A coronary artery FFR measurement system based on blood flow velocity monitoring device

Abstract

The present invention discloses a coronary artery FFR measurement method based on a blood flow velocity monitoring device, comprising the following steps: obtaining a target coronary artery; setting a blood flow velocity monitoring device at the entrance position of the target coronary artery; reading the blood flow velocity detected by the blood flow velocity monitoring device; obtaining the entrance blood pressure of the coronary artery, and calculating the FFR value in combination with the blood flow velocity; the present invention can quickly and accurately obtain the blood flow velocity by setting the blood flow velocity monitoring device at the target position of the blood vessel, and the time efficiency of the detection is high due to the fast transmission speed of the electrical signal, and at the same time, a heat insulation layer is set at the position of the measuring head to prevent the heat sensitive layer from being taken away during the heating process or before entering the blood vessel, so that the calculation result of the blood flow velocity is more accurate, and the measurement result of the FFR is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of biomedical engineering, and in particular to a coronary artery FFR measurement system based on a blood flow velocity monitoring device. Background Art

[0002] The coronary artery is a series of blood vessels wrapped around the surface of the human heart, mainly transporting blood and energy for the heart. Because of its crown-like shape, it is called the coronary artery, or coronary vein for short. Whether the blood in the coronary artery can flow normally will directly affect the blood circulation of the entire heart, and it is also one of the important criteria for judging coronary heart disease.

[0003] The fractional flow reserve, or FFR for short, is an important indicator for judging the smoothness of blood flow in the coronary arteries. It refers to the ratio of the maximum blood flow that can be obtained in the myocardial area supplied by the blood vessel to the maximum blood flow that can be obtained in the same area under normal conditions in theory when there is a stenotic lesion in the coronary artery, that is, the ratio of the mean pressure in the stenotic distal coronary artery (Pd) under the state of maximum myocardial hyperemia to the mean pressure at the entrance of the coronary artery (Pa). Currently, the FFR value is mainly obtained by clinical doctors using a pressure guidewire to intervene in the human coronary artery. Currently, not many doctors have mastered this method, and this measurement method is expensive and has certain risks.

[0004] In recent years, several non-invasive FFR measurement methods have been developed, such as radionuclide imaging, magnetic resonance perfusion, CT non-invasive blood flow reserve fraction measurement (i.e., FFR-CT), and DSA-based FFR measurement (i.e., QFR). Among these methods, the first two are still traditional methods and are highly dependent on equipment. For example, radionuclide imaging requires SPECT equipment, and magnetic resonance perfusion requires magnetic resonance equipment, and the detection costs are very high. The latter two methods have only been developed recently, especially QFR, which was first approved for use in China last year. In addition, other technologies such as a method for determining coronary artery FFR are also included, such as the invention disclosed in publication number CN108992057A.

[0005] FFR-CT was first obtained by the American company Heartflow in 2014 and obtained the FDA certificate in the United States. It is based on the images of CT coronary angiography (CTA for short), simulates the blood flow of coronary arteries, and simulates the main cardiovascular indicators of the human body, such as blood pressure, blood flow velocity, coronary artery blood flow reserve fraction, etc., for post-processing of clinical quantitative analysis. Its process method is to first obtain CTA images in the CT room, then process the CTA images, reconstruct the three-dimensional structure of the coronary artery, and then mesh and mathematically model the three-dimensional structure, and finally submit some boundary conditions to the supercomputer for calculation to obtain the FFR value of each coronary artery.

[0006] However, in the existing FFR calculation methods, the blood flow velocity values ​​obtained have large errors, resulting in inaccurate calculated FFR values.

[0007] For example, Chinese patent CN202011233059.7 discloses a low-error coronary artery blood flow reserve fraction measurement method. It calculates the FFR value by combining CTA and DSA, but the blood flow velocity obtained is still estimated, and the accuracy is not high. Summary of the invention

[0008] The present invention mainly solves the problem in the prior art that the blood flow velocity in the blood vessels cannot be accurately obtained, resulting in large errors in the accuracy of blood flow reserve fraction measurement; a coronary artery FFR measurement system based on a blood flow velocity monitoring device is provided, which uses the blood flow velocity monitoring device to accurately obtain the blood flow velocity and reduce the calculation error of FFR.

[0009] The above technical problems of the present invention are mainly solved by the following technical solutions: A coronary artery FFR measurement system based on a blood flow velocity monitoring device, comprising the following steps: obtaining a target coronary artery; setting a blood flow velocity monitoring device at the entrance of the target coronary artery; reading the blood flow velocity detected by the blood flow velocity monitoring device; obtaining the entrance blood pressure of the coronary artery, and calculating the FFR value in combination with the blood flow velocity. The present invention sets a blood flow velocity monitoring device at the entrance of the target coronary artery to obtain the blood flow velocity intuitively and accurately. Compared with the traditional method of first obtaining the length of the blood vessel and then calculating the blood flow velocity by obtaining the blood flow time through the contrast agent, it has better accuracy, effectively reduces the calculation error, and obtains a more accurate FFR measurement value.

[0010] Preferably, the blood flow velocity monitoring device includes a measuring probe, a guide wire and a signal receiving end; the measuring probe is inserted into the blood vessel of the coronary artery and performs heat exchange with the blood after being energized; one end of the guide wire is connected to the measuring probe, and the other end of the guide wire is connected to the signal receiving end, for transmitting the conductive current and the voltage signal of the measuring probe; the signal receiving end is used to calculate the blood flow velocity based on the change degree of the voltage signal fed back by the measuring probe. The blood flow velocity is measured in the form of heat driven by the liquid flow rate and thus causing the temperature change of the thermosensitive material, which is more accurate than the traditional contrast agent to calculate the blood flow velocity, and there will be no calculation error caused by vascular tributaries.

[0011] Preferably, the measuring probe comprises a substrate and a measuring head connected to the substrate, the substrate is connected to the guide wire, an insulating layer is arranged on the surface of the substrate, and the measuring head is provided with a powered mandrel, a thermosensitive layer and an insulating jacket from the inside to the outside. The powered mandrel conducts electricity to the thermosensitive layer, so that the thermosensitive layer generates heat.

[0012] Preferably, the measuring head further comprises a heat-insulating layer, the heat-insulating layer wraps the insulating jacket, a permanent magnet is arranged on the inner wall of the heat-insulating layer, an electromagnet is arranged on the outer wall of the insulating jacket, and the electromagnet is attracted to the permanent magnet after being energized so that the heat-insulating layer is fixed on the insulating jacket. The heat-insulating layer is provided to prevent the heat-sensitive layer from being taken away by heat during the heating process or before entering the blood vessel, thereby further reducing the calculation error of the blood flow velocity and improving the accuracy of the result.

[0013] Preferably, it further comprises an elastic connecting line, through which the heat insulating layer is connected to the substrate, and the elastic connecting line is provided to prevent the heat insulating layer from flowing into the blood vessel.

[0014] Preferably, the process of obtaining the designated coronary artery entrance blood pressure includes: obtaining the dynamic blood pressure at the coronary artery entrance through a blood pressure monitor, and generating a dynamic blood pressure time variation waveform diagram based on the dynamic blood pressure variation data with the cardiac cycle. The existing technology for measuring dynamic blood pressure at the coronary artery entrance is already very mature, but in order to improve the accuracy of subsequent calculations, this solution superimposes the cardiac cycle variation data, and can obtain a dynamic blood pressure time variation waveform diagram by multiple measurements and recordings, thereby improving the measurement accuracy of FFR.

[0015] Preferably, the process of calculating the FFR value includes: using the dynamic blood pressure value as the proximal blood pressure Pa, using the blood flow velocity Vi detected by the blood flow velocity monitoring device as the distal blood flow velocity, calculating the distal blood pressure Pd according to the Navier-Stokes equation, and then obtaining the target coronary FFR value = Pd / Pa. Based on the distal blood pressure value and the proximal blood pressure value, an accurate FFR measurement value is obtained.

[0016] Preferably, the signal receiving end calculates the blood flow velocity by: obtaining the resistance change of the thermistor layer according to the change of the voltage signal, obtaining the temperature change according to the material coefficient of the thermistor layer, and obtaining the blood flow velocity according to the temperature change based on the hot wire thermal film method. The hot wire thermal film method is often used to measure the thermal conductivity or flow velocity of a fluid, and the flow velocity is determined by using the solution of the thermal convection equation. Blood is a type of fluid. The present invention uses the hot wire thermal film method to detect blood flow velocity, which has unexpected effects in the medical field. It can accurately obtain the blood flow velocity without affecting the blood vessels.

[0017] The beneficial effects of the present invention are as follows: by arranging a blood flow velocity monitoring device at a target position of a blood vessel, the blood flow velocity can be obtained quickly and accurately, and because the transmission speed of the electrical signal is fast, the time efficiency of the detection is high. At the same time, an insulating layer is arranged at the position of the measuring head to prevent the heat sensitive layer from being taken away during the heating process or before entering the blood vessel, so that the calculation result of the blood flow velocity is more accurate, and the measurement result of the FFR is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 4 is a flow chart of the FFR measurement method according to an embodiment of the present invention.

[0019] Figure 2 Schematic diagram of the structure of a blood flow velocity monitoring device according to an embodiment of the present invention.

[0020] Figure 3 Schematic diagram of the structure of the measuring probe according to the embodiment of the present invention.

[0021] In the figure, 1 is a signal receiving end, 2 is a guide wire, 3 is a measuring probe, 4 is a substrate, 5 is a measuring head, 6 is a thermal insulation layer, 7 is a permanent magnet, 8 is an electromagnet, and 9 is an elastic connecting wire. DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the technical solution in the embodiments of the present invention is further described in detail through the following embodiments and in combination with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0024] Embodiment: A coronary artery FFR measurement system based on a blood flow velocity monitoring device, such as Figure 1 As shown, the following steps are included:

[0025] S1: Acquire the target coronary artery; the specific process is: using CTA coronary angiography and performing three-dimensional reconstruction, a three-dimensional simulation image of any target coronary artery can be obtained.

[0026] S2: A blood flow velocity monitoring device is set at the entrance of the target coronary artery; Figure 2 As shown, the blood flow velocity monitoring device includes a measuring probe 3, a guide wire 2 and a signal receiving end 1; the measuring probe is inserted into the blood vessel of the coronary artery and performs heat exchange with the blood after being energized; one end of the guide wire is connected to the measuring probe, and the other end of the guide wire is connected to the signal receiving end, which is used to transmit the conductive current and the voltage signal of the measuring probe; the signal receiving end is used to calculate the blood flow velocity based on the change degree of the voltage signal fed back by the measuring probe and the guide wire is provided with a powered core shaft and an insulating layer from the inside to the outside.

[0027] like Figure 3 As shown, the measuring probe includes a substrate 4 and a measuring head 5 connected to one end of the substrate, the other end of the substrate is fixedly connected to the guide wire, an insulating layer is provided on the surface of the substrate, and a powered core shaft is provided inside, the measuring head is provided with a powered core shaft, a thermistor layer, an insulating jacket and a thermal insulation layer 6 from the inside to the outside, a conductive wire for connecting to the powered core shaft is provided on the thermistor layer, the thermal insulation layer wraps the insulating jacket, a permanent magnet 7 is provided on the inner wall of the thermal insulation layer, an electromagnet 8 is provided on the outer wall of the insulating jacket, and the electromagnet is attracted to the permanent magnet after being energized so that the thermal insulation layer is fixed on the insulating jacket, and the thermal insulation layer is connected to the substrate through an elastic connecting line 9.

[0028] The shape of the measuring head is cylindrical, and the round end is the head that enters the blood vessel. The round head can effectively prevent damage to the inner wall of the blood vessel. The cylindrical measuring head and the guide wire are inserted into the interior of the blood vessel entrance. The signal receiving end energizes and heats the thermistor layer. The thermistor layer generates a voltage signal according to the current flowing through it, and its resistance value changes linearly according to the temperature. During this process, the electromagnet is always in a powered-on state and attracts the permanent magnet, so that the thermal insulation layer is effectively insulated. When the thermistor layer is powered on, the electromagnet is powered off, and the electromagnet and the permanent magnet are no longer attracted, so that the thermal insulation layer changes with the blood. The blood flows away from the measuring head, but the thermal insulation layer is always connected to the substrate under the traction of the elastic connecting line. The blood flow acts on the thermosensitive layer and takes away the heat of the thermosensitive layer. After the heat of the thermosensitive layer changes, the resistance changes linearly, causing the voltage values ​​at both ends to change linearly accordingly, and the changed voltage signal is transmitted to the signal receiving end through the energized core shaft. The signal receiving end has command output capability and signal processing capability, such as a single-chip microcomputer. The signal receiving end calculates and displays the blood flow velocity according to the set program, or does not display it and directly transmits it to the FFR measurement terminal.

[0029] S3: Read the blood flow velocity detected by the blood flow velocity monitoring device; the method for calculating the blood flow velocity at the signal receiving end is: obtain the resistance change of the thermistor layer according to the change of the voltage signal, obtain the temperature change according to the material coefficient of the thermistor layer, and obtain the blood flow velocity according to the temperature change based on the hot wire thermal film method.

[0030] The hot wire and hot film method of the present invention utilizes the thermal convection equation to measure the flow velocity, wherein the thermal convection equation is H=A+B√U, wherein H represents heat dissipation, A and B are constants, and U is the flow velocity. The blood flow velocity is obtained by mapping the obtained voltage change signal with the temperature change. Since the transmission speed of the electrical signal is very fast, the obtained blood flow velocity is an instantaneous velocity, which has a strong timeliness and improves the accuracy of the obtained blood flow velocity.

[0031] S4: Obtain the blood pressure at the entrance of the coronary artery, and calculate the FFR value in combination with the blood flow velocity; the process of obtaining the designated coronary entrance blood pressure includes: obtaining the dynamic blood pressure at the entrance of the coronary artery through a blood pressure monitor, and generating a dynamic blood pressure time change waveform diagram based on the data of the dynamic blood pressure changing with the cardiac cycle.

[0032] The process of calculating the FFR value includes: using the dynamic blood pressure value as the proximal blood pressure Pa, the blood flow velocity Vi detected by the blood flow velocity monitoring device as the distal blood flow velocity, calculating the distal blood pressure Pd according to the Navier-Stokes equation, and then obtaining the target coronary FFR value = Pd / Pa.

[0033] The FFR measurement terminal obtains the blood flow velocity transmitted by the signal receiving end and the dynamic blood pressure time change waveform transmitted by the blood pressure monitor, and calculates the distal blood pressure Pd using the Navier-Stokes equation, where the Navier-Stokes equation is:

[0034]

[0035] in, is the stress tensor of the flow field, is the gradient operator, t is the time variable, I is the unit matrix, express The transpose of f is the source term, which is gravity here, u represents the blood flow velocity, p f is the blood flow pressure, ρ f is the blood density, μ is the viscosity coefficient of blood, Ωf is the fluid calculation area, are the inlet and outlet boundaries of the fluid computational domain. f is defined in the entire fluid calculation area, so the p obtained by the above formula f Includes the blood pressure value Pd at the distal end of the blood vessel.

[0036] The present invention can quickly and accurately obtain the blood flow velocity by arranging a blood flow velocity monitoring device at the target position of the blood vessel, and the time efficiency of the detection is high due to the fast transmission speed of the electrical signal. At the same time, a heat insulation layer is arranged at the position of the measuring head to prevent the heat sensitive layer from being taken away during the heating process or before entering the blood vessel, so that the calculation result of the blood flow velocity is more accurate, and the measurement result of FFR is more accurate.

[0037] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A coronary artery FFR measurement system based on a blood flow velocity monitoring device, characterized in that: The following steps are involved: Acquire the target coronary artery; A blood flow velocity monitoring device is arranged at the entrance of the target coronary artery. The blood flow velocity monitoring device comprises a measuring head. The measuring head is provided with a thermosensitive layer, an insulating outer jacket and a heat insulating layer from the inside to the outside. A permanent magnet is arranged on the inner wall of the heat insulating layer. An electromagnet is arranged on the outer wall of the insulating outer jacket. The electromagnet is attracted to the permanent magnet after being energized. The blood flow velocity is obtained according to the temperature change of the thermosensitive layer based on the hot wire thermal film method. reading the blood flow velocity detected by a blood flow velocity monitoring device; The inlet blood pressure of the coronary artery is obtained as the proximal blood pressure, and the distal blood pressure is calculated in combination with the blood flow velocity, and then the target coronary FFR value is obtained.

2. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 1, characterized in that: The blood flow velocity monitoring device comprises a measuring probe, a guide wire and a signal receiving end; The measuring probe is inserted into the blood vessel of the coronary artery and performs heat exchange with the blood after being energized; One end of the guide wire is connected to the measuring probe, and the other end of the guide wire is connected to the signal receiving end, so as to transmit the conductive current and the voltage signal of the measuring probe; The signal receiving end is used to calculate the blood flow velocity according to the change degree of the voltage signal fed back by the measuring probe.

3. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 2, characterized in that: The measuring probe comprises a substrate and a measuring head connected to the substrate, the substrate is connected to the guide wire, an insulating layer is arranged on the surface of the substrate, and the measuring head is provided with an energized core shaft, a thermal sensitive layer and an insulating jacket from the inside to the outside.

4. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 3, characterized in that: The measuring head also includes a heat insulation layer, which wraps an insulating jacket. A permanent magnet is arranged on the inner wall of the heat insulation layer, and an electromagnet is arranged on the outer wall of the insulating jacket. When the electromagnet is energized, it attracts the permanent magnet to fix the heat insulation layer on the insulating jacket.

5. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 4, characterized in that: It also includes an elastic connecting line, and the thermal insulation layer is connected to the substrate via the elastic connecting line.

6. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 1, 2, 3 or 4, characterized in that: The process of obtaining the designated coronary artery entrance blood pressure includes: obtaining the dynamic blood pressure at the coronary artery entrance through a blood pressure monitor, and generating a dynamic blood pressure time variation waveform diagram based on the data of the dynamic blood pressure variation with the cardiac cycle.

7. A coronary artery FFR measurement system based on a blood flow velocity monitoring device according to claim 6, characterized in that: The process of calculating the FFR value includes: using the dynamic blood pressure value as the proximal blood pressure Pa, using the blood flow velocity Vi detected by the blood flow velocity monitoring device as the distal blood flow velocity, calculating the distal blood pressure Pd according to the Navier-Stokes equation, and then obtaining the target coronary FFR value = Pd / Pa.

8. The coronary artery FFR measurement system based on the blood flow velocity monitoring device according to claim 3, characterized in that: The method for calculating the blood flow velocity at the signal receiving end is: obtaining the resistance change of the thermosensitive layer according to the change of the voltage signal, obtaining the temperature change according to the material coefficient of the thermosensitive layer, and obtaining the blood flow velocity according to the temperature change based on the hot wire thermal film method.

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