[The role of prostaglandin I2 in heart transplantation under deep hypothermia].

The role of Prostaglandin I2 (PGI2) on heart transplantation under deep hypothermia were investigated using 25 weighing an average of 5 kg. They were put to deep hypothermia by surface cooling with either anesthesia until rectal temperature reached 18 degrees C. Then the heart was arrested with cardioplegic solution, removed and re-transplanted. They were divided into 2 groups according to the usage of PGI2, i.e., non PGI2 group (n = 12) and PGI2-treated group (n = 13). In PGI2-treated group, PGI2 was administered intravenously 1 micrograms/kg/min during cooling and rewarming periods, and was added 500 ng/ml into cardioplegic solution. In the last 13 dogs (7 dogs in non PGI2 group and 6 dogs in PGI2 group) about which left ventricular functions were mainly examined, topical cooling of the myocardium was omitted. Results were as follows; compared with non PGI2 group, PGI2-treated group showed significantly higher cooling and rewarming rates, more rapid recovery of cardiac output after transplantation, and lower systemic vascular resistance throughout the experimental period. Left ventricular functions after resumption of heart beats were better in PGI2-treated group than in non PGI2 group. Microscopic examinations of the heart revealed that ischemic changes of myocardial cells were less prominent in PGI2-treated group than in non PGI2 group. It is concluded that PGI2 is useful additive for heart transplantation under deep hypothermia in that it could shorten operative time due to quicker control of the body temperature with rather stable haemodynamics and also it might protect myocardium during ischemia.