The Effect of High-Altitude Acclimatisation on Ultra-Short Heart Rate Variability.

Introduction: High-altitude (HA) exposure affects heart rate variability (HRV) and has been inconsistently linked to acute mountain sickness (AMS). The influence of increasing HA exposure on ultra-short HRV and its relationship to gold standard HRV measures at HA has not been examined.

Methods: This was a prospective observational study of adults aged ≥ 18 years undertaking a HA trek in the Dhaulagiri region of the Himalayas.

The Effect of Sex on Heart Rate Variability at High Altitude.

Unlabelled: There is evidence suggesting that high altitude (HA) exposure leads to a fall in heart rate variability (HRV) that is linked to the development of acute mountain sickness (AMS). The effects of sex on changes in HRV at HA and its relationship to AMS are unknown.

Methods: HRV (5-min single-lead ECG) was measured in 63 healthy adults (41 men and 22 women) 18-56 yr of age at sea level (SL) and during a HA trek at 3619, 4600, and 5140 m, respectively.

Smartphone-Enabled Heart Rate Variability and Acute Mountain Sickness.

Introduction: The autonomic system and sympathetic activation appears integral in the pathogenesis of acute mountain sickness (AMS) at high altitude (HA), yet a link between heart rate variability (HRV) and AMS has not been convincingly shown. In this study we investigated the utility of the smartphone-derived HRV score to predict and diagnose AMS at HA.

Methods: Twenty-one healthy adults were investigated at baseline at 1400 m and over 10 days during a trek to 5140 m.

A Four-Way Comparison of Cardiac Function with Normobaric Normoxia, Normobaric Hypoxia, Hypobaric Hypoxia and Genuine High Altitude.

Background: There has been considerable debate as to whether different modalities of simulated hypoxia induce similar cardiac responses.

Materials And Methods: This was a prospective observational study of 14 healthy subjects aged 22-35 years. Echocardiography was performed at rest and at 15 and 120 minutes following two hours exercise under normobaric normoxia (NN) and under similar PiO2 following genuine high altitude (GHA) at 3,375 m, normobaric hypoxia (NH) and hypobaric hypoxia (HH) to simulate the equivalent hypoxic stimulus to GHA.

The Effects of Sex on Cardiopulmonary Responses to Acute Normobaric Hypoxia.

Unlabelled: Boos, Christopher John, Adrian Mellor, John Paul O'Hara, Costas Tsakirides, and David Richard Woods. The effects of sex on cardiopulmonary responses to acute normobaric hypoxia. High Alt Med Biol.

A comparison of two methods of heart rate variability assessment at high altitude.

Heart rate variability (HRV) is a useful index of autonomic function and has been linked to the development of high altitude (HA) related illness. However, its assessment at HA has been undermined by the relative expense and limited portability of traditional HRV devices which have mandated at least a minute heart rate recording. In this study, the portable ithlete HRV system, which uses a 55 s recording, was compared with a reference method of HRV which utilizes a 5 min electrocardiograph recording (CheckMyHeart ).

The effects of exercise at high altitude on high-sensitivity cardiac troponin release and associated biventricular cardiac function.

Background: It has been consistently shown that heavy exercise leads to cardiac troponin (cTn) release and variable changes in post exercise cardiac function. This relationship has not been explored at increasing or significant high altitude (HA). This study assessed the effects of exercise at progressively increasing HA on high-sensitivity (hs)-cTnT levels and their relationship to biventricular cardiac function and severity of acute mountain sickness (AMS).