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Is the heart a source for elevated circulating endothelin levels during aorta-coronary artery bypass grafting surgery
1Department of Cardiology, Sackler School of Medicine, Tel Aviv University, Petah Tikva, Israel.
Insights
Increased endothelins during heart surgery likely stem from systemic sources, not the heart muscle itself. This study investigated endothelin production during coronary artery bypass grafting.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Surgical Medicine
Background:
- Systemic endothelin levels increase during coronary artery bypass grafting (CABG).
- The source of elevated endothelins (systemic vs. myocardial) during CABG remains unclear.
- Distinguishing between general surgical response and myocardial ischemia/reperfusion response is crucial.
Purpose of the Study:
- To determine whether elevated endothelin levels during CABG originate from systemic production or increased myocardial production due to ischemia/reperfusion.
- To investigate the temporal changes in endothelin levels in different circulatory compartments during CABG.
Main Methods:
- Measured endothelin levels in the right atrium and proximal aorta of 15 patients undergoing CABG.
- Assessed endothelin levels immediately before aortic crossclamping and after cardiopulmonary bypass cessation.
- Additionally measured coronary sinus endothelin levels in five patients during cardiopulmonary bypass circulation.
Main Results:
- Endothelin levels remained elevated throughout the CABG procedure.
- Right atrial endothelin levels significantly increased post-cardiopulmonary bypass compared to pre-crossclamping values (p = 0.008).
- Proximal aortic endothelin levels showed no significant change, while coronary sinus levels tended to decrease during bypass (p = 0.06).
Conclusions:
- The observed rise in right atrial endothelin during CABG reflects systemic production, likely from vasculature or organs distal to the proximal aorta.
- Increased myocardial production of endothelins in response to ischemia/reperfusion is not the primary cause of elevated levels during CABG.
- Findings suggest a non-myocardial origin for the systemic endothelin increase during this cardiac surgery.
Abstract:
Reports have shown increased systemic levels of endothelins during coronary artery bypass grafting in human beings. It was not known whether increased endothelin levels during coronary artery bypass grafting reflect a general systemic response to the surgical procedure or increased myocardial production of endothelins in response to ischemia and reperfusion. We therefore measured endothelin levels in the right atrium and proximal aorta of 15 patients undergoing coronary artery bypass grafting for anginal syndrome immediately before aortic crossclamping and again after cessation of cardiopulmonary bypass. In five patients, we also measured coronary sinus levels of endothelins during cardiopulmonary bypass circulation. We found that endothelin levels were elevated throughout the surgical procedure. Right atrial endothelin levels were significantly elevated after cessation of cardiopulmonary bypass circulation with respect to values immediately before aortic crossclamping (11.1 +/- 3.1 vs 14.2 +/- 3.7 pg/ml, p = 0.008), whereas endothelin levels in the proximal aorta did not rise significantly (10.5 +/- 2.3 vs 11.6 +/- 2.4 pg/ml, p > 0.5). Coronary sinus endothelin levels tended to decline temporarily during cardiopulmonary bypass circulation (11.1 +/- 2.1 pg/ml before aortic crossclamping, 7.9 +/- 1.9 1 minute after release of aortic crossclamp, and 9.9 +/- 2.1 pg/ml after release of partial aortic crossclamping, p = 0.06). We conclude that the rise in right atrial endothelin levels during coronary artery bypass grafting reflects systemic production and secretion of endothelins, probably by vasculature or organs distal to the proximal aorta, and is not the result of increased myocardial production and secretion of endothelins.