title: Exercise-induced pulmonary arterial hypertension.
abstract: BACKGROUND
  The clinical relevance of exercise-induced pulmonary arterial hypertension (PAH) is uncertain, and its existence has never been well studied by direct measurements of central hemodynamics. Using invasive cardiopulmonary exercise testing, we hypothesized that exercise-induced PAH represents a symptomatic stage of PAH, physiologically intermediate between resting pulmonary arterial hypertension and normal.
  
  
  RESULTS
  A total of 406 consecutive clinically indicated cardiopulmonary exercise tests with radial and pulmonary arterial catheters and radionuclide ventriculographic scanning were analyzed. The invasive hemodynamic phenotype of exercise-induced PAH (n=78) was compared with resting PAH (n=15) and normals (n=16). Log-log plots of mean pulmonary artery pressure versus oxygen uptake (V(.)o(2)) were obtained, and a "join-point" for a least residual sum of squares for 2 straight-line segments (slopes m1, m2) was determined; m2<m1="plateau," and m2>m1="takeoff" pattern. At maximum exercise, V(.)o(2) (55.8+/-20.3% versus 66.5+/-16.3% versus 91.7+/-13.7% predicted) was lowest in resting PAH, intermediate in exercise-induced PAH, and highest in normals, whereas mean pulmonary artery pressure (48.4+/-11.1 versus 36.6+/-5.7 versus 27.4+3.7 mm Hg) and pulmonary vascular resistance (294+/-158 versus 161+/-60 versus 62+/-20 dyne x s x cm(-5), respectively; P<0.05) followed an opposite pattern. An exercise-induced PAH plateau (n=32) was associated with lower o(2)max (60.6+/-15.1% versus 72.0+/-16.1% predicted) and maximum cardiac output (78.2+/-17.1% versus 87.8+/-18.3% predicted) and a higher resting pulmonary vascular resistance (247+/-101 versus 199+/-56 dyne x s x cm(-5); P<0.05) than takeoff (n=40). The plateau pattern was most common in resting PAH, and the takeoff pattern was present in nearly all normals.
  
  
  CONCLUSIONS
  Exercise-induced PAH is an early, mild, and clinically relevant phase of the PAH spectrum.
authors.affiliation: Pulmonary and Critical Care Unit, BUL 1-148, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114, USA. jjtolle@yahoo.com
authors.forename: James J
authors.initials: JJ
authors.lastname: Tolle
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Waxman
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Van Horn
authors.forename: Paul P
authors.initials: PP
authors.lastname: Pappagianopoulos
authors.forename: David M
authors.initials: DM
authors.lastname: Systrom
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D015444:Exercise; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D011859:Radiography; D014655:Vascular Resistance