Document Detail

Effect of thyroid hormones on cardiac function, geometry, and oxidative metabolism assessed noninvasively by positron emission tomography and magnetic resonance imaging.
MedLine Citation:
PMID:  10843159     Owner:  NLM     Status:  MEDLINE    
Thyroid hormones influence cardiac performance directly and indirectly via changes in peripheral circulation. Little, however, is known about the effect on myocardial oxidative metabolism and its relation to cardiac function and geometry. Patients with a history of thyroidectomy for thyroid cancer present a unique model to investigate the cardiac effects of hypothyroidism. Ten patients without heart disease were investigated in the hypothyroid state and again 4-6 weeks later under euthyroid conditions. Myocardial oxidative metabolism was measured by positron emission tomography with [11C]acetate and the clearance constant k(mono). Cine magnetic resonance imaging was applied to determine left ventricular geometry. A stroke work index (SWI = stroke volume x systolic blood pressure/ventricular mass) was calculated. Then, to estimate myocardial efficiency, a work metabolic index [WMI = SWI x heart rate/k(mono)] was obtained. Compared to hormone replacement, systemic vascular resistance and left ventricular mass were significantly higher in hypothyroidism. Ejection fraction and SWI were significantly lower. Despite an additional reduction of k(mono), the WMI was significantly lower, too. In summary, cardiac oxygen consumption is reduced in hypothyroidism. This reduction is associated with increased peripheral resistance and reduced contractility. Estimates of cardiac work are more severely suppressed than those of oxidative metabolism, suggesting decreased efficiency. These findings may provide an explanation for development or worsening of heart failure in hypothyroid patients with preexisting heart disease.
F M Bengel; S G Nekolla; T Ibrahim; C Weniger; S I Ziegler; M Schwaiger
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of clinical endocrinology and metabolism     Volume:  85     ISSN:  0021-972X     ISO Abbreviation:  J. Clin. Endocrinol. Metab.     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-06-16     Completed Date:  2000-06-16     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0375362     Medline TA:  J Clin Endocrinol Metab     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1822-7     Citation Subset:  AIM; IM    
Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, Munich, Germany.
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MeSH Terms
Acetates / metabolism
Blood Pressure
Carbon Radioisotopes / pharmacokinetics
Heart / radionuclide imaging
Heart Rate
Hypothyroidism / metabolism,  physiopathology*
Image Processing, Computer-Assisted
Magnetic Resonance Imaging
Middle Aged
Myocardium / metabolism*
Oxygen Consumption*
Stroke Volume
Thyroid Neoplasms / surgery
Thyroxine / therapeutic use*
Tomography, Emission-Computed
Vascular Resistance
Reg. No./Substance:
0/Acetates; 0/Carbon Radioisotopes; 7488-70-2/Thyroxine

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

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