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Updated: Jul 16, 2026
Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction
Published on: October 14, 2016
Perioperative infarction: effects of cardiopulmonary bypass on collateral circulation in an acute canine model
A T Miyamoto1, L Robinson, J M Matloff
1Department of Thoracic, Cardiac and Vascular Surgery, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, California 90048, USA.
Insights
Normothermic cardiopulmonary bypass significantly impairs coronary collateral flow (CCI) in dogs, leading to severe ischemia and infarction. This suggests current myocardial preservation techniques may be insufficient for collateral-dependent regions during surgery.
Area of Science:
- Cardiovascular Physiology
- Surgical Research
- Myocardial Protection
Background:
- Intracoronary collateralization is crucial for maintaining blood flow to ischemic myocardium.
- Collateral circulation index (CCI) quantifies collateral flow, with higher values indicating better collateralization.
- Acute occlusion of the left anterior descending (AD) coronary artery can induce collateral formation from the circumflex (Cx) artery.
Purpose of the Study:
- To evaluate the impact of normothermic total cardiopulmonary bypass (TCPBP) on established intracoronary collateral function.
- To compare myocardial injury in dogs undergoing TCPBP versus control dogs with similar collateralization levels.
Main Methods:
- Canine hearts with significant collateralization (CCI > 80%) underwent 60-90 minutes of TCPBP.
- Control group (CCI < 80%) did not undergo TCPBP.
- Collateral circulation index (CCI) was measured, defined as distal coronary diastolic pressure x 100/aortic diastolic pressure.
Main Results:
- Dogs undergoing TCPBP experienced an abrupt fall in CCI to 30% (P < 0.03).
- TCPBP group showed severe myocardial ischemia and infarction.
- Two dogs in the TCPBP group became "pump dependent," requiring external circulatory support.
Conclusions:
- Ventricular pressure work is a critical determinant of flow through collateral channels.
- Normothermic cardiopulmonary bypass adversely affects collateral circulation, potentially compromising myocardium supplied by collaterals.
- Current myocardial preservation strategies during coronary surgery may need re-evaluation for collateral-dependent areas.
Abstract:
Significant intracoronary collateralization [circumflex (Cx) to anterior descending (AD)] can be established acutely by selective hypertensive perfusion of the circumflex (through left main) after acute occlusion of the AD in working canine hearts. Intracoronary collateral flow can be estimated by a collateral circulation index (CCI) = distal coronary diastolic pressure x 100/aortic diastolic pressure. The effects of 60 to 90 min of normothermic, total cardiopulmonary bypass (TCPBP) on such collaterals were evaluated in four dogs with CCI > 80%, and compared to six control dogs with CCI < 80% and without TCPBP. Three hours after AD ligation, control dogs had minimal myocardial injury despite significantly lower CCI. In contrast, the four study dogs placed on TCPBP experienced an abrupt fall of the CCI to 30% (P < 0.03), severe ischemia, and infarction in each; two became pump dependent. Thus, ventricular pressure work seems to be an important determinant of flow through collateral channels. These results suggest that preservation techniques for myocardium supplied by collaterals during coronary surgery may require considerations other than intermittent perfusion via existing coronary inflow.
