EVIDENCE OF IMPROVED MICROVASCULAR PERFUSION WHEN USING ANTEGRADE ANDRETROGRADE CARDIOPLEGIA

Background. The maximum degree of microvascular distribution of cardio plegic solution is considered important to achieve optimum myocardial protection. This study attempts to demonstrate that the addition of re trograde cardioplegia to antegrade cardioplegia improves overall micro vascular perfusion. Methods. Explanted human hearts (n = 6) were treat ed with cold cardioplegic arrest and bicaval cardiectomy. Blood cardio plegia (37 degrees C) containing colored microspheres (color A for ant egrade, color B for retrograde) was simultaneously infused antegrade a t a pressure of 80 mm Hg and retrograde at a pressure of 40 mm Hg for 2 minutes. The ventricular myocardium was then sampled at three sites to determine absolute and relative cardioplegic microvascular flow. Re sults. Of the total microvascular capillary flow, 27% to 32% was found to be the contribution of retrogradely delivered cardioplegia. Conclu sions. Despite being delivered simultaneously and at a lower pressure, retrograde cardioplegia contributed substantially to overall microvas cular perfusion. This suggests that antegrade cardioplegia alone does not perfuse all available myocardial capillaries and that the addition of retrograde cardioplegia enhances overall microvascular distributio n and perfusion.