Left ventricular adaptation to high altitude: speckle tracking echocardiography in lowlanders, healthy highlanders and highlanders with chronic mountain sickness

Male Sympathetic Nervous System Acclimatization Altitude Sickness Ventricular Function, Left 0302 clinical medicine Anoxia Physiologie générale Heart Rate middle aged Peru heart rate systole Hypoxia comparative study pathophysiology predictive value https://purl.org/pe-repo/ocde/ford#3.02.04 adult Altitude anoxia Middle Aged Echocardiography, Doppler 3. Good health acclimatization female heart stroke volume young adult Female altitude Adult Adolescent Systole adrenergic system Young Adult 03 medical and health sciences male Predictive Value of Tests Humans human Myocardial deformation echography Stroke Volume case control study Doppler echocardiography Left ventricular strain adolescent Chronic mountain sickness Case-Control Studies Chronic Disease heart left ventricle function chronic disease
DOI: 10.1007/s10554-015-0614-1 Publication Date: 2015-02-09T09:35:22Z
ABSTRACT
Hypoxic exposure depresses myocardial contractility in vitro, but has been associated with indices of increased cardiac performance in intact animals and in humans, possibly related to sympathetic nervous system activation. We explored left ventricular (LV) function using speckle tracking echocardiography and sympathetic tone by spectral analysis of heart rate variability (HRV) in recently acclimatized lowlanders versus adapted or maladapted highlanders at high altitude. Twenty-six recently acclimatized lowlanders, 14 healthy highlanders and 12 highlanders with chronic mountain sickness (CMS) were studied. Control measurements at sea level were also obtained in the lowlanders. Altitude exposure in the lowlanders was associated with slightly increased blood pressure, decreased LV volumes and decreased longitudinal strain with a trend to increased prevalence of post-systolic shortening (p = 0.06), whereas the low frequency/high frequency (LF/HF) ratio increased (1.62 ± 0.81 vs. 5.08 ± 4.13, p < 0.05) indicating sympathetic activation. Highlanders had a similarly raised LF/HF ratio, but no alteration in LV deformation. Highlanders with CMS had no change in LV deformation, no significant increase in LF/HF, but decreased global HRV still suggestive of increased sympathetic tone, and lower mitral E/A ratio compared to healthy highlanders. Short-term altitude exposure in lowlanders alters indices of LV systolic function and increases sympathetic nervous system tone. Life-long altitude exposure in highlanders is associated with similar sympathetic hyperactivity, but preserved parameters of LV function, whereas diastolic function may be altered in those with CMS. Altered LV systolic function in recently acclimatized lowlanders may be explained by combined effects of hypoxia and changes in loading conditions.
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