Non-blood contacting biventricular support for severe heart failure

Background. Direct mechanical ventricular actuation (DMVA) is a non-blood contacting method of biventricular support. DMVA employs a vacuum attached, pneumatically regulated, flexible membrane to transfer both systolic and diastolic forces to the ventricular myocardium. The purpose of this study was to determine if DMVA effectively restores pump performance when applied to the severely failing heart. Methods. Bovines (n = 10) underwent thoracotomy and were instrumented for continuous hemodynamic monitoring. Cardiac failure was induced by β₁-blockade to achieve a cardiac index of < 1.51/min/m² for 1 hour. Heart rate was maintained at 100 bpm by atrioventricular sequential pacing. Synchronous DMVA support was then applied for 3 hours. Results. Eight animals achieved significant reductions in cardiac index and mean arterial pressures (35%* and 43%* control, respectively; *p < 0.05). DMVA restored cardiac index to baseline and significantly increased arterial pressures (p < 0.05; DMVA versus cardiac failure). Pulmonary flow and mean pulmonary artery pressures were similar to baseline during DMVA (p = NS). Pathologic exam did not demonstrate evidence of significant device trauma. Conclusions. DMVA support can effectively restore pump performance of the acutely failing heart. Synchronization may be inherent to the stimulus of cardiac compression. These data further substantiate DMVA's potential as an adjunct to the field of circulatory support.