Development of an Electrohydraulic Total Artificial Heart System

Abstract

An electrohydraulic total artificial heart (EHTAH) system is being developed in our institute. Components of the EHTAH system were evaluated in in vitro and in vivo studies. The system comprises a blood pump system with diaphragm-type ellipsoidal ventricles, an energy converter system consisting of a regenerative pumpbrushless DC motor assembly, and an electronics system with transcutaneous energy transfer (TET) and optical telemetry (TOT) systems. Excellent anatomic fit of the ventricles to the human chest cavity was confirmed by computer graphics based on magnetic resonance imaging. The durability and antithrombogenicity of the blood pump were examined in a series of air-driven chronic implantations into calves for up to 16 weeks. The energy converter is connected to alternate ventricles through flexible conduits, and is placed separately in the abdominal region to minimize anatomic constraints. Maximum output of the pumping unit (the integrated blood pump and energy converter systems) was 10.71/min in a mock circulation at 2500 rpm motor speed. The TET and TOT systems were evaluated in chronic animal studies. The TET system, consisting of a pair of annular coils, demonstrated around 80% DC/DC efficiency for 40 days when 20 W of energy was finally transferred into a simulated load. The TOT system, at a signal transmission rate of 19 200 bits per second (bps) allowed up to 12mm misalignment. These favorable characteristics of the components indicate that the EHTAH system has the capacity to be used as a totally implantable cardiac replacement.