A hemodilution cardioplegia and a proposed delivery system. 1980.

We have previously reported our studies of blood cardioplegia and our delivery system for it (1, 2). Our experimental results showing blood cardioplegia to be superior to asanguineous cardioplegia were reported recently (3, 4), and we have used blood cardioplegia for the past two and a half years. Although our clinical results have been gratifying, and the whole blood cardioplegia system was designed with simplicity and patient safety in mind (Fig. 1), there were a number of practical and physiologic limitations to the whole blood cardioplegia delivery system as we have used it (Table I). The two principal practical limitations were the need for two pumps and a cardioplegic reservoir with only a one liter capacity. The sequestering of blood into the cardioplegic reservoir led to the need to recirculate the blood cardioplegic mixture constantly, to keep the contents mixed, as well as a constant flow through the heat exchanger to avoid rewarming. The prime of the extracorporeal circuit had to be increased to compensate for the volume removed temporarily from this circuit in order to make the cardioplegic mixture. Furthermore, the need to alternate clamps to draw and recirculate was slightly cumbersome. The principal physiologic limitation of a whole blood (greater than 20%) cardioplegic system is that the level of hypothermia had to be limited to avoid the potential of blood sludging, which might occur at lower temperatures. To avoid these practical and physiologic problems, we desired a more simplified system which would allow