Effects of thyroxine therapy on right ventricular systolic and diastolic function in patients with subclinical hypothyroidism: a study by pulsed wave tissue Doppler imaging.
BACKGROUND
The effects of l-thyroxine (l-T(4)) replacement for subclinical hypothyroidism (SH) on right ventricle (RV) functions has not been previously studied by means of pulsed wave tissue Doppler imaging (PWTDI). We investigated the effects of l-T(4) therapy on RV function in patients with SH using PWTDI.


METHODS
Fifty-three patients with newly diagnosed SH and 25 controls were evaluated by standard echocardiography and PWTDI. After euthyroidism was restored by l-T(4), measurements were repeated. Myocardial systolic wave (S(m)) velocity, isovolumic acceleration (IVA), myocardial precontraction time (PCT(m)), and PCT(m) to contraction time (CT(m)) ratio were calculated as systolic indices. Early (E(m)) velocity, late (A(m)) velocity, E(m) to A(m) ratio, and myocardial relaxation time (RT(m)) were determined as diastolic measurements.


RESULTS
S(m) was similar in patients and controls, whereas IVA was significantly lower in patients with SH (P < 0.001). SH patients had significantly decreased E(m) velocity, whereas A(m) velocity and E(m) to A(m) ratio did not differ. PCT(m) and RT(m) were significantly longer, and PCT(m) to CT(m) ratio was significantly higher in patients (P = 0.002, P = 0.002, P < 0.001, respectively). S(m) velocities were similar before and after l-T(4) replacement, whereas IVA significantly increased after therapy (P < 0.001). E(m) tended to increase (P = 0.05), whereas A(m) and E(m) to A(m) ratio were not changed. PCT(m), PCT(m) to CT(m) ratio, and RT(m) decreased significantly (P < 0.001 for all).


CONCLUSIONS
SH is associated with RV systolic and diastolic dysfunction, and l-T(4) treatment improves these abnormalities. PWTDI, especially IVA, may be a suitable tool for the early detection of RV systolic dysfunction.
Turhan
Sibel
S
Department of Cardiology, Ibn-i Sina Hospital, 06100 Samanpazari, Ankara, Turkey. sblturhan@yahoo.com
Tulunay
Cansin
C
Ozduman Cin
Mine
M
Gursoy
Alptekin
A
Kilickap
Mustafa
M
Dincer
Irem
I
Candemir
Basar
B
Gullu
Sevim
S
Erol
Cetin
C
D000328:Adult; D003971:Diastole / Q000187:drug effects; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013599:Systole / Q000187:drug effects; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood; D018497:Ventricular Dysfunction, Right / Q000097:blood / Q000150:complications*
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine