Myocardial outflow of prostacyclin in relation to metabolic stress during off-pump coronary artery bypass grafting.
BACKGROUND
The metabolic changes, possible myocardial damage, and influence on the vascular endothelium during off-pump coronary artery bypass grafting have been investigated.


METHODS
Coronary sinus and arterial blood samples were obtained before coronary arterial occlusion, after 10 minutes of ischemia, and after 1 and 10 minutes of reperfusion in 9 patients who had an anastomosis performed to the left anterior descending coronary artery off-pump bypass


RESULTS
The mean ischemic time was 14 +/- 1 minutes. The arteriovenous difference in lactate decreased during ischemia to reach a minimum at 1 minute of reperfusion (-0.15 +/- 0.06 micromol/L compared to 0.21 +/- 10 micromol/L before ischemia; p < 0.01). Myocardial lactate extraction decreased from 14.2 +/- 6.8 micromol/min before ischemia to -10.9 +/- 6.5 micromol/min after 1 minute of reperfusion (p < 0.01). Simultaneously, the arteriovenous difference in 6-keto-PGF(1alpha), the stable metabolite of prostacyclin, decreased from -30 +/- 26 pg/mL to -258 +/- 80 pg/mL at 1 minute of reperfusion (p < 0.05), and the 6-keto-PGF(1alpha) extraction over the heart decreased -556 +/- 466 pg/min to -18,560 +/- 5,683 pg/min (p < 0.01).


CONCLUSIONS
The localized myocardial ischemia associated with these procedures causes changes in the myocardium and endothelial influence. Coronary bypass surgery performed on the beating heart may not be superior in preventing cardiac ischemia and endothelial disturbance, compared with conventional bypass surgery.
Department of Thoracic Surgery, Karolinska Hospital, Stockholm, Sweden. ulflockowandt@yahoo.com
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Lockowandt
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Owall
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Franco-Cereceda
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000368:Aged; D000369:Aged, 80 and over; D001026:Coronary Artery Bypass; D019332:Endothelin-1 / Q000097:blood; D011464:Epoprostenol / Q000097:blood*; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009569:Nitric Oxide / Q000097:blood
D019332:Endothelin-1; D007773:Lactates; D009569:Nitric Oxide; D015121:6-Ketoprostaglandin F1 alpha; D011464:Epoprostenol