title: Submaximal Exercise Pulmonary Gas Exchange in Left Heart Disease Patients With Different Forms of Pulmonary Hypertension.
abstract: BACKGROUND
  We determined whether pulmonary gas exchange indices during submaximal exercise are different in heart failure (HF) patients with combined post- and pre-capillary pulmonary hypertension (PPC-PH) versus HF patients with isolated post-capillary PH (IPC-PH) or no PH.
  
  
  RESULTS
  Pulmonary hemodynamics and pulmonary gas exchange were assessed during rest and submaximal exercise in 39 HF patients undergoing right heart catheterization. After hemodynamic evaluation, patients were classified as having no PH (n = 11), IPC-PH (n = 12), or PPC-PH (n = 16). At an equivalent oxygen consumption, end-tidal CO2 (PETCO2) and arterial oxygen saturation (SaO2) were greater in no-PH and IPC-PH versus PPC-PH patients (36.1 ± 3.2 vs. 31.7 ± 4.5 vs. 26.2 ± 4.7 mm Hg and 97 ± 2 vs. 96 ± 3 vs. 91 ± 1%, respectively). Conversely, dead-space ventilation (VD/VT) and the ventilatory equivalent for carbon dioxide (V˙(E)/V˙CO2 ratio) were lower in no-PH and IPC-PH versus PPC-PH patients (0.37 ± 0.05 vs. 0.38 ± 0.04 vs. 0.47 ± 0.03 and 38 ± 5 vs. 42 ± 8 vs. 51 ± 8, respectively). The exercise-induced change in V(D)/V(T), V˙(E)/V˙CO2 ratio, and PETCO2 correlated significantly with the change in mean pulmonary arterial pressure, diastolic pressure difference, and transpulmonary pressure gradient in PPC-PH patients only.
  
  
  CONCLUSIONS
  Noninvasive pulmonary gas exchange indices during submaximal exercise are different in HF patients with combined post- and pre-capillary PH compared with patients with isolated post-capillary PH or no PH.
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota. Electronic address: b.taylor@exeter.ac.uk.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Taylor
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Smetana
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Frantz
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D015444:Exercise / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology*
keywords: Diastolic pressure difference; pre- and post-capillary pulmonary hypertension; right-heart catheterization; submaximal exercise