Intraoperative myocardial protection by potassium arrest and local cardiac hypothermia

Abstract

The combined modalities of potassium arrest and local cardiac hypothermia were used for myocardial protection in 82 patients. The cardioplegic solution used was Ringer's lactate to which potassium chloride and sodium bicarbonate were added so that the final solution had a pH of 7.5 and 30 meq/liter potassium. The myocardium was cooled externally by cold Ringer's lactate at 4 °C and through coronary circulation by cold cardioplegic solution at 8 °C. The myocardial temperature was continuously monitored and kept between 12 and 18 °C. Moderate systemic hypothermia was used (26 to 30 °C). Eighty-two patients have been operated upon using this technique. Eighteen patients had single or double valve replacements, 4 had valve replacements with coronary bypass, and 60 had coronary bypass procedures. The operating conditions have been excellent and the myocardial protection offered by this technique has been good. Perioperative myocardial infarctions, as diagnosed by ECG and CPK (MB isoenzymes) and myocardial scans, were seen in 6 patients. In conclusion the combined modalities of potassium arrest and local cardiac hypothermia give excellent myocardial protection during cardiac surgery.