RETROGRADE VERSUS ANTEGRADE DELIVERY OF CARDIOPLEGIC SOLUTION IN MYOCARDIAL REVASCULARIZATION - A CLINICAL-TRIAL IN PATIENTS WITH 3-VESSEL CORONARY-ARTERY DISEASE WHO UNDERWENT MYOCARDIAL REVASCULARIZATION WITH EXTENSIVE USE OF THE INTERNAL MAMMARY ARTERY

The effects of retrograde and antegrade delivery of cardioplegic solut ion on myocardial function were evaluated and compared in 60 patients who underwent myocardial revascularization. All patients had three-ves sel coronary artery disease, and the revascularization was done with e xtensive use of the internal mammary artery. Seventy-five percent of t he distal anastomoses were performed with the internal mammary artery. Myocardial protection consisted of St. Thomas' Hospital cardioplegic solution, topical slushed ice, and systemic hypothermia (28-degrees-C) . The patients were randomly separated into two groups: group A (n = 3 0), who received antegrade cardioplegia, and group B (n = 30), who rec eived retrograde cardioplegia. With the exception of the total dose of cardioplegic solution (p = 0.02), there was no significant difference between the two groups that concerned septal myocardial temperature a t the moment of asystole and after infusion of the total dose of cardi oplegic solution. Cardiac function was assessed before and after the p atient was weaned from cardiopulmonary bypass. In the immediate postop erative period there was a significant increase in right atrial pressu re of the patients who underwent antegrade cardioplegia. For the other registered parameters there was no significant difference either in t he immediate postoperative period or 6 hours later. Release of creatin e kinase MB isoenzyme was the same in the two groups. Clinical outcome in terms of mortality, prevalence of perioperative infarction, preval ence of low cardiac output, and rhythm and conduction disturbances was similar in both groups. Technical problems related to cannulation and decannulation of the coronary sinus were not encountered. Multivariat e analysis showed that occlusion of the left anterior descending coron ary artery (p = 0.012) is an essential contraindication of antegrade d elivery of cardioplegic solution. Analysis of the patients with an occ lusion of the left anterior descending coronary artery who underwent a ntegrade (n = 9) and retrograde (n = 10) cardioplegia showed a signifi cant difference in the total dose of cardioplegic solution (p = 0.02) and septal myocardial temperature at the moment of asystole (p = 0.008 ) and after infusion of the total dose of cardioplegic solution (p = 0 .015). The mean arterial systolic blood pressure in the antegrade grou p was significantly lower than in the retrograde group (p = 0.003). Pr eservation of the left ventricular stroke work index was significantly better in the retrograde group (namely, 85% of its initial value vers us 71% in the antegrade group, p = 0.0116). We conclude that retrograd e cardioplegia provides better myocardial protection than antegrade ca rdioplegia in patients with three-vessel coronary artery disease and o cclusion of the left anterior descending coronary artery who undergo m iocardial revascularization with extensive use of the internal mammary artery. We also conclude that occlusion of the left anterior descendi ng coronary artery is an essential parameter in the inhomogeneous dist ribution of antegrade cardioplegia.