TY - JOUR
T1 - Arrhythmic risk evaluation during exercise at high altitude in healthy subjects
T2 - Role of microvolt T-wave alternans
AU - Gibelli, Giuseppe
AU - Fantoni, Cecilia
AU - Anzà, Claudio
AU - Cattaneo, Paolo
AU - Rossi, Andrea
AU - Montenero, Annibale S.
AU - Baravelli, Massimo
PY - 2008/10
Y1 - 2008/10
N2 - 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 μV and 23 ± 3 μV, 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.
AB - 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 μV and 23 ± 3 μV, 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.
KW - Altitude
KW - Arrhythmias
KW - Neural sympathetic activity
KW - T-wave alternans
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U2 - 10.1111/j.1540-8159.2008.01178.x
DO - 10.1111/j.1540-8159.2008.01178.x
M3 - Article
C2 - 18811808
AN - SCOPUS:51849099096
VL - 31
SP - 1277
EP - 1283
JO - PACE - Pacing and Clinical Electrophysiology
JF - PACE - Pacing and Clinical Electrophysiology
SN - 0147-8389
IS - 10
ER -