THE INFLUENCE OF COLLATERAL FLOW ON THE ANTEGRADE AND RETROGRADE DISTRIBUTION OF CARDIOPLEGIA IN PATIENTS WITH AN OCCLUDED RIGHT CORONARY-ARTERY

Background: The predictive value of electrocardiography (ECG) and coro nary angiography for cardioplegia distribution in patients with an occ luded right coronary artery was evaluated. Methods: Coronary angiogram s and ECGs were evaluated in 15 patients with right coronary artery oc clusion. Prediction of antegrade cardioplegia distribution was based o n ECG evidence of infarction and coronary collateral flow determined f rom the angiogram. Antegrade and retrograde delivery of cardioplegia w as directly assessed in all patients by myocardial contrast echocardio graphy. Intraoperative transesophageal echocardio graphic images of th e right ventricular free wall, the apex, and the intraventricular sept um were recorded while 4 mi of Albunex (Mallinckrodt Medical, St. Loui s, MO) was injected into antegrade and retrograde cardioplegic cathete rs during cardioplegia delivery. The observed (myocardial contrast ech ocardiography) cardioplegia distribution was compared to the predicted cardioplegia distribution. Sensitivity, specificity, positive predict ive values, and negative predictive values were calculated. Results Ei ghty seven of 90 (97%) segments were analyzed. Angiography and ECG poo rly predicted incomplete cardioplegia distribution. Electrocardiograph y was a better predictor of inadequate cardioplegia distribution to th e right ventricle than was angiography. The negative predicted values of cardioplegia distribution ranged from 20 to 50% for the septum and right ventricle, respectively, with ECG criteria and from 0 to 33% for the septum and apex, respectively, with angiographic criteria. Antegr ade cardioplegia delivery was distributed to the right ventricle in 31 % of patients, despite 100% occlusion of the right coronary artery; wh ereas retrograde cardioplegia delivery to the right ventricle occurred 20% of the time. Conclusions In the presence of 100% right coronary a rtery occlusion, retrograde cardioplegia delivery is not often observe d and antegrade delivery of cardioplegia to the right ventricle is not easily predicted. The preoperative angiography and ECG are not predic tive of coronary collateral circulation and therefore not predictive o f cardioplegia distribution to the right ventricle.