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Intermittent coronary sinus occlusion after coronary arterial ligation results in venous retroperfusion
R Beyar1, A D Guerci, H R Halperin
1Peter Belfer Laboratory for Myocardial Research, Johns Hopkins Medical Institutions, Baltimore, MD 21205.
Insights
Coronary sinus occlusion can reduce heart muscle damage by enabling retrograde venoarterial flow. This alternating flow into the ischemic area is a potential mechanism for myocardial salvage during intermittent occlusion.
Area of Science:
- Cardiovascular Physiology
- Myocardial Ischemia Research
Background:
- Coronary sinus occlusion is known to reduce necrosis in ischemic heart muscle.
- The mechanism by which this occurs, specifically regarding blood flow dynamics, requires further elucidation.
Purpose of the Study:
- To test the hypothesis that coronary sinus occlusion induces retrograde venoarterial flow.
- To investigate the pressure and flow patterns during coronary sinus occlusion in ischemic myocardium.
Main Methods:
- Measurements of coronary arteriovenous pressure gradient and coronary arterial oxygen saturation in dogs with a ligated left anterior descending coronary artery.
- Construction of a mathematical model of coronary physiology to simulate pressure and flow during coronary sinus occlusion.
Main Results:
- Coronary sinus occlusion created significant systolic and diastolic pressure gradients between the coronary artery and sinus.
- A notable reduction in oxygen saturation in the ligated coronary artery indicated admixture of venous blood.
- Mathematical modeling supported the possibility of venoarterial pressure gradients and flow reversal.
Conclusions:
- Evidence suggests retrograde flow into the ischemic myocardium occurs during intermittent coronary sinus occlusion.
- Alternating flow patterns may be the mechanism responsible for myocardial salvage in this context.
Abstract:
Coronary sinus occlusion retards necrosis of ischemic myocardium. To test the hypothesis that coronary sinus occlusion induces retrograde venoarterial flow, the coronary arteriovenous pressure gradient and the coronary arterial oxygen saturation were measured distal to a left anterior descending coronary artery ligature in dogs. In parallel, we constructed a mathematical model of known coronary physiology to characterize pressure and flow patterns during coronary sinus occlusion. In dogs, coronary sinus occlusion produced a systolic pressure gradient between the coronary artery and the coronary sinus of -20 +/- 9 mm Hg (higher venous pressure, p less than 0.0001) and a positive diastolic gradient of 3 +/- 5 mm Hg (lower venous pressure p less than 0.01). An average reduction in the oxygen saturation in the ligated coronary artery of 20 +/- 13% was also observed (p less than 0.005) consequent to admixture of venous (desaturated) blood. By graded inflation of the coronary sinus balloon, it was demonstrated that desaturation of arterial blood typically occurs above a coronary sinus systolic pressure of 40-50 mm Hg. The mathematical model indicates the possibility of venoarterial pressure gradients and reversal of flow at the microcirculatory level during coronary sinus occlusion. These studies provide evidence that retrograde flow into the ischemic zone occurs in association with intermittent coronary sinus occlusion. Thus, alternating flow over the ischemic territory may be the mechanism of myocardial salvage during intermittent coronary sinus occlusion.