Potassium-verapamil cardioplegia for myocardial protection: an experimental evaluation through preservation and transplantation

The efficacy of potassium-verapamil cardioplegia for myocardial protection was studied using the canine heart preservation and transplantation system. Coronary vascular washout of the grafts was performed via the aortic root both in Group I (n=8) with 4 degrees C high potassium cardioplegic solution and in Group II (n=8) with 4 degrees C high potassium and 1 mg/L verapamil solution. The heart were immersed into the same solution as used for washout and stored at 4 degrees C for 6 hours, without oxygenation and perfusion. The grafts were transplanted orthotopically under conditions of cardiopulmonary (CP) bypass. Adequate hemodynamics without the support of CP bypass was obtained in all the grafts of Group II during a 2-hour observation period. In contrast, only five out of eight grafts in Group I were able to support the recipient circulation. Contraction bands were more prominently and frequently observed in the histology in Group I. Thus, the combination of coronary vascular washout with cold potassium-verapamil cardioplegia and storage at 4 degrees C with the same solution seems to be effective for myocardial protection of the canine heart in cases of orthotopic transplantation.