• Victor I Peinado, Federico P Gómez, Joan Albert Barberà, Antonio Roman, M Angels Montero, Josep Ramírez, Josep Roca, and Roberto Rodriguez-Roisin.
• Servei de Pneumologia (Institut del Tòrax), Hospital Clínic, Institut d'Investigacions Biomédiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Ciber Enfermedades Respiratories. Electronic address: vpeinado@clinic.ub.es.
• J. Heart Lung Transplant. 2013 Dec 1; 32 (12): 1262-9.

BackgroundLittle is known about the structure and function relationships of pulmonary vessels in the most severe chronic obstructive pulmonary disease (COPD) spectrum. We investigated morphometric, cellular, and physiologic characteristics of pulmonary arteries from COPD patients undergoing bilateral lung transplant.MethodsSeventeen patients with very severe COPD (forced expiratory volume in 1 second, 24% ± 7%) were assessed using inert gas exchange and pulmonary hemodynamics while breathing ambient air and 100% oxygen. Morphometry, in vitro reactivity to hypoxia, and inflammatory cell counts of pulmonary arteries were measured in explanted lungs.ResultsPatients had moderate ventilation-perfusion imbalance along with mild release of hypoxic pulmonary vasoconstriction. Mild pulmonary hypertension was observed in 7 patients. Explanted lungs had predominant emphysema with mild small airway involvement. In vitro reactivity was modestly altered, with relatively preserved endothelium-dependent relaxation, and vascular remodelling was discrete, with intense CD8+ T lymphocytes infiltrate. In vitro reactivity correlated with pulmonary vascular resistance (on ambient air) and oxygen-induced pulmonary artery pressure changes. Patients with pulmonary hypertension had more severe morphologic and physiologic emphysema.ConclusionsIn end-stage COPD patients undergoing lung transplant, pulmonary vascular involvement is unexpectedly modest, with low-grade endothelial dysfunction. In this sub-set of COPD patients, pulmonary emphysema may constitute the major determinant of the presence of pulmonary hypertension.© 2013 International Society for Heart and Lung Transplantation Published by International Society for the Heart and Lung Transplantation All rights reserved.

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