Abstract 16433: A Novel Approach to Measure Distal Pulmonary Vascular Remodeling in Pulmonary Aterial Hypertension: Microfil® Perfused Lungs and CT-Scan Analysis in Different Pulmonary Hypertension Models
Background: Pulmonary arterial hypertension (PAH) is a vascular disease that is restricted to small pulmonary arteries (PA). PAH is characterized by distal PA remodeling, elevating pulmonary vascular resistance, and decreasing blood lung perfusion. This causes right ventricular failure and premature death. This distal PA remodeling is mainly caused by pulmonary arterial smooth muscle cells proliferation phenotype. In addition, the most dramatic pathological findings in PAH are the plexiform lesions, which are usually found at branch points, often distal to an occluded arteriole further decreasing lung perfusion. However, in vivo assessment of lung perfusion abnormalities in PAH remains limited, indirect or restrictive to lung histology. We hypothesize that CT-scan Microfil®-perfused lung angiogram is an efficient way in assessing lung perfusion and thus overall lung microcirculation abnormalities accounting for pulmonary vascular remodeling.
Methods/Results: Microfil®-CT angiograms were perform in control, chronic hypoxic (PAH with limited vascular remodeling), Monocrotaline (PAH with medium vascular remodeling) and Sugen®-hypoxia-normoxia rats (PAH with severe vascular remodeling). Lung perfusion was calculated as the amount of PA signal/total lung signal. We have observed that total lung perfusion decreases with PA remodeling severity. The hypoxic model, known to be the less remodeled, has the smallest lung perfusion decrease (5.35%; n=4), followed by the Monocrotaline model (9.24%; n=7, p<0.001) and the Sugen®-hypoxia-normoxia model (11.37%; n=3, p<0.001), compared to control. Finally, to assess whether lung perfusion measurement by Microfil®-CT angiograms is a good PAH surrogate, we correlated lung perfusion measurements with mean PA pressure, Pulmonary Artery Acceleration Time (PAAT), and pulmonary resistance measured by Echo-Doppler. We demonstrated that lung perfusion correlates with PA pressure (r2=0.6576; p<0.0001; n=20), PAAT (r2=0.6257; p<0.0001; n=24) and pulmonary resistance (r2=0.6535; p<0.0001; n=19).
Conclusion: We have shown that CT angiogram performed on Microfil®-perfused lungs represent a novel and efficient way of assessing lung microcirculation abnormalities and PAH severity.
- © 2011 by American Heart Association, Inc.