Triiodothyronine administration in coronary artery bypass surgery: effect on hemodynamics

The purpose of this study was to investigate any potential hemodynamic effect of intravenously administered triiodothyronine in patients undergoing coronary artery bypass surgery.

Thirty patients were randomized in this single-blind, placebo-controlled trial. Hemodynamic parameters including heart rate, stroke volume index, cardiac index, pulmonary wedge pressure, pulmonary vascular resistances, systemic vascular resistances, and mean blood pressure, were compared between the two groups preoperatively, before the initiation of cardiopulmonary bypass (CPB), 5 minutes after the end of CPB, and 2, 4, 10, 16, and 22 hours thereafter.

Triiodothyronine was administered as a bolus infusion over a 1 min period after removal of the aortic cross-clamp, (0.15 microgram/kg), before the end of CPB (0.1 microgram/kg), 4 hours after the end of CPB (0.1 microgram/kg), 9 hours after CPB (0.1 microgram/kg), and 14 hours after CPB (0.1 microgram/kg). Patients received inotropes, vasodilators, and diuretics only if specifically indicated.

Plasma FT3 levels were higher in the T3 group, but within the normal range. No significant differences were noted in the pre and post CPB hemodynamics between the two groups for the most part of the study except that heart rate was increased in T3 group. A greater number of patients in the control group received vasodilators. No adverse reactions were noted with triiodothyronine administration.

Triiodothyronine administration in patients undergoing cardiopulmonary bypass surgery is safe, may lessen the need for pharmacological (vasodilator) therapy, but may increase heart rate.