New approaches to blood cardioplegic delivery to reduce hemodilution and cardioplegic overdose.

These studies present modifications of the cardioplegic components of a standard cardioplegic formulation, delivered previously at 4:1, to allow an 8:1 blood:cardioplegic mixture, thereby limiting hemodilution. Data are included to show that the hyperkalemic (20 mEq/L) glutamate/aspartate enriched solution used previously for warm induction can be used also for warm reperfusion (instead of the 10 mEq/L KCl solution), thereby avoiding the need to formulate two different solutions that vary only in potassium concentration. Studies of cold (4 degrees C) retrograde noncardioplegic blood infusion after arrest with hyperkalemic blood cardioplegia document the safety of maintaining arrest with continuous retrograde infusion of cold normokalemic blood, thereby indicating that ischemia and cardioplegia are unnecessary during aspects of cardiac operations where perfusion does not impair visualization (i.e., construction of proximal anastomoses). A new cardioplegic delivery system containing a shunt line is presented to expedite conversion from blood cardioplegia to blood infusion when continuous infusion is used.