High thoracic epidural anesthesia, but not clonidine, attenuates the perioperative stress response via sympatholysis and reduces the release of troponin T in patients undergoing coronary artery bypass grafting

In this prospective study, we evaluated whether high thoracic epidural anes thesia (TEA) or TV clonidine, in addition to general anesthesia, affects th e cardiopulmonary bypass- and surgery-associated stress response and incide nce of myocardial ischemia by their sympatholytic properties. Seventy patie nts scheduled for elective coronary artery bypass graft (CABG) received gen eral anesthesia with sufentanil and propofol. TEA was randomly induced befo re general anesthesia and continued during the study period in 25 (anesthet ized dermatomes C6-T10). Another 24 patients received IV clonidine as a bol us of 4 mu g/kg before the induction of general anesthesia. Clonidine was t hen infused at a rate of 1 mu g.kg(-1).h(-1) during surgery and at 0.2-0.5 mu g.kg(-1).h(-1) postoperatively. The remaining 21 patients underwent gene ral anesthesia as performed routinely (control). Hemodynamics, plasma epine phrine and norepinephrine, cortisol, the myocardial-specific contractile pr otein troponin T, and other cardiac enzymes were measured pre- and postoper atively. During the preoperative night and a follow-up of 48 h after surger y, five-lead electrocardiogram monitoring was used for ischemia detection. Both TEA and clonidine reduced the postoperative heart rate compared with t he control group without jeopardizing cardiac output or perfusion pressure. Plasma epinephrine increased perioperatively in all groups but was signifi cantly lower in the TEA group. Neither TEA nor clonidine affected the incre ase in plasma cortisol. The release of troponin T was attenuated by TEA. Ne w ST elevations greater than or equal to 0.2 mV or new ST depression greate r than or equal to 0.1 mV occurred in >70% of the control patients but only in 40% of the clonidine group and in 50% of the TEA group. We conclude tha t TEA (but not IV clonidine) combined with general anesthesia for CABG demo nstrates a beneficial effect on the perioperative stress response and posto perative myocardial ischemia. Implications: Thoracic epidural anesthesia co mbined with general anesthesia attenuates the myocardial sympathetic respon se to cardiopulmonary bypass and cardiac surgery. This is associated with d ecreased myocardial ischemia as determined by less release of troponin T. T hese findings may have an impact on the anesthetic management for coronary artery bypass grafting.