Our technique used was as follows: Potassium Chloride 80 mEq was added to the perfusion circuit prime. Following initiation of CPB and systemic cooling to 24 degrees centigrade, an additional 240 mEq of potassium chloride in 40 mEq increments were added as needed to the perfusate to achieve and maintain electrical quiescence over the course of the operation (Figures 1 and 2). A total of 320 mEq of potassium chloride was used.