Transcutaneous energy transmission for mechanical circulatory support systems: history, current status, and future prospects.

A totally implantable mechanical circulatory support system would be very desirable for destination therapy. However, implanting all components of a pulsatile total artificial heart (TAH) or left ventricular assist device (LVAD) is complex because of the requirement for a continuous electrical power supply and the need for volume compensation. Implantable compliance chambers were developed for early LVAD designs, and although they functioned properly during initial laboratory tests, air loss by diffusion and the development of fibrous tissue around the sac eventually rendered them ineffective. Because these problems have not yet been overcome, volume displacement LVADs are currently designed with either a direct communication to an external drive console or an atmospheric vent. Transcutaneous energy transmission systems (TETSs) were also developed, but because the skin was being penetrated for volume compensation, it seemed more efficient to transmit electrical power through wires incorporated into the venting apparatus. More recently, TETSs were used clinically for both a pulsatile TAH and LVAD in a small number of patients, but for reasons unrelated to the TETS, neither of these devices is presently in use. Because the newer continuous-flow LVADs do not require a compliance chamber, they present a potential future application for TETS technology, because infections of the percutaneous tube continue to be one of the most important limitations of long-term circulatory support. A totally implantable LVAD with an incorporated TETS for destination therapy could become an important advance in the treatment of end-stage heart failure.