Left Ventricular Myocardial Impairment in Subclinical Hypothyroidism Assessed by a New Ultrasound Tool: Pulsed Tissue Doppler

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Abstract
Pulsed tissue Doppler (TD) is a new ultrasound tool that allows quantification of myocardial regional wall motion. To investigate the cardiac effects of subclinical hypothyroidism (SH), the present study assessed left ventricular (LV) myocardial regional function in SH by pulsed TD. Twenty women with SH and 20 healthy women underwent standard Doppler echocardiograms and pulsed TD, placing a sample volume at the level of posterior septum and LV mitral annulus. Myocardial systolic and diastolic velocities and time intervals were determined for both levels. Doppler-echocardiographic and TD measurements were adjusted for body surface area and heart rate. Standard Doppler showed an increases in LV preejection period, preejection period/LV ejection time ratio, and isovolumic relaxation time (IVRT) in SH. By TD analysis, myocardial precontraction time (PCT(m)), PCT(m)/myocardial contraction time ratio, and myocardial relaxation time (RT(m)) were prolonged at the level of both posterior septum and mitral annulus in SH. In the whole population, IVRT, PCT(m), and RT(m) were negatively related to FT(4), whereas IVRT, PCT(m)/myocardial contraction time ratio, and RT(m) were positively correlated to TSH. In conclusion, this study underscores the usefulness of TD to detect cardiac functional abnormalities due to stable SH, mainly by changes in myocardial time intervals in several LV segments.