Myocardial tissue pCO2 and calcium content during ventricular fibrillation and reperfusion periods

Forty-one patients who underwent cardiac surgery under conditions of systemic hypothermia and intermittent cold crystalloid potassium cardioplegia were studied, in order to elucidate the effects of ventricular fibrillation and reperfusion on the myocardium, by using the intramyocardial pCO2 and temperature sensor. All patients were assigned to 2 groups, namely; group A (21 cases), in which the time between the aorta declamping and defibrillation was under 10 minutes, and group B (20 cases) in which the time was over 10 minutes. In both groups A and B, myocardial pCO2 increased at the rate of 3.58 +/- 1.70 and 2.16 +/- 0.62 mmHg/min (p less than 0.05) after aorta declamping, respectively and the myocardial pCO2 decreased at the rate of 5.59 +/- 0.60 and 4.18 +/- 0.76 mmHg/min (p less than 0.05) after defibrillation, respectively. In group A, the myocardial calcium content, pre-CPB (cardio pulmonary bypass) was 10.98 +/- 1.62 nmol/mg/dry weight and at the time of aorta declamping it was 15.90 +/- 1.81 nmol/mg/dry weight (p less than 0.05). In group B, the myocardial calcium content, pre-CPB, was 14.62 +/- 2.15 nmol/mg/dry weight and at the time of aorta declamping it was 18.23 +/- 4.36 nmol/mg/dry weight (p less than 0.05). At both three and six hours after the operation, the left ventricular work index per minute (LVWI) in group A showed better cardiac pump function than that in group B. We therefore conclude that when reperfusion is encountered, acidosis can be minimized by prompt defibrillation.