WO2020098139A1

WO2020098139A1 - Method for calculating instantaneous wave-free ratio and resting diastolic pressure ratio on basis of contrast image

Info

Publication number: WO2020098139A1
Application number: PCT/CN2019/071205
Authority: WO
Inventors: 霍云飞; 刘广志; 吴星云
Original assignee: 苏州润迈德医疗科技有限公司
Priority date: 2018-11-13
Filing date: 2019-01-10
Publication date: 2020-05-22
Also published as: CN111166315B; CN111166315A

Abstract

A method for calculating an instantaneous wave-free ratio and a resting diastolic pressure ratio on the basis of a contrast image, comprising: measuring the pressure Pa of a coronary artery port during diastole; obtaining the two-dimensional diameter and length of a blood vessel by means of a contrast image, generating a three-dimensional blood vessel mesh model by means of two contrast images, and obtaining the three-dimensional diameter and length of the blood vessel; during diastole of the heart, measuring the time taken by blood containing a contrast agent from a start point to an end point of a specified blood vessel, and calculating blood flow velocity V1 according to the measured time and the three-dimensional length of the blood vessel; calculating blood flow velocity V2 in a resting state; using V2 as the flow rate at a coronary artery inlet to calculate a pressure drop ΔP from the coronary artery inlet to a narrow distal end of the coronary artery, wherein the mean pressure within the narrow distal end of the coronary artery is Pd=Pa-ΔP; and calculating to obtain an instantaneous wave-free ratio and a resting diastolic pressure ratio. Thus, iFR, dPR and DFR may be obtained by means of conventional contrast images without using a vasodilator.

Description

Method for calculating instantaneous wave-free ratio and resting diastolic pressure ratio based on contrast image

Technical field

The present invention relates to the field of coronary artery imaging evaluation, and in particular to a method of determining instantaneous wave-free ratio (iFR) and resting diastolic pressure ratio (dPR and DFR) only by contrast image and aortic pressure.

Background technique

The blood flow reserve fraction (FFR) can indicate the influence of coronary stenosis on the distal blood flow, and the diagnosis of myocardial ischemia has become a recognized index for the functional evaluation of coronary stenosis. FFR is defined as the ratio of the maximum blood flow provided by the narrow coronary artery to the myocardium in the innervation area and the maximum blood flow provided to the myocardium when the same coronary artery is normal. It can be simplified to the ratio of the mean intra-coronary artery pressure (P _d ) to the mean aortic pressure (P _a ) in the ostium of the coronary artery in the state of maximum myocardial hyperemia, that is, FFR = P _d / P _a .

When determining FFR, it is necessary to calculate the FFR based on the average blood pressure of the myocardial hyperemia and the average pressure of the coronary aorta at the distal coronary artery through different means. However, the maximum congestion of the myocardium requires intracoronary or intravenous injection of adenosine or ATP. Injection of adenosine or ATP will cause aortic pressure drop and have certain side effects such as atrioventricular block, sinus remission, sinus arrest, etc., contraindications Including 2 degree or 3 degree atrioventricular block, sinus disease, tracheal or bronchial asthma, and adenosine allergy.

The instantaneous waveform-free ratio (iFR) can provide a method for measuring coronary pressure similar to the fractional flow reserve (FFR). iFR does not require vasodilators, is simple to operate, and will be more used in coronary interventional therapy. The ADVISE study found that during a certain period of diastole (called the non-wave period), the intravascular coronary microvascular resistance is relatively stable and the lowest, and during the coronary congestion made with vasodilator drugs such as adenosine The average resistance reached is similar. As shown in Figure 1, iFR = P _{dWave-free period} / P _{aWave-free period} (P _{dWave-free period} : the mean coronary pressure at the distal end of the stenotic lesion during the non-waveform period. P _{aWave-free period} : during the non-waveform period Average aortic pressure. Computation time of the instant non-waveform period: 25% of the time after the start of the non-waveform period in diastole, and 5 ms before the start of the systole. A research article was published in the top medical journal NEJM. In patients with stable angina or acute coronary syndrome, IFR-guided revascularization strategies are not inferior to FFR-guided reconstruction strategies, and major adverse cardiac events occur within 12 months. The rate is similar.

As shown resting diastolic pressure ratio (DPR and DFR) 2 can be represented _{as: dPR = P dDiastolic period / P} aDiastolic period (P dDiastolic period: distal coronary stenosis mean pressure during diastole state _.P aDiastolic _period : the average aortic pressure during diastole); as shown in Figure 3, DFR = _{PdDiastolic hyperemia free period} / _{PaDiastolic hyperemia free period} ( _{PdDiastolic hyperemia} _{free period} : when the aortic pressure is less than the average aortic pressure to the aorta In the interval with the lowest pressure, the average coronary pressure at the distal end of the stenotic lesion. _{PaDiastolic hyperemia free period} : in the interval where the aortic pressure is less than the average aortic pressure to the minimum aortic pressure, the average aortic pressure). Further research shows that the resting diastolic pressure ratio (dPR and DFR) is substantially equivalent to the instantaneous waveform-free ratio (iFR). Therefore, we can get iFR≌DFR≌dPR = P _{dDiastolic period} / P _{aDiastolic period} .

At present, the existing measurement methods of instantaneous wave-free ratio (iFR) and resting diastolic pressure ratio (dPR and DFR) are mainly as follows: the corresponding diastolic interval is measured under the resting state of the pressure guide wire to determine iFR and dPR , DFR. It needs to rely on the pressure guide wire for measurement. The pressure guide wire needs to intervene in the end of the blood vessel, which increases the difficulty and risk of surgery. At the same time, the expensive price of the pressure guide wire also limits its large-scale application.

Summary of the invention

In order to solve the above technical problems, the object of the present invention is to provide a method for calculating the instantaneous wave-free ratio and the resting diastolic pressure ratio based on contrast images to detect myocardial ischemia in patients with coronary heart disease by conventional coronary angiography Circumstances where no vasodilators are needed (ie no myocardial hyperemia and no adenosine or ATP). Calculate the instantaneous wave-free ratio (iFR) and resting diastolic pressure ratio (dPR and DFR) from conventional contrast images, aortic pressure and blood flow.

The technical solution of the present invention is:

A method for calculating instantaneous wave-free ratio and resting diastolic pressure ratio based on contrast image includes the following steps:

S01: blood pressure sensor by measuring the diastolic pressure of coronary port P _a;

S02: Obtain the two-dimensional tube diameter and length of the blood vessel through the contrast image, and generate the three-dimensional blood vessel grid model from the two contrast images at an angle of more than 30 ° and obtain the three-dimensional tube diameter and length of the blood vessel;

S03: During the diastolic phase, measure the time taken by the blood containing the contrast agent from the start point to the end point of a specified blood vessel, and calculate the blood flow velocity V ₁ according to the time and the three-dimensional length of the blood vessel;

S04: According to the following calculation formula, the blood flow velocity V _{2 in the} resting state is calculated, and the calculation formula is:

When V ₁ ≤100mm / s, V ₂ = 0.53 * V ₁ +20;

When 100mm / s <V ₁ ≤200mm / s, V ₂ = 0.43 * V ₁ +35;

When V ₁ > 200mm / s, V ₂ = 0.35 * V ₁ +55;

S05: The state of the blood flow velocity in the contrast calculated as V ₂ coronary inlet velocity, the inlet pressure is calculated coronary artery stenosis drop [Delta] P of the distal end, the distal coronary stenosis mean pressure P _d = P _a - ΔP is calculated by the formula iFR≌DFR≌dPR = P _d / P _{a to} obtain the instantaneous waveless ratio (iFR) and the resting diastolic pressure ratio (dPR and DFR).

In a preferred technical solution, the step S01 includes connecting the pressure tube of the blood pressure sensor to the multi-way tee, and then connecting the coronary ostium of the heart through a contrast catheter, filling the pressure tube of the blood pressure sensor with saline, and maintaining the blood pressure sensor At the same horizontal position as the heart, the pressure wave measured by the blood pressure sensor is the pressure wave of the coronary ostium of the heart, and the average value of the instantaneous pressure during the diastolic period is _Pa .

In a preferred technical solution, the method for generating a three-dimensional blood vessel grid model in step S02 includes the following steps:

S21: Perform 3D reconstruction on the 2D structure data of two segmented blood vessels with a mapping relationship on two X-ray coronary angiography images at an angle of more than 30 ° to obtain 3D structure data of the segmented blood vessel;

S22: Repeat step S21 until the three-dimensional reconstruction of all segmented blood vessels is completed, and then merge the reconstructed segmented blood vessels to obtain a complete three-dimensional blood vessel grid model.

In a preferred technical solution, the specific method for calculating the blood flow velocity V ₁ in step S03 includes the following steps:

S31: Obtain the specified patient's heart rate H times / minute, and obtain the image frequency from the contrast image information as S frames / second. The calculation formula of the number of frames X is as follows: X = (1 ÷ (H ÷ 60)) × S;

S32: Through the number of frames the image traverses during the diastolic period of a heartbeat cycle, obtain the start point and end point of a diastolic period of the heartbeat cycle on the images corresponding to the two-dimensional start frame and end frame, and then pass the start point and end point Point in the three-dimensional vascular grid model to intercept the length of a blood vessel during the diastolic period of the heartbeat cycle;

S33: Through the formula V ₁ = L ÷ P, the blood flow velocity V _{1 is} calculated, L is the length of the blood vessel, P is the time spent in the diastolic phase of a heartbeat cycle, P = X ÷ S.

In a preferred technical solution, the specific method for calculating the pressure drop ΔP from the entrance of the coronary artery to the distal end of the coronary stenosis in the step S05 is as follows:

S41: Solve the basic formula of incompressible flow based on the blood flow velocity and the three-dimensional vascular grid model, solve the three-dimensional vascular grid model, and use numerical methods to solve the continuity and Navier-Stokes equations:

among them

P, ρ, μ are flow velocity, pressure, blood flow density, blood flow viscosity;

The inlet boundary condition is the blood flow velocity, and the outlet boundary condition is the out-flow boundary condition;

S42: Calculate the pressure drop ΔP from the inlet to the downstream points along the center line of the blood vessel.

Compared with the prior art, the advantages of the present invention are:

For patients with coronary heart disease, routine coronary angiography is used to detect myocardial ischemia, that is, without the use of vasodilators (that is, without the maximum congestion of myocardium and without the use of adenosine or ATP). Calculate the instantaneous wave-free ratio (iFR) and resting diastolic pressure ratio (dPR and DFR) from conventional contrast images, aortic pressure and blood flow. There is no need to insert an additional pressure guide wire for measurement. The operation is simple, greatly reducing the difficulty and risk of surgery, and can be widely applied in the clinic.

BRIEF DESCRIPTION

The present invention will be further described below with reference to the drawings and embodiments:

Figure 1 is a schematic diagram of the instantaneous wave-free ratio (iFR) (Instantaneous Wave-Free Ratio); the horizontal axis is the average Pd / Pa during WFP,

Figure 2 is a schematic diagram of resting diastolic pressure ratio (dPR) (Disatolic Pressure Ratio); the horizontal axis is the average Pd / Pa of the entire diastolic period,

Figure 3 is a schematic diagram of the resting diastolic pressure ratio (DFR) (Diastolic Hyperemia Free Ratio); the horizontal axis is the average Pd / Pa for the entire period, between Pa <average value Pa and downhill surface Pa;

4 is a flowchart of the method of the present invention;

Figure 5 is a two-dimensional blood vessel image;

Fig. 61 is an image of the position-contrast agent flowing to the catheter port;

Fig. 62 is an image of the position-contrast agent flowing to the distal end of the blood vessel;

Figure 63 is an image of the second position of the contrast agent flowing to the catheter port;

Figure 64 is an image of the second position of the contrast agent flowing to the distal end of the blood vessel;

Figure 7 is a screenshot of the cross section of the grid;

Figure 8 is a screenshot of the longitudinal section of the grid.

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

As shown in FIG. 4, a method of the present invention for determining instantaneous wave-free ratio (iFR) and resting diastolic pressure ratio (dPR and DFR) only by contrast image and aortic pressure includes the following steps.

Step S1: coronary artery diastolic pressure port P _a, which is specifically as follows by measuring the blood pressure sensor:

The pressure tube using the blood pressure sensor is connected to the multi-way tee, and then connected to the coronary ostium of the heart through the contrast catheter. The pressure tube of the blood pressure sensor is filled with saline and keeping the blood pressure sensor and the heart at the same horizontal position. The pressure wave is the pressure wave of the coronary ostium of the heart, and the average value of the instantaneous pressure during the diastolic period is _Pa .

Step S2: Obtain the two-dimensional diameter and length of the blood vessel from the contrast image, as shown in FIG. 5, and generate the three-dimensional vessel mesh model from the two contrast images at an angle of more than 30 ° and obtain the three-dimensional diameter and length of the blood vessel ;

The specific method of the three-dimensional blood vessel grid model is as follows:

3D reconstruction of the 2D structure data of two segmented blood vessels on two X-ray coronary angiography images at different angles and in a mapping relationship, and obtaining the 3D structure data of the segmented blood vessel;

Repeat the above steps until the three-dimensional reconstruction of all segmented blood vessels is completed, and then merge the reconstructed segmented blood vessels to obtain a complete three-dimensional blood vessel, as shown in FIGS. 7 and 8.

Step S3: As shown in FIGS. 61-64, during the diastolic phase, the blood (including contrast agent) is measured from the start point (61, 63) to the end point (62, 64) of a specified blood vessel (including possible criminal vessels) The time used and the blood flow velocity V ₁ is calculated according to the time and the three-dimensional length of the blood vessel. The specific method is as follows:

Obtain the specified patient's heart rate H times / minute, and the image frequency obtained from the contrast image information is S frames / second. The calculation formula of the number of frames X is as follows: X = (1 ÷ (H ÷ 60)) × S;

Through the number of frames that the image traverses during a diastolic period of a heartbeat cycle, the corresponding images of the two-dimensional start frame and end frame, as shown in Figure 61 and Figure 62 or Figure 63 and Figure 64, respectively, obtain a heartbeat period during the diastolic period Start point and end point, and then use the start point and end point to intercept the length of a diastolic blood vessel in the three-dimensional synthetic data;

Assuming that the length of the intercepted blood vessel is L, and the time taken for a diastolic phase of a heartbeat cycle is P, the blood flow velocity V _{1 is} obtained by formula 1: P = X ÷ S; formula 2: V ₁ = L ÷ P.

Step S4: Calculate the blood flow velocity V _{2 in the} resting state;

The formula for calculating the blood flow velocity V ₂ at rest is as follows:

When V ₁ ≤100 millimeters per second (mm / s), V ₂ = 0.53 * V ₁ +20;

When 100mm / s <V ₁ ≤200mm / s, V ₂ = 0.43 * V ₁ +35;

When V ₁ > 200mm / s, V ₂ = 0.35 * V ₁ +55;

Step S5: Use the blood flow velocity V2 in the contrast state calculated in step S4 as the coronary inlet flow rate, calculate the pressure drop ΔP from the coronary inlet to the distal end of coronary stenosis, and the average pressure in the coronary artery Pd during the diastolic stenosis = Pa-ΔP, and then calculated by the formula iFR≌DFR≌dPR = Pd / Pa to obtain the instantaneous waveless ratio (iFR) and the resting diastolic pressure ratio (dPR and DFR).

The specific method for calculating the pressure drop ΔP from the entrance of the coronary artery to the distal end of the coronary stenosis in step S5 is as follows:

Based on the blood flow velocity and the three-dimensional vascular grid model, the basic formula for incompressible flow is solved, the three-dimensional vascular grid model is solved, and the continuity and Navier-Stokes equations are solved numerically:

among them

Calculate the pressure drop ΔP from the inlet to the downstream points along the center line of the blood vessel.

It should be understood that the above-mentioned specific embodiments of the present invention are only used to exemplarily explain or explain the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

A method for calculating the instantaneous wave-free ratio and the resting diastolic pressure ratio based on contrast images is characterized by the following steps:

S01: blood pressure sensor by measuring the diastolic pressure of coronary port P a;

S02: Obtain the two-dimensional tube diameter and length of the blood vessel through the contrast image, and generate the three-dimensional blood vessel grid model from the two contrast images at an angle of more than 30 ° and obtain the three-dimensional tube diameter and length of the blood vessel;

S03: During the diastolic phase, measure the time taken by the blood containing the contrast agent from the start point to the end point of a specified blood vessel, and calculate the blood flow velocity V 1 according to the time and the three-dimensional length of the blood vessel;

S04: According to the following calculation formula, the blood flow velocity V 2 in the resting state is calculated, and the calculation formula is:

When V 1 ≤100mm / s, V 2 = 0.53 * V 1 +20;

When 100mm / s <V 1 ≤200mm / s, V 2 = 0.43 * V 1 +35;

When V 1 > 200mm / s, V 2 = 0.35 * V 1 +55;

S05: The state of the blood flow velocity in the contrast calculated as V 2 coronary inlet velocity, the inlet pressure is calculated coronary artery stenosis drop [Delta] P of the distal end, the distal coronary stenosis mean pressure P d = P a - ΔP is calculated by the formula iFR≌DFR≌dPR = P d / P a to obtain the instantaneous waveless ratio (iFR) and the resting diastolic pressure ratio (dPR and DFR).
The method for calculating the instantaneous waveless ratio and the resting diastolic pressure ratio based on the contrast image according to claim 1, wherein the step S01 includes connecting a pressure tube using a blood pressure sensor to the multi-way tee, Then it is connected to the coronary ostium of the heart through a contrast catheter, and the pressure tube of the blood pressure sensor is filled with saline, and the blood pressure sensor and the heart are kept at the same horizontal position. The pressure wave measured by the blood pressure sensor is the pressure wave of the coronary ostium of the heart. During diastole, the average value of instantaneous pressure is Pa .
The method for calculating the instantaneous wave-free ratio and the resting diastolic pressure ratio based on the contrast image according to claim 1, wherein the method for generating a three-dimensional blood vessel grid model in the step S02 includes the following steps:

S21: Perform 3D reconstruction on the 2D structure data of two segmented blood vessels with a mapping relationship on two X-ray coronary angiography images at an angle of more than 30 ° to obtain 3D structure data of the segmented blood vessel;

S22: Repeat step S21 until the three-dimensional reconstruction of all segmented blood vessels is completed, and then merge the reconstructed segmented blood vessels to obtain a complete three-dimensional blood vessel grid model.
The method for calculating the instantaneous waveless ratio and the resting diastolic pressure ratio based on the contrast image according to claim 1, wherein the specific method for calculating the blood flow velocity V 1 in step S03 includes the following steps:

S31: Obtain the specified patient's heart rate H times / minute, and obtain the image frequency from the contrast image information as S frames / second. The calculation formula of the number of frames X is as follows: X = (1 ÷ (H ÷ 60)) × S;

S32: Through the number of frames the image traverses during the diastolic period of a heartbeat cycle, obtain the start point and end point of a diastolic period of the heartbeat cycle on the images corresponding to the two-dimensional start frame and end frame, and then pass the start point and end point Point in the three-dimensional vascular grid model to intercept the length of a blood vessel during the diastolic period of the heartbeat cycle;

S33: Through the formula V 1 = L ÷ P, the blood flow velocity V 1 is calculated, L is the length of the blood vessel, P is the time spent in the diastolic phase of a heartbeat cycle, P = X ÷ S.
The method for calculating the instantaneous waveless ratio and the resting diastolic pressure ratio based on the contrast image according to claim 1, wherein in step S05, the pressure drop ΔP from the entrance of the coronary artery to the distal end of the coronary stenosis is calculated The specific method is as follows:

S41: Solve the basic formula of incompressible flow based on the blood flow velocity and the three-dimensional vascular grid model, solve the three-dimensional vascular grid model, and use numerical methods to solve the continuity and Navier-Stokes equations:

among them
P, ρ, μ are flow velocity, pressure, blood flow density, blood flow viscosity;

The inlet boundary condition is the blood flow velocity, and the outlet boundary condition is the out-flow boundary condition;

S42: Calculate the pressure drop ΔP from the inlet to the downstream points along the center line of the blood vessel.