Cardiac function in congenital hypothyroidism: impairment and response to L-T4 therapy.
Electrocardiograms (heart rate, QRS voltage, QRS axis in the frontal plane. Q-Tc interval) echocardiograms [left ventricular fractional shortening (LVFS); preejection period (PEP); PEP/left ventricular ejection time (PEP/LVET) ratio; end-diastolic left ventricular free wall and interventricular septum thickness; presence of pericardial effusion], and thyrotropin (TSH), thyroxine (T4), and triiodothyronine (T3) serum levels were evaluated before and 1 week, 1 and 2 months after the start of L-thyroxine (L-T4) therapy in 11 infants with congenital hypothyroidism (CH), aged 16-59 days when first seen. Before the start of therapy, infants with CH had significantly lower QRS complexes and LVFS and significantly higher values for Q-Tc, PEP, and PEP/LVET than normal infants of the same age. The QTc interval, PEP and PEP/LVET ratio of infants with CH were significantly greater before than 1 week after L-T4 therapy, and LVFS was significantly lower before than 1 month after L-T4 therapy. Four of the infants with CH had small pericardial effusions, which disappeared within the first week of therapy. QRS axis in the frontal plane, Q-Tc interval, and PEP were negatively correlated with logT4 and logT3 serum levels. PEP/LVET ratios were negatively correlated with logT4 serum values. The QRS voltage values were positively correlated with logT4 and logT3 serum values. The frontal-plane QRS axis, Q-Tc interval, and PEP/LVET ratio were positively correlated with logTSH serum levels. The QRS voltages were negatively correlated with TSH serum levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Balducci
G
G
Institute of Clinical and Preventive Pediatrics, University of Bari, Italy.
Acquafredda
A
A
Amendola
F
F
Natuzzi
M
M
Laforgia
N
N
Cavallo
L
L
D003409:Congenital Hypothyroidism; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000503:physiopathology*; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D013974:Thyroxine / Q000494:pharmacology / Q000627:therapeutic use
D013974:Thyroxine