Pressure based blood vessel assessment systems and methods

Abstract

To provide systems and methods for determining whether and how to treat a patient based on blood pressure measurements.SOLUTION: A system for assessing a vascular condition includes a pressure sensing catheter and a pressure guidewire. Heartbeats of a patient can be detected while the pressure sensing catheter and the pressure guidewire are positioned at a proximal position and at a distal position, respectively. A diastolic pressure ratio zone (dPR zone) is located within a heartbeat from analysis of a signal from at least one of the pressure sensing catheter and the pressure guidewire. The dPR value can be obtained by calculating an average of several ratios of Pa to Pd taken over time within the heartbeat. A multi-beat metric (dPRc) is calculated that includes the dPR value and that also includes a high frequency sample whole heartbeat pressure ratio.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application is directed to systems and methods for determining whether and how to treat a patient based on blood pressure measurements. [Background technology]

[0002]

[0002] Fractional Flow Reserve (FFR) is a known technique for determining whether to treat a vascular occlusion with balloon angioplasty and / or a stent. FFR is a test performed under hyperemia. In this technique, blood pressure is measured in the coronary vasculature distal and proximal to the occlusion. Traditionally, the ratio of these pressures is calculated and compared to a threshold below which balloon angioplasty and / or stent placement is indicated and above which such treatment is not performed.

[0003]

[0003] A more recent trend has been to calculate pressure ratios based on data acquired at the same location in the vasculature relative to the occlusion, but only on pressures acquired during the diastolic portion of the cardiac cycle without congestion. Summary of the Invention [Problem to be solved by the invention]

[0004]

[0004] Improved devices and methods are needed for determining when and how to treat a coronary artery blockage. Such methods can advantageously include data from more than just the diastolic segment and can consider data from one or more cardiac cycles. Sampling from multiple cardiac cycles and / or from multiple segments of one or more cardiac cycles can provide more information about the state of blood flow through the heart. Sampling from multiple cardiac cycles and / or from multiple segments of one or more cardiac cycles can allow clinicians to analyze cardiovascular conditions during resting cardiac cycles. Better clinical decisions come from more comprehensive and more refined data.

[0005]

[0005] A method for evaluating a patient is provided. A metric, referred to herein as dPRc, can be calculated. The metric uses an aortic or proximal pressure curve, referred to as the Pa curve, and a distal pressure curve, referred to as the Pd curve. The proximal pressure curve can be provided by a guide catheter pressure sensor, a pressure guidewire, or another device capable of sensing pressure in the aorta. The distal pressure curve can be provided by a pressure guidewire or other device capable of sensing pressure distal to a vascular occlusion. dPRc can be a multi-beat metric incorporating data sampling from segments of one or more adjacent beats and from one or more adjacent whole beats.

[0006]

[0006] In one technique, the heartbeat is detected. The pulse can be detected from the successive Pa values. The pulse can be detected by the Pd value. The pulse can be detected from both the Pa value and the Pd value.

[0007] In one technique, the dicrotic notch and end of diastole (EoD) locations are recognized from the pressure data. These locations can define, or can be used to define, a segment of the heartbeat that is used to calculate a heartbeat segment metric, referred to herein as dPR. The segment over which dPR is calculated may be referred to as a dPR zone. A dPR value may be calculated for each heartbeat in a series of detected heartbeats.

[0008]

[0008] A total beat metric may be calculated. The total beat metric includes data from both the systolic and diastolic portions of the heartbeat. The total beat metric may include a pulse transmission coefficient, referred to herein as a PTC(B) value. A PTC(B) value may be calculated for each heartbeat in a series of detected heartbeats.

[0009]

[0009] In some cases, the median value of PTC(B), hereinafter referred to as PTC(B)med, is calculated over several consecutive heart beats in time. The PTC(B)med value reduces, or in some cases minimizes, the effects of signal instability and artifacts. A new PTC(B)med value can be calculated for each consecutive heart beat. The number of consecutive heart beats used to calculate PTC(B)med may depend on the type of analysis performed, as further explained below.

[0010]

[0010] The ratio of average Pd to average Pa is calculated at the sampling rate. The ratio of average Pd to average Pa can be calculated over a period corresponding to the most recent heartbeat used in calculating the PCT(B)med value. One new ratio of average Pd to average Pa can be calculated for each pressure sample or measurement made. The pressure samples can be at any suitable sample rate, such as 125 Hertz (every 8 ms).

[0011]

[0011] The dPRc metric may be calculated for a time corresponding to the duration of the most recent group of beats used to calculate the PTC(B)med value. The dPRc value may be calculated and displayed rapidly, for example after each pressure sample, for example every 8 ms.

[0012] In one embodiment, a system for assessing a vascular condition is provided. The system includes a pressure sensing catheter, a pressure guidewire, and one or more hardware processors. The pressure sensing catheter is configured to be located at a proximal position within the vasculature of a patient. The pressure guidewire is configured to be located at a distal position within the vasculature. The distal position is located distal to the proximal position. The one or more hardware processors are configured to detect a heartbeat of the patient while the pressure sensing catheter and the pressure guidewire are disposed at the proximal and distal positions within the vasculature, respectively. The one or more hardware processors are configured to locate a diastolic pressure ratio (dPR) zone within the heartbeat from an analysis of signals from at least one of the pressure sensing catheter and the pressure guidewire. The one or more hardware processors are configured to calculate a dPR value, including calculating an average of multiple ratios of Pa to Pd taken over time within the dPR zone. The one or more hardware processors are configured to calculate a multi-beat metric including the dPR value and a high frequency sampled total beat pressure ratio. The one or more hardware processors are configured to output the multi-beat metric.

[0013] In one embodiment, a method of assessing vascular status is provided. A pressure sensing catheter is placed at a proximal location, e.g., proximal to an occlusion in a coronary artery of a patient. A pressure guidewire is placed at a distal location, e.g., distal to the occlusion, in the vasculature. A patient's heartbeat is detected while in the vasculature, including when the pressure sensing catheter and the pressure guidewire are positioned at proximal and distal locations, e.g., proximal and distal to the occlusion, respectively. A diastolic pressure ratio (dPR) zone is located within the heartbeat from an analysis of signals from at least one of the pressure sensing catheter and the pressure guidewire. A dPR value is calculated. The calculation of the dPR value may include calculating an average of multiple ratios of Pa to Pd taken over time within the dPR zone. A multi-beat metric is calculated that includes the dPR value and also includes a high frequency sampled total beat pressure ratio. The multi-beat metric may be displayed to a user.

[0014]

[0014] These and other features, aspects and advantages are described below with reference to the drawings, which are intended for illustrative purposes and should not be construed as limiting the scope of the embodiments in any way. Furthermore, various features of different disclosed embodiments can be combined to form additional embodiments that are part of this disclosure. In the drawings, like reference characters indicate corresponding features consistently throughout like embodiments. Each of the drawings is briefly described below. [Brief description of the drawings]

[0015] [Figure 1]

[0015] A schematic diagram showing a blood vessel having a notched portion into which a pressure guidewire is inserted and spaced proximally therefrom, and a guide catheter positioned proximally of the notched portion, for example within the patient's aorta. [Diagram 2]

[0016] 1 is a schematic diagram of an occlusion analysis system including a pressure guidewire and a monitor assembly capable of processing vascular pressure data in connection with vascular occlusion analysis. [Diagram 3]

[0017] 1 is a graphical representation of a pressure signal over time including identification of diastolic pressure ratio zones (dPR zones) for calculating metrics during segments or portions of a cardiac cycle. [Figure 4]

[0018] 4 is a graphical representation similar to FIG. 3 in connection with which the total cardiac cycle metrics are described. [Diagram 5]

[0019] 1 illustrates the analysis of multiple consecutive cardiac cycles in calculating multi-beat metrics useful in determining whether to treat a patient. [Figure 6] 1 illustrates the analysis of multiple consecutive cardiac cycles in calculating multi-beat metrics useful in determining whether to treat a patient. [Figure 7]

[0020] A technique is presented for developing a stream of data for use in static measurements including high frequency sampled pressure ratio metrics as well as segment and whole beat metrics over multiple consecutive beats. [Figure 8]

[0021] A technique is presented for developing a stream of data for use in pullback measurements that includes high frequency sampled pressure ratio metrics as well as segment and whole beat metrics over multiple consecutive beats. [Figure 8A]

[0022] 10 shows another technique similar to that of FIG. 8 for pullback measurements. [Figure 9]

[0023] 3 illustrates an exemplary output provided on a user interface of a monitor assembly of the system of FIG. 2. [Figure 10] 3 illustrates an exemplary output provided on a user interface of a monitor assembly of the system of FIG. 2. [Figure 11] 3 illustrates an exemplary output provided on a user interface of a monitor assembly of the system of FIG. 2. [Figure 12] 3 illustrates an exemplary output provided on a user interface of a monitor assembly of the system of FIG. 2. [Figure 13]3 illustrates an exemplary output provided on a user interface of a monitor assembly of the system of FIG. 2. [Figure 14]

[0024] FIG. 1 is a schematic diagram of a blood vessel being evaluated using the methods discussed herein. [Figure 15]

[0025] FIG. 15 is a schematic diagram of a vessel being treated following the evaluation performed as shown in FIG. 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016]

[0026] The present application is directed to systems and methods for determining whether and how to treat a patient in which data from multiple segments of the cardiac cycle and / or multiple cardiac cycles is taken into account. By incorporating data indicative of both stressed and resting cardiac conditions, a patient's condition can be more accurately assessed and outcomes can be improved.

[0017] I. Overview of Pressure Wire Systems and Their Use

[0027] 1 and 2 illustrate a lesion diagnostic system 100 and its use in a patient's vasculature. FIG. 1 illustrates a left coronary vasculature with a pressure guidewire 108 positioned in a proximal portion of the left anterior descending artery (LAD). The pressure guidewire 108 is positioned within the left anterior descending artery LAD, with its distal portion distal to an occluded OCL. Blood flow within the left anterior descending artery LAD flows from proximal to distal through the occluded OCL and over the distal tip of the pressure guidewire 108. The occluded OCL impedes flow at least to some extent. The lesion diagnostic system 100 is configured to determine whether the degree of occlusion is great enough to indicate that balloon angioplasty, a stent, or other catheter intervention should be performed.

[0018]

[0028] Lesion diagnostic system 100 can include a monitor assembly 104 configured to be coupled to a pressure guidewire 108. In one embodiment, lesion diagnostic system 100 includes a connection (indicated by dashed line A) that facilitates connection and disconnection of monitor assembly 104 to pressure guidewire 108. Connection and disconnection from monitor assembly 104 is useful to allow a clinician to use pressure guidewire 108 to initially assess the effect of an occluded OCL on flow distal to it in the left anterior descending artery LAD (or other coronary vessel) and later use pressure guidewire 108 to deliver a therapeutic device, such as a balloon catheter or stent delivery system.

[0019]

[0029] A connection indicated by dashed arrow A may also couple a pressure sensing component of a guide catheter assembly 128 with the monitor assembly 104. The guide catheter assembly 128 may include a tubular catheter body used to access the vascular system. The distal tip of the guide catheter assembly 128 may be positioned, for example, proximal to an occluded OCL such that a pressure signal corresponding to pressure proximal to the occluded OCL in the aorta may be obtained. The proximal pressure may be referred to herein as Pa.

[0020]

[0030] The pressure guidewire 108 may take any suitable form. In one embodiment, the pressure guidewire 108 includes a proximal segment having a proximal end located outside the patient's body and a distal end that may be within the guide catheter assembly 128. The intermediate portion of the pressure guidewire 108 may be configured to have flexibility to navigate the tortuous vasculature of the left anterior descending artery LAD (or other coronary vessel) while maintaining structural integrity. The distal portion may include a sensor housing and an atraumatic tip. Any sensing modality may be used. For example, an optical sensor may be configured to sense pressure when exposed to blood in the left anterior descending artery LAD (or other coronary vessel). The optical sensor may be disposed within an interior space of the pressure guidewire 108 in fluid communication with the exterior of the pressure guidewire 108. The optical sensor can be selectively positioned to communicate with the monitor assembly 104 by a fiber optic signal line disposed between the sensor and a proximal end of the pressure guidewire 108 configured to be coupled with a fiber optic interface cable (not shown), which may include a guidewire connector for connecting the pressure guidewire 108 with the rest of the system. Further details of the optical sensor-based configuration of the pressure guidewire 108 can be found in U.S. Patent Application Publication No. 2015 / 0057532, which is incorporated herein by reference in its entirety.

[0021]

[0031] When the pressure guidewire 108 is configured with an optical sensor, the ability to provide a robust optical connection with the monitor assembly 104 is of interest. Any suitable connection structure or method can be used. One approach is described in detail in U.S. Patent No. 9,405,078, which is incorporated herein by reference in its entirety.

[0022]

[0032] FIG. 2 illustrates the signal data flow more specifically. The clinician attending to the patient places the guide catheter assembly 128 into the vasculature and places the pressure guidewire 108 through the guide catheter assembly 128 into the vasculature. The pressure guidewire 108 provides a signal to a processor 152, which processes the signal to determine a Pd value. The processor 152 also receives a Pa value from a guide catheter signal processor 156. The Pd and Pa signals are processed within the processor 152 to generate a value of dPRc (as described further below). These values ​​may be displayed in a dPRc value window 144. A signal trace window 148 may also be provided to display traces of Pa, Pd, dPRc, and / or any metrics combined with dPRc (described below). The processor 152, the processor 152, and other processors that may be located within the monitor assembly 104 or elsewhere in the system 100 may be separate or combined into a single entity.

[0023] II. Exemplary Methodology A. Metrics that combine heart rate segment analysis with whole heart rate data

[0033] Improved analysis of a patient may combine data from segments of a cardiac cycle with data including the entire cardiac cycle over one or more consecutive cardiac cycles.

[0024] 1. Heart Rate Segment Metrics - Diastolic Pressure Ratio (dPR) Calculation

[0034] In one technique, heartbeat segment data is included as part of a multi-beat analysis of patient status. Diastolic Pressure Ratio (dPR) calculation is an example of a heartbeat segment metric. The dPR value for a given heartbeat is determined by the average value of the ratio of distal pressure (Pd) to proximal pressure (Pa) with a diastolic pressure ratio zone (dPR zone) as shown in Equation 1. As an example, Pd can be measured distal to the occluded OCL and Pa can be measured proximal to the occluded OCL. Pd and Pa can also be measured in an unoccluded vessel segment.

number

[0025]

[0035] As mentioned above, Pd is the pressure measured distal to the occluded OCL and is based on the pressure sensed by the pressure guidewire 108. Pa can be measured by any suitable means, such as the guide catheter 128. A separate pressure wire or other pressure sensing device may also be used to measure Pa.

[0026]

[0036] FIG. 3 illustrates that in one technique, the dPR value is calculated based on a pressure signal generated at or during a dPR zone 200. The dPR zone 200 corresponds to a segment of a heartbeat as illustrated in FIG. 3. The dPR zone 200 can extend from or away from any of several distinct portions of the heartbeat signal. In one embodiment, the dPR zone 200 is found within a first heartbeat 204. The dPR zone 200 can end before a second heartbeat 208. The second heartbeat 208 is immediately following the first heartbeat 204. The dPR zone 200 can be defined between a dicrotic notch 220 and an end-diastolic 224 position. FIG. 3 illustrates that the time length of the dPR zone 200 is less than the time of a beat length 210. The beat length 210 can be defined as the length of time between the systolic onset of the first heartbeat 204 and the systolic onset of the second heartbeat 208.

[0027]

[0037] A new dPR value may be obtained for each detected heart beat, for example, the first heart beat 204, the second heart beat 208, and, as further described below, the third heart beat 304, the fourth heart beat 308, and the fifth heart beat 312.

[0028] 2. PTC(B) calculation

[0038] The patient analysis may include whole beat and beat segment data. For example, a Pulse Transmission Coefficient (PTC) value may be obtained using the following method.

[0029]

[0039] First, calculate the ratio of Pd to Pa. The ratio can be calculated as the average distal pressure during all beats (Pd) divided by the average proximal pressure during all beats (Pa). This value can be calculated using Equation 2, shown below.

number

[0030]

[0040] The Pd and Pa values ​​that are combined into the averages may be samples taken according to a sampling frequency such as 125 Hertz. Figure 4 shows that the samples may be taken throughout the first heartbeat 204. For example, the samples used to calculate these averages may be taken from just after end diastole 222 of the beat prior to the first heartbeat 204 (sometimes referred to herein as X0_EoD) to end diastole 224 of the first heartbeat 204 (sometimes referred to herein as X1_EoD).

[0031]

[0041] Any suitable technique for identifying end diastole of the beat prior to the first heartbeat 204 and end diastole 224 of the first heartbeat 204 may be used. For example, analysis of the pressure signal itself from the pressure guidewire 108, the guide catheter assembly 128, or both of these devices may be used to detect EoD. End diastole 222 for the prior beat may also be calculated by subtracting the beat length (however calculated) from end diastole 224 (however determined).

[0032]

[0042] If available, the ECG signal can be used to detect these end diastole stages with other techniques.

[0033]

[0043] A value for the metric that includes the heartbeat segment data and the total heartbeat data can then be provided. In one technique, a value called PTC(B) can be calculated as the ratio of the heartbeat segment data to the total heartbeat data according to Equation 3:

number

[0034]

[0044] This value may be calculated after the end of the first heart beat 204, and may be calculated for subsequent heart beats, as discussed further below.

[0035] 3. PTC(B)med calculation

[0045] 5-6 illustrate further calculations of values ​​that consider not only beat segment data and whole beat data, but also data from multiple beats. As explained further below, multi-beat metrics can include different numbers of consecutive beats depending on the test being performed.

[0036]

[0046] In one embodiment, the multi-beat metric 300 is calculated as a median value of, for example, four consecutive PTC(B) values ​​weighted based on the beat-to-beat length of the corresponding heartbeat. In another embodiment, the multi-beat metric associated with the pullback procedure described below in connection with FIG. 8A is calculated as a median value of, for example, two consecutive PTC(B) values ​​weighted based on the beat-to-beat length of the corresponding heartbeat. This value may be referred to herein as PTC(B)med. The purpose of this weighted median is to minimize the effect of unstable signals, such as arrhythmias or other artifacts, on metrics including the PCT(B) value. One metric described below that includes PTC(B)med is the dPRc value.

[0037]

[0047] One approach for calculating PTC(B)med involves the following steps: For each cardiac period there is a PTC(B)i value (PTC(B)1, PTC(B)2, ..., PTC(B)N) and a period length Li (L1, L2, ..., LN). See Fig. 5. PTC(B)med is the weighted median taken for all PTC(B)i. The weight for a PTC(B)i corresponds to its cardiac cycle (Li). See Fig. 6. In this way, PTC(B)med is stable enough with some PTC(B) corresponding to shorter beats than others. In Fig. 5, values ​​PTC(B)1 and PTC(B)3 correspond to shorter cardiac cycles and values ​​PTC(B)2 and PTC(B)4 correspond to longer cardiac cycles.

[0038]

[0048] In one methodology for static measurements, a new PTC(B)med is calculated for each beat using all four consecutive preceding beats. In another method of the pullback procedure described below in connection with FIG. 8A, a new PTC(B)med is calculated for each beat using all two consecutive preceding beats.

[0039] 4. dPRc calculation - static measurement

[0049] Some analyses may provide metrics that combine heartbeat segments spanning multiple beats with whole-beat data. One example of this type of metric is dPRc. The dPRc value is calculated as the ratio of the average Pd to the average Pa over a period corresponding to the duration of four consecutive heartbeats used to calculate PTC(B)med, multiplied by the previously obtained PTC(B)med value. dPRc may be calculated according to Equation 4:

number

[0040]

[0050] In this formula, L_dPRc may be calculated as the sum of the lengths in time of the beats used to calculate the current PTC(B)med value. One static measurement protocol uses four consecutive beats.

[0041]

[0051] Calculating the dPRc over a multiple beat (e.g., 4 beat) period provides good stability in the dPRc results. It also provides a very rapid, continuous, or rapid and continuous stream of new dPRc values. This rapid stream of data is useful for measuring status over time.

[0042]

[0052] For very stable signals, the dPR and dPRc results are similar or even identical, however, for unstable signals such as arrhythmias, the dPRc results are more reliable than the discrete dPR values, which can potentially vary significantly.

[0043]

[0053] FIG. 7 shows how to determine the end points (labeled x1 and x2) at which the pressure average multibeat ratio is calculated. x2 is the position of the current sample, and x1 is obtained by subtracting L_dPRc from x2, where L_dPRc is the sum of the beat durations used in calculating PTC(B)med. In the illustrated case, L_dPRc=L1+L2+L3+L4. Because a delay is required to detect any beat (analyzing many samples), there is always a delay between x2 and the last beat detected.

[0044]

[0054] 9-13 show how the foregoing may be displayed on the signal trace window 148 or in another portion of the user interface 140 of the monitor 104. In each figure, the Pa and Pd traces are displayed and labeled. At any given time, the value of Pd is generally lower than the value of Pa if an occluded OCL is impeding flow downstream of it. The blue vertical lines above the traces represent separate heart beats. The horizontal lines below the traces labeled "dPR" correspond to each dPR zone 200.

[0045]

[0055] FIG 9 shows a first portion of an analysis of pressure data from the pressure guidewire 108 and guide catheter assembly 128. The initial portion includes the rising pressure associated with systole and the decreasing pressure associated with the onset and initial portions of diastole in a first heartbeat 204. FIG 9 shows only a portion of the first heartbeat 204. FIG 10 shows the first heartbeat 204, the second heartbeat 208, and the third heartbeat 304. For each beat, a dPR value can be calculated as described above in the corresponding dPR zone 200.

[0046]

[0056] FIG. 11 shows the first, second, and third beats and the fourth beat 308. After the first beat 204, the second beat 208, the third beat 304, and the fourth beat 308 have been detected and analyzed, a dPRc or another multi-beat metric combining segment and full beat data can be calculated for these four beats. The user interface 140 can be configured to include a dPRc trace window 150 to display the dPRc or another multi-beat metric combining segment and full beat data. FIG. 10 shows that before enough consecutive beats are detected, a zero value can be displayed for dPRc and no trace is presented in the dPRc trace window 150. After four (or another sufficient number of beats) have been detected and analyzed, the dPRc trace window 150 can be modified to display one or both of a dPRc value and a dPRc trace, as shown in FIG. 11.

[0047]

[0057] 12 shows how the user interface 140 indicates that the analysis of dPRc is updated for the fifth or subsequent consecutive beat. A new dPRc value is calculated based on the first beat 204, the third beat 304, the fourth beat 308, and the fifth beat 312. The new dPRc value is generated according to the same protocol as above, where the PTC(B) median is the weighted median of the second, third, fourth, and fifth beats, and the pressure ratio multiplier in Equation 4 is based on the new period of L_dPRc as the sum of the beat lengths (the sum of L1, L2, L3, and L4) of the second beat 208, the third beat 304, the fourth beat 308, and the fifth beat 312. The new dPRc value and / or dPRc trace is updated in the dPRc trace window 150 on the user interface 140. 13 illustrates further calculation of the dPRc metric later in time using the third heart beat 304, the fourth heart beat 308, the fifth heart beat 312, and the sixth heart beat 316. Again, the new dPRc value and / or dPRc trace is updated in the dPRc trace window 150 on the user interface 140.

[0048]

[0058] Based on the analysis, a threshold can be established above which the patient is not treated and below which treatment such as angioplasty or stenting is performed. As shown in Figures 14 and 15, both dPRc assessment and treatment can be performed on the pressure guidewire 108. By updating the dPRc value over time, the user can see the stability of the metric and gain confidence in the next clinical step, such as whether to treat with a balloon, stent, or other method. Also, the output in the dPRc trace window 150 can be updated at the same rate that the Pa and Pd samples are taken, for example, every 8 ms based on a sampling rate of 125 Hertz. In some cases, the screen can be updated less frequently but still much faster than every second, for example, 30 times per second. This protocol effectively provides a continuous stream of data, for example, updated more frequently than every heartbeat, updated more than once per second, updated more than twice per second, updated more than five times per second, updated more than ten times per second, updated more than 50 times per second, updated more than 100 times per second.

[0049] 5. dPRc Calculation – Pullback Measurement

[0059] While the above has focused primarily on static position measurements, i.e., measurements made with at least the pressure guidewire 108 stationary, another mode involves acquiring pressure data and analyzing the data while at least the pressure guidewire 108 is moving. Generally, the movement of the guidewire 108 provided is in a proximal direction from a distal location within the vasculature toward a proximal location adjacent the distal end of the guide catheter assembly 128. This movement may be provided by the clinician directly manually pulling back on the pressure guidewire 108 or by using a device configured to generate controlled proximal movement.

[0050]

[0060] 8 shows one embodiment of the pullback mode analysis. In this example, dPRc is calculated by Equation 4.

number

[0051]

[0061] However, one difference is that PTC(B)med may be based on the last three beats. And, L_dPRc is the average duration of the three beats (e.g., first beat 204A, second beat 208A, and third beat 304A) used to calculate PTC(B)med. In other words, the first term in Equation 4 is the average distal pressure over time L_dPRc divided by the average proximal pressure over time L_dPRc. FIG. 8 shows a window between x1 and x2 that goes back in time of the current pressure sample data by the amount of L_dPRc.

[0052]

[0062] FIG. 8A illustrates another technique for performing the analysis in pullback mode. This technique is similar to that of FIG. 8, except as described differently below. Here, two beats (204A, 208A) are used in calculating PTC(B)med. This value is multiplied by the ratio of Pd / Pa, calculated as represented in Equation 4. However, in this calculation, L_dPRc is the sum of the periods of the two beats, shown as the time between X1 and X2. This can be calculated as the time between the start of systole of beat 204A and the time of systole of beat 304A. The window for calculating Pd / Pa shifts in time with each new sample, for example, every 8 milliseconds. The value of L_dPRc can be calculated each time a new value of PTC(B)med is calculated, for example, after the end of each complete beat. One advantage of the approach described in connection with FIG. 8A is that it provides a faster response time than approaches that require more than one beat to present a pullback mode value. If a more stable value is desired, more beats can be used, as in the method of FIG. 8. Another advantage of the algorithm described in connection with FIG. 8A is that it involves similar calculations as used in the static or still mode, but uses two beats instead of four as used in the static or still mode.

[0053]

[0063] The above-described approach to dPRc provides a rapid stream of data over time that provides greater clarity for the pullback mode.

[0054] B. Advantages

[0064] The use of an average of multiple ratios of Pd to Pa has been discussed above as part of calculating useful vascular occlusion assessment metrics. Averaging these ratios provides advantages. For example, whenever noise is present, the average of the ratios is more accurate than other methods of combining multiple measurements, such as calculating the ratio of the average of multiple distal pressure measurements to the average of multiple proximal pressure measurements. This is especially true whenever Pa exhibits large pressure excursions caused by pressure tube movement or other similar noise sources.

[0055]

[0065] The dPRc method, including the calculation of PTC(B)med, allows for reliable dPR calculation without the need to analyze and remove any data associated with a heartbeat that may in some way actually be irregular. Thus, the method can be performed without the need to predetermine any criteria that would justify removing or discarding data associated with an irregular heartbeat.

[0056]

[0066] In the pullback technique, a faster stream of data is available, allowing for a faster response and therefore improved spatial resolution of the dPRc measurement.

[0057] term

[0067] As used herein, the relative terms "proximal" and "distal" are intended to be defined from the perspective of a user of the system, such that proximal refers to a direction toward the user of the system and distal refers to a direction away from the user of the system.

[0058]

[0068] Conditional language such as "can," "could," "might," or "may," unless specifically stated otherwise or understood otherwise within the context in which it is used, is generally intended to convey that certain embodiments include certain features, elements, and / or steps, but not other embodiments. Thus, such conditional language does not generally imply that features, elements, and / or steps are in any way required for one or more embodiments.

[0059]

[0069] Terms such as "comprising," "including," "having," and the like are synonymous and are used in an open-ended, inclusive manner and do not exclude additional elements, features, acts, operations, etc. Also, the term "or," when used to connect, for example, a list of elements, is used in its inclusive sense (and not its exclusive sense) so that the term "or" means one, some, or all of the elements in the list.

[0060]

[0070] As used herein, the terms "approximately," "about," "generally," and "substantially" refer to an amount close to the stated amount that still performs the desired function or achieves the desired result. For example, the terms "approximately," "about," "generally," and "substantially" can refer to an amount that is within less than 10% of the stated amount, as the context may dictate.

[0061]

[0071] Ranges disclosed herein also encompass any and all overlaps, subranges, and combinations thereof. Terms such as "up to," "at least," "greater than," "less than," "between," and the like, are inclusive of the recited numbers. Numbers preceded by terms such as "about" or "approximately" are inclusive of the recited number. For example, "about 4" includes "4."

[0062]

[0072] Any methods disclosed herein do not have to be performed in the order recited. Methods disclosed herein include specific actions taken by a practitioner, but may also include any third-party command of those actions, either explicitly or implicitly. For example, an action such as "distally move a locking element" includes "commanding distal movement of the locking element."

[0063]

[0073] Although specific embodiments and examples are described herein, it will be understood by those skilled in the art that many aspects of the humerus assembly shown and described in this disclosure may be combined differently and / or modified to form yet other embodiments or acceptable examples. All such modifications and variations are intended to be included herein within the scope of the present disclosure. A wide variety of designs and approaches are possible. No feature, structure, or step disclosed herein is essential or essential.

[0064]

[0074] Some embodiments have been described in connection with the accompanying drawings. However, it should be understood that the drawings are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to the actual dimensions and layout of the devices shown. Components can be added, removed, and / or rearranged. Furthermore, any particular features, aspects, methods, properties, characteristics, qualities, attributes, elements, etc. disclosed herein in connection with various embodiments can be used in all other embodiments described herein. In addition, it will be recognized that any method described herein can be practiced using any device suitable for performing the recited steps.

[0065]

[0075] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. It should be understood that not all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, one skilled in the art will recognize that the present disclosure may be embodied or performed in a manner that achieves one advantage or group of advantages as taught herein, without necessarily achieving other advantages as may be taught or suggested herein.

[0066]

[0076] Furthermore, although exemplary embodiments have been described herein, the scope of any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and / or alterations will be understood by those skilled in the art based on this disclosure. Any limitations in the claims should be interpreted broadly based on the language used in the claims and not limited to the examples described herein or during the prosecution of this application, which examples should be interpreted as non-exclusive. Furthermore, the actions of the disclosed processes and methods may be modified in any manner, including by rearranging actions and / or inserting additional actions and / or deleting actions. Accordingly, it is intended that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the full scope of the claims and their equivalents.

Claims

1. A system for assessing vascular status, comprising: a pressure sensing catheter configured to be positioned at a proximal location within the patient's vasculature; a pressure guidewire configured to be positioned at a distal location within the vasculature, the distal location being distal to the proximal location; One or more hardware processors: detecting a heartbeat of the patient while the pressure sensing catheter and the pressure guidewire are positioned at the proximal and distal locations within the vasculature; calculating a diastolic pressure ratio (dPR) value, including calculating an average of multiple ratios of proximal pressure (Pa) to distal pressure (Pd) taken over time within a dPR zone; Calculate the beat-to-beat pressure ratio as the ratio of the mean distal pressure value (Pd) over all beats divided by the mean proximal pressure value (Pa) over all beats; calculating a multi-beat metric including the dPR value and the beat-to-beat pressure ratio; one or more hardware processors configured to output the multi-beat metric; Including, the system.

2. The system described in claim 1, wherein the one or more hardware processors are configured to calculate a total heartbeat pressure ratio using samples from the systolic and diastolic phases of at least two consecutive heartbeats.

3. The one or more hardware processors are [Equation 1] The system of claim 1 , configured to calculate the multibeat metric according to:

4. The system described in claim 1, wherein the one or more hardware processors are configured to detect heartbeats by analyzing continuous signals from at least one of the pressure guidewire and the pressure sensing catheter.

5. The system of claim 1, wherein the one or more hardware processors are configured to locate the dPR zone by identifying the dicrotic notch position and the end of diastolic position from analysis of the signals from at least one of the pressure sensing catheter and the pressure guidewire.

6. The one or more hardware processors: [Equation 2] 2. The system of claim 1, configured to calculate the dPR value for the heart beat as:

7. The one or more hardware processors: [Equation 3] The system of claim 1 , configured to calculate the beat-to-beat pressure ratio as:

8. The one or more hardware processors: [Equation 4] The system of claim 1 , configured to calculate the multi-beat metric by calculating a median value for multiple consecutive heartbeats of

9. The system described in claim 8, wherein the median is based on four consecutive heartbeats.

10. The multi-beat metric is [Equation 5] 10. The system of claim 9, wherein L_dPRc is calculated as: L_dPRc = L_dPRc + ..., where L_dPRc is the time corresponding to the sum of the periods of four consecutive heartbeats.

11. The system described in claim 8, wherein the median is based on two or three consecutive heartbeats.

12. The multi-beat metric is [Equation 6] 2. The system of claim 1, wherein L_dPRc is calculated as: L_dPRc = L_dPRc + ...

13. The multi-beat metric is [Equation 7] 2. The system of claim 1, wherein L_dPRc is calculated as: L_dPRc = L_dPRc + ..., where L_dPRc is the time corresponding to the sum of the periods of two consecutive heartbeats.

14. A monitor assembly comprising: a user interface; One or more hardware processors: Detecting the patient's heartbeat; calculating a diastolic pressure ratio (dPR) value, including calculating an average of multiple ratios of proximal pressure (Pa) to distal pressure (Pd) taken over time within a dPR zone; Calculate the beat-to-beat pressure ratio as the ratio of the mean distal pressure value (Pd) over all beats divided by the mean proximal pressure value (Pa) over all beats; calculating a multi-beat metric including the dPR value and the beat-to-beat pressure ratio; one or more hardware processors configured to output the multi-beat metric; Includes the monitor assembly.

15. A monitor assembly as described in claim 14, wherein the one or more hardware processors are configured to calculate a beat-to-beat pressure ratio using pressure measurement samples from the systolic and diastolic phases of at least two consecutive heartbeats.

16. The one or more processors are configured to: [Equation 8] 15. The monitor assembly of claim 14, configured to calculate the multi-beat metric according to:

17. A monitor assembly as described in claim 14, wherein the monitor assembly is configured to be connected to a pressure guide wire.

18. A monitor assembly as described in claim 14, wherein the monitor assembly is configured to receive data from a pressure sensing component of a guide catheter assembly.

19. A monitor assembly as described in claim 14, wherein the user interface is configured to display a signal trace window showing the proximal pressure (Pa) and the distal pressure (Pd).

20. A monitor assembly as described in claim 14, wherein the user interface is configured to display the multi-beat metrics.

21. A method for operating a system for assessing vascular status, comprising: processing, by a processor, the signals provided to said processor to determine one or more blood pressure values ​​at a first location within the patient's vasculature; receiving at the processor a signal indicative of one or more blood pressure values ​​at a second location within the vasculature of the patient; detecting, by the processor, a heart rate of the patient from one of the one or more blood pressure values ​​at the first location, the one or more blood pressure values ​​at the second location, or the blood pressure values ​​at the first location and the second location; Locating, by the processor, a diastolic pressure ratio (dPR) zone within a heartbeat; calculating, by the processor, a dPR value comprising calculating an average of multiple ratios of blood pressure values ​​at the second location to blood pressure values ​​at the first location taken over time within the dPR zone; calculating, by the processor, a beat-to-beat pressure ratio as the ratio of the mean blood pressure value at the first location during all beats divided by the mean blood pressure value at the second location during all beats; calculating, by the processor, multi-beat metrics over one or more consecutive heartbeats including the dPR value and the beat-to-beat pressure ratio; displaying, by the processor, the multibeat metric for a user; A method comprising:

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