title: A simple echocardiographic method to estimate pulmonary vascular resistance.
abstract: Pulmonary hypertension includes heterogeneous diagnoses with distinct hemodynamic pathophysiologic features. Identifying elevated pulmonary vascular resistance (PVR) is critical for appropriate treatment. We reviewed data from patients seen at referral pulmonary hypertension clinics who had undergone echocardiography and right-side cardiac catheterization within 1 year. We derived equations to estimate PVR using the ratio of estimated pulmonary artery (PA) systolic pressure (PASPDoppler) to right ventricular outflow tract velocity time integral (VTI). We validated these equations in a separate sample and compared them with a published model based on the ratio of the transtricuspid flow velocity to right ventricular outflow tract VTI (model 1, Abbas et al 2003). The derived models were as follows: PVR = 1.2 × (PASP/right ventricular outflow tract VTI) (model 2) and PVR = (PASP/right ventricular outflow tract VTI) + 3 if notch present (model 3). The cohort included 217 patients with mean PA pressure of 45.3 ± 11.9 mm Hg, PVR of 7.3 ± 5.0 WU, and PA wedge pressure of 14.8 ± 8.1 mm Hg. Just >1/3 had a PA wedge pressure >15 mm Hg (35.5%) and 82.0% had PVR >3 WU. Model 1 systematically underestimated catheterization estimated PVR, especially for those with high PVR. The derived models demonstrated no systematic bias. Model 3 correlated best with PVR (r = 0.80 vs r = 0.73 and r = 0.77 for models 1 and 2, respectively). Model 3 had superior discriminatory power for PVR >3 WU (area under the curve 0.946) and PVR >5 WU (area under the curve 0.924), although all models discriminated well. Model 3-estimated PVR >3 was 98.3% sensitive and 61.1% specific for PVR >3 WU (positive predictive value 93%; negative predictive value 88%). In conclusion, we present an equation to estimate the PVR, using the ratio of PASPDoppler to right ventricular outflow tract VTI and a constant designating presence of right ventricular outflow tract VTI midsystolic notching, which provides superior agreement with catheterization estimates of PVR across a wide range of values.
authors.affiliation: Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. sasha.opo@gmail.com
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Opotowsky
authors.forename: Mathieu
authors.initials: M
authors.lastname: Clair
authors.forename: Jonathan
authors.initials: J
authors.lastname: Afilalo
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Landzberg
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Waxman
authors.forename: Lilamarie
authors.initials: L
authors.lastname: Moko
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Maron
authors.forename: Anjali
authors.initials: A
authors.lastname: Vaidya
authors.forename: Paul R
authors.initials: PR
authors.lastname: Forfia
mesh_terms: D006328:Cardiac Catheterization; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014655:Vascular Resistance / Q000502:physiology*