Cardiac structure and function in adolescent Sherpa; effect of habitual altitude and developmental stage
The purpose of this study was to examine ventricular structure and function in Sherpa adolescents to determine whether age-specific differences in oxygen saturation (SpO2) and pulmonary artery systolic pressure (PASP) influence cardiac adaptation to chronic hypoxia early in life. Two-dimensional, Doppler, and speckle-tracking echocardiography were performed on adolescent (9–16 yr) highland Sherpa (HLS; 3,840 m; n = 26) and compared with age-matched lowland Sherpa (LLS; 1,400 m; n = 10) and lowland Caucasian controls (LLC; sea level; n = 30). The HLS were subdivided into pre- and postadolescence; SpO2 was also recorded. Only HLS exhibited a smaller relative left ventricular (LV) end-diastolic volume; however, both HLS and LLS demonstrated a lower peak LV untwisting velocity compared with LLC (92 ± 26 and 100 ± 45 vs. 130 ± 43°/s, P < 0.05). Although SpO2 was similar between groups, PASP was higher in post- vs. preadolescent HLS (30 ± 5 vs. 25 ± 5 mmHg, P < 0.05), which negatively correlated with right ventricular strain rate (r = 0.50, P < 0.01). Much like their adult counterparts, HLS and LLS adolescents exhibit slower LV diastolic relaxation, despite residing at different altitudes. These findings suggest fundamental differences exist in the diastolic function of Sherpa that are present at an early age and may be retained after migration to lower altitudes. The higher PASP in postadolescent Sherpa is in contrast to previous reports of lowland children at high altitude and, unlike that in lowlanders, was not explained by differences in SpO2; thus different regulatory mechanisms seem to exist between these two distinct populations.
This study was supported in part by the Natural Sciences and Engineering Research Council of Canada and a Canada Research Chair to P. N. Ainslie.
Published inAmerican Journal of Physiology-Heart and Circulatory Physiology
PublisherAmerican Physiological Society
- AM (Accepted Manuscript)
CitationStembridge, M., Ainslie, P., Donnelly, J., MacLeod, N.T., Joshi, S., Hughes, M.G., Sherpa, K and Shave, R. (2016) 'Cardiac structure and function in adolescent Sherpa; effect of habitual altitude and developmental stage', American Journal of Physiology: Heart and Circulatory Physiology, 310(6), pp.740-746
Cardiff Met Affiliation
- Cardiff School of Sport and Health Sciences
Cardiff Met AuthorsMike Stembridge
Cardiff Met Research Centre/Group
- Cardiovascular Physiology
- © The Publisher