Swine model of chronic postcapillary pulmonary hypertension with right ventricular remodeling: long-term characterization by cardiac catheterization, magnetic resonance, and pathology.

Pulmonary hypertension (PH) is prevalent and carries high morbidity and mortality, mostly due to right ventricular (RV) dysfunction. Postcapillary PH is the most frequent form but there are no large-animal models available. We developed and characterized a porcine model of postcapillary PH by non-restrictive banding of the confluent of both inferior pulmonary veins (n = 10; sham controls n = 3). Right heart catheterization and magnetic resonance were performed before the procedure and monthly during 4 months. All banded animals developed PH. Compared to controls, banded animals presented higher mean pulmonary artery pressure [median (first to third quartile) 30 mmHg (25-37) vs. 20 mmHg (18-23); p = 0.018] and higher pulmonary vascular resistance [5.2 WU (3.8-7.1) vs. 2.3 WU (2.1-3.5); p = 0.028] after 2 months. Differences in indexed RV end-systolic volume [42 mL/m(2) (36-53) vs. 24 mL/m(2) (24-33); p = 0.028] and RV ejection fraction [59 % (54-63) vs. 66 % (64-68); p = 0.028] were also significant after 2 months. Differences remained significant throughout the study. Histopathology revealed increased lung weight and fibrosis but no increase in average water content. Also, remodeling on pulmonary arteries including increased medial and intimal thickness and fibrosis and RV myocardial disarray and fibrosis was demonstrated. Lung remodeling findings were similar in all pulmonary lobes.