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

在本项目中，执行了以下三项任务。(1)VAD对双心室衰竭的治疗作用：实验研究评价VAD对双心室衰竭的治疗作用。在常温下用钳夹法建立山羊BVF模型，并应用LVAD（8只山羊）或BVAD（2只山羊）。在无肺动脉高压的情况下，单独LVAD联合容量负荷可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量负荷。BVF恢复的可能性取决于应用VAD前心肌损害的严重程度。(2)供儿科使用的VAD;已开发了两种尺寸的气动隔膜式VAD供儿科使用。每搏输出量分别为20 ml和40 ml。通过模拟回路测试，获得了儿科使用的足够输出。在10 ~ 20 kg犬的体外实验中，该导管可顺利插入左心房，并与主动脉吻合。 关于我们 (3)LVAD泵送期间心输出量的无创和连续监测方法的开发：为了开发一种可以从VAD上的动脉脉压和压力-流量关系预测左心室每搏输出量的方法，在模拟循环回路中评价了三种方法。作为压力-流量关系，在第一、第二和第三方法中分别使用动脉顺应性、外周血管阻力和动脉阻抗。与电磁流量法相比，第二、三种方法的相关系数更高，据此，对16例心源性休克患者进行了VAD。其中9例患者的整个循环良好地维持在正常水平，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功能衰竭。在临床情况下，正确的判断及时使用LVAD是很重要的。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