Reduced-size porcine lung transplantation: long-term studies of pulmonary vascular resistance.

The use of isolated adult lobes for pediatric lung transplantation has recently been reported and could potentially help alleviate the profound pediatric donor lung shortage. However, the effect of chronic denervation on pulmonary vasculature of isolated mature lobar transplants is not well understood. Previously, we reported that chronic denervation of the immature porcine lobe results in abnormal pulmonary vascular compliance. We now present studies of long-term pulmonary hemodynamics in young pigs 12 weeks after transplantation of a reduced-size mature left lower lobe. Resting pulmonary vascular resistance of the transplanted mature lobes was similar to that of innervated lobes of age-matched controls. In addition, pulmonary vascular resistance of the transplanted mature lobes did not rise abnormally in response to increased flow caused by clamping the contralateral pulmonary artery. We conclude that denervation of the mature porcine lobe does not result in abnormal pulmonary vascular resistance. In addition, vascular compliance of reduced-size mature porcine lobar transplants is superior to that of denervated reimplanted immature lobes. These findings suggest a deleterious effect of denervation on pulmonary vascular development of the growing porcine lung.