Effect evaluation method, system and storage medium for external counterpulsation treatment of coronary heart disease

Abstract

The invention relates to the technical field of external counterpulsation, and in particular to an effect evaluation method, system and storage medium for treating coronary heart disease with external counterpulsation. The method comprises the following steps: obtaining a plurality of physiological parameters of a person to be evaluated through a monitoring device, wherein the plurality of physiological parameters include blood viscosity of the person to be evaluated, blood flow generated by the heart's own pulsation, cardiac cycle, blood vessel radius, pressure holding time, ejection time, and the ratio of counterpulsation pressure to systolic pressure; calculating the coronary artery wall shear stress of the person to be evaluated according to a formula; and evaluating the effect of treating coronary heart disease with external counterpulsation according to the calculated coronary wall shear stress. The invention analyzes the hemodynamic changes during the external counterpulsation process, divides the shear stress into a cardiac origin part and a counterpulsation part, calculates a cardiac output model through an impedance cardiogram, establishes a calculation relationship between the wall shear force of a microscopic hemodynamic indicator and a D / S value, and provides hemodynamic support for the scientific nature of the evaluation indicator.

Description

Technical Field

[0001] The present invention relates to the technical field of external counterpulsation, and in particular to a method, system and storage medium for evaluating the effect of external counterpulsation in treating coronary heart disease. Background Art

[0002] Counterpulsation is a method of assisting circulation by mechanically lowering the systolic blood pressure and increasing the diastolic blood pressure in the aorta to assist the heart in doing work, improve blood circulation, and increase blood perfusion to the heart, brain, kidneys and other organs. Counterpulsation increases the blood supply to the coronary arteries by increasing the diastolic pressure of the aorta, rescues the ischemic myocardium, and improves the heart's pumping function. Commonly used counterpulsation methods include intra-aortic balloon counterpulsation and external counterpulsation.

[0003] EECP is a method of non-invasive external compression of the lower body to relieve and eliminate angina symptoms and improve the hypoxic-ischemic state of important organs. It is also a medical device used to prevent and treat cardiovascular and cerebrovascular diseases. The common balloon-type EECP device uses balloons wrapped around the limbs and buttocks to inflate and pressurize the balloons during diastole, which drives the blood in the limb arteries back to the aorta, significantly increases diastolic pressure, increases blood flow to the heart, and reduces cardiac afterload; during systole, the balloons are quickly deflated, the pressure is released, and the systolic pressure in the aorta drops, which minimizes the resistance of the heart during ejection, and accelerates the blood flow to the distal end, thereby achieving the counterpulsation effect. The main indications for EECP are coronary heart disease and ischemic stroke. From 2002 to 2006, EECP therapy was successively included in the clinical treatment guidelines for angina pectoris caused by coronary heart disease by the American College of Cardiology, the Chinese Medical Association's Cardiovascular Disease Branch, and the European Society of Cardiology (IIb); in 2013, EECP therapy was included in the American Stroke Guidelines (IIa).

[0004] Generally, whether EECP can fully improve the aortic diastolic blood pressure is one of the key indicators to measure whether it can play an effective role. It is generally required that the ratio (D / S) of the diastolic boost wave (D) and the contraction wave (S) during the treatment process should be greater than 1.2, that is, the therapeutic effect of EECP is judged by the D / S value. However, the D / S value is a macroscopic effect evaluation indicator, and it still has many deficiencies in the effect evaluation of EECP. Since it is difficult to monitor non-invasive and continuous arterial blood pressure under EECP, it is a common practice to use the D / S of the fingertip pulse wave to replace the D / S of arterial blood pressure in clinical treatment of EECP. However, it is difficult to evaluate the actual therapeutic effect of EECP by relying solely on the empirical value of D / S. D / S reflects the perfusion pressure of the blood vessels to a certain extent, but the greater the perfusion pressure, the greater the perfusion flow. At the same time, the blood perfusion volume is only one aspect of the complex hemodynamic changes during EECP, and cannot evaluate the overall EECP process.

[0005] Coronary heart disease is also known as coronary atherosclerotic heart disease. It is a heart disease caused by atherosclerotic lesions in the coronary arteries, which lead to narrowing or blockage of the blood vessel lumen, resulting in myocardial ischemia, hypoxia or necrosis.

[0006] Numerous biomechanical studies have shown that vascular wall shear stress (WSS) has great clinical value for atherosclerosis, cell growth, metabolism, plaque formation and shedding, especially atherosclerosis, which is an important cause of coronary heart disease and stroke (ischemic). According to experimental measurements, the shear stress at the site of atherosclerosis is often below 1.0Pa, while the site with shear stress higher than 1.2Pa is usually not prone to atherosclerosis. Higher shear stress helps inhibit the occurrence of atherosclerosis. EECP quickly squeezes the lower limbs during diastole, increasing blood flow velocity and thus increasing vascular wall shear stress. Therefore, EECP's increase in vascular wall shear stress is the fundamental reason why it can treat coronary heart disease and stroke (ischemic). Summary of the invention

[0007] The purpose of the embodiment of the present invention is to provide a method for evaluating the effect of external counterpulsation in treating coronary heart disease. From the perspective of microscopic hemodynamics, the effect of external counterpulsation in treating coronary heart disease is evaluated by using the shear stress of the vascular wall, providing a new idea for the feedback control and regulation of external counterpulsation.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for evaluating the effect of external counterpulsation in treating coronary heart disease, the method comprising:

[0009] The monitoring device is used to obtain multiple physiological parameters of the subject to be evaluated, including: blood viscosity of the subject to be evaluated, blood flow generated by the heart's own beating, cardiac cycle, blood vessel radius, pressure holding time, ejection time, and the ratio of counterpulsation pressure to systolic pressure;

[0010] The coronary artery wall shear stress of the subject to be evaluated is calculated according to the following formula (1):

[0011]

[0012] Among them, TAWSS EECP,Coronary is the average wall shear stress per unit time of the coronary artery under external counterpulsation, μ is the blood viscosity, SV is the blood flow generated by the heart's own beating, T is the cardiac cycle, R is the vascular radius, T keep is the holding time, LVET is the ejection time, and D / S is the ratio of counterpulsation pressure to systolic pressure;

[0013] To evaluate the effect of external counterpulsation in the treatment of coronary heart disease based on the calculated coronary artery wall shear stress.

[0014] On the other hand, the present invention also provides a system for evaluating the effect of external counterpulsation in treating coronary heart disease. The system includes a processor, and the processor is used to execute the above method.

[0015] In yet another aspect, the present invention further provides a storage medium storing instructions for being read by a machine so as to enable the machine to execute the above method.

[0016] Compared with the prior art, the present invention divides the shear stress into the cardiac origin part and the counterpulsation part on the vascular wall shear stress model by analyzing the changes in hemodynamics during the external counterpulsation process, and then calculates the cardiac output model through the impedance cardiogram to establish the calculation relationship between the microscopic hemodynamic indicator wall shear force and the D / S value, providing hemodynamic support for the scientific nature of the evaluation indicators.

[0017] The method provided by the present invention establishes a calculation relationship between the D / S value, a macroscopic effect evaluation index of traditional extracorporeal counterpulsation, and the microscopic hemodynamic wall shear stress. On the one hand, it illustrates that the D / S value has a certain theoretical basis as a traditional counterpulsation effect evaluation index. On the other hand, it establishes a bridge between macroscopic and microscopic hemodynamic parameters, providing a technical basis for further research on the mechanism of extracorporeal counterpulsation treatment, and also providing new ideas for the later feedback control adjustment of extracorporeal counterpulsation.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It shows a flow chart of effect evaluation of an external counterpulsation treatment for coronary heart disease provided according to a specific embodiment of the present invention;

[0020] Figure 2 Shown is a computational model for vascular wall shear stress;

[0021] Figure 3 The figure shows the changes in the waveform of the impedance cardiopulmonary flow diagram during external counterpulsation. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific embodiments.

[0023] As mentioned above, combined with Figure 1 As shown, the present invention provides a method for evaluating the effect of external counterpulsation in treating coronary heart disease, the method comprising:

[0024] S101, obtaining multiple physiological parameters of the subject to be evaluated through monitoring equipment, wherein the multiple physiological parameters include: blood viscosity of the subject to be evaluated, blood flow generated by the heart's own beating, cardiac cycle, blood vessel radius, pressure holding time, ejection time, and the ratio of counterpulsation pressure to systolic pressure;

[0025] S102. Calculate the coronary artery wall shear stress of the subject to be evaluated according to the following formula (1):

[0026]

[0027] Among them, TAWSS EECP,Coronary is the average wall shear stress per unit time of the coronary artery under external counterpulsation, μ is the blood viscosity, SV is the blood flow generated by the heart's own beating, T is the cardiac cycle, R is the vascular radius, T keep is the pressure holding time, LVET is the ejection time, and D / S is the ratio of counterpulsation pressure to systolic pressure.

[0028] S103. Evaluate the effect of extracorporeal counterpulsation in treating coronary heart disease based on the calculated coronary artery wall shear stress.

[0029] It is known to those skilled in the art that the main reason for the occurrence of atherosclerotic lesions in arteries is the reduction of blood flow shear stress in arterial vessels. At the same time, atherosclerosis is an important cause of cardiovascular and cerebrovascular diseases such as coronary heart disease and ischemic stroke. According to experimental measurements, the shear stress at the site of atherosclerosis is often below 1.0Pa, and the site with shear stress higher than 1.2Pa is usually not prone to atherosclerosis. Higher shear stress helps to inhibit the occurrence of atherosclerosis. Therefore, increasing shear force can prevent related cardiovascular and cerebrovascular diseases caused by atherosclerotic lesions. When squeezing the lower limbs, the blood flow velocity increases, while the blood vessel radius does not change much (except for the direct squeezing site). Therefore, EECP increases the blood flow shear stress of the blood vessels.

[0030] The following is a detailed introduction to the overall concept of the inventor of this application:

[0031] like Figure 2 As shown, the inventor of the present application assumes that the blood vessel is cylindrical, and the calculation formula for the shear stress of the blood vessel wall is:

[0032]

[0033] Among them, τ represents the shear stress WSS of the vascular wall, μ is the blood viscosity, υ is the blood flow velocity in the blood vessel, R is the vascular radius, It is the wall shear rate (WSR).

[0034] In actual clinical studies, it was found that for normal people, the effect of blood viscosity μ on vascular wall shear stress WSS can be ignored. Therefore, although μ is not a constant in theory, current studies use it as a constant for calculation.

[0035] In addition to the definition formula of WSS, assuming that the cross-sectional area of ​​the blood vessel is a standard circle, the following formulas for calculating WSS can be obtained.

[0036]

[0037] Q=V mean S=V mean πR 2 (4)

[0038]

[0039] In addition, in actual clinical environments, the instantaneous wall shear stress of blood vessels is meaningless, so the average wall shear stress per unit time TAWSS (time averaged WSS) is used to express the actual shear stress of blood vessels. Since the blood flow in blood vessels changes periodically according to the heart rate, and the possible backflow during diastole and systole is considered, the absolute value of the instantaneous shear stress is used. The calculation formula of TAWSS is:

[0040]

[0041] Where T is the period of one heart beat, which is 60 / HR. Under resting conditions, the calculation formula for vascular wall shear stress, that is, formula (5), is used to obtain:

[0042]

[0043] Since EECP changes the blood flow in the aorta macroscopically, thereby changing the blood flow in the systemic arterial system, the inventors of the present application first studied the wall shear stress of the aorta. According to the above derivation, the wall shear stress in the aorta is:

[0044]

[0045] Among them, Q is the instantaneous value of blood flow in the blood vessel, SV is the heart rate, T is the cardiac cycle, and when the blood viscosity μ and the blood vessel radius R are assumed to be constant, the average wall shear stress is proportional to the heart rate.

[0046] Under external counterpulsation, counterpulsation blood flow is generated during diastole, so the average wall shear stress TAWSS EECP,A0It is divided into two parts, one is the wall shear stress formed by the flow generated by the heart's own beating, and the other is the wall shear stress formed by the counterpulsation flow, and the two are in opposite directions. The flow generated by the heart's origin is mainly in the period from the opening to the closing of the aortic valve, that is, the ejection period of the heart, while the counterpulsation flow is from the closing of the aortic valve to the opening of the aortic valve in the next cardiac cycle. Simply put, one is in the systolic period of the heart and the other is in the diastolic period of the heart, and there is no intersection between the two.

[0047]

[0048] Among them, Q EECP is the counterpulsation flow generated by the external counterpulsation, Te is the ejection time, SV is the blood flow generated by the heart's own beating, and SV EECP SV is the blood flow generated by one external counterpulsation. EECP The calculation of can use the SV model, except that the ejection time is the external counterpulsation pressure holding time, and the maximum impedance differential is given by (dz / dt) max Replace with (dz / dt) EECP,max .

[0049] In actual clinical practice, the wall shear stress of coronary arteries and cerebral blood vessels is more meaningful. Under EECP, the factors affecting the wall shear stress are the heart's own intrinsic flow and the EECP-generated counterpulsation flow. At the same time, the flow perfused into a specific blood vessel is only a part of the heart's intrinsic flow and the EECP-generated counterpulsation flow.

[0050]

[0051] Among them, k1, k2 are constants, SV part Indicates the fraction of stroke volume, SV EECP,part Represents the portion of flow produced by one external counterpulsation.

[0052] like Figure 3 The waveform of the impedance blood flow diagram during external counterpulsation is shown. According to the cardiac output model, the maximum value of the differential of stroke volume SV and impedance (dz / dt) max , ejection time LVET is proportional, so SV EECP The counterpulsation pressure (dz / dt) on the impedance signal after external counterpulsation EECP,max And holding time T keep Proportional, so there is,

[0053]

[0054] because It is actually (D / S) on the impedance differential signal, so the above expression can be expressed as:

[0055]

[0056] In formula (14), except for k1, k2 and the coronary vessel radius R, the others are measurable parameters or can be considered as constants. According to relevant research, the flow rate of the coronary artery is about 5% of the cardiac output. Therefore, k1 can be taken as 5%.

[0057] Since k2 is the ratio of the additional coronary flow generated by EECP to the counterpulsation flow generated by EECP, the change in coronary flow under EECP is used here to determine the value of k2. According to the study of Michaels et al., in 10 patients treated with EECP, the test results showed that diastolic blood pressure increased from 71±10 mmHg to 136±22 mmHg under EECP; systolic blood pressure decreased from 114±19 mmHg to 101±28 mmHg; the average peak velocity in the coronary artery increased from 11±5 cm / s to 23±5 cm / s (increased by 109%, P=0.001); at the same time, according to the arterial pressure waveform during counterpulsation, the ratio of pressure holding time to ejection time was about 1.2.

[0058] Based on the above data, the D / S value is 1.35 (136 / 101), and the coronary artery flow velocity increases by 109%, which can be considered as a 109% increase in flow (coronary cross-sectional area remains unchanged), T keep / LVET=1.2, so from formula (14), we can know that

[0059]

[0060] Solving equation (15), we can get k2 = 0.034, so equation (14) can be rewritten as equation (1):

[0061]

[0062] In the above formula (1), for the vascular radius R of the coronary artery, considering the characteristics of the coronary artery itself, the coronary artery mainly includes the left main coronary artery (LMCA) and the right coronary artery (RCA). According to the study of Mahadevappa et al., the diameter of the left main coronary artery is 4.08±0.29mm, and the diameter of the right coronary artery is 3.17±0.34mm. The left main coronary artery branches out the left anterior descending branch (LAD) and the left circumflex branch (LCX), and their average inner diameters are 3.39±0.27mm and 3.05±0.37mm, respectively. Considering that the flow rate of the coronary artery is proportional to the cross-sectional area of ​​the coronary artery, the average coronary artery diameter is defined as:

[0063]

[0064] R mean =5.56mm.

[0065] In order to verify the validity of the wall shear force calculation model of the coronary artery under external counterpulsation, the parameters obtained from the relevant research of Beijing University of Technology were used to reconstruct the 3D model of the coronary artery and cerebral artery CTA images of two volunteers without lesions, and the two subjects were subjected to clinical trials of external counterpulsation, and the resting state hemodynamic concentrated parameter modeling was used to simulate the hemodynamic changes of external counterpulsation. Among them, the cardiac cycle is 800ms, the systolic period is 250ms, one of which keeps the pressure holding time unchanged (from 250ms to 600ms), and the other keeps the counterpulsation pressure unchanged (200mmHg), and the pressure holding time gradually increases (starting from 250ms, and the pressure application time point is from 500ms to 600ms), and 18 sets of data are obtained as shown in Table 1 below.

[0066] Table 1 Real-time macroscopic indexes and long-term coronary parameters under external counterpulsation

[0067]

[0068] Based on the data in Table 1 above, the research team of Beijing University of Technology derived an estimation formula for TAWSS, which is negatively correlated with the D / S value and positively correlated with the carotid artery flow. The specific relationship is as follows:

[0069] TAWSS EECP,Coronary =12.933×(D / S) -2 +4.489×In(ICAF)-11.338 (16)

[0070] According to relevant literature, EECP accelerates blood flow velocity and significantly increases arterial shear stress, while the above formula has the maximum wall shear stress in the absence of EECP (D / S minimum), so the above formula cannot fully reflect the relationship between shear stress and macroscopic parameters.

[0071] As can be seen from Table 1 above, when the counterpulsation pressure is increased, both the systolic pressure and the diastolic pressure (the counterpulsation pressure at this time) increase. In some groups of data, the increase in systolic pressure is greater than that in the counterpulsation pressure, which makes the D / S value decrease, but the wall shear stress is still increasing at this time, thus concluding that the wall shear stress is negatively correlated with D / S. However, some studies have shown that systolic pressure will decrease during external counterpulsation treatment, so the conclusions are contradictory. Considering the phase misalignment that affects external counterpulsation: balloon inflation too early or too late, balloon deflation too early or too late. When deflation is too late, the lower limb artery is still squeezed, so that the pressure in the aorta is high at the beginning of the new cardiac cycle, that is, the systolic pressure will increase significantly, which indirectly increases the resistance of the ejection period. Therefore, the above table is the result of the negative correlation between wall shear stress and D / S value due to the late deflation of external counterpulsation.

[0072] Since Group 6 and Group 15 in Table 1 above are two volunteers in the initial stage of counterpulsation (with relatively low systolic blood pressure), these two groups are least affected by late deflation, so these two groups of data are used to verify the validity of formula (1). Among them, blood viscosity μ is taken as 4×10 -3 Pa·s, SV is the corresponding stroke volume, the cardiac cycle is 800ms, and the T of the first subject keep and Te were 250ms and 350ms (600ms-250ms), respectively. The T of the second subject (Group 15) keep and Te are 250ms and 300ms (550ms-250ms) respectively, so:

[0073]

[0074] As above, the coronary artery shear stress under EVCP of Group 6 and Group 15 in Table 1 was calculated using Formula (1), which were 3.09Pa and 4.08Pa, respectively. This is close to the results of 2.94Pa and 4.23Pa given in Table 1, with errors of 5.1% and 3.5%, respectively, which proves the effectiveness and accuracy of using Formula (1) provided by the present invention to calculate the coronary wall shear stress under EVCP.

[0075] At the same time, according to formula (1), increasing the D / S value and increasing the holding time T keep Both can increase the wall shear force, but it should be noted that the pressure holding time should not be too long, otherwise the systolic pressure of the next cardiac cycle will increase significantly, which will cause the heart's ejection resistance to increase significantly in the next cardiac cycle, thereby increasing the heart's work.

[0076] In general, the present invention analyzes the changes in hemodynamics during the external counterpulsation process, divides the shear stress into the cardiac origin part and the counterpulsation part, and then calculates the cardiac output model through the impedance cardiogram to establish the calculation relationship between the microscopic hemodynamic indicator wall shear force and the D / S value, thereby providing hemodynamic support for the scientific nature of the evaluation indicators.

[0077] The formula (1) provided by the present invention establishes a calculation relationship between the D / S value, a macroscopic effect evaluation index of traditional extracorporeal counterpulsation, and the microscopic hemodynamic wall shear stress. On the one hand, it illustrates that the D / S value has a certain theoretical basis as a traditional counterpulsation effect evaluation index. On the other hand, it establishes a bridge between macroscopic and microscopic hemodynamic parameters, providing a technical basis for further studying the mechanism of extracorporeal counterpulsation treatment and providing new ideas for the later feedback control adjustment of extracorporeal counterpulsation.

[0078] The above shows and describes the basic principles, main features and characteristics of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A system for evaluating the effect of external counterpulsation in treating coronary heart disease, characterized in that: The system includes a processor, and the processor is used to execute a method for evaluating the effect of external counterpulsation in treating coronary heart disease; The method comprises: The monitoring device is used to obtain multiple physiological parameters of the subject to be evaluated, including: blood viscosity of the subject to be evaluated, blood flow generated by the heart's own beating, cardiac cycle, blood vessel radius, pressure holding time, ejection time, and the ratio of counterpulsation pressure to systolic pressure; The coronary artery wall shear stress of the subject to be evaluated is calculated according to the following formula (1): Among them, TAWSS EECP,Coronary is the average wall shear stress per unit time of the coronary artery under external counterpulsation, μ is the blood viscosity, SV is the blood flow generated by the heart's own beating, T is the cardiac cycle, R is the vascular radius, T keep is the holding time, LVET is the ejection time, and D / S is the ratio of counterpulsation pressure to systolic pressure; To evaluate the effect of external counterpulsation in the treatment of coronary heart disease based on the calculated coronary artery wall shear stress.

2. A storage medium, characterized in that: The storage medium stores instructions for being read by a machine so as to enable the machine to execute a method for evaluating the effect of external counterpulsation in treating coronary heart disease; The method comprises: The monitoring device is used to obtain multiple physiological parameters of the subject to be evaluated, including: blood viscosity of the subject to be evaluated, blood flow generated by the heart's own beating, cardiac cycle, blood vessel radius, pressure holding time, ejection time, and the ratio of counterpulsation pressure to systolic pressure; The coronary artery wall shear stress of the subject to be evaluated is calculated according to the following formula (1): Among them, TAWSS EECP,Coronary is the average wall shear stress per unit time of the coronary artery under external counterpulsation, μ is the blood viscosity, SV is the blood flow generated by the heart's own beating, T is the cardiac cycle, R is the vascular radius, T keep is the holding time, LVET is the ejection time, and D / S is the ratio of counterpulsation pressure to systolic pressure; To evaluate the effect of external counterpulsation in the treatment of coronary heart disease based on the calculated coronary artery wall shear stress.

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