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Estimation of the second ventilatory threshold through ventricular repolarization profile analysis
Author(s) -
Milagro Javier,
HernándezVicente Adrián,
Hernando David,
Casajús José A.,
Garatachea Nuria,
Bailón Raquel,
Pueyo Esther
Publication year - 2021
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.13849
Subject(s) - repolarization , medicine , cardiology , ventricular repolarization , heart rate , ventilatory threshold , electrocardiography , electrophysiology , blood pressure , vo2 max
Under the hypothesis that sympathetic control of ventricular repolarization may change once the second ventilatory threshold (VT2) has been reached, a novel methodology for non‐invasive VT2 estimation based on the analysis of the T wave from the electrocardiogram (ECG) is proposed, and potential underlying physiological mechanisms are suggested. 25 volunteers (33.4 ± 5.2 years) underwent an incremental power cycle ergometer test (25 W/minute). During the test, respiratory gas exchange and multi‐lead ECG were acquired. The former was employed to determine VT2, used here as a reference, whereas the latter was used to compute the temporal profiles of an index of ventricular repolarization instability ( d T) and its low‐frequency (LF) oscillations (LF d T). The sudden increases observed in d T and LF d T profiles above an established heart rate threshold were employed to derive VT2 estimates, referred to as VT2 d T and VT2 LF d T , respectively. Estimation errors of −4.7 ± 25.2 W were obtained when considering VT2 d T . Errors were lower than the one‐minute power increment of 25 W in 68% of the subjects and lower than 50 W in 89.5% of them. When using VT2 LF d T , estimation error was of 15.3 ± 32.4 W. Most of the subjects shared common characteristic d T and LF d T profiles, which could be reflecting changes in the autonomic control of ventricular repolarization before and after reaching VT2. The analysis of ventricular repolarization dynamics during exercise allows non‐invasive ECG‐based estimation of VT2, possibly in relation to changes in the autonomic control of ventricular electrical activity when VT2 is reached.