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High Resolution ECG for Evaluation of QT Interval Variability during Exposure to Acute HypoxiaVentricular repolarization instability as quantified by the index of QT interval variability (QTVI) is one of the best predictors for risk of malignant ventricular arrhythmias and sudden cardiac death. Because it is difficult to appropriately monitor early signs of organ dysfunction at high altitude, we investigated whether high resolution advanced ECG (HR-ECG) analysis might be helpful as a non-invasive and easy-to-use tool for evaluating the risk of cardiac arrhythmias during exposure to acute hypoxia. 19 non-acclimatized healthy trained alpinists (age 37, 8 plus or minus 4,7 years) participated in the study. Five-minute high-resolution 12-lead electrocardiograms (ECGs) were recorded (Cardiosoft) in each subject at rest in the supine position breathing room air and then after breathing 12.5% oxygen for 30 min. For beat-to-beat RR and QT variability, the program of Starc was utilized to derive standard time domain measures such as root mean square of the successive interval difference (rMSSD) of RRV and QTV, the corrected QT interval (QTc) and the QTVI in lead II. Changes were evaluated with paired-samples t-test with p-values less than 0.05 considered statistically significant. As expected, the RR interval and its variability both decreased with increasing altitude, with p = 0.000 and p = 0.005, respectively. Significant increases were found in both the rMSSDQT and the QTVI in lead II, with p = 0.002 and p = 0.003, respectively. There was no change in QTc interval length (p = non significant). QT variability parameters may be useful for evaluating changes in ventricular repolarization caused by hypoxia. These changes might be driven by increases in sympathetic nervous system activity at ventricular level.
Document ID
20100011141
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Zupet, P.
(Ljubljana Univ. Ljubljana, Slovenia)
Finderle, Z.
(Ljubljana Univ. Ljubljana, Slovenia)
Schlegel, Todd T.
(NASA Johnson Space Center Houston, TX, United States)
Starc, V.
(Ljubljana Univ. Ljubljana, Slovenia)
Date Acquired
August 24, 2013
Publication Date
January 1, 2010
Subject Category
Aerospace Medicine
Report/Patent Number
JSC-CN-20091
Meeting Information
Meeting: 31st FIMS Sports Medicine World Congress
Location: San Juan
Country: Puerto Rico
Start Date: May 19, 2010
End Date: May 22, 2010
Distribution Limits
Public
Copyright
Other

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