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Myocardial protection with postconditioning is not enhanced by ischemic preconditioning
Michael E Halkos1, Faraz Kerendi, Joel S Corvera
1Cardiothoracic Research Laboratory, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Crawford Long Hospital, Emory University School of Medicine, Atlanta, Georgia 30308-2225, USA.
The Annals of Thoracic Surgery
|September 1, 2004
Summary
Combining ischemic preconditioning (IPC) and postconditioning (postcon) did not offer additional cardioprotection beyond individual methods in a canine ischemia-reperfusion model. Postconditioning alone effectively attenuated myocardial injury, suggesting clinical applicability in surgeries like OPCAB.
Area of Science:
- Cardiovascular Science
- Myocardial Protection Strategies
- Surgical Interventions
Background:
- Ischemic preconditioning (IPC) is used in off-pump coronary artery bypass surgery (OPCAB) to mitigate injury from vessel ligation.
- Postconditioning (postcon), involving brief reperfusion-reocclusion cycles, also attenuates myocardial injury.
- This study investigated if combining IPC and postcon enhances cardioprotection against ischemia-reperfusion injury.
Purpose of the Study:
- To test the hypothesis that combined IPC and postcon provide superior cardioprotection compared to either intervention alone.
- To evaluate the combined effect on inhibiting oxidant-mediated injury following ischemia and reperfusion.
- To assess the efficacy of these interventions in a canine model of regional ischemia and reperfusion.
Main Methods:
- Four groups of open-chest canines underwent 60 minutes of coronary occlusion followed by 3 hours of reperfusion.
- Groups included: control, IPC, postcon, and combined IPC+postcon.
- Interventions involved specific protocols of coronary occlusion/reperfusion cycles before prolonged occlusion or immediately upon reperfusion.
Main Results:
- Infarct size was significantly reduced by IPC and postcon individually compared to control, with no further reduction by the combined approach.
- Tissue water content and superoxide anion generation were reduced in all intervention groups versus control.
- Plasma malondialdehyde levels, a marker of lipid peroxidation, were lower in all intervention groups.
- Ventricular fibrillation incidence decreased in all treated groups.
Conclusions:
- No additive cardioprotective effects were observed when combining IPC and postcon in this canine model.
- Postconditioning demonstrated potent attenuation of myocardial injury.
- Postconditioning may represent a clinically applicable strategy for procedures such as OPCAB.