Chemoreflex mediated arrhythmia during apnea at 5,050 m in low- but not high-altitude natives
Key result
High-altitude apnea provokes bradyarrhythmias in ~79% of lowlanders but completely spares Nepalese Sherpa.
- n=22
Why the study?
Peripheral chemoreflex mediated increases in parasympathetic and sympathetic drive under chronic hypoxia may evoke bradyarrhythmias during apneic periods, but differences between low- and high-altitude natives were unclear.
Does voluntary apnea at high altitude induce bradyarrhythmias in Lowlanders compared to high-altitude natives?
Comparison
Voluntary apnea at 344 m vs 5,050 m in Lowlanders; Lowlanders vs Sherpa at 5,050 m; hypoxia vs 100% oxygen in Lowlanders
Design
Observational study
Authors
Discussion
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Implication
Apnea at high altitude may provoke bradyarrhythmias in lowlanders; leaves open whether chemoreflex modulation or native adaptations confer protection.
Study Design
Type
Observational (n=22)
Structured PICO
Does voluntary apnea at high altitude induce bradyarrhythmias in Lowlanders compared to high-altitude natives?
P
Population
22 participants (14 Lowlanders and 8 Nepalese Sherpa) assessed for heart rate and rhythm during rest and voluntary end-expiratory apnea at low and high altitudes.
E
Exposure
Voluntary end-expiratory apnea at high altitude (5,050 m), with a subset of Lowlanders also assessed after 100% oxygen
C
Comparator
Voluntary end-expiratory apnea at low altitude (344 m) for Lowlanders, and comparison between Lowlanders and Sherpa at high altitude
O
Outcome
Heart rate and rhythm (arrhythmia incidence) during rest and voluntary end-expiratory apneasurrogate
Main Result
Absolute Event Rate: 78.6% vs 0%
Voluntary apnea at high altitude induces chemoreflex-mediated bradyarrhythmias in Lowlanders, which are absent in high-altitude natives (Sherpa) likely due to cardioprotective adaptations.
Cite This Study
Busch et al. (2017) conducted an observational in Hypoxia-induced bradyarrhythmias (n=22). Voluntary apnea at high altitude (5,050 m) vs. Nepalese Sherpa at high altitude was evaluated on Incidence of arrhythmias during apnea. Voluntary apnea at 5,050 m altitude induced bradyarrhythmias in 78.6% of Lowlanders, whereas Nepalese Sherpa developed no arrhythmias and had a blunted bradycardia response (P<0.001).