Evaluation of recovery directed left ventricular assist device using isolated perfused rabbit hearts

We have developed a recovery directed left ventricular assist device (RDLVAD) that can promote cardiac recovery by achieving very low ventricular work and ensuring full ventricular relaxation and filling. It consists of a valved apical conduit, an afterload controlling chamber, and a centrifugal pump. To test the previously described effects of RDLVAD on the left ventricle, we made an RDLVAD suitable for isolated perfused rabbit hearts. The control LVAD was of a continuous flow type (CLVAD). Thirty-two rabbits were used. The working left heart model proved inappropriate for evaluation of LVAD. In the isolated heart-lung preparation (n = 4), the CLVAD showed a substantial backward flow and a severe negative pressure during diastole. This negative pressure may have resulted in severe restriction of ventricular relaxation and filling. In contrast, in the RDLVAD with the afterload controlling chamber pressure kept as low as possible, the pump flow was stable and increased by 86% (NS), and the peak left ventricular pressure, max dP/dt, and systolic pressure time index decreased by 22.3% (p = 0.022), 29.4% (p = 0.017), and 42% (p = 0.022), respectively. In conclusion, these results indicate that the RDLVAD does not restrict ventricular relaxation or filling and greatly reduces ventricular workload. The RDLVAD, therefore, can promote cardiac recovery.