[Left ventricular function in congenital hypothyroidism neonates before and after thyroxine substitution therapy].
OBJECTIVE
To evaluate left the systolic and diastolic functions in neonates with congenital hypothyroidism (CH) as well as the effect of thyroxine substitution therapy on left ventricular function and its correlation with thyroid hormones serum levels.


METHODS
M-mode echocardiography was used to examine the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), pulse wave Doppler was used to examine the peak early diastolic mitral inflow velocity (E(m)) and peak late diastolic mitral inflow velocity (A(m)), quantitative tissue velocity imaging (QTVI) was used to examine the systolic peak mitral annular velocity (s(m)), early diastolic peak mitral annular velocity (E(m)), and the late diastolic peak mitral annular velocity (a(m)), and tissue tracking imaging (TTI) was used to detect the systolic mitral annular displacement (MAD) in 40 neonates with congenital hypothyroidism aged 15-28 days before and after 1-month levothyroxine substitution treatment. Thirty normal neonates were used as controls. Chemiluminescent immunoassay was used to measure the TT(3), TT(4) and TSH levels. Correlation analysis was also made between the ventricular function parameters and the serum TT(3), TT(4), and TSH levels.


RESULTS
The left systolic function parameters (LVEF, s(m), MAD, E(m) and e(m)) was 0.61 +/- 0.08, 2.60 cm/s +/- 0.60 cm/s, 0.29 cm +/- 0.06 cm, 0.59 m/s +/- 0.12 m/s and 2.72 cm/s +/- 1.43 cm/s respectively, in CH group, and 0.67 +/- 0.06, 3.25 cm/s +/- 0.51 cm/s, 0.41 cm +/- 0.08 cm, 0.72 m/s +/- 0.11 m/s and 4.51 cm/s +/- 1.23 cm/s in control group (P < 0.01). Left function in CH neonates before treatment were all lower than those of the controls (P < 0.01), which significantly increase after 1-months L-T(4) substitution therapy, 0.69 +/- 0.05, 3.46 cm/s +/- 0.64 cm/s, 0.45 cm +/- 0.08 cm, 0.82 m/s +/- 0.17 m/s and 5.09 cm/s +/- 1.37 cm/s, (P < 0.01). Those parameters were positively correlated with TT(4) serum levels (P < 0.01), and were negatively correlated with TSH (all P < 0.01). In particular, MAD, sm, E(m), and em were highly correlated with serum TT(4) and TSH (r = 0.667, 0.538, 0.478, and 0.599 respectively, all P < 0.001;and r = -0.670, -0.521, -0.490, and -0.583 respectively, all P < 0.001).


CONCLUSIONS
Neonates with CH have lower left systolic and diastolic functions. Early L-T(4) substitution therapy can reverse these changes.
Mao
Shan-shan
SS
Department of Child Health Care, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
Zhao
Zheng-yan
ZY
Jiang
Guo-ping
GP
D003409:Congenital Hypothyroidism / Q000188:drug therapy* / Q000503:physiopathology*; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D013974:Thyroxine / Q000627:therapeutic use*; D016277:Ventricular Function, Left / Q000502:physiology*
D013974:Thyroxine