Losartan ameliorates “upstream” pulmonary vein vasculopathy in a piglet model of pulmonary vein stenosis

Objectives Pulmonary vein stenosis (PVS) is a relentless disease with a poor prognosis. Although surgical repair can effectively treat "downstream" (near left atrial junction) PVS, residual "upstream" (deep in lung parenchyma) PVS commonly dictates long-term survival. Our initial studies revealed an association between PVS and transforming growth factor-β signaling, which led us to investigate the effect of losartan on upstream pulmonary vein vasculopathy in a piglet model of PVS. Methods Neonatal Yorkshire piglets underwent sham surgical banding (sham, n = 6), staged bilateral pulmonary vein banding of all pulmonary veins except the right middle pulmonary vein (banded, n = 6), and staged pulmonary vein banding with losartan treatment (losartan, 1 mg/kg/d, n = 7). After 7 weeks, the hemodynamic data were obtained and the piglets killed. Results Pulmonary vein banding (compared with sham) was associated with continuous turbulent flow in banded pulmonary veins, pulmonary hypertension (pulmonary artery/systemic blood pressure ratio 0.51 ± 0.06 vs 0.23 ± 0.02, P P P  = .007) but it remained greater than those in the sham group ( P  = .001). Losartan was also associated with diminished pulmonary vein intimal hyperplasia compared with that in the banded piglets ( P P  = .035). Pulmonary vein banding reduced vascular endothelial-cadherin expression, indicative of diminished endothelial integrity, which was restored with losartan. Conclusions Losartan treatment improved PVS-associated pulmonary hypertension and intimal hyperplasia and might be a beneficial prophylactic therapy for patients at high risk of developing PVS after pulmonary vein surgery.