Objective To optimise an echocardiographic estimation of pulmonary vascular resistance (PVRe) for diagnosis and follow-up of pulmonary hypertension (PHT).
Design Cross-sectional study.
Setting Tertiary referral centre.
Patients Patients undergoing right heart catheterisation and echocardiography for assessment of suspected PHT.
Methods PVRe ([tricuspid regurgitation velocity ×10/(right ventricular outflow tract velocity-time integral+0.16) and invasive PVRi ((mean pulmonary artery systolic pressure-wedge pressure)/cardiac output) were compared in 72 patients. Other echo data included right ventricular systolic pressure (RVSP), estimated right atrial pressure, and E/e' ratio. Difference between PVRe and PVRi at various levels of PVR was sought using Bland–Altman analysis. Corrected PVRc ((RVSP−E/e')/RVOTVTI) (RVOT, RV outflow time; VTI, velocity time integral) was developed in the training group and tested in a separate validation group of 42 patients with established PHT.
Results PVRe>2.0 had high sensitivity (93%) and specificity (91%) for recognition of PVRi>2.0, and PVRc provided similar sensitivities and specificities. PVRe and PVRi correlated well (r=0.77, p<0.01), but PVRe underestimated marked elevation of PVRi—a trend avoided by PVRc. PVRc and PVRe were tested against PVRi in a separate validation group (n=42). The mean difference between PVRe and PVRi exceeded that between PVRc and PVRi (2.8±2.7 vs 0.8±3.0 Wood units; p<0.001). A drop in PVRi by at least one SD occurred in 10 patients over 6 months; this was detected in one patient by PVRe and eight patients by PVRc (p=0.002).
Conclusion PVRe distinguishes normal from abnormal PVRi but underestimates high PVRi. PVRc identifies the severity of PHT and may be used to assess treatment response.
- Pulmonary vascular resistance
- pulmonary artery pressure
- pulmonary hypertension
- pulmonary arterial hypertension (PAH)
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