title: Noninvasive assessment of pulmonary vascular resistance by Doppler echocardiography.
abstract: BACKGROUND
  The ratio of tricuspid regurgitation velocity (TRV) to the time-velocity integral of the right ventricular outflow tract (TVIRVOT) has been studied as a reliable measure to distinguish elevated from normal pulmonary vascular resistance (PVR). The equation TRV/TVIRVOT × 10 + 0.16 (PVRecho) has been shown to provide a good noninvasive estimate of PVR. However, its role in patients with significantly elevated PVR (> 6 Wood units [WU]) has not been conclusively evaluated. The aim of this study was to establish the validity of the TRV/TVIRVOT ratio as a correlate of PVR. The role of TRV/TVIRVOT was also compared with that of a new ratio, TRV(2)/TVIRVOT, in patients with markedly elevated PVR (>6 WU).
  
  
  METHODS
  Data from five validation studies using TRV/TVIRVOT as an estimate of PVR were compared with invasive PVR measurements (PVRcath). Multiple linear regression analyses were generated between PVRcath and both TRV/TVIRVOT and TRV(2)/TVIRVOT. Both PVRecho and a new derived regression equation based on TRV(2)/TVIRVOT: 5.19 × TRV(2)/TVIRVOT - 0.4 (PVRecho2) were compared with PVRcath using Bland-Altman analysis. Logistic models were generated, and cutoff values for both TRV/TVIRVOT and TRV(2)/TVIRVOT were obtained to predict PVR > 6 WU.
  
  
  RESULTS
  One hundred fifty patients remained in the final analysis. Linear regression analysis between PVRcath and TRV/TVIRVOT revealed a good correlation (r = 0.76, P < .0001, Z = 0.92). There was a better correlation between PVRcath and TRV(2)/TVIRVOT (r = 0.79, P < .0001, Z = -0.01) in the entire cohort as well as in patients with PVR > 6 WU. Moreover, PVRecho2 compared better with PVRcath than PVRecho using Bland-Altman analysis in the entire cohort and in patients with PVR > 6 WU. TRV(2)/TVIRVOT and TRV/TVIRVOT both predicted PVR > 6 WU with good sensitivity and specificity.
  
  
  CONCLUSIONS
  TRV/TVIRVOT is a reliable method to identify patients with elevated PVR. In patients with TRV/TVIRVOT > 0.275, PVR is likely > 6 WU, and PVRecho2 derived from TRV(2)/TVIRVOT provides an improved noninvasive estimate of PVR compared with PVRecho.
authors.affiliation: Department of Cardiology, Beaumont Health System, Royal Oak, Michigan; Oakland University/William Beaumont School of Medicine, Rochester, Michigan.
authors.forename: Amr E
authors.initials: AE
authors.lastname: Abbas
authors.affiliation: Department of Cardiology, Beaumont Health System, Royal Oak, Michigan. Electronic address: aabbas@beaumont.edu.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Franey
authors.affiliation: Menzies Research Institute of Tasmania, Hobart, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Marwick
authors.affiliation: Baker IDI Heart and Diabetes Institute, Melbourne, Australia; Heart Center, Alfred Hospital, Melbourne, Australia; Cardiology Division, Kantonsspital St. Gallen, St. Gallen, Switzerland.
authors.forename: Micha T
authors.initials: MT
authors.lastname: Maeder
authors.affiliation: Baker IDI Heart and Diabetes Institute, Melbourne, Australia; Heart Center, Alfred Hospital, Melbourne, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Kaye
authors.affiliation: Pediatric Cardiology Division, University of Ioannina, Ioannina, Greece.
authors.forename: Antonios P
authors.initials: AP
authors.lastname: Vlahos
authors.affiliation: Cardiopulmonary Department, University Hospital, Parma, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Serra
authors.affiliation: Department of Internal Medicine, St. Joseph Mercy Oakland, Pontiac, Michigan.
authors.forename: Karim
authors.initials: K
authors.lastname: Al-Azizi
authors.affiliation: University of San Francisco, San Francisco, California.
authors.forename: Nelson B
authors.initials: NB
authors.lastname: Schiller
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lester
mesh_terms: D000368:Aged; D000465:Algorithms; D006328:Cardiac Catheterization; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014261:Tricuspid Valve / Q000000981:diagnostic imaging*; D014655:Vascular Resistance / Q000502:physiology*
keywords: CI; Confidence interval; Doppler echocardiography; PCWP; PVR; Pulmonary capillary wedge pressure; Pulmonary hypertension; Pulmonary vascular resistance; TPR; TRV; TVI(RVOT); Time-velocity integral of the right ventricular outflow tract; Total pulmonary resistance; Tricuspid regurgitation velocity; WU; Wood units