Development of an epicardial circulatory assist device

The overall purpose of this project was to develop a circulatory assist device that could be used as a bridge to heart transplantation. Although heart muscle damage was one of the disadvantages with the original epicardial assist devices, as long as no bleeding occurs, such trauma would be of secondary importance in this particular application. The development of the proposed epicardial circulatory assist device (ECAD) was evolutionary in nature, with the second prototype design based on the lessons learned from that of the first. In vivo results from both phases of the project are reported. ECAD prototype 1 (ECAD-1) was composed of a flexible outer housing and two driving balloons. Fixation to the heart was adjustable for various heart sizes using Velcro fasteners. The design of the ECAD prototype 2 (ECAD-2) was based on the results of ECAD-1. Fixation to the heart was accomplished by suturing the outer housing onto the heart along the anterior descending artery and at the posterior atrioventricular groove. Each device was tested in five dogs. ECAD-1 was able to maintain the systemic circulation for 5 hours. However, unstable fixation and myocardial damage due to rubbing were the major problems. ECAD-2 passive effects on natural heart filling were acceptable. Under conditions of severe heart failure, a flow of more than 85% of control was obtained with a driving rate of 90-110 beats/min and 30% systole. The longest pumping was conducted for 8 hours. The ECAD was demonstrated to be a device useful in assisting the failing heart for short periods. Proper design will play a fundamental role in successful extended use.