Parathyroid hormone and myocardial performance in dialysis patients.

Whether parathyroid hormone (PTH) has a clinically important effect on myocardial performance is unclear. Previous investigations of cardiac function before and after parathyroidectomy have failed to control for ionized calcium, other biochemical parameters, or heart rate and cardiovascular loading conditions. We performed load- and rate-independent measurements of myocardial contractility in seven stable hemodialysis patients before and after surgical parathyroidectomy under identical conditions of blood ionized calcium (Ca2+), electrolytes, pH, PO2, and hematocrit. Mid-molecule PTH decreased from 44 +/- 8 to 2 +/- 1 ng/mL. Aortic systolic and diastolic pressures, left ventricular chamber dimensions, end systolic wall stress, left ventricular contractility at a common level of afterload, and contractile reserve evaluated with dobutamine were similar before and after parathyroidectomy. Thus, PTH appears not to have a direct effect on myocardial contractile state in dialysis patients.