title: Feasibility of routine pulmonary arterial impedance measurements in pulmonary hypertension.
abstract: OBJECTIVE
  Right ventricular (RV) afterload is best described by a pulmonary arterial impedance (PVZ) spectrum, which integrates pulmonary vascular resistance (PVR), elastance, and wave reflection. We evaluated the feasibility of PVZ determinations in patients with pulmonary arterial hypertension (PAH) during routine right heart catheterization and Doppler echocardiography.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Academic hospital.
  
  
  METHODS
  Twenty-two patients with PAH.
  
  
  METHODS
  Right heart catheterization with a fluid-filled Swan-Ganz catheter, Doppler echocardiography, and administration of inhaled nitric oxide (NO) [10 to 20 ppm; 17 patients], maximum tolerated dose of IV epoprostenol (average, 8.5 ng/kg/min; 5 patients), and IV dobutamine (8 micro g/kg/min; 8 patients).
  
  
  RESULTS
  PVZ was calculated from the spectral analysis of synchronized pulmonary artery pressure (Ppa) and flow waves. The mean (+/- SE) Ppa was 63 +/- 3 mm Hg, and the mean PVR was 16 +/- 2 Wood units. The PVZ spectrum was markedly shifted to higher than normal pressures and frequencies, with a mean 0-Hz impedance (Z(0)) of 1,506 +/- 138 dyne. s. cm(-5), and a mean characteristic impedance (Zc) of 124 +/- 11 dyne. s. cm(-5), which are in keeping with data from previous studies. Inhaled NO levels decreased Ppa, PVR, Z(0), and Zc without a change in cardiac output. Epoprostenol administration did not affect Ppa, increased cardiac output, and decreased Z(0) and Zc. Dobutamine administration increased cardiac output and Ppa, and decreased PVR and Z(0), without changing Zc.
  
  
  CONCLUSIONS
  The determination of PVZ to quantify RV afterload is feasible during routine right heart catheterization and Doppler echocardiography. The measurement is sensitive to pharmacologic interventions.
authors.affiliation: Department of Cardiology, the Erasme Hospital and the Faculty of Medicine of the Free University of Brussels, Belgium.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Huez
authors.forename: Serge
authors.initials: S
authors.lastname: Brimioulle
authors.forename: Robert
authors.initials: R
authors.lastname: Naeije
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vachiéry
mesh_terms: D000328:Adult; D000368:Aged; D006328:Cardiac Catheterization; D016022:Case-Control Studies; D003955:Diagnostic Tests, Routine; D004280:Dobutamine; D015150:Echocardiography, Doppler; D017097:Electric Impedance; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide; D011336:Probability; D011446:Prospective Studies; D011652:Pulmonary Circulation; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014655:Vascular Resistance
chemical_list: D009569:Nitric Oxide; D004280:Dobutamine