Analysis of the interventricular pressure waveform in the moving-actuator total artificial heart

Right and left filling pressures are important parameters in the automatic control of a total artificial heart (TAH) within normal physiologic ranges. Our TAH is composed of a moving actuator, right and left ventricles, and a n interventricular space (IVS) enclosed by a semirigid housing. During oper ation of the TAH, the IVS volume is changed dynamically by the difference b etween the ejection volume of one ventricle and the inflow volume of the ot her. We measured the interventricular pressure (IVP) waveform by using a pr essure sensor and analyzed the relationship between the IVP and the preload condition. From in vitro and in vivo experiments, we found that the measur ed filling pressures were linearly related to the negative peak value of th e IVP. Additionally, we found that we could use the time interval from actu ator start to the positive peak Value of the IVP (outflow valve opening) as a useful parameter to estimate the blood filling volume of the diastole ve ntricle.