Effects of cardioplegic flushing, storage, and reperfusion on coronary circulation in the pig

Background. The aim of the study was to investigate how flush-perfusion of the heart with cold cardioplegic solution, 2 or 12 hours of cold ischemic s torage, and 24 hours of reperfusion affect coronary endothelial function an d coronary vascular resistance. Methods. Porcine coronary arterial endothelial and smooth muscle function w as studied in organ baths. An adult porcine working heart model was used to investigate coronary vascular resistance after 24 hours of reperfusion. Results. Flushing the heart with 1 L of St. Thomas' cardioplegic solution, using a perfusion pressure of 60 to 65 mm Hg, significantly reduced endothe lium-dependent relaxation. Flushing followed by 12 hours of storage gravely impaired endothelium-dependent relaxation, and 24 hours of reperfusion wor sened it still more. Conclusions. Flushing the heart with cold cardioplegic solution impairs end othelium-dependent relaxation, as does prolonged cold ischemic storage. Rep erfusion of injured coronary endothelium may injure it still more. A correl ation was found (p < 0.001) between high coronary vascular resistance and l ow endothelium-dependent relaxation. (Ann Thorac Surg 1999;67:1345-9) (C) 1 999 by The Society of Thoracic Surgeons.