A system and method for obtaining coronary artery blood flow reserve fraction

Abstract

The present invention discloses a system and method for acquiring a coronary blood flow reserve fraction, comprising a target coronary acquisition module, for acquiring a target coronary artery vascular model; a blood flow velocity monitoring device, for acquiring the blood flow velocity of the target coronary artery; a proximal blood pressure monitoring device, for acquiring the proximal blood pressure of the target coronary artery, and installed at the entrance of the target coronary artery according to the vascular model of the target coronary acquisition module; the present invention can quickly and accurately obtain the blood flow velocity by arranging the blood flow velocity monitoring device at the target vascular position, and at the same time, arranging a heat insulation layer 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; by calculating the branch blood vessel loss, the monitored blood flow velocity is corrected, so that the blood flow velocity is more in line with reality, and the accuracy of the calculated FFR value is improved.

Description

Technical Field

[0001] The present invention relates to the field of biomedical engineering control technology, and in particular to a system and method for acquiring coronary artery blood flow reserve fraction. 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 system and method for obtaining coronary blood flow reserve fraction are provided, which uses a 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 blood flow reserve fraction acquisition system, including a target coronary artery acquisition module, used to acquire a target coronary artery vascular model; a blood flow velocity monitoring device, used to acquire the blood flow velocity of the target coronary artery; a proximal blood pressure monitoring device, used to acquire the proximal blood pressure of the target coronary artery, installed at the entrance of the target coronary artery according to the vascular model of the target coronary artery acquisition module; a processing module, receiving the blood flow velocity acquired by the blood flow velocity monitoring device and the proximal blood pressure acquired by the proximal blood pressure monitoring device, and calculating the distal blood pressure based on the Navier-Stokes equation, and calculating the blood flow reserve fraction based on the proximal blood pressure and distal blood pressure of the target coronary artery. By setting the blood flow velocity monitoring device at the vascular entrance of the target coronary artery, the blood flow velocity is acquired intuitively and accurately, and the blood flow velocity has better accuracy than the traditional method of first acquiring the vascular length and then obtaining the blood flow time through the contrast agent to calculate the blood flow velocity, effectively reducing the calculation error, and obtaining a more accurate FFR measurement value. The processing module is in a real-time working state, so that the blood flow reserve fraction at every moment can be calculated in real time and quickly, with high efficiency.

[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 proximal blood pressure monitoring device is a blood pressure monitor. Using a blood pressure monitor to monitor proximal blood pressure is more intuitive and accurate.

[0015] A method for obtaining coronary artery blood flow reserve fraction comprises the following steps:

[0016] Acquire a target coronary artery vascular model;

[0017] A blood flow velocity monitoring device is installed according to the target coronary artery vascular model to obtain the blood flow velocity V of the target coronary artery;

[0018] A proximal blood pressure monitoring device is installed according to the target coronary artery vascular model to obtain the proximal blood pressure of the target coronary artery;

[0019] Distal blood pressure is calculated based on blood flow velocity and proximal blood pressure, and the blood flow reserve fraction is calculated based on the proximal and distal blood pressures of the target coronary artery.

[0020] Preferably, the main vessel cross-sectional area and the number of branch vessels of the target coronary artery are obtained according to the target coronary artery model, and the main vessel is divided into several sections according to the difference in the main vessel cross-sectional area, and the difference between the inlet cross-sectional area and the outlet cross-sectional area of ​​each section of the main vessel is equal. The blood flow velocity of each section of the main vessel is measured respectively, and the branch vessel loss amount R=(Vi-Vi+1) / A is calculated, where Vi represents the blood flow velocity of the current main vessel, Vi+1 represents the blood flow velocity of the next section of the main vessel, and A represents the number of branch vessels. The corrected blood flow velocity Vn=VR / Y is calculated according to the branch vessel loss amount, and Y represents the difference in the cross-sectional area between the inlet and outlet of the main vessel. By further correcting the blood flow velocity, the calculation accuracy of the blood flow reserve fraction is improved.

[0021] 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 due to the fast transmission speed of the electrical signal, the time efficiency of the detection is high. 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 the FFR is more accurate; by calculating the loss amount of the branch blood vessel, the monitored blood flow velocity is corrected, so that the blood flow velocity is more in line with reality, and the accuracy of the calculated FFR value is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 4 is a structural block diagram of a system for acquiring coronary blood flow reserve fraction according to an embodiment of the present invention.

[0023] Figure 2 Schematic diagram of the structure of a blood flow velocity monitoring device according to an embodiment of the present invention.

[0024] Figure 3 Schematic diagram of the structure of the measuring probe according to the embodiment of the present invention.

[0025] 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, 9 is an elastic connecting line, 10 is a target coronary artery acquisition module, 11 is a blood flow velocity monitoring device, 12 is a proximal blood pressure monitoring device, and 13 is a processing module. DETAILED DESCRIPTION

[0026] 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.

[0027] Embodiment: A system for obtaining coronary blood flow reserve fraction, such as Figure 1As shown, it includes a target coronary artery acquisition module 10, a blood flow velocity monitoring device 11, a proximal blood pressure monitoring device 12 and a processing module 13. The target coronary artery acquisition module is connected to the blood flow velocity monitoring device and the proximal blood pressure monitoring device respectively, and the blood flow velocity monitoring device and the proximal blood pressure monitoring device are both connected to the processing module. The target coronary artery acquisition module is used to obtain a target coronary artery vascular model. By using CTA coronary angiography and performing three-dimensional reconstruction, a three-dimensional simulation image of the coronary artery of any target can be obtained; the blood flow velocity monitoring device is used to obtain the blood flow velocity of the target coronary artery, and the proximal blood pressure monitoring device is used to obtain the proximal blood pressure of the target coronary artery. The processing module receives the blood flow velocity obtained by the blood flow velocity monitoring device and the proximal blood pressure obtained by the proximal blood pressure monitoring device, and calculates the distal blood pressure based on the Navier-Stokes equation, and calculates the blood flow reserve fraction based on the proximal blood pressure and the distal blood pressure of the target coronary artery.

[0028] like 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.

[0029] 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.

[0030] 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.

[0031] The method for calculating the blood flow velocity at the signal receiving end is: 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.

[0032] The hot wire hot film method of the present invention uses the heat convection equation to measure the flow rate, wherein the heat convection equation is: Among them, H represents heat dissipation, A and B are constants, and U is the flow velocity. The blood flow velocity is obtained by mapping the 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.

[0033] The proximal blood pressure monitoring device is a blood pressure monitor, which obtains the dynamic blood pressure at the entrance of the coronary artery and generates a dynamic blood pressure time change waveform based on the data of dynamic blood pressure changes with the cardiac cycle.

[0034] This embodiment also provides a method for obtaining coronary artery blood flow reserve fraction, comprising the following steps:

[0035] A: Obtain the target coronary artery vascular model.

[0036] B: Install a blood flow velocity monitoring device according to the target coronary artery model to obtain the blood flow velocity V of the target coronary artery; obtain the main vessel cross-sectional area and the number of branch vessels of the target coronary artery according to the target coronary artery model, divide the main vessel into several sections according to the difference in the main vessel cross-sectional area, and the difference between the inlet cross-sectional area and the outlet cross-sectional area of ​​each section of the main vessel is equal. Measure the blood flow velocity of each section of the main vessel respectively, and calculate the branch vessel loss R = (Vi -V i+1 ) / A,V i Indicates the current blood flow velocity of the main blood vessel, V i+1 represents the blood flow velocity of the next main blood vessel, A represents the number of branch blood vessels, and the corrected blood flow velocity Vn=VR / Y is calculated based on the loss of branch blood vessels, where Y represents the difference in cross-sectional area between the inlet and outlet of the main blood vessel.

[0037] C: Install a proximal blood pressure monitoring device according to the target coronary artery vascular model to obtain the proximal blood pressure of the target coronary artery; obtain the instantaneous voltage in real time according to the blood pressure time variation waveform.

[0038] D: Distal blood pressure is calculated based on blood flow velocity and proximal blood pressure, and the blood flow reserve fraction is calculated based on the proximal and distal blood pressures of the target coronary artery.

[0039] The process of calculating the blood flow reserve fraction 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.

[0040] 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:

[0041]

[0042]

[0043]

[0044]

[0045] 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, Γ f inlet , Γ f outlet 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 formulaf Includes the blood pressure value Pd at the distal end of the blood vessel.

[0046] 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 system for obtaining coronary artery blood flow reserve fraction, characterized in that: include: A target coronary artery acquisition module, used to acquire a target coronary artery vascular model; A blood flow velocity monitoring device, used for obtaining the blood flow velocity of a target coronary artery, comprises a measuring probe, a guide wire and a signal receiving end, wherein the measuring probe comprises a substrate and a measuring head connected to the substrate, wherein the measuring head comprises a heat insulating layer, the heat insulating layer wraps an insulating jacket, a permanent magnet is arranged on the inner wall of the heat insulating layer, and an electromagnet is arranged on the outer wall of the insulating jacket; A proximal blood pressure monitoring device, used to obtain the proximal blood pressure of the target coronary artery, is installed at the entrance position of the target coronary artery according to the vascular model of the target coronary artery acquisition module; The processing module receives the blood flow velocity obtained by the blood flow velocity monitoring device and the proximal blood pressure obtained by the proximal blood pressure monitoring device, calculates the distal blood pressure based on the Navier-Stokes equation, and calculates the blood flow reserve fraction based on the proximal blood pressure and the distal blood pressure of the target coronary artery.

2. A system for obtaining coronary artery blood flow reserve fraction 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 system for obtaining coronary artery blood flow reserve fraction 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 system for obtaining coronary blood flow reserve fraction 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 system for obtaining coronary blood flow reserve fraction 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 system for acquiring coronary blood flow reserve fraction according to claim 1, 2 or 3, characterized in that: The proximal blood pressure monitoring device is a blood pressure monitor.

7. A system for obtaining coronary artery blood flow reserve fraction according to claim 1, characterized in that: The main vessel cross-sectional area and the number of branch vessels of the target coronary artery are obtained according to the target coronary artery model. The main vessel is divided into several sections according to the difference in the main vessel cross-sectional area. The difference between the inlet cross-sectional area and the outlet cross-sectional area of ​​each section of the main vessel is equal. The blood flow velocity of each section of the main vessel is measured respectively, and the branch vessel loss R=(V i -V i+1 ) / A, V i Indicates the current blood flow velocity of the main blood vessel, V i+1 It represents the blood flow velocity of the next main blood vessel, A represents the number of branch blood vessels, and the corrected blood flow velocity Vn=VR / Y is calculated based on the loss of branch blood vessels. Y represents the difference in cross-sectional area between the inlet and outlet of the main blood vessel.

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