Document Detail

Impaired Cardiac Reserve and Severely Diminished Skeletal Muscle Oxygen Utilization Mediate Exercise Intolerance in Barth Syndrome.
MedLine Citation:
PMID:  21873497     Owner:  NLM     Status:  Publisher    
Background: Barth syndrome (BTHS) is a mitochondrial myopathy characterized by reports of exercise intolerance. We sought to determine if 1) BTHS leads to abnormalities of skeletal muscle oxygen extraction/utilization and 2) exercise intolerance in BTHS is related to impaired oxygen extraction/utilization, impaired cardiac function or both. Methods and Results: Participants with BTHS (age 17 ± years, n=15) and controls participants (age 13 ± 4 years, n=9) underwent graded exercise testing on a cycle ergometer with continuous EKG and metabolic measurement. Echocardiography was performed at rest and at peak exercise. Near infrared spectroscopy (NIRS) of the vastus lateralis muscle was continuously recorded for measurement of skeletal muscle oxygen extraction. Adjusting for age, peak VO2 (16.5 ± 4.0 vs. 39.5 ±12.3 ml/kg/min, p<0.001) and peak work rate (58 ± 19 vs.166 ± 60 watts, p<0.001) were significantly lower in BTHS than controls. The % increase from rest to peak exercise in ejection fraction (BTHS: 3 ± 10 vs. Control: 19 ± 4%, p <0.01) was blunted in BTHS compared to controls. Muscle tissue oxygen saturation (StO2) change from rest to peak exercise was paradoxically opposite (BTHS: 8 ± 16 vs. Control: -5 ± 9, p <0.01) and de-oxy hemoglobin change was blunted (BTHS: 0 ± 12 vs. Control: 10 ± 8, p <0.09) in BTHS compared to controls indicating impaired skeletal muscle extraction in BTHS. Conclusions: Severe exercise intolerance in BTHS is due to both cardiac and skeletal muscle impairments which are consistent with cardiac and skeletal mitochondrial myopathy. These findings provide further insight to the pathophysiology of BTHS.
Carolyn T Spencer; Barry J Byrne; Randall M Bryant; Renee Margossian; Melissa Maisenbacher; Petar Breitenger; Paul B Benni; Sharon Redfearn; Edward Marcus; William Todd Cade
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-8-26
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  -     ISSN:  1522-1539     ISO Abbreviation:  -     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-8-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1East Carolina University.
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