title: Echocardiography can identify patients with increased pulmonary vascular resistance by assessing pressure reflection in the pulmonary circulation.
abstract: BACKGROUND
  Pulmonary hypertension is a frequent finding in patients with cardiopulmonary disorders. It is important to recognize pulmonary hypertension due to increased pulmonary vascular resistance (PVR), as this affects treatment and prognosis. Patients with increased PVR have an increased pulmonary pressure reflection. We hypothesized that pressure reflection can be described by echocardiography and that variables related to pressure reflection can identify patients with increased PVR.
  
  
  RESULTS
  The study comprised 98 patients investigated within 24 hours of right heart catheterization and 20 control subjects. The pressure reflection variables were obtained by pulsed Doppler in the pulmonary artery and continuous Doppler of tricuspid regurgitation. We selected 3 variables related to pressure reflection: the interval from valve opening to peak velocity in the pulmonary artery (AcT, ms), the interval between pulmonary artery peak velocity and peak tricuspid velocity (tPV-PP, ms), and the right ventricular pressure increase after peak velocity in the pulmonary artery (augmented pressure, AP, mm Hg). The correlation between simultaneous catheter- and echocardiography-determined AP was strong (n=19, R=0.83). The AcT, tPV-PP, and AP in patients with a PVR of >3 Woods units (n=71) was (mean+/-SD) 77+/-16 ms, 119+/-36 ms, and 22+/-12 mm Hg, respectively, and differed from patients with a PVR of </=3 Woods units (n=27, P<0.0001), 111+/-32 ms, 39+/-54 ms, and 3+/-4 mm Hg, and from controls, 153+/-32 ms, -19+/-45 ms, and 0 mm Hg, respectively (P<0.0001). The AcT, tPV-PP, and AP values were not correlated with capillary wedge pressure (R=0.08-0.16). The areas under the receiver operator characteristic curve (95%CI) for AcT, tPV-PP, and AP were 0.87 (0.82 to 0.95), 0.94 (0.89 to 0.99), and 0.98 (0.95 to 1.0), respectively.
  
  
  CONCLUSIONS
  In this study, we describe a novel echocardiography method for assessing pressure reflection in the pulmonary circulation. This method can be used to identify patients with pulmonary hypertension due to increased PVR.
authors.affiliation: Departments of Cardiology and Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden. odd.bech-hanssen@klinfys.gu.se
authors.forename: Odd
authors.initials: O
authors.lastname: Bech-Hanssen
authors.forename: Fredrik
authors.initials: F
authors.lastname: Lindgren
authors.forename: Nedim
authors.initials: N
authors.lastname: Selimovic
authors.forename: Bengt
authors.initials: B
authors.lastname: Rundqvist
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D018709:Statistics, Nonparametric; D014262:Tricuspid Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology; D014655:Vascular Resistance