title: Ventricular structure, function, and mechanics at high altitude: chronic remodeling in Sherpa vs. short-term lowlander adaptation.
abstract: Short-term, high-altitude (HA) exposure raises pulmonary artery systolic pressure (PASP) and decreases left-ventricular (LV) volumes. However, relatively little is known of the long-term cardiac consequences of prolonged exposure in Sherpa, a highly adapted HA population. To investigate short-term adaptation and potential long-term cardiac remodeling, we studied ventricular structure and function in Sherpa at 5,050 m (n = 11; 31 ± 13 yr; mass 68 ± 10 kg; height 169 ± 6 cm) and lowlanders at sea level (SL) and following 10 ± 3 days at 5,050 m (n = 9; 34 ± 7 yr; mass 82 ± 10 kg; height 177 ± 6 cm) using conventional and speckle-tracking echocardiography. At HA, PASP was higher in Sherpa and lowlanders compared with lowlanders at SL (both P < 0.05). Sherpa had smaller right-ventricular (RV) and LV stroke volumes than lowlanders at SL with lower RV systolic strain (P < 0.05) but similar LV systolic mechanics. In contrast to LV systolic mechanics, LV diastolic, untwisting velocity was significantly lower in Sherpa compared with lowlanders at both SL and HA. After partial acclimatization, lowlanders demonstrated no change in the RV end-diastolic area; however, both RV strain and LV end-diastolic volume were reduced. In conclusion, short-term hypoxia induced a reduction in RV systolic function that was also evident in Sherpa following chronic exposure. We propose that this was consequent to a persistently higher PASP. In contrast to the RV, remodeling of LV volumes and normalization of systolic mechanics indicate structural and functional adaptation to HA. However, altered LV diastolic relaxation after chronic hypoxic exposure may reflect differential remodeling of systolic and diastolic LV function.
authors.affiliation: Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom; mstembridge@cardiffmet.ac.uk.
authors.forename: Mike
authors.initials: M
authors.lastname: Stembridge
authors.affiliation: School of Health and Exercise Sciences, University of British Columbia Okanagan Campus, Kelowna, Canada; and.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Ainslie
authors.affiliation: Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom;
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hughes
authors.affiliation: Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom;
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Stöhr
authors.affiliation: School of Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.
authors.forename: James D
authors.initials: JD
authors.lastname: Cotter
authors.affiliation: Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom;
authors.forename: Amanda Q X
authors.initials: AQ
authors.lastname: Nio
authors.affiliation: Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom;
authors.forename: Rob
authors.initials: R
authors.lastname: Shave
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000818:Animals; D003971:Diastole / Q000502:physiology; D004452:Echocardiography / Q000379:methods; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology
keywords: Sherpa; cardiac remodeling; hypoxia; ventricular mechanics