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Intramural coronary collateral flow in dogs
K W Scheel1, G Daulat, H J Mass
1Department of Physiology, Texas College of Osteopathic Medicine, Fort Worth 76107-2690.
Insights
Intramural collaterals significantly contribute to coronary collateral flow, accounting for approximately half of the total retrograde flow even after epicardial collaterals are blocked. This finding highlights the importance of intramural vessels in maintaining blood supply.
Area of Science:
- Cardiovascular Physiology
- Coronary Circulation Research
Background:
- Coronary collateral circulation is vital for myocardial perfusion during ischemia.
- The relative contributions of epicardial versus intramural collaterals to overall collateral flow remain incompletely understood.
Purpose of the Study:
- To quantify the contribution of intramural collaterals to total retrograde coronary flow.
- To differentiate between epicardial and intramural collateral flow pathways.
Main Methods:
- Isolated, blood-perfused beating dog heart preparation.
- Cannulation of major coronary arteries (left circumflex, left anterior descending, right, septal).
- Cauterization of epicardial collaterals followed by retrograde flow measurement.
Main Results:
- After epicardial collateral cauterization, 58% +/- 3.6% of total retrograde flow persisted.
- The septal and left anterior descending coronary arteries were major contributors to this remaining intramural flow.
- Intramural collaterals accounted for a substantial portion of the measured retrograde flow.
Conclusions:
- Intramural collaterals represent a significant component of the coronary collateral circulation.
- These findings underscore the importance of intramural pathways in dogs with native collateral networks.
Abstract:
The objective of this study was to determine whether intramural collaterals contribute significantly to total retrograde flow (index of collateral flow). The left circumflex, left anterior descending, right, and septal coronary arteries were separately cannulated, and blood flows through these vessels were monitored on an isolated, blood-perfused beating heart preparation. Epicardial collaterals between the borders of the circumflex and right coronary perfusion territories were cauterized, and retrograde flow from the circumflex coronary artery was determined before and after cauterization. This procedure unmasked the intramural collateral flow component to retrograde flow. By occluding and unoccluding the coronary flows from the right, septal, and left anterior descending coronary arteries during these measurements, we were able to determine their contribution to epicardial and intramural collateral flow. We found that, after cauterization, an average of 58 +/- 3.6% of the total retrograde flow remained. The septal and left anterior descending coronary arteries contributed almost equally to this retrograde flow. We concluded that, because the epicardial collaterals were cauterized, the source of retrograde flow was from intramural collaterals and constituted about one-half of the measured retrograde flow in dogs with a native collateral circulation.