TEPID ANTEGRADE AND RETROGRADE CARDIOPLEGIA

To determine the optimal temperature for the combination of antegrade and retrograde cardioplegia, 42 patients undergoing coronary artery by pass grafting were randomized to receive cold (9 degrees C; n = 14), t epid (29 degrees C; n 14), or warm (37 degrees C; n = 14) blood cardio plegia delivered continuously retrograde and intermittently antegrade. Myocardial oxygen utilization, lactate and acid metabolism, and coron ary vascular resistance were measured during the operation and cardiac function was assessed postoperatively. Myocardial oxygen consumption, lactate release and acid release were greatest with warm, intermediat e with tepid, and least with cold cardioplegia (p = 0.0001). However, washout of lactate and acid at the time of cross-clamp release was red uced (p = 0.022) with tepid or cold compared with warm cardioplegia. E arly postoperative left ventricular function was best preserved (p 0.0 1) after tepid than after cold or warm combination cardioplegia. These results suggest that tepid combination cardioplegia reduced metabolic demands but permitted immediate recovery of cardiac function. This te chnique may provide better myocardial protection than cold or warm com bination cardioplegia.