| Background and ObjectiveIt was well known that thyroid hormone had profound effects on the heart. Studies of patients with spontaneously occurring hyperthyroidism and hypothyroidism indicated that thyroid disease could change cardiac systolic or diastolic performance acting through genomic and nongenomic mechanisms. Conventional echo-cardiography was commonly used for the evaluation of left ventricular contractility and relaxation of thyroid disease. Right ventricular function of heart had not been evaluated in detail since it had a complex structure, echocardiographic evaluation was difficult. Furthermore, it was assumed to be unimportant clinically.Tissue Doppler imaging (TDI) was a relatively recent addition to the diagnostic ultrasonographic examination, focusing on high amplitude, lower velocity frequency shifts. It had been used frequently in the evaluation of systolic and diastolic ventricular function independent of heart rate and ventricular geometry. The regional and global right ventricular function could be measured in a sensitive, specific, practical and reproducible way using tissue Doppler. Tei-index had been clinically useful in assessing global ventricular function. It was defined as the sum of isovolumetric contraction time and isovolumetric relaxation time divided by ejection time.In the present study, using the tissue Doppler and Tei-index method, right ventricular function was assessed in our patients with overt hypothyroidism and hyperthyroidism, and healthy controls, and the results were compared.Methods1. Object of study Collected30patients diagnosed with overt hypothyroidism and30with hyperthyroidism and30healthy subjects in December2011-December2012of Henan Province People’s Hospital. The hypothyroidism group (8males and22females) aged34～72years, with an average52.6±13.1years; The hyperthyroidism group (5males and25females) aged35～74years, with an average49.5±15.3years; The healthy subjects (7males and23females) aged38-70years, with an average50.3±16.2years. All controls subjects had an entirely normal Thyroid Hormone, laboratory evaluation, physical examination, ECG, M-mode, two-dimensional, and Doppler echocardiography.For each subjects, all blood samples for circulating serum TSH, FT3, FT4were collected from an antecubital vein after an overnight fast. The diagnosis of hyperthyroidism was made when low TSH levels (<0.55uIU/ml) and high FT4(>22.7pmol/1) were found. The diagnosis of hypothyroidism was made when high TSH levels(>4.78uIU/ml) and low FT4(<11.5pmol/1) were found. Patients who had Congenital heart disease, Systemic Lupus Erythematosus, Coronary heart disease, LV hypertrophy, valvular heart disease, atrial fibrillation, pericardial and obstructive pulmonary disease etc were excluded from the study. Newly diagnosed and untreated history were confirmed in the study population.2. TDI Measurement:Application with Philips IE33color doppler ultrasound diagnostic instrument, cardiac probe S5-1with frequency1-5MHZ, connected with synchronous limb lead ECG and with TDI related software.All subjects rested for10minutes in the supine position before imaging. Conventional two-dimensional, M-mode and Doppler echocardiographic studies were performed with all subjects. The following parameters were calculated:left ventricular end-diastolic diameter (LVDd), left ventricular ejection fraction (LV EF), right ventricular end-diastolic diameter (RVDd) and right atrium diameter. The frequency spectrogram of tricuspid annular motion was obtained by Tissue Doppler imaging. The peak systolic velocity (Sa), The peak velocity at early diastole (Ea) and at late diastole (Aa), isovolumetric contraction time (ICT),ejection time(ET), isovolumetric relaxation time(IRT) were calculated and right ventricular Tei index was measured. Tei index=(ICT+IRT)/ET.3. Collecting of serum TSH,FT3,FT4:Evaluation of TSH, FT3and FT4levels were performed by a chemiluminescent picroparticle immunoassay (SIEMENS CENTAUR XP).4. Statistical analysis Application SPSS17.0Statistical software for Statistical analysis, Masurement data in X±S. Continuous variables were compared using an unpaired t test. Categorical variables were compared using the chisquare test. Ap value<0.05was considered statistically significant.Results1. Characteristics of the patients and the controlsThere were lower serum TSH, higher FT4, higher body weight and faster heart rate in hyperthyroidism group than that in the control group(P<0.05). Patients with hypothyroidism had significantly higher TSH and lower FT4compared with the controls(P<0.05). There was statistically difference between the hyperthyroidism group and the hypothyroidism group with regard to TSH, FT4, and weight(P<0.05)2. Tissue Doppler variablesSa and Aa of lateral wall in hyperthyroidism group were significantly higher and Ea/Aa, ICT were lower than that in the control group (P<0.05). The IRT of lateral wall in hypothyroidism group were significantly higher and Ea, Ea/Aa were lower than that in the control group (P<0.05).The Sa, Ea and Aa were significantly higher and ICT, IRT were significantly lower in hyperthyroidism group than that in hypothyroidism group (P<0.05). The Sa of septal wall was significantly higher and ICT was lower in hyperthyroidism group than that in the control group (P<0.05) The IRT was significantly higher in hypothyroidism group than that in the control group (P<0.05). The Sa was higher and ICT, IRT were lower in hyperthyroidism group than that in hypothyroidism group (P<0.05)3. TDI-Tei variablesWhen TDI-Tei index was compared, it was found to be significantly higher in both hyperthyroidism and overt hypothyroidism group than that in the control group (P<0.05), either with lateral wall or septal wall. But TDI-Tei index of lateral wall or septal wall in hyperthyroidism group had no statistically difference than that in hypothyroidism group.ConclusionsTDI and TDI-Tei index can accurately and directly assess the function of right ventricular in patients with thyroid dysfunction. |
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