Chemoreflex mediated arrhythmia during apnea at 5,050 m in low-but not high-altitude natives

View/ open
Author
Busch, S.A.
Davies, H.E.
Van Diepen, S
Simpson, L.L.
Sobierajski, F.
Riske, L.
Stembridge, Mike
Ainslie, Philip N.
Willie, C.K.
Hoiland, R.L.
Moore, J.P.
Date
2018-04-12Acceptance date
2017-08-29
Type
Article
Publisher
American Physiological Society
Metadata
Show full item recordAbstract
Peripheral chemoreflex mediated increases in both parasympathetic and sympathetic drive under chronic hypoxia may evoke bradyarrhythmias during apneic periods. We determined whether 1) voluntary apnea unmasks arrhythmia at low (344 m) and high (5,050 m) altitude, 2) high-altitude natives (Nepalese Sherpa) exhibit similar cardiovagal responses at altitude, and 3) bradyarrhythmias at altitude are partially chemoreflex mediated. Participants were grouped as Lowlanders (n = 14; age = 27 ± 6 yr) and Nepalese Sherpa (n = 8; age = 32 ± 11 yr). Lowlanders were assessed at 344 and 5,050 m, whereas Sherpa were assessed at 5,050 m. Heart rate (HR) and rhythm (lead II ECG) were recorded during rest and voluntary end-expiratory apnea. Peripheral chemoreflex contributions were assessed in Lowlanders (n = 7) at altitude after 100% oxygen. Lowlanders had higher resting HR at altitude (70 ± 15 vs. 61 ± 15 beats/min; P < 0.01) that was similar to Sherpa (71 ± 5 beats/min; P = 0.94). High-altitude apnea caused arrhythmias in 11 of 14 Lowlanders [junctional rhythm (n = 4), 3° atrioventricular block (n = 3), sinus pause (n = 4)] not present at low altitude and larger marked bradycardia (nadir −39 ± 18 beats/min; P < 0.001). Sherpa exhibited a reduced bradycardia response during apnea compared with Lowlanders (P < 0.001) and did not develop arrhythmias. Hyperoxia blunted bradycardia (nadir −10 ± 14 beats/min; P < 0.001 compared with hypoxic state) and reduced arrhythmia incidence (3 of 7 Lowlanders). Degree of bradycardia was significantly related to hypoxic ventilatory response (HVR) at altitude and predictive of arrhythmias (P < 0.05). Our data demonstrate apnea-induced bradyarrhythmias in Lowlanders at altitude but not in Sherpa (potentially through cardioprotective phenotypes). The chemoreflex is an important mechanism in genesis of bradyarrhythmias, and the HVR may be predictive for identifying individual susceptibility to events at altitude.
Journal/conference proceeding
Journal of Applied Physiology;
Citation
Busch, S.A., Davies, H.E., Van Diepen, S., Simpson, L.L., Sobierajski, F., Riske, L., Stembridge, M., Ainslie, P.N., Willie, C.K., Hoiland, R.L. and Moore, J.P. (2017) 'Chemoreflex Mediated Arrhythmia during Apnea at 5050m in Low but not High Altitude Natives', Journal of Applied Physiology, 124(4), pp.930-937
Description
Article published in Journal of Applied Physiology on 12 April 2018 - available at https://doi.org/10.1152/japplphysiol.00774.2017
Collections
- Import [796]
Related items
Showing items related by title, author, subject and abstract.
-
Global REACH: Assessment of brady-arrhythmias in Andeans and Lowlanders during apnea at 4330m
Busch, Stephen; van Diepen, Sean; Steele, Andrew; Meah, Victoria L.; Simpson, Lydia; Figueroa-Mujica, Romulo; Vizcardo Galindo, Gustavo; Villafuerte, Francisco C.; Tymko, Mike M.; Ainslie, Philip N.; Moore, Jonathan; Stembridge, Mike; Steinback, Craig (Frontiers Media, 2020-01-22)BACKGROUND: Ascent to altitude increases the prevalence of arrhythmogenesis in low-altitude dwelling populations (Lowlanders). High altitude populations (ie. Nepalese Sherpa) may have arrhythmias resistant adaptations that ... -
Muscle sympathetic reactivity to apneic and exercise stress in high-altitude Sherpa
Busch, Stephen; Simpson, Lydia; Sobierajski, Frances; Riske, Laurel; Ainslie, Philip; Willie, Chris; Stembridge, Mike; Moore, Jonathan; Steinback, Craig (American Physiological Society, 2020-01-08)Lowland-dwelling populations exhibit persistent sympathetic hyperactivity at altitude that may alter vascular function. High altitude populations, such as Sherpa, exhibit greater peripheral blood flow in response to acute ... -
Baroreflex control of sympathetic vasomotor activity and resting arterial pressure at high altitude: insight from Lowlanders and Sherpa
Simpson, Lydia; Busch, Stephen; Oliver, Samuel; Ainslie, Philip; Stembridge, Mike; Steinback, Craig; Moore, Jonathan (Wiley, 2019-03-20)Exposure to high altitude (HA) is characterized by heightened muscle sympathetic neural activity (MSNA); however, the effect on arterial baroreflex control of MSNA is unknown. Furthermore, arterial baroreflex control at ...