Background Enhanced external counterpulsation (EECP) is an effective method for treating patients with cerebral ischemic stroke, while hemodynamics is the major contributing factor in the treatment of EECP. Different counterpulsation modes have the potential to lead to different acute and long-term hemodynamic changes, resulting in different treatment effects. However, various questions about appropriate counterpulsation modes for optimizing hemodynamic effects remain unanswered in clinical treatment. Methods A zero-dimensional/three-dimensional (0D/3D) geometric multiscale model of the cerebral artery was established to obtain acute hemodynamic indicators, including mean arterial pressure (MAP) and cerebral blood flow (CBF), as well as localized hemodynamic details for the cerebral artery, which includes wall shear stress (WSS) and oscillatory shear index (OSI). Counterpulsation was achieved by applying pressure on calf, thigh and buttock modules in the 0D model. Different counterpulsation modes including various pressure amplitudes and pressurization durations were applied to investigate hemodynamic responses, which impact acute and long-term treatment effects. Both vascular collapse and cerebral autoregulation were considered during counterpulsation. Results Variations of pressure amplitude and pressurization duration have different impacts on hemodynamic effects during EECP treatment. There were small differences in the hemodynamics when similar or different pressure amplitudes were applied to calves, thighs and buttocks. When increasing pressure amplitude was applied to the three body parts, MAP and CBF improved slightly. When pressure amplitude exceeded 200 mmHg, hemodynamic indicators almost never changed, demonstrating consistency with clinical data. However, hemodynamic indicators improved significantly with increasing pressurization duration. For pressurization durations of 0.5, 0.6 and 0.7 s, percentage increases for MAP during counterpulsation were 1.5%, 23.5% and 39.0%, for CBF were 1.2%, 23.4% and 41.6% and for time-averaged WSS were 0.2%, 43.5% and 85.0%, respectively. Conclusions When EECP was applied to patients with cerebral ischemic stroke, pressure amplitude applied to the three parts may remain the same. Patients may not gain much more benefit from EECP treatment by excessively increasing pressure amplitude above 200 mmHg. However, during clinical procedures, pressurization duration could be increased to 0.7 s during the cardiac circle to optimize the hemodynamics for possible superior treatment outcomes.
Traditional clinical mode of enhanced external counterpulsation is not targeted for different diseases. Specialized strategies in the treatment of enhanced external counterpulsation for coronary heart disease and cerebral ischemic stroke are supposed to be distinguished. The goal of treatment for coronary heart disease is diastolic blood pressure/systolic blood pressure = Q ≥ 1.2 after counterpulsation, while the goal of treatment for cerebral ischemic stroke is the improvement of mean arterial pressure. A computational lumped parameter model was established for the simulation of hemodynamic effect of enhanced external counterpulsation on two diseases. Vessel collapse was considered during the simulation of counterpulsation. Based on different pressurized and decompressed rate, pressurized moment, pressure duration, and pressure amplitude, different counterpulsation modes were applied to the model and the immediate hemodynamic effects were compared. Results showed that the pressure duration and pressure amplitude had most influence on two diseases. For cerebral ischemic stroke, the longer pressure duration and the higher pressure amplitude of thighs, the higher mean arterial pressure; while for coronary heart disease, the value of Q was highest when the pressure end moment was 0.6 s during a 0.88-s cardiac cycle, and Q had a linear increase in the pressure amplitude of buttocks, but little change with the increase of calves and thighs pressure amplitude. For patients with coronary heart disease, the pressure duration was not supposed to be too long to avoid the increase of systolic blood pressure, and the improvement of pressure amplitude of buttocks could promise a positive treatment effect for coronary heart disease. While for patients with cerebral ischemic stroke, both the long pressure duration of each part and the high pressure amplitude of thighs could result in the systolic blood pressure and diastolic blood pressure have a certain increase, thus promoting the maximum mean arterial pressure and a best treatment. Graphical abstract The specialized treatment strategies of EECP for cardiovascular and cerebrovascular disease.
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