Hemodynamics Optimization Based Patient-specific Treatment Decision Making For EECP

Enhanced external counterpulsation(EECP)is a non-invasive method that uses cuffs to mechanically compress the human lower body and increase the diastolic blood pressure(DBP).By greatly increasing the aortic DBP,EECP assists heart work,so that increasing the blood perfusion of the organs during diastole,which is clinically significant to the prevention,treatment and rehabilitation for cardiovascular and cerebrovascular ischemic diseases.After the application to the human body,EECP causes the redistribution of blood flow.By increasing the DBP,EECP increases the coronary blood flow and improves the myocardial ischemia.Whereas by increasing the mean arterial pressure(MAP)to increase cerebral perfusion pressure,a high cerebral flow can be maintained to improve the cerebral ischemia.These are the acute hemodynamic effects of EECP.After a long-term application,EECP improves the local hemodynamic environment of target vascular endothelial cells(VECs)to reduce vascular inflammation,protect vascular intima,improve vascular function,and promote benign vascular remodeling.These are the long-term hemodynamic effects of EECP.The improvement of hemodynamics for the ischemic organs caused by both of the acute and the long-term effects are significant to rehabilitation and treatment of cardiovascular and cerebrovascular diseases.However,traditional clinical treatment of EECP only aims at an indicator:diastolic/systolic blood pressure(Q=D/S?1.2).There are a few proofs of the hemodynamic mechanism for this indicator,which leads to some limitations for the scientific treatment of EECP.First of all,an in-depth study on the quantitative mechanism of the hemodynamic effects of EECP is missing.During the process of counterpulsation,the quantitative relationships between the different counterpulsation modes,the redistribution of human blood flow,and the variation of local hemodynamic environment around the diseased vessels are still unclear.Also,there are no specialized treatment strategies of EECP therapy distinguished for different indications,such as coronary heart disease and cerebral ischemic stroke,resulting in insufficient technological innovation in the treatment precision and the varied treatment effects for different diseases.In addition,no patient-specific treatment strategy is designed for each individual,resulting in obvious differences in the treatment benefits of some patients.Therefore,this study quantitatively investigated the cardio-cerebrovascular hemodynamic effects of different counterpulsation modes,and developed specialized and patient-specific treatment strategies of EECP based on optimization of hemodynamic effects for different indications and different individuals.The specific research contents are shown as follows:1.In this study,a closed-loop lumped parameter model(LPM)of blood circulatory system was established to study the macroscopic acute hemodynamic effects of different counterpulsation modes,including variations in the aortic blood pressure and the cardio-cerebrovascular blood perfusion.The model considered the arterial collapse caused by the application of counterpulsation to the lower limb of human body,as well as the neural regulation of the circulatory system,heart,and brain.It was found that the increase in pressure amplitude and the extension of pressurization duration in each cardiac cycle would lead to an increase in the MAP,coronary blood flow,and cerebral blood flow,which was benifit to the improvement of the acute hemodynamic effects for the cardiovascular and cerebrovascular systems.Whereas the effect of pressurization duration was more significant.In addition,the accuracy and effectiveness of the model calculation were verified by comparing the simulation results with the clinical report data.2.By the establishment of 0D/3D coupled geometric multiscale models of coronary arteries and cerebral arteries,this study precisely investigated the variations in the local hemodynamic environment of cardiovascular and cerebrovascular systems during counterpulsation.Mechanical parameters,including wall shear stress(WSS),oscillatory shear index(OSI),etc.,were calculated to demonstrate the long-term hemodynamic effects of EECP by aiming at VECs.It was found that in the counterpulsation state,the WSS after coronary artery stenosis was significantly increased and OSI was decreased,forming a good hemodynamic environment that inhibited the development of atherosclerosis,which was beneficial to promote the benign remodeling of blood vessels.Whereas the results of different counterpulsation modes' influences were similar to the regulation of acute hemodynamic effects.The increase of the pressure amplitude and the extension of the pressurization duration would result in an increase in the WSS,and reduce the OSI of the coronary and cerebral arteries.However,due to the significant impact of pressurization duration,prolonged pressurization duration might result in an excessive time-averaged WSS(TAWSS)of the global coronary arteries,increasing local hemodynamic risk areas.Also,excessive TAWSS at the stenosis might be a risk signal for the plaque rupture.Unlike the coronary arteries,the TAWSS of the global cerebral arteries was in a reasonable range under prolonged pressurization duration.Therefore,for patients with coronary heart disease,it was not recommended to perform a prolonged pressurization duration therapy during each cardiac cycle.The long-term treatment effects could be improved by increasing the pressure amplitude.While for stroke patients,the long-term treatment benefits could be improved by appropriately extending the pressurization duration.3.The long-term effects are important factors for the treatment of EECP,but the mechanical parameters that affect the long-term effects cannot be clinically measured in real time.Therefore,this study carried out clinical experiments and establish mathematical models to evaluate the long-term hemodynamic effects of EECP for different indications,including coronary heart disease and cerebral ischemic stroke.The long-term treatment effects could be evaluated by clinically measurable macroscopic hemodynamic indicators.Based on the geometric multiscale models of coronary arteries and cerebral arteries,this study quantitatively simulated the macroscopic indicators and the hemodynamic parameters that affect the long-term effects under different counterpulsation modes.By the curve fitting of these data,the mathematical models of function mapping were determined,that were,the long-term hemodynamic effects evaluation models of EECP in the treatment of cardiovascular and cerebrovascular diseases.The mathematical models could be used to evaluate the long-term treatment effects of counterpulsation modes in real time by clinically measurable hemodynamic indicators.4.For different patients,this study developed a planning system for patient-specific EECP treatment strategy.Based on the physiological data of 30 cases collected clinically,an individualization algorithm for the LPM of the blood circulatory system was developed for patient-specific hemodynamic simulation of EECP.Combined with the evaluation model of long-term effects,the macroscopic indicators calculated by the patient-specific LPM could be used to evaluate the long-term treatment effects of the current counterpulsation mode.After that,based on the regulation of EECP intervention in the acute hemodynamics of the blood circulatory system,and aiming at improving the long-term hemodynamic effects of cardiovascular and cerebrovascular diseases,the counterpulsation treatment mode could be optimized with the consideration of patient-specific degree of stenosis.Finnally,hemodynamic optimization-based specialized,patient-specific,and precise EECP treatment strategies could be proposed for different diseases and different individuals.In addition,this study developed a planning system of patient-specific EECP strategy to provide technical approach for assisting clinical treatment.In summary,this study quantitatively investigates the regulation of the real-time redistribution of blood flow and the long-term hemodynamic effects of the cardio-cerebrovascular system after the application of EECP to the human body.Qualitative suggestions of specialized EECP treatment methods were proposed for patients with coronary heart disease and cerebral ischemic stroke.The quantitative evaluation models for long-term effects were established,and an individual EECP simulation method was developed.Hemodynamics-optimization speaking,optimal counterpulsation treatment strategies could be formulated for different indications and different patients,so as to provide hemodynamic theoretical basis for assisting the scientific clinical EECP treatment.At the same time,based on the above research contents,this study has developed a planning system of patient-specific EECP therapy strategy to provide theoretical solution and technical approach for improving the clinical treatment outcomes,which has potential application value in the rehabilitation of patients with chronic ischemic cardiovascular and cerebrovascular diseases.