Original Article

Myocardial Recovery During Mechanical Circulatory Support After Acute Myocardia/Ischemia

Clinic for Cardiovascular Surgery, Department of Medicine and Institute of Anesthesiology, University Hospital, Zurich, Switzerland

^* Address correspondence to: Ludwig K. von Segesser, MD Clinic for Cardiovascular Surgery, University Hospital, CH-8091 Zurich, Switzerland

Abstract

Irreversible myocardial failure due to severe ischemia is a challenging problem in clinical practice. The present study was performed to evaluate the potential benefit of mechanical circulatory support in a bovine model with prolonged, acute myocardial ischemia. Seven calves (74+6 kg) underwent 6 hours of regional ischemia by temporary (6h) ligation of the left circumflex coronary artery. Ventricular assist was started 10 minutes after occlusion of left circumflex coronary artery. Ventricular fibrillation occurred in all animals after a mean interval of 4.0±2.4 hours. Defibrillation was attempted immediately and every hour thereafter. Successful defibrillation was achieved in 6/7 animals after 4.1±2.5 hours of ventricular fibrillation during mechanical circulatory support. Weaning from biventricular assist was attempted after 24 hours and was successful in 5 I 6 animals. Hence timely mechanical circulatory support in acute, prolonged ischemia with subsequent “irreversible” cardiac failure allows not only maintainence of acceptable hemodynamics for bridging to heart transplantation but also significant myocardial recovery if coronary artery blood flow is restored within 6 hours.