Original Article

Preoperative Intravenous Nitroglycerin: A Potential Complication for Cardiopulmonary Bypass

Division of Cardiac Surgery, University of Mississippi Medical Center Jackson, MS

^* Direct communications to: Pat H. Courtney, Jr., C.C.P., Division of Cardiac Surgery, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216-4505

Abstract

(J. Extra-Corpor. Technol. 19[3] p. 369-371 Fall 1987, 13 ref.) It has been reported that intravenous nitroglycerin may interfere with the anticoagulation effect of heparin.1 A literature search reports this only in low dose heparin management for coronary care unit patients. We have observed this same effect but on a much larger scale with complete heparinization required for cadiopulmonary bypass. We began to observe an inadequate response to the calculated dose of heparin approximately one year ago (400 units/kg.). Some adult patients required as much as four times the calculated dose of heparin to achieve an activated clotting time of greater than 600 seconds.

Preoperative PTT and A T3 levels and postoperative levels were obtained on 25 adult patients. These tests yielded normal values and we then expanded our investigation. A systematic breakdown of medications administered to patients preoperatively was begun, checking for potential heparin neutralization.

The studies of the medications administered revealed nitroglycerin to be the only common denominator for all the patients that required large heparin doses. Many coronary artery bypass patients at our institution are placed on intravenous nitroglycerin prior to surgery. Our search of the literature revealed this to be a previously unreported potential complication for cardiopulmonary bypass in patients on high dose intravenous nitroglycerin.