Improved cardiac allograft function following triiodothyronine therapy to both donor and recipient

Brain death is associated with neuroendocrine changes, in particular with a significant reduction of plasma-free triiodothyronine (T3) that results in impaired aerobic metabolism. Myocardial energy stores are reduced and tissue lactate increased. Cardiac function deteriorates. Similar metabolic changes are seen in patients undergoing open-heart surgery on cardiopulmonary bypass, including those undergoing heart transplantation. Therapy with T3 leads to a reversal of these metabolic changes, resulting in improved cardiac function. One hundred and sixteen consecutive potential donors have been so treated, as have 70 of the recipients. Immediate posttransplant cardiac function was good in all but 3, and these hearts recovered to normal within a maximum of 24 hr of mechanical support. In 2 small randomized trials in patients undergoing myocardial revascularization on cardiopulmonary bypass, postoperative T3 therapy was associated with a reduced need for inotropic support and diuretic therapy in the first study and improved cardiac output in the second study.

Triiodothyronine as an inotropic agent after open heart surgery

Two small, randomized, blind clinical trials comparing the administration of triiodothyronine with that of placebo have been carried out in patients undergoing myocardial revascularization. In patients with a left ventricular ejection fraction of less than 30% (study I), triiodothyronine administration at the end of operation and during the initial 24 hours after operation was associated with a significantly reduced need for conventional inotropic agents (p less than 0.02) and diuretics (p less than 0.02). In patients with a left ventricular ejection fraction of greater than 40% (study II), triiodothyronine administration resulted in significantly improved stroke volume (p less than 0.01) and cardiac output (p less than 0.02) and reduced systemic (p less than 0.01) and pulmonary (p less than 0.05) vascular resistances. There were no adverse reactions to triiodothyronine in the dosages that were used. Triiodothyronine appears to be beneficial to all patients undergoing open heart surgery.

The pathophysiological effects of brain death on potential donor organs, with particular reference to the heart

Major electrocardiographic, haemodynamic, and histopathological changes take place during the development of brain death; myocardial and pulmonary injury may result. Significant depletion of certain circulating hormones occurs, resulting in an inhibition of mitochondrial function, leading to reduced aerobic metabolic oxidative processes, affecting the body as a whole. Major organ energy stores are therefore diminished, leading to deterioration of function. Replacement of the depleted hormones, in particular triiodothyronine (T3), cortisol, and insulin, leads to rapid replacement of organ energy stores, associated with a return to normal function. T3 alone leads to reactivation of the mitochondria, stimulating aerobic metabolism. Hormonal therapy to brain-dead potential organ donors has been shown to lead to metabolic and haemodynamic stability, resulting in no wastage of organs, and in improved function after transplantation.

Does central nervous system toxicity occur in transplant patients with hypocholesterolemia receiving cyclosporine?

A syndrome of severe central nervous system toxicity (confusion, cortical blindness, quadriplegia, seizures, and coma) associated with cyclosporine therapy and a low serum cholesterol level in patients with liver transplants has been described. We present a case history of a patient who demonstrated several similar features after heart-lung transplantation. Possible cyclosporine neurotoxicity should be considered in any patients with hypocholesterolemia receiving this drug.

Experience with endomyocardial biopsy in 23 patients with heart transplants

In the 33-month period April 1985 to December 1987, endomyocardial biopsy was performed 314 times in 23 patients with orthotopic (21) or heterotopic (2) heart transplants at Baptist Medical Center. The technique is described. Adequate tissue was obtained in 99% of cases and there was only one complication from the procedure. Mild to severe acute rejection was seen in 105 specimens (33%). The histopathological interpretation has proved invaluable in the care of patients with heart transplants.

Inotropic effect of triiodothyronine (T3) in low cardiac output following cardioplegic arrest and cardiopulmonary bypass: an initial experience in patients undergoing open heart surgery

A significant reduction in plasma free triiodothyronine (T3) (P less than 0.0001) has been observed in patients undergoing open heart surgery. The beneficial effect of T3 would appear to be associated with increased synthesis and utilization of myocardial high energy stores. We have therefore administered T3 (4-10 micrograms iv) to 10 patients either when difficulty was being experienced in weaning from cardiopulmonary bypass (CPB) support (n = 5), or when myocardial function remained extremely poor (n = 5), despite inotropic and intraaortic balloon pump support. Mean preoperative NYHA functional class of the 10 patients was 3.2, left ventricular enddiastolic pressure (LVEDP) 20 mm Hg and ejection fraction (EF) 40%. The mean myocardial ischaemia time was 72 min (range 40-120 min). Within 1 h of T3 administration the mean plasma free T3 level had risen from 1.03 to 3.56 micrograms/ml and CPB was discontinued in all 5 cases. Balloon pump support (n = 2) was no longer essential within 3 h. At 1 h, the mean arterial pressure (MAP) had risen from 42 to 78 mm Hg, and heart rate (HR) from 90 to 104 beats/min; the left atrial pressure (LAP) had fallen from 30 to 14 mm Hg, and the central venous pressure (CVP) from 20 to 11 cm H2O. (All changes significant at P less than 0.0001.) Inotropic support had been significantly reduced or discontinued. To our knowledge, T3 has not been administered previously as an inotropic agent to patients who have undergone cardiac surgery. We believe that T3 may have an important role in the rescue of failing hearts following a period of myocardial ischaemia in patients who have undergone open heart surgery.

Prediction of acute cardiac rejection by changes in left ventricular volumes

Sixteen patients underwent heart transplantation (11 orthotopic, five heterotopic). Monitoring for acute rejection was by both endomyocardial biopsy (EMB) and multigated equilibrium blood pool scanning with technetium 99m-labelled red blood cells. From the scans information was obtained on left ventricular volumes (stroke, end-diastolic, and end-systolic), ejection fraction, and heart rate. Studies (208) were made in the 16 patients. There was a highly significant correlation between the reduction in stroke volume and end-diastolic volume (and a less significant correlation in end-systolic volume) and increasing acute rejection seen on EMB. Heart rate and ejection fraction did not correlate with the development of acute rejection. Correlation of a combination of changes in stroke volume and end-diastolic volume with EMB showed a sensitivity of 85% and a specificity of 96%. Radionuclide scanning is therefore a useful noninvasive tool for monitoring acute rejection.

Effect of triiodothyronine (T3) on myocardial high energy phosphates and lactate after ischemia and cardiopulmonary bypass. An experimental study in baboons

Cardiopulmonary bypass is associated with a reduction in plasma free triiodothyronine in patients undergoing cardiac operations. A previous experimental study in pigs demonstrated a marked inotropic effect when triiodothyronine was administered after a period of myocardial ischemia and cardiopulmonary bypass; this was associated with a significant reduction in mortality compared with the mortality in control pigs. To clarify the effect of triiodothyronine on myocardial high energy phosphate stores and lactate, a series of experiments was done in baboons undergoing 3 hours of myocardial ischemia while supported by cardiopulmonary bypass. Seven baboons received no triiodothyronine and six received 6 micrograms of triiodothyronine at the end of the ischemic period. Seventy minutes after cardiopulmonary bypass, the myocardial adenosine triphosphate level was significantly higher (p less than 0.01) in the treated animals. In untreated animals, a steady increase in myocardial lactate occurred after cardiopulmonary bypass; by 120 minutes after ischemia (70 minutes after cardiopulmonary bypass) there was a significant difference in lactate levels between the two groups (p less than 0.01). We postulate that a combination of global ischemia and depletion of triiodothyronine results in reduced mitochondrial function, inhibition of the tricarboxylic acid cycle, and increased anaerobic metabolism and depletion of myocardial phosphates. Triiodothyronine replacement therapy leads to improved mitochondrial function and increased aerobic metabolism, which results in increased synthesis of myocardial phosphates. We suggest that there may be a place for the administration of triiodothyronine in patients undergoing cardiac operations with a prolonged myocardial ischemic period or in whom there is any evidence of low cardiac output after discontinuation of cardiopulmonary bypass.

Triiodothyronine therapy for heart donor and recipient

Both (1) brain-dead donors and (2) transplant recipients on cardiopulmonary bypass suffer a depletion in plasma-free triiodothyronine (T3), which leads to metabolic changes (from inhibition of mitochondrial function), resulting in myocardial energy store depletion. Replacement therapy with T3 reverses these changes in both donor and recipient. Donor heart energy stores and function will be maintained at optimum levels if T3 therapy is administered to both donor and recipient at the time of transplantation.