Heparin Resistance during Cardiopulmonary Bypass in Adult Cardiac Surgery

Abstract

The use of heparin for anticoagulation has changed the face of cardiac surgery by allowing a bloodless and motionless surgical field through the introduction of cardiopulmonary bypass (CPB). However, heparin is a drug with complex pharmacological properties which can cause significant interpatient differences in terms of responsiveness. Heparin resistance during CPB is a weighty issue due to the catastrophic consequences stemming from inadequate anticoagulation and the treatment of it necessitates a rationalized stepwise approach due to the multifactorial contributions towards this entity. The widespread utilization of activated clotting time (ACT) as a measurement of anticoagulation during CPB will also be examined as it may be a false indicator of heparin resistance. Heparin resistance has also been repeatedly reported in patients with COVID-19 infections which deserves further exploration in this pandemic era. This review aims to examine the variability in heparin potency, underlying mechanisms, limitations of using ACT for monitoring and provides a framework towards the current management of heparin resistance.