Intravascular ultrasound assessment of pulmonary vascular disease in patients with pulmonary hypertension

Background: Measurements of pulmonary pressure and resistance are still con sidered to be the "gold standard" in the evaluation of pulmonary hypertensi on (PH), despite their limitations in predicting irreversible disease. Hemo dynamic assessment also only provides a global evaluation of the pulmonary vascular bed, whereas PH is an inhomogeneous disease of the vessel wall. Methods and results: We assessed the value of intravascular ultrasound (IVU S) in 30 patients with suspected PH and correlated the structural changes i n distal pulmonary arteries found on IVUS with conventional hemodynamic dat a. Plasma endothelin (ET)-1 levels and pulmonary ET-1 extraction also were measured as markers of the severity of PH. The anatomic abnormalities revea led by IVUS were more severe in the lower lobes than in the upper lobes, as evidenced by the greater percentage of wall thickness (WT), the smaller lu men diameter/WT and lumen area/total vessel area (p < 0.05 for each). IVUS anatomic indexes correlated directly with hemodynamic data (eg, with pulmon ary arterial systolic pressure; r = 0.56; p < 0.001) and ET-1 levels but in versely with pulmonary ET-1 extraction. Conclusion: Patients with PH have greater pulmonary arterial WT that is mor e severe in the lower lobes than in the upper lobes. The severity of struct ural abnormalities found on IVUS is directly correlated with hemodynamic fi ndings and ET-1 levels. IVUS may provide useful additional information in t he assessment of patients with PH.