title: Evidence supportive of impaired myocardial blood flow reserve at high altitude in subjects developing high-altitude pulmonary edema.
abstract: An exaggerated increase in pulmonary arterial pressure is the hallmark of high-altitude pulmonary edema (HAPE) and is associated with endothelial dysfunction of the pulmonary vasculature. Whether the myocardial circulation is affected as well is not known. The aim of this study was, therefore, to investigate whether myocardial blood flow reserve (MBFr) is altered in mountaineers developing HAPE. Healthy mountaineers taking part in a trial of prophylactic treatment of HAPE were examined at low (490 m) and high altitude (4,559 m). MBFr was derived from low mechanical index contrast echocardiography, performed at rest and during submaximal exercise. Among 24 subjects evaluated for MBFr, 9 were HAPE-susceptible individuals on prophylactic treatment with dexamethasone or tadalafil, 6 were HAPE-susceptible individuals on placebo, and 9 persons without HAPE susceptibility served as controls. At low altitude, MBFr did not differ between groups. At high altitude, MBFr increased significantly in HAPE-susceptible individuals on treatment (from 2.2 +/- 0.8 at low to 2.9 +/- 1.0 at high altitude, P = 0.04) and in control persons (from 1.9 +/- 0.8 to 2.8 +/- 1.0, P = 0.02), but not in HAPE-susceptible individuals on placebo (2.5 +/- 0.3 and 2.0 +/- 1.3 at low and high altitude, respectively, P > 0.1). The response to high altitude was significantly different between the two groups (P = 0.01). There was a significant inverse relation between the increase in the pressure gradient across the tricuspid valve and the change in myocardial blood flow reserve. HAPE-susceptible individuals not taking prophylactic treatment exhibit a reduced MBFr compared with either treated HAPE-susceptible individuals or healthy controls at high altitude.
authors.affiliation: Dept. of Cardiology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland.
authors.forename: B A
authors.initials: BA
authors.lastname: Kaufmann
authors.forename: A M
authors.initials: AM
authors.lastname: Bernheim
authors.forename: S
authors.initials: S
authors.lastname: Kiencke
authors.forename: M
authors.initials: M
authors.lastname: Fischler
authors.forename: J
authors.initials: J
authors.lastname: Sklenar
authors.forename: H
authors.initials: H
authors.lastname: Mairbäurl
authors.forename: M
authors.initials: M
authors.lastname: Maggiorini
authors.forename: H P
authors.initials: HP
authors.lastname: Brunner-La Rocca
mesh_terms: D000064:Acclimatization; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D002243:Carbolines / Q000627:therapeutic use*; D003907:Dexamethasone / Q000627:therapeutic use*; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000187:drug effects*; D005938:Glucocorticoids / Q000627:therapeutic use*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009051:Mountaineering; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use*; D011654:Pulmonary Edema / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D000068581:Tadalafil; D013997:Time Factors; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects
chemical_list: D002243:Carbolines; D005938:Glucocorticoids; D010726:Phosphodiesterase Inhibitors; D000068581:Tadalafil; D003907:Dexamethasone