Cardiac Adaptation to Prolonged High Altitude Migration Assessed by Speckle Tracking Echocardiography

Abstract

ObjectiveExposure to high altitudes represents physiological stress that leads to significant changes in cardiovascular properties. However, long-term cardiovascular adaptions to high altitude migration of lowlanders have not been described. Accordingly, we measured changes in cardiovascular properties following prolonged hypoxic exposure in acclimatized Han migrants and Tibetans.MethodsEchocardiographic features of recently adapted Han migrant (3–12 months, n = 64) and highly adapted Han migrant (5–10 years, n = 71) residence in Tibet (4,300 m) using speckle tracking echocardiography were compared to those of age-matched native Tibetans (n = 75) and Han lowlanders living at 1,400 m (n = 60).ResultsShort-term acclimatized migrants showed increased estimated pulmonary artery systolic pressure (PASP) (32.6 ± 5.1 mmHg vs. 21.1 ± 4.2 mmHg, p < 0.05), enlarged right ventricles (RVs), and decreased fractional area change (FAC) with decreased RV longitudinal strain (−20 ± 2.8% vs. −25.5 ± 3.9%, p < 0.05). While left ventricular ejection fraction (LVEF) was preserved, LV diameter (41.7 ± 3.1 mm vs. 49.7 ± 4.8 mm, p < 0.05) and LV longitudinal strain (−18.8 ± 3.2% vs. −22.9 ± 3.3%, p < 0.05) decreased. Compared with recent migrants, longer-term migrants had recovered RV structure and functions with slightly improved RV and LV longitudinal strain, though still lower than lowlander controls; LV size remained small with increased mass index (68.3 ± 12.7 vs. 59.3 ± 9.6, p < 0.05). In contrast, native Tibetans had slightly increased PASP (26.1 ± 3.4 mmHg vs. 21.1 ± 4.2 mmHg, p < 0.05) with minimally altered cardiac deformation compared to lowlanders.ConclusionRight ventricular systolic function is impaired in recent (<1 year) migrants to high altitudes but improved during the long-term dwelling. LV remodeling persists in long-term migrants (>5 years) but without impairment of LV systolic or diastolic function. In contrast, cardiac size, structure, and function of native Tibetans are more similar to those of lowland dwelling Hans.

The Impact of High-Altitude Migration on Cardiac Structure and Function: A One-Year Prospective Study

“…Our longitudinal study observed decreases in RV dimensional parameters one month and one year after HA exposure in healthy lowlanders, mirroring changes in the other three chambers. While LV and LA responses aligned with previous reports, the RA response differed unexpectedly, exhibiting a decrease unlike observations in earlier studies [14,18].…”

“…Over the years, studies examining RV area in healthy lowlanders upon initial HA exposure have yielded inconsistent results, reporting slight increases [16], no changes[6, 17], or decreases after prolonged acclimatization (after more than 5 years) [14]. Additionally, RV dimensions vary across populations at different altitudes: lower in Himalayan Sherpa (5050 m) [17], higher in Peruvian Andeans at La Rinconada (5100 m)[18], similar to lowlanders in Tibetans (4300 m) [14] and Peruvian Andeans at Puno (3800 m) [18]. These discrepancies potentially arise from differences in age, ethnicity, and exposure time among crosssectional study participants.…”

“…This information would aid them in planning their itinerary safely and effectively. However, limited cross-sectional studies provide the only existing data, and several cardiac parameters in these studies exhibit inconsistencies [13,14]. To date, no published prospective studies exist with follow-up periods exceeding one month, attributed to the logistical challenges associated with tracking subjects over extended periods in the harsh HA environment.…”

A Conserved Mechanism of Cardiac Hypertrophy Regression through FoxO1

“…However, insight into the broad scope of molecular mechanisms that govern cardiac plasticity remains limited. There are several notable examples of robust, reversible cardiac remodeling occurring in vertebrates including in fish with thermal acclimation [1][2][3][4] , birds flying at high altitudes [5][6][7] , and pythons following consumption of large prey [8][9][10][11][12] . Such unconventional model organisms represent unique platforms in which to discover the molecular biology underlying cardiac plasticity.…”

Protective effects of epigallocatechin-3-gallate counteracting the chronic hypobaric hypoxia-induced myocardial injury in plain-grown rats at high altitude

“…The myocardial high oxygen consumption rate makes it sensitive to hypoxia. While a series of physiological adaptations of the cardiovascular system enable the organs to better cope with increased oxygen demand, the chronic HH conditions can still impair the myocardium (Jing et al 2020 ; Chen et al 2022 ). Therefore, understanding the biochemical mechanisms underlying chronic HH-induced myocardial impairment and exploring the therapeutic method has been a focus of research in high-altitude medicine.…”