Global REACH: Assessment of brady-arrhythmias in Andeans and Lowlanders during apnea at 4330m
van Diepen, Sean
Meah, Victoria L.
Vizcardo Galindo, Gustavo
Villafuerte, Francisco C.
Tymko, Mike M.
Ainslie, Philip N.
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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 prevent arrhythmogenesis at altitude, though this has not been documented in other High altitude groups, including those diagnosed with chronic mountain sickness (CMS). We investigated whether healthy (CMS-) and CMS afflicted (CMS+) Andeans exhibit cardiac arrhythmias under acute apneic stress at altitude. METHODS AND RESULTS: Electrocardiograms (lead II) were collected in CMS- (N=9), CMS+ (N=8), and Lowlanders (N= 13) following several days at 4330m (Cerro de Pasco, Peru). ECG rhythm and HR were assessed at both rest and during maximal volitional apnea (End-Expiratory [EXP]). Both CMS- and CMS+ had similar basal HR (69 ± 8 beats/min vs. 62 ± 11 beats/min), while basal HR was higher in Lowlanders (77 ± 18 beats/min; P<0.05 versus CMS+). Apnea elicited significant bradycardia (nadir -32 ± 15 beats/min; P<0.01) and the development of arrhythmias in 8/13 Lowlanders (junctional rhythm, 3° atrio-venticular block, sinus pause). HR was preserved was prior to volitional breakpoint in both CMS- (nadir -6 ± 1 beat/min) and CMS+ (1 ±12 beats/min), with 2/17 Andeans developing arrhythmias ( 1 CMS+ and 1 CMS-; both Premature Atrial Contraction) prior to breakpoint. CONCLUSIONS: Andeans showed an absence of arrhythmias and preserved HR response to volitional apnea at altitude, demonstrating that potential cardio-resistant adaptations to arrhythmogenesis exist across permanent HA populations. Acclimatized Lowlanders have further demonstrated an increased prevalence of arrhythmias at altitude.
Frontiers in Physiology;
Busch, S., van Diepen, S., Steele,A., Meah, V., Simpson, L., Figueroa-Mujica, R., Vizcardo Galindo, G., Villafuerte, F., Tymko, M., Ainslie, P., Moore, J., Stembridge, M. and Steinback, C.(2019) 'Global REACH: Assessment of brady-arrhythmias in Andeans and Lowlanders during apnea at 4330m', Frontiers in Physiology, doi: 10.3389/fphys.2019.01603
Dynodwr Gwrthrych Digidol (DOI)https://doi.org/10.3389/fphys.2019.01603
Article published in Frontiers in Physiology on 22 January 2020, available open access at: https://www.frontiersin.org/articles/10.3389/fphys.2019.01603/abstract
Cardiff Metropolitan University (Grant ID: Cardiff Metropolian (Internal))
- Sport Research Groups 
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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. (American Physiological Society, 2018-04-12)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 ...
Highs and Lows of Sympathetic Neuro-cardiovascular Transduction: Influence of Altitude Acclimatization and Adaptation Berthelsen, Lindsey; Fraser, Graham; Simpson, Lydia; Vanden Berg, Emily; Busch, Stephen A.; Steele, Andrew R.; Meah, Victoria L.; Lawley, Justin; Figueroa-Mujica, Romulo; Vizcardo-Galindo, Gustavo; Villafuerte, Francisco; Gasho, Chris; Willie, Christopher; Tymko, Michael M.; Ainslie, Philip N.; Stembridge, Mike; Moore, Jonathan P.; Steinback, Craig D. (American Physiological Society, 2020-09-28)High-altitude (>2500m) exposure results in increased muscle sympathetic nervous activity (MSNA) in acclimatizing lowlanders. However, little is known about how altitude affects MSNA in 66 indigenous high-altitude populations. ...
The overlooked significance of plasma volume for successful adaptation to high altitude in Sherpa and Andean natives Stembridge, Mike; Williams, Alexandra M.; Gasho, Christopher; Dawkins, Tony; Drane, Aimee L.; Villafuerte, Francisco C.; Levine, Benjamin D.; Shave, Rob; Ainslie, Philip N. (National Academy of Sciences, 2019-07-29)In contrast to Andean natives, high altitude Tibetans present with a lower hemoglobin concentration that correlates with reproductive success and exercise capacity. Decades of physiological and genomic research have assumed ...