold, relative extreme values ​​of flow, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) values, coronary flow velocity reserve (CFVR) values, instantaneous flow reserve (IFR) values, and one or more myocardial resistance index (IMR) values. The flow threshold may be specified as a level above which the measured flow level is classified as peak flow or high flow.

[0204] Alternatively, the maximum flow rate or the absolute value of a flow rate measurement may be identified as a flow threshold or peak flow rate, at which point in the cardiac cycle one or more pressure values ​​or other intravascular parameters of interest are measured. By selecting a flow threshold, the sensing device can acquire a relative pressure difference, flow rate, or other value described herein (e.g., statistical values ​​or other indicators) relative to that point in time. Diagnostic data collected at each flow threshold (e.g., peak flow rate or maximum flow rate) may be displayed as values, plotted or processed in other forms, used to generate correlation values, which may also be displayed or plotted.

[0205] This section describes diagnostic methods and related thermal convection systems and apparatus suitable for evaluating coronary artery stenosis. These systems and methods make it possible to detect flow peaks (or other values ​​or time points described herein) that can provide clues to identifying points of interest or events during the cardiac cycle. These points of interest or events may be used as a reference for measuring pressure ratios or pressure differences at those events or time points. These methods and systems can be used to perform non-congestive measurements, such as measuring FFR values ​​in a non-congestive or resting state.

[0206] Some of the methods currently used to determine FFR independently of flow data or other indicators associated with flow peaks or other time points during the cardiac cycle assume that the FFR value is determined by clearly defining the region where high flow rates always occur. Unlike such restrictive methods that merely specify the selection of such a region for data collection, the systems and methods based on flow velocity measurement or other flow measurement described herein are capable of accurately measuring the flow rate when high flow rates or peak flow rates occur, or accurately measuring other indicators that correlate with or can be derived from such flow measurement values. In some embodiments, the peak flow rate referred to herein may correspond to the occurrence of maximum blood flow, and the maximum blood flow rate is associated with the peak of maximum blood flow or other relative extreme values ​​during the cardiac cycle.

[0207] The site of interest (at flow thresholds such as the peak of maximum blood flow) can always be found, and a pressure drop is measured at that site during the cardiac cycle. The occurrence of the flow peak can be located at any point during the cardiac cycle, and therefore the cycle ratio is not determined by pre-selecting a region based on predictions about the behavior of the heart during systole and diastole. Pressure drops can be measured at rest and / or during hyperemia. The occurrence of the flow peak can be located at any point during the cardiac cycle, and the ratio of distal pressure (Pd) to aortic pressure (Pa) can be measured at this site (or several neighboring sites / samples). If a pressure drop is of interest, the difference (Pa-Pd) is measured at the same one or more sites. As shown in Figure 18, aortic pressure (P 大動脈The curve shows Pa values ​​at the peak flow rate of the illustrated cardiac cycle, and Pd values ​​at the vertical bidirectional arrows. By finding and using these values, it is possible to calculate FFR, pressure difference, and other values ​​for each cardiac cycle at the peak flow rate or other specified flow thresholds. In one embodiment, the arithmetic mean or other statistical or data index (mean, median, mode, standard deviation, etc.) of the measurements over several heartbeats is calculated. This ratio is Pd / Pa at the flow peak or other flow threshold. This is the minimum Pd / Pa during the cardiac cycle at baseline (when congestion is not introduced) and represents the non-congestive resting index.

[0208] Figure 16 shows a series of method steps for a diagnostic method, such as a method for evaluating a vessel or stenosis using a flow threshold and other measured intravascular parameters. As one step of this method, a step is performed in which a flow threshold is detected using an interface or other intravascular measurement system and one or more detection devices in a non-congestive (or congestive) state (Step A1). As a result, the detection device or system component can output one or more peak flow values ​​(or one or more other identified values) (Step A2). Furthermore, the system and associated control logic can determine the pressure ratio and / or pressure difference in response to the identified peak flow values ​​(or one or more other identified values) or when those values ​​occur (Step A3). Using such a pressure ratio or pressure difference, the system can generate a statistical index or other index (e.g., arithmetic mean, mode, deviation, or other index or statistic) of the pressure ratio, pressure difference, or both over one or more heartbeats (Step A4).

[0209] Furthermore, the system can display or output diagnostic information (Step A5), for example, plots, ratios, or differences acquired at flow thresholds such as peak flow or maximum flow. Flow values ​​can be generated using intravascular sensors, and these flow values ​​can be used to provide input to the system for selecting flow thresholds. The system can display one or more numerical values ​​of pressure ratios (Pd / Pa) or correlated values ​​at identified values ​​such as maximum flow or other identified values ​​(Step A6). If the data was collected in a non-congestive state, the system can display / classify the output as a baseline in a non-congestive, resting state (Step A6-1). If a vasodilator is used, the system can display / classify the output as congestive data (Step A6-2). In addition, the system can display one or more numerical values ​​of pressure difference at identified values ​​such as maximum flow or other identified values ​​(Step A7). The system can display / classify the output as a baseline in a non-congestive, resting state (Step A7-1). This system can display / classify the output as data related to congestion (Step A7-2).

[0210] Figure 17A shows another embodiment of a diagnostic method related to pressure ratios, suitable for use with one or more of the pressure and flow detection systems described herein. Figure 17A outlines the various steps related to the Pd / Pa ratio, as illustrated. The system is first used in the step of transmitting / providing intravascular data relating to a vessel of interest (step B1). Next, the step of determining a first flow value at a first flow threshold during a first period or cardiac event is performed (step B2). The step of determining the ratio of distal pressure to aortic pressure (pd / pa) during the first flow threshold is performed (step B3). Furthermore, the system may be set up for the step of determining one or more indices relating to pressure ratios over multiple periods or cardiac events (step B4). The system can then display one or more of the pd / pa, the determined indices, the determined flow values, or values ​​derived therefrom as numerical values, as a plot against time, or for each cardiac event (step B5). Figure 18 is an illustrative display of the results of the method of Figure 17A, showing a plot suitable for showing a flow threshold and the Pa and Pd values ​​found at such a threshold, where the Pa and Pd values ​​are shown, for example, along vertical line A in the first cardiac cycle A.

[0211] Figure 17B shows another embodiment of a diagnostic method relating to a pressure ratio, suitable for use with one or more of the pressure and flow sensing systems described herein. Figure 17B outlines the steps of a diagnostic method relating to the pressure difference between an intravascular pressure value and a pressure value of another object of interest. The system may be used to perform the step of transmitting / providing intravascular data relating to a vessel of interest (step B1). Another step may be performed to determine a first flow value at a first flow threshold during a first period or cardiac event (step B2). Flow values ​​measured by flow sensors described herein (e.g., using temperature and voltage) may be used to select a flow threshold at which measurements will be taken. A step may be performed to determine the pressure difference (pa-pd) between aortic pressure and distal pressure between the first flow thresholds (step C1).

[0212] Alternatively, a step (step C2) may be performed to determine one or more indices relating to the pressure difference over multiple periods or cardiac events, for example, by user selection or by a predetermined selection in the system. The system displays one or more of the determined indices, determined flow values, or values ​​derived therefrom as numerical values, as a plot against time, or for each cardiac event (step C3). Figure 18 shows an exemplary display of results for the method of Figure 17B.

[0213] Referring to Figure 18, two plots or follow-up records are generated using intravascular data measured (for example, by one or more of the methods in Figures 16, 17A, and 17B). Plots 910 (upper part of the figure) and 920 (lower part of the figure) show time-versus-pressure and time-versus-flow values, respectively, for cardiac cycles A-E. That is, a series of pressure curves against time are shown over multiple cardiac cycles. In the upper figure, plot 910, the solid line corresponds to the upper curve and shows the aortic pressure rising and falling over time as the heart goes through a series of cardiac cycles. The lower pressure curve corresponds to the distal pressure measured intravascularly, indicated by the dotted lines 100A, 100B, 100C, 100D, and 100E, which correspond to the flow threshold. Pd and Pa values ​​can be found at the intersection of the double-headed arrows, and these can be used to determine a first parameter such as Pd-Pa or Pd / Pa, or a second parameter that correlates with the first parameter in another form.

[0214] Each of the vertical dotted lines labeled A through E represents a flow threshold, where data is collected and diagnostic data is refined for each cardiac cycle. The illustrated vertical lines correspond to the maximum flow rate. However, other flow thresholds may be used, for example, X% of the maximum flow rate. The range of X is approximately 1 to approximately 100. There are five cardiac cycles illustrated, A through E. The pressure differences, indicated by double-headed arrows and identified as PD-A, PD-B, PD-C, PD-D, and PD-E, are the pressure differences or pressure ratios obtained at the associated time cross-sections, indicated by the vertical dotted lines corresponding to the flow thresholds selected in this system. As shown herein, the maximum flow rate or peak flow rate was the basis for the flow thresholds used to determine where to measure the pressure ratio or pressure difference. The flow thresholds indicated by the vertical lines may be selected as the maximum flow rate values ​​for each cycle, which are determined using temperature-based flow measurement values ​​or other flow sensors as described herein.

[0215] In the case of the illustrated five heartbeats, the vertical bidirectional arrows correspond to the difference between the first and second pressures. These bidirectional arrows extend in the upper diagram and are aligned with vertical dotted lines that continue into the lower diagram. These dotted lines indicate the occurrence of flow thresholds, such as peak flow. These dotted lines may be set using a control system and flow thresholds of other interests (e.g., flow measurements, or other correlated values). Diagnostic values ​​that may be determined and displayed at the flow threshold, or plotted therein, include, but are not limited to, one or more fractional flow reserve (FFR) values, coronary flow reserve (CFR) values, coronary velocity reserve (CFVR) values, instantaneous flow reserve (IFR) values, and one or more myocardial resistance index (IMR) values.

[0216] The various pressure differences and pressure problems described herein may be expressed as numerical values ​​used in diagnostic procedures or other procedures. These differences and ratios may be used to generate various indices and other indicators, such as statistics. Examples of such statistics include weighted mean, mean, arithmetic mean, mode, median, standard deviation from parameters such as baseline (whether hypertensive or non-hypertensive), and other statistics related to intravascular system parameters and coronary system parameters. Non-limiting software functions and embodiments for implementing methods and systems for data acquisition and analysis related to pressure and flow rate.

[0217] The following description is intended to provide an overview of the apparatus hardware and other operating components suitable for carrying out the methods disclosed herein. This description is not intended to limit the applicable environment or scope of this disclosure. Similarly, the hardware and other operating components may be suitable as part of the apparatus described above. This disclosure may also be carried out in other system configurations, such as personal computers, multiprocessor systems, multiprocessor-based or programmable electronic devices, network PCs, minicomputers, mainframe computers, etc. This disclosure may also be carried out in a distributed computing environment, in which the task is performed by remote processing units linked over a communication network (for example, in multiple different rooms of a catheterization laboratory).

[0218] Some parts of the detailed description are described in terms of algorithms and symbolic representations of operations on data bits in computer memory. These algorithmic descriptions and representations are usable by those skilled in the computer and software-related fields. In one embodiment, an algorithm is considered here, and generally, to be a self-consistent set of operations that leads to a desired result. Method steps, or operations performed in other forms described herein, require the physical manipulation of physical quantities. Although not essential, these quantities usually take the form of electrical or magnetic signals that can be stored, transferred, combined, converted, compared, and other forms of manipulation.

[0219] As will be clear from the following explanation, unless otherwise specified, throughout this explanation, any use of terms such as “process,” “calculate,” “search,” “detect,” “measure,” “compare,” “generate,” “detect,” “request,” or “display,” or any operation related to Boolean logic or other sets, should be understood to mean the operation or processing of a computer system or electronic device that manipulates data represented as physical quantities (electronic quantities) within the registers and memory of the computer system or electronic device, or similarly converts it into other data represented as physical quantities within electronic memory or registers or other such information storage devices.

[0220] Depending on the embodiment, this disclosure also relates to an apparatus for performing the calculations described herein. This apparatus may be built specifically for a particular application, or may include a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Various circuits and circuit components may be used to perform some of the data collection, transformation, and processing described herein.

[0221] The algorithms and representations presented herein are not, in essence, tied to any particular computer or other device. Various general-purpose systems may be used with programs following the teachings herein, or it may be preferable to construct devices more specialized to perform the necessary method steps. The structures required for these various systems will become apparent from the following description. Furthermore, the descriptions in this disclosure are not related to any particular programming language, and therefore various embodiments using various programming languages ​​may be implemented.

[0222] Embodiments of the present disclosure may be implemented in a variety of forms, including, but are not limited to, computer program logic used with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general-purpose computer), programmable logic used with a programmable logic device (e.g., a field-programmable gate array (FPGA) or other programmable logic device), discrete components, integrated circuits (e.g., application-specific integrated circuits (ASICs)), or any other means including any combination thereof. In a typical embodiment of the present disclosure, some or all of the processing of data collected using an OCT probe and a processor-based system is performed as a set of computer program instructions, which are converted into a form executable by a computer, stored in such form on a computer-readable medium, and executed by a microprocessor under the control of an operating system. Accordingly, the queries, responses, transmitted probe data, input data, and other data and signals described herein are converted into instructions that the processor can understand, and these instructions are suitable for generating pressure and flow data, detecting stenosis, determining maximum flow values, calibrating using CVEX-based transfer functions, calibrating using CTA-based transfer functions, determining maximum flow values, determining CFR values, determining FFR values, displaying and plotting the data and parameters described herein in areas of the GUI, or otherwise performing pressure-to-flow curves and flow measurements, and other analyses and comparisons based on the features and embodiments described above. Data and parameters suitable for display as plotted curves, values, or other representations in a graphical user interface may include, but are not limited to, fractional flow reserve (FFR) values, coronary flow reserve (CFR) values, coronary velocity reserve (CFVR) values, instantaneous flow reserve (IFR) values, flow thresholds, mean flow thresholds, and myocardial resistance index (IMR) values.

[0223] Computer program logic that implements all or part of the functionality already described herein may be implemented in various forms, for example, but not limited to, source code form, computer executable form, or various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator). Source code may include a set of computer program instructions implemented in any various programming language (e.g., object code, assembly language, or a high-level language such as Fortran, C, C++, Java®, or HTML) for use in various operating systems or operating environments. Source code may define and use various data structures and communication messages. Source code may be made computer executable (e.g., by an interpreter), or source code may be converted to computer executable (e.g., by a translator, assembler, or compiler).

[0224] Computer programs may be stored permanently or temporarily in any format (e.g., source code format, computer executable format, or intermediate format) on tangible storage media, such as semiconductor memory devices (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), magnetic memory devices (e.g., diskettes or fixed disks), optical memory devices (e.g., CD-ROMs), PC cards (e.g., PCMCIA cards), or other memory devices. Computer programs may also be stored in any format in signals that can be transmitted to a computer using any of the various communication technologies, including, but not limited to, analog technology, digital technology, optical technology, wireless technology (e.g., Bluetooth®), networking technology, and internetworking technology. Computer programs may be distributed in any form as removable storage media (e.g., shrink-wrapped software) accompanied by printed or electronic documents, or they may be pre-loaded into a computer system (e.g., on system ROM or a fixed disk), or they may be distributed from servers or electronic bulletin boards via communication systems (e.g., the Internet or the World Wide Web).

[0225] Hardware logic (including programmable logic used with programmable logic devices) that implements all or part of the functionalities already described herein may be designed by conventional manual methods, or may be designed, captured, simulated, or electronically documented using various tools, such as computer-aided design (CAD), hardware description languages ​​(e.g., VHDL or AHDL), or PLD programming languages ​​(e.g., PALASM, ABEL, or CUPL).

[0226] Programmable logic may be stored permanently or temporarily in tangible storage media, such as semiconductor memory devices (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), magnetic memory devices (e.g., diskettes or fixed disks), optical memory devices (e.g., CD-ROMs), or other memory devices. Programmable logic may also be stored in signals that can be transmitted to a computer using any of various communication technologies, including, but not limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies. Programmable logic may be distributed as removable storage media (e.g., shrink-wrapped software) accompanied by printed or electronic documents, or pre-loaded into a computer system (e.g., on system ROM or fixed disks), or distributed from servers or electronic bulletin boards via communication systems (e.g., the Internet or the World Wide Web).

[0227] The following describes in detail various examples of suitable processing modules. In this specification, a module means software, hardware, or firmware suitable for performing a specific data processing or data transmission task. Typically, in a preferred embodiment, a module means a software routine, program, or other memory-resident application suitable for receiving, transforming, routing, and processing instructions or various types of data, such data being, for example, resistance changes, guidewire probe data, temperature data, intravascular flow data, intravascular pressure data, transfer function output calibration data, excitation voltage, and other information of interest.

[0228] The computers and computer systems described herein may include operationally associated computer-readable media, for example, memory for storing software applications used for data acquisition, processing, storage, and / or transmission. Such memory may be internal, external, distant, or near the operationally associated computer or computer system.

[0229] Memory may include any means for storing software or other instructions, such means include, but are not limited to, hard disks, optical disks, floppy disks, DVDs (Digital Multipurpose Disks), CDs (Compact Discs), Memory Sticks, flash memory, ROMs (Read-Only Memory), RAMs (Random Access Memory), DRAMs (Dynamic Random Access Memory), PROMs (Programmable ROMs), EEPROMs (Extended Erasable PROMs), and / or other similar computer-readable media.

[0230] In general, computer-readable memory media applicable in connection with embodiments of the disclosure described herein may include any memory medium capable of storing instructions executed by a programmable device. Where applicable, the steps of the method described herein may be implemented or executed as instructions stored in one or more computer-readable memory media. These instructions may be software implemented in various programming languages, for example, C++, C, Java, and / or various other types of software programming languages ​​that may be applied to form instructions according to embodiments of the disclosure.

[0231] A storage medium may be non-transient, or it may include a non-transient device. Therefore, a non-transient storage medium or non-transient device may include a tangible device, which means a device having a concrete physical form, but whose physical state may change. Thus, for example, non-transient means that even if such a change in state occurs, the device remains tangible.

[0232] The aspects, embodiments, features, and examples of this disclosure should be considered illustrative in all respects and are not intended to limit the disclosure, with the scope of this disclosure defined solely by the claims. It will be apparent to those skilled in the art that there are other embodiments, modifications, and uses that do not depart from the spirit and scope of the claimed disclosure.

[0233] The use of headings and sections in this application is not intended to limit the disclosure, and each section applies to any aspect, embodiment, or feature of the disclosure.

[0234] Throughout this application, where a component is described as having, including, or being composed of specific components, or where a process is described as having, including, or being composed of specific process steps, it is reasonable to assume that the components of this teaching are also fundamentally composed of (or composed of) those described components, and that the processes of this teaching are also fundamentally composed of (or composed of) those described process steps.

[0235] Where it is stated in this application that an element or component is included in and / or selected from a list of elements or components described, that element or component may be any one of the elements or components described, and may be selected from a group of two or more elements or components described. Furthermore, the elements and / or features of the constructs, apparatus, or methods described herein may be combined in various ways, whether expressly or implicitly herein, as long as they do not deviate from the spirit and scope of this teaching.

[0236] Unless otherwise specified, the use of the words "include," "includes," "including," "have," "has," and "having" should generally be understood as unrestricted and non-limiting.

[0237] In this specification, the use of singular words includes plural words unless otherwise specified (and conversely, the use of plural words includes singular words). Furthermore, the singular forms "a," "an," and "the" include plural forms unless the context indicates otherwise. In addition, when the word "about" is used before a quantitative value, this instruction includes the specific quantitative value itself unless otherwise specified.

[0238] Naturally, the order of the steps, or the order in which specific actions are performed, is not important as long as this instruction works. Furthermore, two or more steps or actions may be performed simultaneously.

[0239] Where a range or list of values ​​is given, each intermediate value between the upper and lower limits of that range or list is considered individually and is included in this disclosure, as if each value were specifically enumerated herein. Furthermore, smaller ranges between the upper and lower limits of a given range, including those upper and lower limits, are also considered and are included in this disclosure. Listing exemplary values ​​or ranges does not preclude other values ​​or ranges between the upper and lower limits of a given range, including those upper and lower limits.

[0240] Naturally, the drawings and descriptions in this disclosure have been simplified to illustrate relevant elements for the sake of clarity, while other elements have been omitted for clarity. However, as will be understood by those skilled in the art, these and other elements may also be desirable. However, since such elements are well known in the art and do not contribute to a better understanding of this disclosure, such elements are not described herein. Naturally, each drawing is provided for illustrative purposes only and is not intended as a structural drawing. Omitted details and modifications or alternative embodiments are within the realm of knowledge for those skilled in the art.

[0241] Depending on the aspects of this disclosure, it will be understood that a single component may be replaced by multiple components, and multiple components may be replaced by a single component, in order to provide a certain element or structure, or to perform one or more desired functions. Unless such a replacement is considered not to function in carrying out a particular embodiment of this disclosure, such replacement will be considered to fall within the scope of this disclosure.

[0242] Each embodiment shown herein is intended to illustrate a potential and specific embodiment of the Disclosure. Those skilled in the art will understand that these embodiments are primarily illustrative of the Disclosure. Variations of these drawings or operations described herein are possible, as long as they do not deviate from the spirit of the Disclosure. For example, in some cases, method steps or operations may be performed or carried out in a different order, or operations may be added, deleted, or modified.

[0243] [Note 1] One or more memory devices, An intravascular pressure and flow rate monitoring system comprising a computing device communicating with the memory device, wherein the memory device is executable by the computing device, The steps include determining one or more intravascular pressure values ​​as a response to a first electrical signal from a measurement circuit formed from a guidewire probe and interface device, The steps include determining one or more intravascular flow values ​​using a transfer function as a response to a second electrical signal from the measurement circuit formed by the guidewire probe and the interface device, The command includes causing the computing device to perform the steps of: displaying a pressure-to-flow curve that changes with respect to time, which is generated based on one or more intravascular pressure values ​​and intravascular flow values; Intravascular pressure and flow rate monitoring system. [Note 2] The aforementioned pressure-flow curve is displayed in near real-time in the intravascular pressure and flow monitoring system described in Appendix 1. [Note 3] The transfer function T(x) is of the form T(x) = a + b × ln(x), where x is the flow rate and a and b are constants, as described in Appendix 1, for the intravascular pressure and flow rate monitoring system. [Note 4] The transfer function T(x) is given by T(x) = a + b × x cThe intravascular pressure and flow rate monitoring system described in Appendix 1 is in the format shown, where x is the flow rate and a, b, and c are constants. [Note 5] The intravascular pressure and flow monitoring system described in Appendix 1 further includes a command to display one or more cardiovascular-related values ​​obtained between one or more time points. [Note 6] The intravascular pressure and flow monitoring system described in Appendix 5, wherein the one or more cardiovascular-related values ​​are selected from the group consisting of flow velocity, pressure value, maximum flow rate, minimum flow rate, relative extreme value of flow rate, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values. [Note 7] The intravascular pressure and flow monitoring system as described in Appendix 5, further comprising commands for displaying one or more trajectories or signatures generated in response to intravascular probe data relating to one or more locations within an artery. [Note 8] An intravascular pressure and flow monitoring system as described in Appendix 5, further comprising commands for displaying a user interface that includes flow velocity, pressure values, maximum flow rate, minimum flow rate, relative extreme values ​​of flow rate, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) values, coronary velocity reserve (CFVR) values, instantaneous flow reserve (IFR) values, or one or more myocardial resistance index (IMR) values, generated using pressure and flow data from an intravascular probe. [Note 9] The intravascular pressure and flow monitoring system according to Appendix 5, further comprising commands for determining one or more temperature values ​​using a linear function or other function as a response to a second electrical signal from the measurement circuit formed from the guidewire probe and the interface device. [Note 10] The intravascular pressure and flow monitoring system according to Appendix 5, further comprising the following calibration steps: selecting an excitation voltage for the pressure sensor such that the temperature of the pressure sensor is substantially equal to the temperature of the blood in which the pressure sensor is located; determining the absolute temperature of the blood in a blood vessel of interest; and measuring the flow rate in the blood vessel using the pressure sensor. [Note 11] The intravascular pressure and flow monitoring system according to Appendix 10, wherein the step of determining the absolute temperature of the blood in the blood vessel of interest includes the step of obtaining the measurement value during a change in the switch configuration in the interface system. [Note 12] Display system and, The display system is electrically connected to the pressure and flow rate measuring system, which includes the computing device, The computing device located in either the display system or the pressure and flow rate measuring system, One or more panels generated using the computing device and drawn on the display, the one or more panels including flow rate values ​​and pressure values ​​acquired using an intravascular probe equipped with pressure and flow sensors, An intravascular pressure and flow monitoring system as described in Appendix 5, further comprising the features described therein. [Note 13] An intravascular pressure and flow monitoring system according to Appendix 12, wherein one or more panels include a pressure-to-flow curve, the pressure-to-flow curve includes one or more trajectories generated using intravascular pressure and flow data, and further includes an input for receiving data signals from the intravascular probe, the intravascular probe comprising a temperature sensor for measuring temperature changes correlated with flow values. [Note 14] An intravascular pressure and flow monitoring system as described in Appendix 12, wherein one or more panels include signature, trajectory, slope, maximum point, minimum point, ratio of measured values, ratio of measured values ​​to derived values, ratio of primary derived values ​​to secondary derived values, range, one or more ratio flow reserve (FFR) values, coronary flow reserve (CFR) value, coronary velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and one or more myocardial resistance index (IMR) values. [Note 15] The instruction further includes processing coronary blood flow reserve data using an intravascular pressure or flow sensor, the instruction being: The steps include sampling an intravascular data acquisition probe to obtain one or more distal pressure values ​​(Pd) and one or more thermal convection data values ​​from the distal region of the blood vessel, The steps include receiving one or more aortic pressure values ​​(Pa) obtained from the proximal region of the aforementioned blood vessel in an intravascular data processing system, The steps include determining one or more fractional flow reserve (FFR) values ​​from the one or more distal pressure values ​​and the one or more aortic pressure values, The steps include determining one or more coronary flow reserve (CFR) values ​​from the one or more thermal convection data values, The step of displaying one or more FFR values ​​and one or more CFR values ​​on a display device, wherein each CFR value is determined using a transfer function, is included in the said step. The intravascular pressure and flow rate monitoring system described in Appendix 12. [Note 16] The transfer function is of the form T = a + c × lnQ, where T is the measured temperature of the temperature variable resistor of the thermal convection device, Q is the flow rate, and a and c are constants, as described in Appendix 15 for the intravascular pressure and flow rate monitoring system. [Note 17] Each CFR value, format value

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Claims

1. An intravascular pressure and flow rate monitoring system, One or more sensors that are part of an intravascular guidewire probe positioned at the distal end of a guidewire, An active resistance that is sensitive to temperature and pressure, Passive resistance that is sensitive to temperature but not to pressure, A sensor equipped with, A control system, During each of multiple cardiac cycles, multiple intravascular blood flow values, multiple proximal blood pressure values, and multiple distal blood pressure values ​​are measured using one or more of the sensors. The control system is The steps include processing a first electrical signal associated with the active resistor and the passive resistor, A step of determining the distal blood pressure value based on the first electrical signal, The system is configured to measure the multiple distal blood pressure values ​​by performing the following actions: The control system is The steps include processing a second electrical signal associated with the passive resistor, The steps include determining the intravascular blood flow value using a transfer function based on the second electrical signal, The system is configured to measure the multiple intravascular blood flow values ​​by performing the following actions: For each cardiac cycle, the peak blood flow value among the multiple intravascular blood flow values ​​during that cardiac cycle is determined. For each cardiac cycle, the proximal and distal pressure values ​​at the peak blood flow value are determined. Based on the proximal and distal pressure values ​​at the peak blood flow values ​​for the plurality of cardiac cycles, a first diagnostic parameter is calculated. A control system configured to display the first diagnostic parameters for the plurality of cardiac cycles, or the second diagnostic parameters determined using the first diagnostic parameters, on a user display, A system equipped with these features.

2. The system according to claim 1, wherein the first diagnostic parameter is the pressure difference obtained by subtracting the distal pressure value from the proximal pressure value.

3. The system according to claim 1, wherein the first diagnostic parameter is the pressure ratio of the distal pressure value to the proximal pressure value.

4. The system according to any one of claims 1 to 3, wherein the proximal pressure value is a proximal pressure value measured relative to the stenosis.

5. The system according to any one of claims 1 to 3, wherein the proximal pressure value is the aortic pressure value.

6. The system according to claim 1, wherein the first and second diagnostic parameters are selected from the group consisting of aortic pressure, distal pressure, flow velocity, maximum flow rate, minimum flow rate, relative extreme value of flow rate, ratio of flow reserve (FFR) value, coronary flow reserve (CFR) value, coronary flow velocity reserve (CFVR) value, instantaneous flow reserve (IFR) value, and myocardial resistance index (IMR) value.

7. The system according to claim 1, wherein the first diagnostic parameter is the average of the pressure ratios in a plurality of cardiac cycles, or the average of the pressure differences in a plurality of cardiac cycles.

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