The systolic function of the left ventricle of the heart in patients with hyperthyroidism during therapy

Hyperthyroidism is associated with enhanced systolic function. The present study was designed to evaluate systolic cardiac function in patients with hyperthyroidism during a short-term and a long-term pharmacotherapy. The diagnostic value of various indices of the left ventricle function was analysed. Fifty-one hyperthyroid patients were investigated before initiation of the treatment, after 14 days of therapy with thiamazol (mean dose 54 mg/24 hr), a short-term treatment and after attainment of normal thyroid function, a long-term treatment (mean period 9 months). Control values were obtained from 30 healthy individuals. All investigated subjects were aged 18-50 yr. The following indices were determined with ultrasonocardiographic method: preejection period (PEP), left ventricle ejection time (LVET), preejection period index (PEPI) and left ventricle ejection time index (LVETI), index PEP/LVET, left ventricle shortening fraction (LVSF), left ventricle ejection fraction (LVEF), mean velocity of the circumferential fiber shortening (mVcf), contractility index (CIx), stroke volume (SV), cardiac index (CI), output-pressure index (OPI) and end-systolic wall stress (ESWS). Additionally, total peripheral resistance index (TPRI) and double product (DP) were calculated. In patients with untreated hyperthyroidism, a significant shortening of PEP, PEPI, LVET and low PEP/LVET index and TPRI as well as increased LVSF, LVEF, mVcf, CIx, CI, OPI and DP were shown. There was no changes in LVETI, SV and ESWS. A short-term treatment resulted in changes in PEP, PEPI, LVET, mVcf, CI and OPI in direction of normal values. After a long-term treatment all altered indices were normal with an exception of OPI, CI and DP. It is concluded that enhanced systolic function of the heart in patients with hyperthyroidism becomes normal after pharmacological control of the thyroid gland. Some changes are seen after a short-term treatment with thiamazol. The indices which reverse early are PEP, PEPI, LVET, mVcf and CI. Changes in ejection function of the left ventricle in patients with hyperthyroidism are resulted from increased heart rate and were found to be related to total peripheral vascular resistance.