title: A simple method for noninvasive estimation of pulmonary vascular resistance.
abstract: OBJECTIVE
  We sought to test whether the ratio of peak tricuspid regurgitant velocity (TRV, ms) to the right ventricular outflow tract time-velocity integral (TVI(RVOT), cm) obtained by Doppler echocardiography (TRV/TVI(RVOT)) provides a clinically reliable method to determine pulmonary vascular resistance (PVR).
  
  
  BACKGROUND
  Pulmonary vascular resistance is an important hemodynamic variable used in the management of patients with cardiovascular and pulmonary disease. Right-heart catheterization, with its associated disadvantages, is required to determine PVR. However, a reliable noninvasive method is unavailable.
  
  
  METHODS
  Simultaneous Doppler echocardiographic examination and right-heart catheterization were performed in 44 patients. The ratio of TRV/TVI(RVOT) was then correlated with invasive PVR measurements using regression analysis. An equation was modeled to calculate PVR in Wood units (WU) using echocardiography, and the results were compared with invasive PVR measurements using the Bland-Altman analysis. Using receiver-operating characteristics curve analysis, a cutoff value for the Doppler equation was generated to determine PVR >2WU.
  
  
  RESULTS
  As calculated by Doppler echocardiography, TRV/TVI(RVOT) correlated well (r = 0.929, 95% confidence interval 0.87 to 0.96) with invasive PVR measurements. The Bland-Altman analysis between PVR obtained invasively and that by echocardiography, using the equation: PVR = TRV/TVI(RVOT) x 10 + 0.16, showed satisfactory limits of agreement (mean 0 +/- 0.41). A TRV/TVI(RVOT) cutoff value of 0.175 had a sensitivity of 77% and a specificity of 81% to determine PVR >2WU.
  
  
  CONCLUSIONS
  Doppler echocardiography may provide a reliable, noninvasive method to determine PVR.
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, 13400 East Shea Boulevard, Scottsdale, Arizona 85259, USA.
authors.forename: Amr E
authors.initials: AE
authors.lastname: Abbas
authors.forename: F David
authors.initials: FD
authors.lastname: Fortuin
authors.forename: Nelson B
authors.initials: NB
authors.lastname: Schiller
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Appleton
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Moreno
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lester
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D006328:Cardiac Catheterization; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015150:Echocardiography, Doppler; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014261:Tricuspid Valve / Q000000981:diagnostic imaging / Q000503:physiopathology; D014655:Vascular Resistance / Q000502:physiology*