ABSTRACT
The heart is a major target organ for thyroid hormone action, and marked changes occur in cardiac function in patients with hypothyroidism. The hemodynamic changes typical of hypothyroidism are opposite to those of hyperthyroidism, but they are accompanied by fewer symptoms and signs. Thyroxine therapy reverses all the cardiovascular changes associated with hypothyroidism. This work was planned to evaluate prospectively the cardiac performance and structure in children with primary hypothyroidism by echocardiography before and after replacement therapy with thyroxine. Twenty one infants and children with untreated primary hypothyroidism were included. Twenty age and sex matched healthy controls were also included. All patients were subjected to complete physical examination, thyroid function tests, ECG and M-mode, 2-dimensional, pulsed and continuous wave Doppler examination before and 6 months after therapy. The results proved that following parameters were significantly higher in cases compared to their control subjects: LVDd[0. 56 +/- 2.2 VS-0.8 +/- 2, p=0.04], Ao [0.38 +/- 1.2 VS-0.67 +/- 1.1, p=0. 007], RPA [-.16 +/- 15 VS-2.5 +/- 0.7, p= 0.018] and LPA [1.13 +/- 2.3 VS -2.3 +/- 0.87, p=0.021]. By comparing the baseline echocardiographic parameters to those after 6 months of therapy, the following were observed: increased LVDd after therapy [0.56 +/- 2.2 VS 1.31 +/- 2, p=0.03]; diminished LV mass [0.32 +/- 1.6 VS -0.91 +/- 1.1, p=0.03]; diminished RVDd [0.82 +/- 0.8 vs 0.43 +/- 0.7, p=0.01]; significant improvement in all systolic function after therapy: EF% [71.6 +/- 6.5 VS 75 +/- 5.2, p=0.019], FS% [34.8 +/- 5.3 VS 39.3 +/- 5.1, p=0.008], VCF [1.32 +/- 0.27 VS 1.5 +/- 0.31, p=0.001], Aortic peak flow [0.95 +/- 0.2 VS 1.069 +/- 0.29, p=0.05] and pulmonary AT [0.149 +/- 0.13 VS 0.09 +/- 0.03, p=0. 047]. Moreover, the following parameters of diastolic function showed significant change at 6 month after therapy: mitral A[0.44 +/- 0.11 VS 0.61 +/- 0.28, p=0.02], mitral E/A [1.98 +/- 0.61 VS 1.46 +/- 0.49, p=0.006] and tricuspid E [0.58 +/- 0.13 VS 0.65 +/- 0.13, p=0.05]. The following echocaidiographic structural findings were also observed in our cases: PFO was found in 6 cases [28%] with a mean diameter 013 t 1.26mm; TR in 15 cases [71%], mean PG 15.71 +/- 7.6 mm Hg, PR in 11 cases [52%], mean PG 8.86 +/- 4.2 mm Hg, MR in 2 cases [0.09%, mean PG 14.5 +/- 6.3 mm Hg. None of our patients showed pericardial effusion. me duration of the illness was significantly correlated to base line Ao [p=0.001], LVDD [p=0.04] and RV p=0. 001]. Both base line FT3, FT4 showed significant correlations to LA [p= 0.04 and 0.016 respectively]. Seam triglycerides showed significant negative correlation to VCF [p=0. 009]. The dose of Ievothyroxin show significant negative correlation to RV [p=0. 04] and significant positive correlation to VCF [p=0. 03]. Meanwhile, the dose of L-thyroxin showed significant positive correlation to LV mass at 6 months [p= 0.04], and duration of illness showed significant positive correlation to RV [p=0. 02] and finally TSH at 6 months showed significant negative correlation to Ao at 6month after therapy [p=0. 04]
Conclusion: Evidence of alteration in cardiac systolic and diastolic functions is seen in children with primary hypothyroidism. These do improve with treatment. Structural cardiac anomalies could be demonstrated as an example of associated extra thyroidal anomalies. Classic teaching descriptions of ECG changes and pericardial effusion in advanced hypothyroidism were not seen