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Hemodynamic effect of calcium channel blockade during anesthesia for coronary artery surgery
P Colson1, P Médioni, M Saussine
1Department of Anesthesiology, St-Eloi Hospital, Montpellier, France.
Insights
Diltiazem may reduce the risk of perioperative ischemia during coronary artery bypass graft surgery. This calcium channel blocker effectively lowers myocardial oxygen demand and increases delivery, especially with sufficient plasma concentrations.
Area of Science:
- Cardiology
- Anesthesiology
- Pharmacology
Background:
- Perioperative myocardial ischemia is a significant risk in cardiac surgery.
- Anesthetic technique alone may not sufficiently reduce ischemic risk.
- Antianginal therapy, such as calcium entry blockers, is crucial for managing ischemic risk.
Purpose of the Study:
- To evaluate the efficacy of diltiazem in reducing perioperative ischemia during coronary artery bypass graft (CABG) surgery.
- To assess diltiazem's impact on myocardial oxygen demand and delivery.
- To determine if therapeutic plasma concentrations of diltiazem lower the ischemic burden.
Main Methods:
- A double-blind, placebo-controlled study involving 29 patients scheduled for CABG surgery.
- Continuous infusion of diltiazem (0.15 mg/kg bolus followed by 2 µg/kg/min) administered during anesthesia and surgery before cardiopulmonary bypass.
- Monitoring of heart rate, mean arterial pressure, inotropy, and plasma diltiazem concentrations.
Main Results:
- Diltiazem significantly reduced determinants of myocardial oxygen demand (heart rate, mean arterial pressure, inotropy) during anesthesia.
- Therapeutic plasma diltiazem concentrations ( > 96 ng/mL) were associated with decreased MVO2 determinants during stressful surgical events.
- Fewer patients in the diltiazem group experienced perioperative ischemia (2/15) compared to the placebo group (4/14).
Conclusions:
- Diltiazem can effectively lower myocardial oxygen demand and increase oxygen delivery during anesthesia for CABG surgery.
- Sufficient plasma concentrations of diltiazem contribute to reducing the ischemic burden in patients undergoing cardiac surgery.
- Diltiazem represents a valuable therapeutic option for managing perioperative ischemia in this patient population.
Abstract:
Because the choice of anesthetic technique does not influence the incidence of perioperative myocardial ischemia, reduction of ischemic risk may require specific antianginal therapy. Calcium entry blockers are effective drugs in antianginal therapy. Diltiazem reduces myocardial oxygen demand through decreases in heart rate, inotropy, and systolic function, while increasing myocardial oxygen delivery through coronary vasodilation. These potentially beneficial effects of diltiazem were evaluated in 15 of 29 patients (diltiazem v placebo, double-blind study) scheduled for coronary artery bypass graft surgery. Continuous infusion of diltiazem (0.15 mg/kg bolus followed by 2 micrograms/kg/min), during anesthesia and surgery before cardiopulmonary bypass, significantly reduced the major MVO2 determinants during anesthesia with moderate doses of fentanyl and a benzodiazepine (midazolam in 8 of 14 control patients and 9 of 15 treated patients, or flunitrazepam in the others). Heart rate, mean arterial pressure, and inotropy were decreased during the most stressful events of surgery when plasma diltiazem concentrations were in the therapeutic range (greater than 96 ng/mL). The number of patients with perioperative ischemia was 2 of 15 in the treated group and 4 of 14 in the control group. Provided that diltiazem plasma concentrations are sufficient, it can contribute to lowering the ischemic burden during anesthesia for coronary artery surgery.