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Superiority of retrograde cardioplegia after acute coronary occlusion
1Department of Cardiothoracic Surgery, Boston University Medical Center, Massachusetts.
Insights
Retrograde coronary sinus cardioplegia offers superior myocardial protection compared to antegrade delivery during acute coronary occlusion revascularization. This method reduces tissue acidosis and myocardial necrosis, improving heart muscle recovery.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- Antegrade cardioplegia may not effectively perfuse areas distal to coronary occlusions.
- Optimal myocardial protection during revascularization of acute coronary occlusions remains a challenge.
Purpose of the Study:
- To compare the efficacy of retrograde coronary sinus cardioplegia versus antegrade cardioplegia in providing myocardial protection during acute coronary occlusion revascularization.
Main Methods:
- Adult pigs (n=20) underwent temporary occlusion of coronary artery branches.
- Cardioplegia was administered either antegrade (aortic root) or retrograde (coronary sinus) during ischemic arrest.
- Myocardial protection was assessed via echocardiography, myocardial pH, and histochemical analysis of necrosis.
Main Results:
- Retrograde cardioplegia resulted in significantly less tissue acidosis (p<0.05) and myocardial necrosis (p<0.0001).
- Wall motion scores were improved with retrograde delivery, though not statistically significant.
- Retrograde coronary sinus cardioplegia demonstrated superior outcomes in mitigating ischemic damage.
Conclusions:
- Retrograde coronary sinus cardioplegia provides more effective myocardial protection than antegrade delivery in the context of acute coronary occlusion revascularization.
- This technique optimizes cardioplegia distribution, enhancing protection of ischemic myocardium.
Abstract:
Because antegrade cardioplegia may limit the distribution of cardioplegia beyond a coronary occlusion, this study was undertaken to determine whether retrograde coronary sinus cardioplegia provides superior myocardial protection during revascularization of an acute coronary occlusion. In 20 adult pigs, the second and third diagonal branches were occluded with a snare for 1 1/2 hours. Animals were then placed on cardiopulmonary bypass and underwent 30 minutes of ischemic arrest with multidose, potassium, crystalloid cardioplegia. In 10 animals, the cardioplegia was given antegrade through the aortic root, whereas in 10 others, it was given retrograde through the coronary sinus. After the arrest period, the coronary snares were released and all hearts were reperfused for 3 hours. Postischemic damage in the myocardium beyond the occlusions was assessed by wall motion scores using two-dimensional echocardiography (4 = normal to -1 = dyskinesia), the change in myocardial pH from preischemia, and the area of necrosis/area of risk (histochemical staining). Hearts protected with retrograde coronary sinus cardioplegia had less tissue acidosis (change in pH = 0.08 +/- 0.03 versus 0.41 +/- 0.13; p less than 0.05), higher wall motion scores (2.0 +/- 0.6 versus 1.3 +/- 0.3; not significant), and less myocardial necrosis (43.4% +/- 3.6% versus 73.3% +/- 3.5%; p less than 0.0001). We conclude that retrograde coronary sinus cardioplegia provides more optimal myocardial protection than is possible with antegrade cardioplegia after revascularization of an acute coronary occlusion.