Document Detail

Arrhythmic risk evaluation during exercise at high altitude in healthy subjects: role of microvolt T-wave alternans.
MedLine Citation:
PMID:  18811808     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Altitude-induced sympathetic hyperactivity can elicit rhythm disturbances in healthy subjects, in particular during exercise. AIM: To asses the real susceptibility of healthy myocardium to malignant ventricular arrhythmias during exercise at high altitude using microvolt T-wave alternans (MTWA). METHODS: We evaluated eight healthy trained participants (one female, 42 +/- 9 years) during a mountain climbing expedition on Gashembrum II (Pakistan, 8,150 m). MTWA and heart rate variability (HRV) were measured in each subject at sea level and at high altitude, both under rest conditions and during exercise. MTWA was determined with the modified moving average method. HRV was expressed as root mean square of successive differences. RESULTS: Rest HRV at high altitude was significantly lower compared to rest HRV at sea level (36 +/- 5 vs 56 +/- 9 ms, P = 0.003). HRV during exercise was significantly lower with respect to rest condition both in normoxia (46 +/- 7 vs 56 +/- 9 ms, P = 0.0001) and hypoxia (27 +/- 4 vs 36 +/- 5 ms, P = 0.005). Moreover, HRV was significantly lower during exercise at high altitude compared to exercise at sea level (27 +/- 4 vs 46 +/- 7 ms, P = 0.0002) and arrhythmias were more frequent during exercise in hypoxia. Nevertheless, MTWA was absent under rest conditions both at sea level and at high altitude and minimally evoked during exercise in both conditions (22 +/- 3 microV and 23 +/- 3 microV, respectively, P = 0.2). CONCLUSIONS: In spite of an enhanced sympathetic activity, MTWA testing during exercise at high altitude was negative in all participants. Healthy trained subjects during exercise under hypoxia seem to be at low risk for dangerous arrhythmias.
Giuseppe Gibelli; Cecilia Fantoni; Claudio Anzà; Paolo Cattaneo; Andrea Rossi; Annibale S Montenero; Massimo Baravelli
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Pacing and clinical electrophysiology : PACE     Volume:  31     ISSN:  1540-8159     ISO Abbreviation:  Pacing Clin Electrophysiol     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-24     Completed Date:  2008-12-08     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7803944     Medline TA:  Pacing Clin Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1277-83     Citation Subset:  IM    
Division of Cardiology, Clinical Institute San Carlo, Paderno Dugnano, Milano, Italy.
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MeSH Terms
Arrhythmias, Cardiac / diagnosis*,  physiopathology*
Electroencephalography / methods*
Middle Aged
Physical Exertion*
Risk Assessment

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

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