THE EFFECTS OF THYROID-HORMONES ON THE HEART FOLLOWING GLOBAL-ISCHEMIA - A CLINICAL AND EXPERIMENTAL-STUDY

Cardiopulmonary bypass pass is associated with a reduction in plasma t hyroid hormone concentrations in patients undergoing cardiac surgery. However, studies of the effects of cardiopulmonary bypass on thyroid f unction are limited and many studies report conflicting data concernin g only the period of cardiopulmonary bypass. In this study, we tried t o clinically determine the effects of cardiopulmonary bypass on concen trations of thyroid hormones by comprehensive thyroid function tests i n 10 patients before and after surgery, and observed the benefits of t riiodothyronine supplementation after global ischemia on myocardial fu nction experimentally in guinea pigs. In patients undergoing surgery, concentrations of total triiodothyronine and free triiodothyronine dec reased progressively on the institution of cardiopulmonary bypass and remained below normal levels until 24 hours postoperatively. In the gu inea pig hearts studied in a Langendorf perfusion apparatus, T3 supple mentation enhanced percentage recovery of ventricular contractile forc e, heart work and heart rate with respect to other groups receiving no T3 supplementation or T3 supplementation without any ischemic interva l.