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

在这个项目中，执行了以下三个任务。(1) VAD对双心室衰竭（BVF）的治疗作用：通过实验研究评价VAD对BVF的治疗效果。采用常温下主动脉夹持诱导BVF，分别应用LVAD（8只）和BVAD（2只）。在没有肺动脉高压的情况下，LVAD单独联合容积负荷可以维持接近正常的循环。在BVAD的情况下，很容易维持循环，而无需容积负荷。BVF恢复的可能性取决于VAD应用前心肌损伤的严重程度。(2)儿童VAD；两种尺寸的气动隔膜式vad已开发用于儿科使用。他们的脑卒中容量分别为20毫升和40毫升。通过模拟循环试验，获得了足够的儿科使用输出。在体重为10 ~ 20 kg的狗的动物实验中，该导管可以顺利插入左心房，并容易地与主动脉缝合。(3) LVAD泵送过程中心输出量的无创连续监测方法的建立：为了建立一种可以通过动脉脉压和VAD压流关系预测左室卒中容量的方法，在模拟循环回路中对三种方法进行了评估。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。与电磁流量法相比，第2、3种方法具有较好的相关系数。基于以上结果，对16例心源性休克患者应用VADs。其中9例患者的整个循环维持在正常水平，LVAD被成功移除。虽然自然心脏可以恢复，但大多数患者死于LVAD辅助前长时间缺血导致的多器官衰竭。在临床情况下，正确判断、及时使用LVAD非常重要。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