Experimental and clinical studies of ventricular assist system for acute profound heart failure.

本课题主要完成了以下三个方面的工作：(1)VAD对双心衰(BVF)的治疗作用：实验研究VAD对BVF的治疗作用。采用常温下阻断主动脉建立山羊BVF模型，分别应用LVAD(8只)或BVAD(2只)。在无肺动脉高压的情况下，单纯LVAD结合容量负荷可维持接近正常循环。在BVAD的情况下，在没有容量负荷的情况下很容易维持循环。BVF恢复的可能性取决于应用VAD前心肌损害的严重程度。(2)儿科用VAD；已开发出两种尺寸的气动隔膜型VAD。每搏输出量分别为20ml和40ml。经模拟环路试验，获得了足够的儿科用输出量。在体重为10~20公斤的犬的模拟实验中，导管可以顺利地插入左心房，并容易与主动脉缝合。…进一步研究(3)建立一种无创、连续监测LVAD术中心输出量的方法：为了建立一种根据动脉压和VAD上的压力-流量关系来预测左心室每搏量的方法，在模拟循环中对三种方法进行了评价。作为压力-流量关系，第一、二、三种方法分别采用动脉顺应性、外周血管阻力和动脉阻抗。与电磁流量计相比，第2、3种方法具有良好的相关性。在此基础上，应用VADS对16例心源性休克患者进行了检测。其中9例患者的全血循环维持在正常水平，并成功地摘除了左冠状动脉前降支。虽然自然心脏可以恢复，但大多数患者死于多器官功能衰竭，这是在LVAD辅助之前的长期缺血过程中发生的。在临床情况下，正确判断及时应用左心功能是非常重要的。较少

In this project, the following three tasks were performed.(1) Therapeutic effect of VAD on bi-ventricular failure(BVF): the therapeutic effect of VAD on BVF were evaluated in experimental study. BVF was induced by aortic-clamping under normothermia in goats, and LVAD (8 goats) or BVAD (2 goats) was applied. Without the pulmonary hypertension, LVAD alone in combination with volume loading could maintain near normal circulation. In case of BVAD, it was easy to maintain the circulation without volume loading. The recovery possibility of BVF depends upon the severity of myocardial damage suffered before VAD application. (2) VAD for pediatric use; two sizes of airdriven, diaphrahm type VADs have been developed for pediatric use. Their stroke volumes were 20 ml and 40 ml. With mock loop test, sufficient output for pediatric use was obtained. In amimal experiment using dogs weighing from 10 to 20 kg, the conduit could be smoothly inserted into the left atrium and easily sutured to the aorta. … More (3) Development of a non-invasive and continuous monitoring method of cardiac output during LVAD pumping: In order to develop a method that can predict left ventricular stroke volume from arterial pulse pressure and pressue-flow relationship on the VAD, three methods were evaluated in a mock circulatory loop. As the pressure-flow relationship, arterial compliance, peripheral vascular resistance, and arterial impedance were used in the first, second, and third method, respectively. In comparison to electro-magnetic flowmetry, the 2nd and 3rd methods showed excellent correlation coefficient.Based on the above results, VADs were applied for 16 patients with cardiogenic shock. In nine of them entire circulation was well maintained at normal level and LVAD was successfully removed. Although the natural heart could recover, the most patients died of multiple organ failure which developed during prolonged ischemia prior to LVAD assistance. In clinical situation, timely use of LVAD by right judgement is important. Less