Experimental evaluation of complete electrically powered ventricular assist system

The LVAS utilizing an intrathoracic blood pump and a parathoracic, electrohydraulic energy converter has a number of promising features. These include: transcutaneous energy transmission and an implanted variable volume device which eliminate the need for percutaneous access; utilization of an intrathoracic blood pump and variable volume device which allow the diaphragm and abdominal cavity to remain intact; parathoracic or subcutaneous location of the transformer secondary, energy converter, internal battery and interconnecting elements allowing replacement with a minor surgical procedure; employment of the "biolized" continuous blood contacting surface which has the potential of long-term use without anticoagulants and utilization of an electrohydraulic energy converter which provides synchronization without requiring transducers and associated electronics and which provides lubrication of mechanical components. The development effort, which began separately in 1977 and has been conducted jointly by Nimbus and the Cleveland Clinic since 1980, has demonstrated that the above features can be incorporated in a reliable LVAS. In particular, the system in vivo test series have demonstrated the soundness of the basic concepts and led to refinements which were demonstrated in the 6-1/2 mo test. All elements of the system have been utilized during the in vivo test program. Component tests of significance include; LVAS and total heart blood pump in vivo experiments of up to 7 mos duration which demonstrate the blood compatibility of the biolized surface without the use of long-term anticoagulation; variable volume device in vivo tests of up to 2 yrs duration which demonstrate that a textured surface produces a stable thin and compliant tissue capsule and energy converter in vitro testing which has demonstrated an energy converter endurance life of at least 5 yrs. Qualification hardware is now being fabricated for use in a device readiness demonstration program which is scheduled for completion in 1987.