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Assessment of retrograde cardioplegia distribution using contrast echocardiography
S Aronson1, B K Lee, J R Liddicoat
1Section of Cardiac Surgery, University of Chicago, Pritzker School of Medicine, Illinois.
Insights
Retrograde cardioplegia offers inconsistent septal delivery compared to antegrade methods. However, retrograde cardioplegia effectively perfuses areas distal to coronary occlusions, as shown by contrast echocardiography in canine models.
Area of Science:
- Cardiology
- Cardiac Surgery
- Medical Imaging
Background:
- Retrograde cardioplegia is increasingly utilized in cardiac surgeries.
- Understanding cardioplegia distribution is crucial for myocardial protection.
Purpose of the Study:
- To compare the distribution of antegrade versus retrograde cardioplegia.
- To assess the impact of coronary occlusion on cardioplegia delivery.
- To evaluate contrast echocardiography for myocardial perfusion assessment.
Main Methods:
- Open-chest canine model.
- Contrast echocardiography to visualize cardioplegia distribution.
- Simulated antegrade (aortic root) and retrograde (coronary sinus) delivery.
- Induction of acute coronary artery occlusions.
Main Results:
- Antegrade cardioplegia achieved homogeneous left ventricular and septal perfusion without occlusion.
- Retrograde cardioplegia provided inconsistent septal perfusion but good left ventricular free wall coverage.
- Antegrade perfusion was significantly reduced (57-65%) with coronary occlusions.
- Retrograde cardioplegia distribution remained unaffected by acute coronary occlusions.
Conclusions:
- Retrograde cardioplegia demonstrates less homogeneous distribution than antegrade delivery in intact coronary circulation.
- Retrograde cardioplegia effectively perfuses myocardium distal to occluded coronary arteries.
- Contrast echocardiography is a valuable tool for assessing myocardial perfusion with potential clinical applications.
Abstract:
Retrograde cardioplegia has gained popularity in coronary and noncoronary cardiac operations. We have used contrast echocardiography in the open-chest canine model to compare the distribution of cardioplegia delivered antegrade in the aortic root versus retrograde through the coronary sinus, and to determine the effect of coronary occlusion on that delivery. With no coronary occlusion, antegrade cardioplegia was distributed to the entire left ventricle and septum whereas retrograde cardioplegia was distributed to the left ventricular free wall but had inconsistent delivery to the septum. Acute occlusion of the left circumflex coronary artery resulted in 57.06% +/- 9.52% of the left ventricle not being perfused by antegrade cardioplegia and occlusion of both the left circumflex and anterior descending coronary arteries caused a 65.46% +/- 18.5% reduction in perfusion by antegrade cardioplegia. Acute coronary occlusion had no effect on retrograde cardioplegia distribution. We conclude that retrograde cardioplegia is less homogeneous than antegrade cardioplegia in the intact coronary circulation but that retrograde cardioplegia preserves cardioplegia distal to acutely occluded coronary arteries. Furthermore, contrast echocardiography is a useful method of assessing myocardial perfusion and may have useful clinical applications.