Figure 2
Resting electrocardiographic measures. (A) QTc (Bazett) interval during the hypoxia study. A 3-day normoxia phase was followed by an acclimatization phase with increasing hypoxia levels to a minimum of 11.8% FIO2 between the study days 16 and 20. Oxygen content was gradually increased back to normal during a 2-day recovery phase. Changes in standard 12-lead resting electrocardiogram intervals at baseline (normoxia), hypoxia and recovery (normoxia) of four individuals after myocardial infarction. (B) QTc(B) = QT correction using Bazett's formula, QTc(B) = QT/√RR; QTc(F) = QT correction using Fridericia's formula, QTc(F) = QT/3√RR; QT interval. (C) QTr(H) = relative QT interval by using Holzmann’s correction formula, QTr(H) = QT/(0.39 × √RR) × 100%. Changes in standard 12-lead resting electrocardiogram intervals at baseline (normoxia), hypoxia and recovery (normoxia) of one healthy control individual. (D) QTc(B) = QT correction using Bazett's formula, QTc(B); QTc(F), QTc(F) = QT/3√RR; QT interval. (E) QTr(H). Echocardiographic variables of right heart strain at baseline (normoxia), hypoxia and recovery (normoxia). (F) TR dPmax, tricuspid regurgitation jet maximal pressure gradient (mmHg); (G) PVAT, pulmonary velocity acceleration time (ms); (H) RA, right atrium area (cm2); (I) TR Vmax, maximal tricuspid regurgitation velocity (m/s). Exercise electrocardiographic measures. (J) ECG during exercise of one individual at 250 Watts under normoxia with a single ventricular extrasystolic beat; 150 bpm; 50 mm/s. (K) ECG during exercise of the same subject at 250 Watts in 17.5% oxygen illustrating multiple ventricular extrasystolic beats including bigemini and couplets; 124 bpm; 50 mm/s. No symptoms were reported. Columns represent means ± standard error of mean and corresponding p-values between different conditions (*p < 0.05; **p < 0.01).
