Heart mechanics at high altitude: 6 days on the top of Europe.
OBJECTIVE
The aim of this study was to analyse the underlying mechanisms of left and right ventricular (LV and RV) functional alterations during several days in high-altitude hypoxia.


RESULTS
Resting evaluations of LV and RV function and mechanics were assessed by Speckle Tracking Echocardiography on 11 subjects at sea level (SLPRE), 3 ± 2 h after helicopter transport to high altitude (D0), at day 2 (D2), day 4 (D4) and day 6 (D6) at 4350 m and 5 ± 2 h after return to sea level (SLPOST). Subjects experienced acute mountain sickness (AMS) during the first days at 4350 m. LV systolic function, RV systolic and diastolic function, LV and RV strains and LV synchrony were unchanged at high altitude. Peak twist was increased at D0, continued to increase until D6 (SLPRE: 9.0 ± 5.1deg; D6: 13.0 ± 4.0deg, P < 0.05), but was normalized at SLPOST. Early filling decreased at high altitude with a nadir at D2 (SLPRE: 78 ± 13 cm s-1; D2: 66 ± 11 cm s-1, P < 0.05). LV filling pressures index was decreased at high altitude with the minimum value obtained at D2 and remained reduced at SLPOST. Untwisting, an important factor of LV filling, was not decreased but was delayed at 4350 m.


CONCLUSIONS
High-altitude exposure impaired LV diastolic function with the greatest effect observed at D2, concomitantly with the occurrence of AMS. The LV early filling impairments resulted from an increased RV afterload, a decrease in LV filling pressure and a delayed LV untwist. However, the increased LV twist probably acted as a compensatory mechanism to maintain cardiac performance during high-altitude hypoxia.
U1042, INSERM, Domaine de la Merci, F-38700, La Tronche - Grenoble, France.|Laboratoire HP2, Grenoble Alpes Université, Avenue Kimberley, F-38434, Echirolles - Grenoble, France.
Claire
C
Maufrais
U1042, INSERM, Domaine de la Merci, F-38700, La Tronche - Grenoble, France.|Laboratoire HP2, Grenoble Alpes Université, Avenue Kimberley, F-38434, Echirolles - Grenoble, France.|Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, 27 rue Marcoz F-73000, Chambéry, France.
Thomas
T
Rupp
Grenoble Institute of Neurosciences, INSERM U1216, Chemin Fortuné Ferrini, F-38700 La Tronche - Grenoble, France.|Pôle Anesthésie Réanimation, CHU de Grenoble, Avenue Maquis du Grésivaudan, F-38700 La Tronche - Grenoble, France.
Pierre
P
Bouzat
Laboratoire Performance et Santé en Altitude, Université de Perpignan, 7 Avenue Pierre de Coubertin, F-66120, Font-Romeu, France.
Gregory
G
Doucende
U1042, INSERM, Domaine de la Merci, F-38700, La Tronche - Grenoble, France.|Laboratoire HP2, Grenoble Alpes Université, Avenue Kimberley, F-38434, Echirolles - Grenoble, France.
Samuel
S
Verges
Avignon University, LAPEC EA4278, 74 Rue Louis Pasteur, F-84000, Avignon, France.
Stéphane
S
Nottin
Avignon University, LAPEC EA4278, 74 Rue Louis Pasteur, F-84000, Avignon, France.
Guillaume
G
Walther
D000222:Adaptation, Physiological; D000328:Adult; D000532:Altitude Sickness / Q000150:complications / Q000503:physiopathology*; D004452:Echocardiography / Q000379:methods*; D005602:France; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D061214:Patient Safety; D011669:Pulmonary Wedge Pressure; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D014655:Vascular Resistance / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*; D055815:Young Adult
echocardiography; hypoxia; ventricle mechanics