Cold storage of the rat heart for transplantation. Two types of solution required for optimal preservation.

Two solutions, our cardioplegic solution and Collins' solution, were tested with regard to preservation of the heart under deep hypothermia before transplantation. The setup used was the isolated perfused working rat heart model and 4 hours of preservation at 0 degree C. The following three groups were prepared: Group 1: the heart was arrested with the cardioplegic solution (potassium: 20 mmol/L, sodium: 87 mmol/L) and then flushed with and stored in Collins' solution (potassium: 117 mmol/L, sodium: 10 mmol/L); Group 2: the heart was arrested with and stored in Collins' solution; and Group 3: the heart was arrested with and stored in the cardioplegic solution. The recovery of cardiac function was more satisfactory in Group 1 than in Groups 2 and 3. The increase in lactate was greater, and adenosine triphosphate and total adenine nucleotide were more depleted during storage in Group 2 than in Groups 1 and 3. In Group 3 myocardial sodium accumulation and potassium depletion during storage were greater than in Groups 1 and 2, and myocardial sodium and calcium overload after reperfusion were greater than in Group 1. Myocardial calcium overload after reperfusion in Group 2 was also greater than that in Group 1. These findings plus coronary vascular resistance analysis revealed that Collins' solution damages the heart during arrest procedures and that the cardioplegic solution is less effective for storage of the arrested heart under deep hypothermia. Therefore the heart should be first arrested with the cardioplegic solution and then flushed with and kept in Collins' solution for simple cold storage.