title: Effects of hypobaric hypoxia exposure at high altitude on left ventricular twist in healthy subjects: data from HIGHCARE study on Mount Everest.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Osculati
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Miriam
authors.initials: M
authors.lastname: Revera
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Branzi
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Faini
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Malfatto
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bilo
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Giuliano
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Gregorini
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Ciambellotti
authors.affiliation: Department Cardiovascular, Neural and Metabolic Sciences, Ospedale San Luca, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milano, Italy.
authors.forename: Carolina
authors.initials: C
authors.lastname: Lombardi
authors.affiliation: Centro Cardiologico Monzino, 20138 Milano, Italy Department of Cardiovascular Sciences, University of Milan, Milan, Italy.
authors.forename: Piergiuseppe
authors.initials: P
authors.lastname: Agostoni
authors.affiliation: 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.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
authors.affiliation: 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.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Parati
mesh_terms: D000328:Adult; D000368:Aged; D000531:Altitude; D000532:Altitude Sickness / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000704:Analysis of Variance; D001562:Benzimidazoles / Q000008:administration & dosage*; D001565:Benzoates / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D064368:Healthy Volunteers; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology* / Q000517:prevention & control; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D000077333:Telmisartan; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology
chemical_list: D001562:Benzimidazoles; D001565:Benzoates; D000077333:Telmisartan
keywords: high altitude; hypobaric hypoxia; left ventricular twist and torsion; subendocardial left ventricle function