CN115645734A - Method, system and storage medium for evaluating effect of external counterpulsation on coronary heart disease treatment - Google Patents

Abstract

The invention relates to the technical field of external counterpulsation, in particular to an effect evaluation method, a system and a storage medium for treating coronary heart disease by external counterpulsation, wherein the method comprises the steps of obtaining a plurality of physiological parameters of a person to be evaluated by monitoring equipment, wherein the plurality of physiological parameters comprise the blood viscosity of the person to be evaluated, the blood flow generated by the heart beat, the cardiac cycle, the radius of a blood vessel, the pressure maintaining time, the blood ejection time, and the ratio of counterpulsation pressure to systolic pressure; calculating the wall shear stress of the coronary artery of the person to be evaluated according to a formula; evaluating the effect of external counterpulsation on treating coronary heart disease according to the calculated coronary wall shear stress; according to the invention, through analyzing the change of the hemodynamics in the external counterpulsation process, the shear stress is divided into a heart origin part and a counterpulsation part, and then a cardiac output model is calculated through an impedance cardiogram, so that the calculation relation between the wall shear force and the D/S value of the microscopic hemodynamics index is established, and a hemodynamics support is provided for the scientificity of the evaluation index.

Description

Method, system and storage medium for evaluating effect of external counterpulsation on coronary heart disease treatment

Technical Field

The invention relates to the technical field of external counterpulsation, in particular to an effect evaluation method and system for treating coronary heart disease by external counterpulsation and a storage medium.

Background

Counterpulsation is an auxiliary circulation method for reducing the systolic blood pressure and increasing the diastolic blood pressure in the aorta in a mechanical way so as to assist the heart to do work, improve blood circulation and increase blood perfusion of organs such as heart, brain, kidney and the like. The counterpulsation can increase the blood supply of coronary artery by increasing the diastolic pressure of aorta, rescue ischemic myocardium and improve the blood pumping function of heart. Commonly used counterpulsation methods include intra-aortic balloon counterpulsation and extra-corporeal counterpulsation.

The external counterpulsation is a method for non-invasively pressing the lower half body in vitro, relieves and eliminates the symptoms of angina pectoris, improves the anoxic and ischemic states of important organs of the body, and is medical equipment for preventing and treating cardiovascular and cerebrovascular diseases. The common air bag type external counterpulsation device inflates and pressurizes the air bag in the diastole of the heart by the air bag wrapped on the limbs and the hip, so that the blood of the artery of the limb is driven to return to the aorta, the diastolic pressure is obviously increased, the blood flow is increased for the heart, and the afterload of the heart is reduced; the air bag can exhaust air rapidly in the systole, the pressure is relieved, the systolic pressure in the aorta is reduced, the resistance in the cardiac ejection period is relieved to the maximum extent, and the blood flows to the far end in an accelerated way, thereby achieving the counterpulsation effect. The main indications of external counterpulsation are coronary heart disease and ischemic stroke, and the external counterpulsation therapy is successively introduced into the clinical treatment guideline (IIb) of coronary heart disease and angina pectoris by the American heart disease society, the Chinese medical society of cardiovascular diseases and the European heart disease society in 2002-2006; 2013 external counterpulsation was also included in the US guidelines for stroke recommendation (IIa).

Generally, whether the diastolic blood pressure of aorta can be sufficiently increased by external counterpulsation is one of key indexes for measuring whether the diastolic blood pressure can play an effective role, and the ratio (D/S) of a diastolic pressure wave (D) to a systolic wave (S) in the treatment process is generally required to be more than 1.2, namely the treatment effect of the external counterpulsation is judged through the D/S value. However, the D/S value is a macroscopic effect evaluation index, and has many defects in the effect evaluation of the external counterpulsation. Because the monitoring of the non-invasive continuous arterial blood pressure under the external counterpulsation is difficult to realize, the D/S of the fingertip pulse wave is used for replacing the D/S of the arterial blood pressure, which is a common practice for the external counterpulsation clinical treatment, but the actual treatment effect of the external counterpulsation is difficult to evaluate only by depending on the D/S, the D/S reflects the perfusion pressure of the blood vessel to a certain extent, but the larger the perfusion pressure is, the larger the perfusion flow is not represented. Meanwhile, the blood perfusion amount is only one aspect of the complex hemodynamic change in the external counterpulsation process, and the whole external counterpulsation process cannot be evaluated.

Coronary heart disease is coronary atherosclerotic heart disease, and is caused by myocardial ischemia, anoxia or necrosis due to stenosis or obstruction of blood vessel cavity caused by coronary artery angiogenesis atherosclerosis.

Numerous biomechanical studies have shown that vascular Wall Shear Stress (WSS) has significant clinical value for atherosclerosis, cell growth, metabolism, plaque formation and shedding, especially atherosclerosis, which is an important cause of coronary heart disease and stroke (ischemia). As measured by experiments, the shear stress of a part where atherosclerosis occurs is usually below 1.0Pa, while the part where the shear stress is higher than 1.2Pa is generally not easy to cause atherosclerosis, and higher shear stress helps to inhibit the occurrence of atherosclerosis. In vitro counterpulsation rapidly squeezes the lower limbs during diastole, increasing blood flow velocity and thus increasing the shear stress of the vessel wall. Therefore, the external counterpulsation increases the shear stress of the wall surface of the blood vessel, which is the root cause for treating coronary heart disease and cerebral apoplexy (ischemia).

Disclosure of Invention

The embodiment of the invention aims to provide an effect evaluation method for treating coronary heart disease by external counterpulsation, which evaluates the effect of treating coronary heart disease by external counterpulsation through the wall shear stress of a blood vessel from the viewpoint of micro hemodynamics and provides a new idea for feedback control and regulation of external counterpulsation.

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

acquiring a plurality of physiological parameters of a person to be evaluated through a monitoring device, wherein the plurality of physiological parameters comprise: the blood viscosity of a person to be evaluated, the blood flow generated by the heart self-pulsation, the cardiac cycle, the radius of a blood vessel, the pressure maintaining time, the ejection time, and the ratio of counterpulsation pressure to systolic pressure;

calculating the coronary artery wall shear stress of the evaluated person according to the following formula (1):

wherein, TAWSS _{EECP,Coronary} Under the condition of external counterpulsation, the mean wall shear stress of coronary artery per unit time, mu is blood viscosity, SV is blood flow produced by heart self-pulsation, T is cardiac cycle, R is vessel radius, T is blood vessel diameter _keep Is the dwell time, LVET is the ejection time, D/S is the ratio of counterpulsation pressure to systolic pressure;

and evaluating the effect of external counterpulsation on treating the coronary heart disease according to the calculated coronary wall shear stress.

In another aspect, the present invention also provides an effect evaluation system for treating coronary heart disease by external counterpulsation, which comprises a processor for executing the method described above.

In yet another aspect, the present invention also provides a storage medium storing instructions for reading by a machine to cause the machine to perform the above-described method.

Compared with the prior art, the invention divides the shear stress into a heart origin part and a counterpulsation part on a blood vessel wall shear stress model by analyzing the change of the hemodynamics in the external counterpulsation process, then calculates a cardiac output model by an impedance cardiogram, establishes a calculation relation between the wall shear force and the D/S value of the microscopic hemodynamics index, and provides a hemodynamics support for the scientificity of the evaluation index.

The method provided by the invention establishes the calculation relationship between the D/S value of the traditional external counterpulsation macroscopic effect evaluation index and the wall shear stress of the micro-hemodynamics, on one hand, the D/S value is proved to have certain theoretical basis as the traditional counterpulsation effect evaluation index, on the other hand, a macroscopic and micro-hemodynamics parameter bridge is established, a technical basis is provided for further researching the external counterpulsation treatment mechanism, and a new thought is provided for the later external counterpulsation feedback control adjustment.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

FIG. 1 is a flow chart illustrating the evaluation of the effectiveness of external counterpulsation for coronary heart disease treatment according to an embodiment of the present invention;

FIG. 2 shows a computational model of vascular wall shear stress;

fig. 3 shows a graph of the variation of a waveform of a cardiac impedance blood flow graph during external counterpulsation.

Detailed Description

The present invention will be further described with reference to the following embodiments in order to make the technical means, the technical features, the technical purposes and the functions of the present invention easy to understand.

As described above, with reference to fig. 1, the present invention provides a method for evaluating the effect of external counterpulsation on coronary heart disease, wherein the method comprises:

s101, acquiring multiple physiological parameters of a person to be evaluated through monitoring equipment, wherein the multiple physiological parameters comprise: the blood viscosity of a person to be evaluated, the blood flow generated by the heart self-pulsation, the cardiac cycle, the radius of a blood vessel, the pressure maintaining time, the ejection time, and the ratio of counterpulsation pressure to systolic pressure;

s102, calculating the coronary artery wall shear stress of the person to be evaluated according to the following formula (1):

wherein, TAWSS _{EECP,Coronary} Under the condition of external counterpulsation, the mean wall shear stress of coronary artery per unit time, mu is blood viscosity, SV is blood flow produced by heart self-pulsation, T is cardiac cycle, R is vessel radius, T is blood vessel diameter _keep Is the dwell time, LVET is the ejection time, and D/S is the ratio of counterpulsation pressure to systolic pressure.

S103, evaluating the effect of external counterpulsation on treating coronary heart disease according to the calculated coronary wall shear stress.

As known to those skilled in the art, the main reason of atherogenic lesions is the reduction of blood flow shear stress in arterial vessels, and atherosclerosis is an important reason for the formation of cardiovascular and cerebrovascular diseases such as coronary heart disease, ischemic stroke and the like, through experimental measurement, the shear stress of the site with atherogenesis is usually below 1.0Pa, while the site with shear stress higher than 1.2Pa is usually not easy to atherogenesis, and higher shear stress helps to inhibit the generation of atherosclerosis, so that the related cardiovascular and cerebrovascular diseases caused by atherogenic lesions can be prevented by improving the shear stress. External counterpulsation increases the blood flow velocity when pressing against the lower limbs, while the relative change in vessel radius is not large (except at the direct press), and thus, external counterpulsation increases the blood flow shear stress of the vessel.

The general concept of the inventors of the present application is described in detail below:

as shown in fig. 2, the inventors of the present application assume that the blood vessel is cylindrical, and the calculation formula of the wall shear stress of the blood vessel is as follows:

wherein tau represents the shearing stress WSS of the vessel wall, mu is the blood viscosity, upsilon is the blood flow velocity in the vessel, R is the vessel radius,

is the vessel Wall Shear Rate (WSR).

In actual clinical studies, the influence of blood viscosity mu on the wall shear stress WSS of the blood vessel is negligible for normal people. Therefore, while μ is not theoretically a constant, current studies are all calculated with it as a constant.

In addition to the WSS defining formula, assuming that the vessel cross-sectional area is a standard circle, several formulas for calculating WSS can be obtained as follows.

Q＝V _mean S＝V _mean πR ² (4)

In addition, in the actual clinical environment, the instantaneous wall shear stress of the blood vessel has no meaning, so the actual shear stress of the blood vessel is expressed by using the mean wall shear stress per unit time TAWSS (time averaged WSS), and since the blood flow in the blood vessel periodically changes according to the heart rate, and the possible backflow in diastole and systole is considered, the absolute value of the instantaneous shear stress is used, and the calculation formula of the TAWSS is as follows:

wherein, T is the period of one beat of the heart, the size is 60/HR, and under the condition of rest, the calculation formula of the wall shear stress of the blood vessel is substituted, namely the formula (5), and the calculation result is obtained:

since the blood flow in the aorta is changed macroscopically by external counterpulsation, and the blood flow in the systemic arterial system is changed, the inventors of the present application first studied the wall shear stress of the aorta, and according to the above derivation, the wall shear stress in the aorta is:

wherein Q is the instantaneous value of blood flow in the blood vessel, SV is the heart stroke volume, T is the cardiac cycle, and the average wall shear stress is in direct proportion to the heart stroke under the condition that the blood viscosity mu and the blood vessel radius R are considered to be unchanged.

In external counterpulsation, counterpulsation blood flow is generated in diastole, so mean wall shear stress TAWSS _EECP,A0 The device is divided into two parts, one part is wall shear stress formed by flow generated by the self-pulsation of the heart, the other part is wall shear stress formed by counterpulsation flow, and the directions of the two parts are opposite. Wherein the flow originally generated by the heart is mainly in the period from the opening to the closing of the aortic valve, namely the ejection period of the heart, and the counterpulsation flow is from the closing of the aortic valve of the heart to the opening of the aortic valve of the next cardiac cycle. In short, there are no intersecting parts between them, one during systole and one during diastole.

Wherein Q _EECP The counterpulsation flow generated by external counterpulsation, te is the ejection time, SV is the blood flow generated by the heart self-pulsation, SV _EECP Is the counterpulsation blood flow volume, SV, generated by one external counterpulsation _EECP The calculation of (2) can use a model of SV, wherein the ejection time is the external counterpulsation dwell time, and the maximum value of the impedance differential is (dz/dt) _max Replacement by (dz/d)t) _EECP,max 。

In actual clinic, the wall shear stress of coronary vessels and cerebral vessels is more significant. Under the external counterpulsation, the influence on the wall shear stress is the intrinsic flow of the heart and the counterpulsation flow generated by the external counterpulsation. Meanwhile, the flow infused to a specific blood vessel is only a part of the heart intrinsic flow and the external counterpulsation flow,

wherein k is ₁ ，k ₂ Is constant, SV _part Representing a portion of stroke volume, SV _EECP,part Representing a portion of the flow generated by a counterpulsation in vitro.

For example, FIG. 3 shows the waveform change of the cardiac impedance blood flow graph during external counterpulsation, according to the cardiac output model, the stroke volume SV and the impedance differential maximum value (dz/dt) _max The ejection time LVET is proportional, and then SV is present _EECP With counterpulsation pressure (dz/dt) on the impedance signal after external counterpulsation _EECP,max And a dwell time T _keep Is in direct proportion to each other, so that,

due to the fact that

In fact (D/S) on the impedance differential signal _ICG Thus, the above expression can again be expressed as:

formula (14) except k ₁ 、k ₂ And coronary vessel radius R, all of which are measurable parameters or can be considered as a constant, the flow of the coronary artery is about 5% of the cardiac output according to the relevant study, and therefore k1 can take a value of 5%.

Due to k ₂ The new coronary flow rate for external counterpulsation is proportional to the counterpulsation flow rate generated by external counterpulsation, and the change of the coronary flow rate under external counterpulsation is used to determine k ₂ The value of (c). According to the research of Michaels et al, in 10 patients, the external counterpulsation treatment is carried out, and the test result shows that the diastolic pressure is increased from 71 +/-10 mmHg to 136 +/-22 mmHg under the external counterpulsation; the systolic pressure is reduced from 114 plus or minus 19mmHg to 101 plus or minus 28mmHg; mean peak velocity in coronary arteries increased from 11 ± 5cm/s to 23 ± 5cm/s (increase 109%, P = 0.001); meanwhile, the ratio of the pressure holding time to the ejection time can be obtained to be about 1.2 according to the arterial pressure waveform in the counterpulsation process.

Based on the above data, a D/S value of 1.35 (136/101), a coronary flow rate increase of 109%, which can be considered as a flow increase of 109% (unchanged coronary cross-sectional area), and a T _keep /LVET =1.2, and therefore can be seen from formula (14),

k is obtained by solving the formula (15) ₂ =0.034, formula (14) can therefore be rewritten as formula (1):

in the above formula (1), regarding the vessel radius R of the Coronary Artery, the Coronary Artery mainly includes the Left Coronary Artery trunk (LMCA) and the Right Coronary Artery (RCA) in consideration of the characteristics of the Coronary Artery itself, and the diameter of the Left Coronary Artery trunk is 4.08 + -0.29 mm and the diameter of the Right Coronary Artery is 3.17 + -0.34 mm according to the study of Mahadevappa et al, wherein the Left Coronary Artery trunk is divided into the Left Anterior Descending branch (LAD) and the Left Circumflex (LCX) having the average inner diameters of 3.39 + -0.27 mm and 3.05 + -0.37 mm, respectively. Considering that the flow of the coronary arteries is proportional to the coronary cross-sectional area, the mean coronary artery diameter is defined as:

can obtain R _mean ＝5.56mm。

In order to verify the effectiveness of a wall shear force calculation model of coronary artery under external counterpulsation, parameters obtained by related research of Beijing university of industry are used, the CTA image 3D model reconstruction of coronary artery and cerebral artery of two disease-free volunteers is utilized, the two subjects are respectively subjected to external counterpulsation clinical test research, resting state hemodynamic centralized parameter modeling is utilized, and the hemodynamic change of external counterpulsation is simulated. Among them, the cardiac cycle was 800ms and the systolic period was 250ms, one was to keep the dwell time constant (250 ms time point to 600ms time point), and the other was to keep the counterpulsation pressure constant (200 mmHg), and the dwell time was gradually increased (250 ms time point, pressure application time point from 500ms to 600 ms), and 18 sets of data shown in table 1 below were obtained.

TABLE 1 immediate macroscopic index and coronary artery long-term parameter under external counterpulsation

From the data in table 1 above, the research group at Beijing university of industry has derived an estimation formula of TAWSS, which is negatively correlated to the D/S value and positively correlated to the carotid artery flow, and the specific relationship is as follows:

TAWSS _{EECP,Coronary} ＝12.933×(D/S) ^-2 +4.489×In(ICAF)-11.338 (16)

according to related documents, the external counterpulsation accelerates the blood flow speed and obviously improves the arterial shear stress, and the above formula has the maximum wall shear stress under the condition of no external counterpulsation (D/S is minimum), so the above formula cannot completely reflect the relationship between the shear stress and macroscopic parameters.

As can be seen from Table 1 above, when the counterpulsation pressure is increased, the systolic pressure and the diastolic pressure (in this case, the counterpulsation pressure) are both increased, and the amplitude of the increase of the systolic pressure is larger than that of the increase of the counterpulsation pressure in some group data, so that the D/S value is reduced but the wall shear stress is still increased at this time, thereby obtaining that the wall shear stress is inversely related to the D/S. However, several studies have shown that systolic blood pressure is reduced during external counterpulsation treatment, and thus the conclusions are contradictory. Considering the phase dislocation affecting external counterpulsation: early or late inflation of the airbag, and early or late deflation of the airbag. When the patient deflates too late, the artery of the lower limb is still squeezed, so that the pressure in the aorta is higher when a new cardiac cycle begins, the systolic pressure is obviously increased, and the resistance in the ejection period is indirectly increased. Thus, the above table is a result of the negative correlation of wall shear stress with D/S values due to too late external counterpulsation deflation.

Since the 6 th and 15 th groups in table 1 above are the initial status of counterpulsation (relatively low systolic pressure) in two volunteers, respectively, the two groups are least affected by too late deflation, and therefore the two groups of data are taken to verify the validity of equation (1). Wherein the blood viscosity μ is 4 × 10 ^-3 Pa.s, SV corresponding to the amount of beats per heart cycle of 800ms, T of the first subject _keep Te are 250ms and 350ms (600 ms-250 ms), respectively, T of the second subject (group 15) _keep And Te are 250ms and 300ms (550 ms-250 ms), respectively, so that there are:

as above, the coronary artery shear stress under the external counterpulsation of the 6 th group and the 15 th group in table 1 is calculated by using the formula (1), and is respectively 3.09Pa and 4.08Pa, which is relatively close to the results of 2.94Pa and 4.23Pa given by table 1, and the error is respectively 5.1% and 3.5%, thus proving the effectiveness and accuracy of calculating the coronary artery wall shear stress under the external counterpulsation by using the formula (1) provided by the invention.

Meanwhile, according to the formula (1), the D/S value and the pressure holding time T are increased _keep The wall shear force can be increased, but it needs to be noted that the pressure maintaining time cannot be prolonged too much, otherwise, the systolic pressure of the next cardiac cycle is obviously increased, so that the ejection resistance of the heart in the next cardiac cycle is obviously increased, and the work of the heart is increased.

In general, the invention divides the shearing stress into a heart intrinsic part and a counterpulsation part by analyzing the change of the hemodynamics in the external counterpulsation process, then calculates a cardiac output model by a cardiac impedance diagram, establishes a calculation relation between the wall shearing force and the D/S value of the microscopic hemodynamics index, and provides a hemodynamics support for the scientificity of the evaluation index.

The formula (1) provided by the invention establishes a calculation relation between the D/S value of the traditional external counterpulsation macroscopic effect evaluation index and the wall shear stress of the micro-hemodynamic, on one hand, the D/S value is proved to have a certain theoretical basis as the traditional counterpulsation effect evaluation index, on the other hand, a macroscopic and micro-hemodynamic parameter bridge is established, a technical basis is provided for further researching the external counterpulsation treatment mechanism, and a new idea is provided for the later external counterpulsation feedback control adjustment.

The foregoing shows and describes the general principles, essential features, and inventive features of this invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and such changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (3)

1. A method for evaluating the effect of external counterpulsation on coronary heart disease, which is characterized by comprising the following steps:

acquiring a plurality of physiological parameters of a person to be evaluated through a monitoring device, wherein the plurality of physiological parameters comprise: the blood viscosity of a person to be evaluated, the blood flow generated by the heart self-pulsation, the cardiac cycle, the radius of a blood vessel, the pressure maintaining time, the 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 the following formula (1):

wherein, TAWSS _{EECP,Coronary} Under the condition of external counterpulsation, the mean wall shear stress of coronary artery per unit time, mu is blood viscosity, SV is blood flow produced by heart self-pulsation, T is cardiac cycle, R is vessel radius, T is blood vessel diameter _keep Is the dwell time, LVET is the ejection time, D/S is the ratio of counterpulsation pressure to systolic pressure;

and evaluating the effect of external counterpulsation on treating the coronary heart disease according to the calculated coronary wall shear stress.

2. An outcome assessment system for the treatment of coronary heart disease by external counterpulsation, the system comprising a processor for performing the method of claim 1.

3. A storage medium storing instructions for reading by a machine to cause the machine to perform the method of claim 1.

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