The Role of Sodium-Hydrogen Ion Exchange in Patients Undergoing Coronary Artery Bypass Grafting

Sodium-hydrogen ion exchange (NHE) is one of the principal mechanisms of restoring intracellular pH following ischemia and reperfusion. However, up-regulation of the NHE process results in a compensatory increase in the activity of the sodium-calcium exchanger. Intracellular hypercalcemia, resulting from the exchange of sodium for calcium, precipitates myocardial stunning and cell death. It has been postulated that NHE inhibition can protect the ischemic/reperfused myocardium, and preclinical studies have uniformly supported this concept. The Guard During Ischemia Against Necrosis (GUARDIAN) trial suggested benefits of NHE inhibition in subjects undergoing coronary artery bypass grafting (CABG). The sodium-hydrogen eXchange inhibition to Prevent coronary Events in acute cardiac conDITIONs (EXPEDITION) trial will further explore the use of cariporide in a randomized, controlled trial of CABG subjects at risk of myocardial necrosis. (J Card Surg 2003; 18:21-26)