Document Detail

Results of resting and ambulatory electrocardiograms in patients with hypothyroidism and after return to euthyroid status.
MedLine Citation:
PMID:  11720599     Owner:  NLM     Status:  MEDLINE    
Hypothyroidism is not infrequently associated with an abnormally long QTc interval (> or = 450 msec). Rarely, marked prolongation of the QTc interval and malignant ventricular arrhythmias have been reported. In this study, QTc intervals on resting electrocardiograms (ECGs) were compared in 10 patients before and after treatment of hypothyroidism. The QTc interval increased in seven patients during euthyroidism compared with hypothyroidism, and decreased in three patients. During hypothyroidism, the QTc interval was mildly prolonged in 2 of the 14 patients; both had mild decreases in triiodothyronine (T3) or thyroxine (T4). The 24-hour ambulatory ECGs measured during hypothyroidism and after restoration of biochemical euthyroidism also were compared in 9 patients. There was no significant difference in ventricular ectopy. None of the 13 patients assessed during hypothyroidism had > or = 4 beats of ventricular tachycardia. There was no relationship between thyroid-stimulating hormone (TSH) or T3 levels and QTc intervals during hypothyroidism. A moderate correlation between lesser degrees of T4 depression and increasing QTc interval was present. Mild QTc prolongations are relatively common in patients with hypothyroidism and are usually associated with milder degrees of thyroid underactivity, but are not associated with clinically significant ventricular tachyarrhythmias.
L A Osborn; B Skipper; I Arellano; S D MacKerrow; M H Crawford
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Heart disease (Hagerstown, Md.)     Volume:  1     ISSN:  1521-737X     ISO Abbreviation:  Heart Dis     Publication Date:    1999 Mar-Apr
Date Detail:
Created Date:  2001-11-26     Completed Date:  2002-01-04     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  100887299     Medline TA:  Heart Dis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8-11     Citation Subset:  IM    
University of New Mexico School of Medicine and University Hospital, Albuquerque, New Mexico 87131, USA.
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MeSH Terms
Hypothyroidism / blood,  complications,  physiopathology*
Long QT Syndrome / blood,  complications,  physiopathology*
Middle Aged
Statistics, Nonparametric
Thyrotropin / blood
Thyroxine / blood
Triiodothyronine / blood
Reg. No./Substance:
6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine; 9002-71-5/Thyrotropin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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