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Studies of functional site of origin of native coronary collaterals
Insights
This study estimates the pressure at the origin of coronary collaterals (Pstem) by measuring peripheral coronary pressure during embolization. Results indicate Pstem can be accurately determined using this method, suggesting a minimal contribution from microvascular anastomoses.
Area of Science:
- Cardiovascular Physiology
- Coronary Circulation Research
- Hemodynamics
Background:
- Understanding coronary collateral circulation is crucial for managing ischemic heart disease.
- Accurate measurement of the pressure at the origin of native coronary collaterals (Pstem) is vital for assessing collateral function.
- Distinguishing contributions from proximal vs. distal collateral vessels remains a challenge.
Purpose of the Study:
- To determine the pressure at the origin of native coronary collaterals (Pstem).
- To assess the contribution of proximal conduit coronary vessels versus distal microvessels to collateral flow.
- To validate a method for estimating Pstem using peripheral coronary pressure measurements.
Main Methods:
- Isolated blood-perfused dog hearts were utilized.
- Aortic pressure was maintained at 80 mmHg.
- Collateral flow was measured using radioactive microspheres before and after sequential embolization of the circumflex vasculature with nonradioactive microspheres, while monitoring peripheral coronary pressure (PCP).
Main Results:
- Sequential microembolization progressively decreased collateral flow and increased peripheral coronary pressure (PCP).
- The relationship between decreasing collateral flow and increasing PCP was linear, yielding a pressure intercept of 74 +/- 3 mmHg.
- This pressure intercept provided an accurate estimate of Pstem, comparable to left anterior descending pressure (75 +/- 2 mmHg).
Conclusions:
- Pstem can be accurately estimated by measuring pressure in a nonoccluded large epicardial vessel.
- The contribution of microvascular anastomoses to total coronary collateral flow appears to be minimal.
- This method offers a reliable approach to assessing coronary collateral function in physiological studies.
Abstract:
Studies were performed to determine the pressure at the origin of the native coronary collaterals (Pstem) and thus assess the contribution of collaterals arising from proximal conduit coronary vessels vs. those arising from distal microvessels. Nine isolated blood-perfused dog hearts were studied. Aortic pressure was maintained at 80 mmHg. Collateral flow to the circumflex perfusion field was measured (radioactive microspheres) repeatedly before and after successive 25-micron nonradioactive microsphere embolization of the circumflex vasculature. After each microembolization, collateral flow decreased and peripheral coronary pressure (PCP) increased. After all embolizations collateral flow decreased from an initial value of 17 +/- 4 to 2 +/- 0.4 ml X min-1 X 100 g-1 and PCP increased from an initial value of 15 +/- 3 to 65 +/- 3 mmHg. The relationship between decreasing collateral flow and increasing PCP was linear with a pressure intercept of 74 +/- 3 mmHg. This pressure intercept predicts the PCP that would be observed if microembolization produced complete cessation of collateral flow. Accordingly, this pressure intercept allowed an accurate estimate of Pstem. This estimate of Pstem was similar to left anterior descending pressure (75 +/- 2 mmHg). These studies show that Pstem may be accurately estimated by measuring pressure in a nonoccluded large epicardial vessel. The contribution of microvascular anastomoses to total collateral flow is likely small.