Cardioplegia and Myocardial Preservation During Cardiopulmonary Bypass

ENGELMAN, RICHARD M. M.D.
LEVITSKY, SIDNEY M.D.
O'DONOGHUE, MICHAEL J. M.D.
AUVIL, JACKSON A.B.

From the Department of Surgery, The Abraham Lincoln School of Medicine, The University of Illinois at the Medical Center, and the Veterans Administration West Side Hospital, Chicago, Illinois.

Address for reprints: Richard M. Engelman, M.D., Chief, Cardiac Surgery, Baystate Medical Center, Springfield, Massachusetts 01107.

Supported by Grant 77-606 from the American Heart Association, Grant 2390-02 from the Veterans Administration, and a grant from the Upjohn Company.

Presented at the 50th Scientific Sessions, American Heart Association, November 28-December 1, 1977, Miami.

Circulation 58:p I-114, September 1978.

SUIM'sMARY A standard experimental protocol was developed to explore the role of hypothermia and potassium cardioplegia in myocardial preservation during 120 minutes of ischemic arrest followed by 30 minutes of reperfusion. Seven different experimental groups of six animals each were evaluated using an in-vivo pig heart preparation. Hypothermic arrest without cardioplegia and cardioplegic arrest at normothermia were each compared to hypothermic cardioplegia. In addition, the use of an asanguineous hypothermic coronary perfusate without cardioplegia was compared to both multidose cardioplegia and single-dose cardioplegia followed by the same asanguineous perfusate. The parameters measured included: myocardial contractility and compliance, myocardial blood flow, endocardial/epicardial blood flow ratio, and electron microscopic studies. Myocardial preservation was inadequate with hypothermic arrest alone (without cardioplegia) and with cardioplegia at normothermia. In both experimental groups, myocardial contractility and compliance were so depressed that they could not be accurately measured following ischemia and reperfusion while coronary blood flow remainedl significantly elevated. Preservation was improved but still inadequate following myocardial washout with a normokalemic or hypokalemic perfusate and following single dose cardioplegia plus myocardial washout. In the latter four groups, contractility ranged from 42 to 78% of control, and there was a decrease in compliance of 16 to 78%. Adequate preservation was found only after hvpothermia and multidose potassium (35 mEq/L) cardioplegia. In this group, contractility was 129 ± 13% of control and compliance increased by 21 ± 24% compared to that of the control.