Key result
Exposure to high altitude hypoxia at 5400 m significantly increased left ventricular twist compared to sea level (12.6° vs. 9.6°, P<0.05), suggesting subendocardial systolic dysfunction.
Why the study?
Does exposure to hypobaric hypoxia at high altitude affect left ventricular twist in healthy subjects?
Observational (n=39)
Does exposure to hypobaric hypoxia at high altitude affect left ventricular twist in healthy subjects?
Absolute Event Rate: 12.6% vs 9.6%
p-value: p=<0.05
Exposure to high altitude hypoxia increases left ventricular twist in healthy subjects, suggesting the occurrence of subendocardial systolic dysfunction.
High-altitude hypoxia was associated with increased LV twist in healthy subjects; hypothesis-generating and requires prospective validation before clinical relevance.
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.
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Osculati et al. (2015) conducted an observational in Healthy subjects (n=39). Hypobaric hypoxia (high altitude exposure at 5400 m) vs. Sea level was evaluated on Left ventricular twist (p=<0.05). Exposure to high altitude hypoxia at 5400 m significantly increased left ventricular twist compared to sea level (12.6° vs. 9.6°, P<0.05), suggesting subendocardial systolic dysfunction.
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