Acute and long-term effects of endovascular debanding of pulmonary arteries in a swine model.

Objectives: The primary objective of this study was to demonstrate that pulmonary artery (PA) debanding via cardiac catheterization using balloon angioplasty is feasible and safe in swine. The secondary objectives were to determine the acute and long-term effects of this therapy.

Design: This is a chronic survival experimental study in newborn swine.

Background: PA bands are used in infants for transient palliation of congenital heart defects with excessive pulmonary blood flow. Although rare, if these defects should close spontaneously or become hemodynamically insignificant, a sternotomy and occasionally cardiopulmonary bypass may still be required for band removal. Alternatively, debanding could be accomplished through less invasive methods.

Interventions: The main pulmonary artery was banded in three piglets, and the left pulmonary artery in five piglets via mini-thoracotomy at a mean weight of 2.5 kg. Following a threefold increase in weight, the piglets underwent PA debanding via balloon angioplasty. Four piglets were sacrificed to evaluate the acute effects. The remainder were followed to evaluate long-term effects. Histopathology was performed on all piglets.

Outcome Measures: Reintervention rates. Histopathologic consequences of high pressure balloon angioplasty used for PA debanding acutely and after reinterventions.

Results: Debanding was performed at a mean weight of 8.1 ± 2.23 kg. The median preintervention gradient across the band was 18 mm Hg. Debanding was successful in all piglets. The median postintervention gradient was 3.5 mm Hg. All piglets in the long-term model required re-interventions for recurrent stenosis at mean weights of 26 ± 1.6 and 61 ± 3.2 kg. Histopathology demonstrated vessel wall injury in only one piglet.

Conclusions: Endovascular PA debanding can be safely achieved in a swine model. Angioplasty following debanding may be necessary for recurrent stenosis. This catheter-based therapy may provide a less-invasive alternative to surgery.