title: Elevated pulmonary artery pressure among Amhara highlanders in Ethiopia.
abstract: OBJECTIVE
  Pulmonary arterioles respond to hypoxia with constriction that raises vascular resistance and pulmonary artery blood pressure. The response is sustained indefinitely by the chronic hypoxia of high-altitude residence among highlanders of European and Andean descent, but not Tibetans. The objective of this study was to identify the consequences of lifelong hypoxia exposure for the pulmonary vasculature among Amhara high-altitude natives from Ethiopia.
  
  
  METHODS
  A three-way static group comparison tested for the effect of Amhara ancestry and high residence altitude on pulmonary hemodynamics measured using echocardiography in samples of 76 healthy adult Amhara lifelong residents at 3700 m, 54 Amhara lifelong residents at 1200 m, and 46 U.S. low-altitude residents at 282 m.
  
  
  RESULTS
  Amhara at 3700 m had average Doppler-estimated pulmonary artery systolic pressure (tricuspid regurgitant gradient) of 27.9 ± 8.4 (SD) mm Hg as compared with 21.9 ± 4.0 among Amhara at low altitude and 16.5 ± 3.6 in the U.S. low-altitude reference sample. However, there was no residence altitude effect on pulmonary blood flow or vascular resistance. Amhara ancestry was associated with greater pulmonary artery systolic pressure and pulmonary blood flow, yet lower pulmonary vascular resistance.
  
  
  CONCLUSIONS
  The Amhara at 3700 m had elevated pulmonary artery pressure, but without the elevated pulmonary vascular resistance characteristic of the classic model of the response to long-term hypoxia by the pulmonary vasculature. The elevated pressure among Amhara may be a consequence of high pulmonary blood flow regardless of altitude and represent a newly identified pattern of response.
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, OH 44106-7125, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Hoit
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Dalton
authors.forename: Amha
authors.initials: A
authors.lastname: Gebremedhin
authors.forename: Allison
authors.initials: A
authors.lastname: Janocha
authors.forename: Peter A
authors.initials: PA
authors.lastname: Zimmerman
authors.forename: Allison M
authors.initials: AM
authors.lastname: Zimmerman
authors.forename: Kingman P
authors.initials: KP
authors.lastname: Strohl
authors.forename: Serpil C
authors.initials: SC
authors.lastname: Erzurum
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Beall
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D001794:Blood Pressure; D005002:Ethiopia; D005006:Ethnicity; D005260:Female; D006352:Heart Ventricles / Q000033:anatomy & histology; D006439:Hemodynamics; D006801:Humans; D000860:Hypoxia; D008168:Lung / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000652:urine; D009573:Nitrites / Q000652:urine; D007703:Peptidyl-Dipeptidase A / Q000235:genetics / Q000378:metabolism; D011651:Pulmonary Artery / Q000378:metabolism*; D014481:United States; D014655:Vascular Resistance; D055815:Young Adult
chemical_list: D009566:Nitrates; D009573:Nitrites; D007703:Peptidyl-Dipeptidase A