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Myocardial tissue pCO2 and calcium content during ventricular fibrillation and reperfusion periods
M Kobayashi1, H Orita, T Shimanuki
1Second Department of Surgery, Yamagata University School of Medicine, Japan.
Insights
Prompt defibrillation after cardiac surgery minimizes myocardial acidosis during reperfusion. Faster defibrillation (under 10 minutes) improved cardiac function and reduced calcium overload compared to delayed defibrillation (over 10 minutes).
Area of Science:
- Cardiovascular Surgery
- Cardiomyopathy Research
- Myocardial Protection
Background:
- Cardiac surgery often involves hypothermia and cardioplegia.
- Ventricular fibrillation and reperfusion can impact myocardial health.
- Understanding myocardial response to reperfusion is crucial for patient outcomes.
Purpose of the Study:
- To investigate the effects of ventricular fibrillation and reperfusion on the myocardium.
- To determine the impact of defibrillation timing on myocardial acidosis and calcium content.
- To assess the correlation between defibrillation timing and post-operative cardiac function.
Main Methods:
- Studied 41 cardiac surgery patients under hypothermia and cardioplegia.
- Utilized intramyocardial pCO2 and temperature sensors.
- Grouped patients based on aorta declamping to defibrillation time (<10 min vs. >10 min).
Main Results:
- Myocardial pCO2 increased post-aorta declamping and decreased post-defibrillation in both groups.
- Faster defibrillation (Group A) showed a lower rate of pCO2 increase and a higher rate of decrease.
- Group A exhibited less myocardial calcium accumulation and better left ventricular work index (LVWI) post-surgery.
Conclusions:
- Prompt defibrillation (under 10 minutes) minimizes myocardial acidosis during reperfusion.
- Delayed defibrillation is associated with increased myocardial calcium content.
- Faster defibrillation improves cardiac pump function after cardiopulmonary bypass.
Abstract:
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.