[Potassium substitution during coronary surgery: K(+)-Mg+(+)-aspartate-complex (Inzolen) versus potassium chloride]

Potassium loss may cause arrhythmias and cardiac injury in patients undergoing heart surgery with cardiopulmonary bypass (CPB). In a prospective, randomized trial two different methods of potassium substitution were investigated regarding their influence on cardiac rhythm following reperfusion. Patients received either potassium chloride (Group I, n = 102) or potassium magnesium aspartate (Inzolen, group II, n = 105) to achieve intraoperative serum potassium concentrations of 4.5 mmol/l. St. Thomas cardioplegic solution was used. CPB was performed in moderate hypothermia (28-32 degrees C) with a non-pulsatile pump flow, a membrane oxygenator and a single two-stage venous catheter. The two study groups were comparable with regard to biometric data, preoperative state, duration of operation, ischemia and clinical outcome. In 6 patients in group I and in 3 patients in group II perioperative myocardial infarction was diagnosed based on ECG and CK-MB findings. One patient in each group died during the postoperative hospital stay. At the time of declamping mean serum potassium concentration was 4.9 +/- 0.7 mmol/l in group I and 4.8 +/- 0.5 mmol/l in group II (n.s.). The concentration of magnesium was significantly lower in the potassium chloride substitution group (1.48 mmol/l) compared to the other group (2.33 mmol/l) (p < 0.05). No significant differences in cardiac electric activity were observed between the two groups. The incidence of ventricular fibrillation in the early reperfusion period was 37% versus 45% (n. s.). In both groups patients with a potassium value of < 4.5 mmol/l showed a significantly higher incidence of ventricular fibrillation. Five percent of the patients had bradycardia requiring temporary pacing.(ABSTRACT TRUNCATED AT 250 WORDS)