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 storage, and 24 hours of reperfusion affect coronary endothelial function and coronary vascular resistance. Methods. Porcine coronary arterial endothelial and smooth muscle function was 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 endothelium-dependent relaxation. Flushing followed by 12 hours of storage gravely impaired endothelium-dependent relaxation, and 24 hours of reperfusion worsened it still more. Conclusions. Flushing the heart with cold cardioplegic solution impairs endothelium-dependent relaxation, as does prolonged cold ischemic storage. Reperfusion of injured coronary endothelium may injure it still more. A correlation was found (p< 0.001) between high coronary vascular resistance and low endothelium-dependent relaxation.