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Continuous versus intermittent cardioplegia in the presence of a coronary occlusion
H L Lazar1, S Rivers, M Cambrils
1Department of Cardiothoracic Surgery, Boston University Medical Center, Massachusetts.
Insights
Continuous antegrade cardioplegia did not improve myocardial temperature or acid washout compared to intermittent delivery during coronary occlusion. Both methods resulted in similar tissue acidosis and abnormal wall motion in pigs.
Area of Science:
- Cardiovascular Surgery
- Cardioplegia Delivery
- Myocardial Protection
Background:
- Coronary artery occlusions can impair cardioplegia distribution, leading to ischemic damage.
- Optimizing cardioplegia delivery is crucial for minimizing myocardial injury during cardiac surgery.
- Understanding the impact of delivery methods on myocardial temperature and metabolite washout is essential.
Purpose of the Study:
- To compare continuous versus intermittent antegrade cardioplegia delivery in the presence of coronary occlusions.
- To assess the effects on myocardial temperature and acid metabolite washout.
- To evaluate the impact on myocardial function post-ischemia.
Main Methods:
- Twenty pigs underwent cardiopulmonary bypass with a 2-hour ischemic arrest and left anterior descending artery occlusion.
- Ten pigs received intermittent antegrade cardioplegia (4°C) every 20 minutes.
- Ten pigs received continuous antegrade cardioplegia (30 mL/min) at 4°C.
Main Results:
- Both continuous and intermittent cardioplegia resulted in similar myocardial acidosis (pH 6.69 vs. 6.73).
- Myocardial temperatures were comparable between groups during arrest (18.3°C vs. 18.2°C).
- Two-dimensional echocardiography showed similar abnormal wall motion in both groups post-reperfusion.
Conclusions:
- Continuous antegrade cardioplegia does not offer significant advantages over intermittent delivery in improving myocardial temperature or metabolite washout during coronary occlusion.
- Both methods led to comparable levels of tissue acidosis and impaired myocardial function in this porcine model.
- Further research may be needed to optimize cardioplegia strategies in the setting of coronary occlusions.
Abstract:
Coronary artery occlusions can alter the distribution of cardioplegia and result in ischemic damage. This study was undertaken to determine whether continuous antegrade cardioplegia delivery would result in colder temperatures and provide better washout of acid metabolites than is possible with intermittent antegrade cardioplegia when coronary occlusions are present. Twenty pigs were placed on cardiopulmonary bypass and underwent 2 hours of ischemic arrest with occlusion of the middle left anterior descending coronary artery followed by 1 hour of reperfusion without occlusion of that artery. Ten pigs received intermittent (every 20 minutes) antegrade potassium crystalloid cardioplegia (4 degrees C), and 10 others had the same solution given continuously (30 mL/min). Cardioplegia distribution was assessed by continuous monitoring of myocardial pH (Khuri pH probe) and temperature in the region beyond the occlusion of the left anterior descending coronary artery. Both cardioplegic techniques resulted in tissue acidosis (continuous group, 6.69 +/- 0.08, versus intermittent group, 6.73 +/- 0.07; not significant). Average temperature in the left anterior descending coronary artery during arrest was also similar in both groups (continuous group, 18.3 degrees +/- 0.5 degrees C, versus intermittent group, 18.2 degrees +/- 0.5 degrees C). Because of these metabolic changes, both cardioplegic techniques resulted in abnormal wall motion in the anteroseptal region using two-dimensional echocardiography, but the scores were not significantly different (continuous group, 1.5 +/- 0.3, versus intermittent group, 1.6 +/- 0.4; 4 = normal to 0 = dyskinesia).(ABSTRACT TRUNCATED AT 250 WORDS)