Mechanical cardiac actuation achieves hemodynamics similar to cardiopulmonary bypass.
The disadvantages of blood/interface interactions and difficult installation are common to current circulatory support devices. Direct mechanical ventricular actuation (DMVA) is a method of biventricular cardiac massage that avoids contact of blood with various surfaces. The purpose of this study was to compare hemodynamic responses and organ perfusion between DMVA and cardiopulmonary bypass (CPB). Twenty adult mixed-breed dogs randomized for DMVA or CPB were anesthetized with alpha-chloralose. During 4 hours of ventricular fibrillation, animals received either DMVA or CPB with aortic arch perfusion (90 to 120 ml/kg/min), bicaval venous return, and full left ventricle venting. Hemodynamics and organ perfusion were assessed by multivariant analysis of variance with repeated measures. Blood flow was similar to normal sinus rhythm (control) with either method; however, average CPB flows (control, 110%) were increased significantly over DMVA flows (control, 75%) (p = 0.016). The resulting mean arterial pressures were significantly greater during DMVA (control, 66%) compared to CPB (control, 49%) (p = 0.0011). Radiolabeled microspheres were the measure of organ perfusion during sinus rhythm and at 2 and 4 hours of circulatory support. Myocardial blood flow was equal to control in all regions during DMVA; CPB resulted in increased flows to the left ventricular epicardium, septum, and right ventricle. DMVA generated significantly greater flows to the renal cortex. All other organs demonstrated similar perfusion with either method. However, CPB displayed declining cerebral flows at 4 hours compared to DMVA (42% vs 55% control, respectively). Overall, DMVA provided hemodynamic stability equal to that of CPB. Rapid application and avoidance of blood/surface contact make DMVA a favorable method of temporary circulatory support.
Anstadt, MP; Hendry, PJ; Plunkett, MD; Menius, JA; Pacifico, AD; Lowe, JE
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