Brigham and Women's Hospital, Medford, MA
Copyright 2016, American College of Chest Physicians. All Rights Reserved.
SESSION TITLE: Pulmonary Vascular Disease II
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM
PURPOSE: Group II pulmonary hypertension is arises from increasing post-capillary pressures which may lead to pre-capillary remodeling. Clinical trials using medications developed for group I disease (PAH) have thus far yielded variable results. It has been proposed that this is, in part, due to inability to clearly identify those patients that would benefit from pulmonary vasodilator therapy. Morphologic changes such as pruning and proximal dilation have been described from CT scans and pulmonary angiography of patients with pulmonary hypertension both in PAH as well as group II disease. The differential arterial versus venous presence of these changes has not been previously quantified.
METHODS: Of 700 patients evaluated for unexplained dyspnea at the Brigham and Women’s Hospital, 179 patients were identified as having CT angiography within one year of right heart catheterization. Fifteen patients with PH and elevated PCWP(>15mmHg) classified as group II by clinicians and fifteen control patients with no evidence of pulmonary vascular disease and sixteen patients with PAH and normal PCWP(<15 mmHg) were identified. 3D reconstruction of the intraparenchymal pulmonary vasculature was generated. In the right upper and lower lobes, arteries and veins were manually labeled by tracing the vessels to the origins in the mediastinum. The blood vessel volumes as a function of cross-sectional area of the vessel were used to compute the small vessel fraction (SVF) which was defined as the volume in vessels less than 5mm2 (BV5) divided by the total blood vessel volume (TBV). Non-parametric statistics (medians, inter-quartile range and Wilcoxon Rank-Sum, SAS 9.3) were used for comparisons of vessel volumes..
RESULTS: Patients in the group II cohort were 47% female (67% in controls), had a mean age of 74.4 (52 in controls) and had elevated mPAP (40 vs 15 mmHg), PVR (260 vs 94 dyn*s/cm5), and PCWP (24 vs 9 mmHg). The arterial SVF was decreased as compared to controls in both RUL (0.47[0.37-0.53] vs 0.66[0.59-0.74] p=0.0003) and RLL (0.36[0.30-0.46] vs 0.59[0.46-0.66] p=0.002). Similarly the venous small arterial vessel fraction was also decreased compared to controls in both the RUL (0.50[0.46-0.55] vs 0.56[0.54-0.60] p=0.01 ) and the RLL (0.45[0.37-0.48] vs 0.51 [0.43-0.60] p=0.02). In contrast, those patients with PAH did have decreased arterial SVF (RUL 0.47[0.39-0.59] vs 0.66[0.59-0.74] p=0.003; RLL 0.41[0.35-0.48] vs 0.59[0.46-0.66] p = 0.005) but the venous SVF was not significantly reduced (RUL 0.52[0.43-0.63] vs 0.56 [0.54-0.60] p=0.42; RLL 0.46[0.35-0.52] vs 0.51[0.43-0.59] p=0.17)
CONCLUSIONS: In this study, subjects with group II PH, had decreased arterial and venous small vessel fraction (SVF) compared to controls, which is in contrast to PAH subjects who only had decreased SVF in the arterial intarparenchymal vessels. These findings suggest that there is pulmonary arterial remodeling in these patients as was observed in PAH, but that there is additional evidence of changes in the venous blood distribution.
CLINICAL IMPLICATIONS: CT imaging based quantification of vascular remodeling in the arterial and venous bed may be a useful tool for distinguishing patients whom may be optimal candidates for pulmonary vasodilatory therapy.
DISCLOSURE: The following authors have nothing to disclose: Jasleen Minhas, Farbod Rahaghi, Ramya Radhakrishnan, James Ross, Aaron Waxman, Raúl San José Estépar, George Washko
Imaging techniques for identifying pulmonary hypertension in CT scans.
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