[Cardiovascular parameters in transient hypothyroidism].

Cardiovascular manifestations are a frequent finding in hypothyroidism. Thus, blood-pressure measurements, longtime electrographic monitoring, and spiroergometry were examined in 20 patients with transitory hypothyroidism. In the patients with thyroid carcinoma, total thyroidectomy was performed. Measurements were made in hypothyroidism and after TSH-suppression with L-thyroxine. Thirty-five patients in whom intracardiac catheter examination ruled out cardiopulmonary disease served as controls. Cardiopulmonary exercise was done by bicycle exercise testing. In transitory hypothyroidism an increase of diastolic blood pressure was found at rest (p = 0.02) and during exercise (p = 0.002), which was reversible after T4-therapy. Compared to the controls diastolic blood pressure in hypothyroidism was increased at rest (p = 0.014) and during exercise (p = 0.005). ECG-monitoring showed a day-night difference in heart rate in hypothyroid patients and after therapy. The mean heart rate (74 vs. 88 beats per minute; p = 0.0006), the minimal (p = 0.0062) and the maximal heart rate (p = 0.0016) during the day were decreased in hypothyroidism compared to euthyroidism. There were no atrioventricular blocks in transitory hypothyroidism and no increase of ventricular or supraventricular premature beats after high-dose T4-treatment. Spiroergometry showed no change in ventilation and an increased growth in heart rate (p = 0.021) associated with good working capacity in hypothyroid patients. Heart rate at rest (p = 0.004) and at the anaerobic threshold (p = 0.03) were decreased in transitory hypothyroidism.