| Enhanced external counterpulsation(EECP)is a non-invasive assisted circulation method triggered by an electrocardiographic signals that compresses the human lower body in the diastole of the heart,which can be used for the treatment of ischemic cardiovascular and cerebrovascular diseases.Clinical observations have shown that EECP provides acute therapeutic benefit and improves ischemic condition of cardiovascular and cerebrovascular vessels by significantly increasing diastolic blood pressure(DBP)and blood perfusion.It is explained as global hemodynamic effects of EECP.After a long-term application of EECP to human body,it improves the local hemodynamic environment by acting on the pathology of vascular endothelial cells(VECs),thereby providing a therapeutic effect.It is explained as local hemodynamic effects of EECP.At present,the global indicators of diastolic/systolic blood pressure(Q=D/S≥1.2)are mostly used to evaluate the efficacy of clinical EECP.However,as important factors affecting the long-term treatment of atherosclerosis,local hemodynamic effects of EECP on VECs cannot be evaluated for the cardiovascular and cerebrovascular system.This has led to significant individual differences in the longterm treatment of patients,resulting in poor efficacy of EECP in patients with cardiovascular and cerebrovascular diseases.Therefore,this thesis qualitatively and quantitatively investigated the global and local hemodynamic effects of EECP on coronary arteries and cerebral arteries based on the 0D/3D coupled geometric multiscale hemodynamic models.Then we established evaluation models of the local hemodynamic effects in patients with coronary heart disease and ischemic stroke,which can provide technical solutions to optimize counterpulsation treatment strategies and improve the long-term efficacy of EECP.In addition,the treatment strategies of EECP for different degrees of cardiovascular and cerebrovascular lesions and the efficacy of different counterpulsation frequencies are unknown.In this study,we qualitatively and quantitatively investigated the global and local hemodynamic effects of EECP on coronary and cerebral arteries with different stenosis and the effects of EECP under different counterpulsation frequencies.With the optimal hemodynamic effects as optimization target,the clinical treatment strategy of EECP for ischemic cardiovascular and cerebrovascular diseases can be optimized.The specific research work is as follows:1.The evaluation models of local hemodynamic effects of EECP in patients with coronary heart disease and ischemic stroke.Local hemodynamic effects affecting longterm efficacy of EECP are important factors in the long-term treatment of atherosclerosis,but they currently cannot be measured clinically.We established 0D/3D geometric multi-scale hemodynamic models of coronary and cerebral arteries of two individuals to calculate the global and local hemodynamic effects of EECP of 18 different counterpulsation modes(i.e.,different pressurization amplitude and pressurization duration).Based on the curve fitting method,the quantitative relationship between clinically measurable global hemodynamic indicators and clinically unmeasurable local hemodynamic indicators was established,so as to establish the evaluation models of local hemodynamic effects in patients with coronary heart disease and ischemic stroke.Based on the global indicators,we can evaluate the local hemodynamic efficacy of EECP in real time,thereby assessing the long-term efficacy of EECP.For coronary heart disease and cerebral ischemic stroke,the local hemodynamic effects of the current counterpulsation mode can be evaluated based on D/S and internal carotid artery flow,mean arterial pressure and cerebral blood flow,respectively.2.The hemodynamic effects of EECP on coronary arteries and cerebral arteries with different stenosis.Currently,the hemodynamic effects of EECP in coronary artery disease and cerebral ischemic stroke are not clear.And especially for patients with different stenosis,there is a lack of optimal treatment strategy.In this study,the 0D/3D multi-scale models of coronary arteries and cerebral arteries with different stenosis were established.Numerical simulations of EECP hemodynamics were carried out under different counterpulsation modes to quantify each hemodynamic indicator of coronary arteries and cerebral arteries.After collecting and analyzing the results of cerebral hemodynamic indicators,we proposed the optimal treatment strategies for different stenotic coronary and cerebral arteries.The results indicated that if the WSS of the cerebral vessel during counterpulsation was taken as optimization target,the pressurization duration should be appropriately prolonged with higher stenosis of cerebral arteries,thereby optimizing the efficacy of counterpulsation.For coronary heart disease,with the WSS of the coronary vessel during counterpulsation as optimization target,the pressurization amplitude should be appropriately increased with higher stenosis of coronary arteries,and thus the efficacy of counterpulsation can be optimized.3.The hemodynamic effects of different counterpulsation frequencies of EECP on coronary and cerebral arteries.At present,the common counterpulsation mode of EECP devices in clinical practice is to apply counterpulsation to the body per cardiac cycle.However,the hemodynamic effects of different counterpulsation frequencies of EECP are unknown.In this study,the global and local hemodynamic effects of different counterpulsation frequencies(i.e.,applying counterpulsation during single-cardiac cycle,two-cardiac cycle and three-cardiac cycle)on coronary and cerebral arteries were simulated based on 0D/3D coupled geometric multi-scale models.The results showed that for cerebral arteries,the hemodynamic effects of applying counterpulsation during two-cardiac cycle and three-cardiac cycle were superior to those of the single-cardiac cycle counterpulsation mode.For coronary arteries,the hemodynamic effects of applying counterpulsation during single-cardiac cycle and three-cardiac cycle were close and weaker than those of the two-cardiac cycle counterpulsation mode.Therefore,for EECP treatment in patients with cerebral ischemic stroke,two-cardiac cycle counterpulsation and three-cardiac cycle counterpulsation modes can be used to improve the treatment effect.For EECP treatment in patients with coronary artery disease,two-cardiac cycle counterpulsation mode can be used to improve the treatment effect.In summary,this study qualitatively and quantitatively investigated the global and local hemodynamic effects of different counterpulsation modes on coronary and cerebral arteries.The evaluation models of local hemodynamic effects in patients with coronary heart disease and cerebral ischemic stroke were established.Based on the global indicators,the evaluation models can assess the local hemodynamic effects of EECP under the current counterpulsation mode in real time.Moreover,the hemodynamic effects of EECP on different stenotic coronary and cerebral arteries were investigated.The optimal treatment strategies for different stenotic coronary and cerebral arteries were proposed respectively.Finally,the hemodynamic effects of different counterpulsation frequencies of EECP on coronary and cerebral arteries were investigated.The results demonstrated that applying counterpulsation during multicardiac cyclewas superior to that during single-cardiac cycle.The multi-cardiac cycle counterpulsation mode can be used to improve the EECP treatment effect.The local hemodynamic effects of EECP can be improved by optimizing counterpulsation mode on coronary and cerebral arteries with WSS 4-7 Pa as the optimization target.It may solve the problem that the efficacy of EECP on ischemic cardiovascular and cerebrovascular diseases varies with different individuals.Hence,it not only provides theoretical reference and support for the optimization of clinical treatment strategies and the improvement of clinical efficacy of EECP,but also has potential clinical application value. |
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