Pathophysiological aspect of an implantable ventricular assist device with short stroke and high frequency

The design concept of short stroke volume and high frequency was adopted for the development of a totally implantable ventricular assist device (VAD). The transcutaneous energy transmission system (TETS) using amorphous fiber was developed to constitute the totally implantable VAD. The vibrating flow pump (VFP), which was developed with short stroke volume in mind, works with a high frequency of 10-50 Hz compared with the natural heart of a biological system. In this research, acute and chronic animal experiments were carried out on healthy adult goats. All hemodynamic data was stored on magnetic tape and analyzed in the computer system through an AD converter. Adequate pump flow was provided by the left ventricular cannulation. A 100% left heart bypass was confirmed by measuring aortic and left ventricular pressures. Peripheral vascular resistance was compared during total left heart bypass with a VFP and a rotary pump (RP). Resistance during VFP assist was significantly higher compared with that during RP assist, suggesting that the effect of a left heart bypass with the VFP upon vascular resistance was lower. During left heart bypass with VFP, blood flow distribution was measured using various pumping frequencies. The results, according to an alteration of the drive frequency, showed that blood flow distribution was significantly changed even during the same total blood flow with 100% left heart bypass. The TETS with amorphous fibers performed well enough in chronic animal experiments and the temperature rise was not significant. It may be possible to control the blood flow distribution during left ventricular assistance with our newly developed VFP system. We are anxious to continue our development of a totally implantable VAD.