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Eur Heart J Cardiovasc Imaging. 2016 Jun;17(6):635-43. doi: 10.1093/ehjci/jev166. Epub 2015 Jul 4.

Effects of hypobaric hypoxia exposure at high altitude on left ventricular twist in healthy subjects: data from HIGHCARE study on Mount Everest.

Author information

1
Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
2
Centro Cardiologico Monzino, 20138 Milano, Italy Department of Cardiovascular Sciences, University of Milan, Milan, Italy.
3
Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy Department of Health Sciences, University of Milano-Bicocca, 20052 Monza, Italy.
4
Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy Department of Health Sciences, University of Milano-Bicocca, 20052 Monza, Italy Chair of Cardiovascular Medicine, University of Milano-Bicocca, Milan, Italy gianfranco.parati@unimib.it.

Abstract

AIMS:

Previous studies investigating the effect of hypoxia on left ventricle focused on its global function, an approach that may not detect a selective dysfunction of subendocardial layers that are most sensitive to an inadequate oxygen supply. In the HIGHCARE study, aimed at exploring the effects of high altitude hypoxia on multiple biological variables and their modulation by an angiotensin receptor blocker, we addressed the effects of hypobaric hypoxia on both systolic and diastolic left ventricular geometry and function, focusing on echocardiographic assessment of left ventricle twist to indirectly examine subendocardial left ventricular systolic function.

METHODS AND RESULTS:

In 39 healthy subjects, physiological and echocardiographic variables, including left ventricular twist and a simplified torsion-to-shortening ratio (sTSR), were recorded at sea level, at 3400 m, and at 5400 m altitude (Mount Everest base camp). Both left ventricular twist and sTSR were greater at 5400 m than at sea level (12.6° vs. 9.6° and 0.285 vs. 0.202, P < 0.05 for both), were linearly related to the reduction in arterial oxygen partial pressure (P < 0.01 for both), and were associated with significant changes in LV dimensions and contractility. No effects of angiotensin receptor blockade were observed on these variables throughout the study.

CONCLUSION:

Our study, for the first time, demonstrates an increase in left ventricular twist at high altitude in healthy subjects exposed to high altitude hypoxia, suggesting the occurrence of subendocardial systolic dysfunction in such condition.

KEYWORDS:

high altitude; hypobaric hypoxia; left ventricular twist and torsion; subendocardial left ventricle function

PMID:
26142456
DOI:
10.1093/ehjci/jev166
[Indexed for MEDLINE]

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