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Does cardiopulmonary bypass alone elicit myoprotective preconditioning?
P G Burns1, I B Krukenkamp, C A Caldarone
1Department of Surgery, Deaconess Hospital, Harvard Medical School, Boston, Mass 02215, USA.
Circulation
|November 1, 1995
Summary
Cardiopulmonary bypass (CPB) alone provides myocardial protection similar to ischemic preconditioning (PC) during cardiac surgery. This effect is mediated by alpha-adrenergic and adenosine receptors, suggesting CPB can elicit a protective response without ischemia.
Area of Science:
- Cardiovascular Physiology
- Cardiac Surgery
- Myocardial Protection
Background:
- Ischemic preconditioning (PC) enhances myocardial protection during cardiac surgery.
- The potential for cardiopulmonary bypass (CPB) alone to induce PC was previously unknown.
Purpose of the Study:
- To investigate if CPB alone can elicit a preconditioning response in sheep myocardium.
- To identify the receptor pathways involved in CPB-induced myocardial protection.
Main Methods:
- Sheep were divided into groups: control, ischemic PC, CPB alone, CPB with alpha-adrenergic blockade, and CPB with adenosine receptor blockade.
- All groups underwent a standardized period of normothermic regional ischemia and reperfusion.
- Infarct size (IS) relative to area at risk (AR) was measured to assess myocardial damage.
Main Results:
- Ischemic PC significantly reduced IS/AR by 54% compared to controls.
- CPB alone also significantly reduced IS/AR, demonstrating a similar protective effect without ischemia.
- This CPB-induced protection was abolished by alpha-adrenergic or adenosine receptor blockade.
Conclusions:
- Cardiopulmonary bypass alone is sufficient to induce myocardial preconditioning during cardiac surgery.
- Alpha-adrenergic and adenosine receptor stimulation are key mechanisms initiating CPB-induced PC.