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Retrograde coronary sinus perfusion provides non-homogeneous myocardial blood flow
M V Smith1, R F Stahl, C Cronin
1Department of Surgery, University of Massachusetts Medical Center, Worchester 01655.
Insights
Retrograde cardioplegia may not adequately perfuse the right ventricle. Studies show uneven blood flow, with some basal areas receiving significantly less flow, potentially compromising cardiac protection.
Area of Science:
- Cardiovascular Physiology
- Cardiac Surgery
Background:
- The efficacy of retrograde cardioplegia in protecting the right ventricle is debated.
- Understanding right ventricular myocardial perfusion is crucial for cardiac surgical outcomes.
Purpose of the Study:
- To assess the distribution of myocardial blood flow during retrograde coronary perfusion in the canine right ventricle.
- To determine if retrograde cardioplegia provides uniform perfusion to all regions of the right ventricle.
Main Methods:
- Canine myocardial circulation was evaluated using colored microspheres infused via the coronary sinus.
- Relative flow index (RFI) was calculated for 76 myocardial sections to quantify regional blood flow.
- Statistical analysis was performed to compare flow in different ventricular regions.
Main Results:
- Three distinct myocardial blood flow regions were identified.
- Basal right ventricular sections showed significantly reduced blood flow (RFI = 0.23 +/- 0.19) compared to normally perfused areas (RFI = 1.12 +/- 0.06).
- The right ventricular apex exhibited augmented flow (RFI = 3.72 +/- 1.18).
Conclusions:
- Retrograde coronary perfusion results in nonuniform blood flow distribution within the right ventricle.
- Certain portions of the right ventricle may receive inadequate perfusion with retrograde cardioplegia, questioning its protective capacity.
Abstract:
The ability of retrograde cardioplegia to protect the right ventricle has been questioned. Canine myocardial circulation was assessed by infusing colored microspheres through the coronary sinus. The relative flow index (RFI), a normalized measure of tissue blood flow, was determined for 76 sections of myocardium. Three distinct flow regions were evident from these measurements. A paucity of blood flow through some basal sections of the right ventricle (RFI = 0.23 +/- 0.19) was found to be significantly different (p < 0.005) from regions of the heart with normal flow (RFI = 1.12 +/- 0.06). Sections from the right ventricular apex demonstrated augmented flow (RFI = 3.72 +/- 1.18). These data indicate that retrograde coronary perfusion provides nonuniform flow and under some conditions may provide inadequate perfusion to portions of the right ventricle.