Abstract 2346: Stenting of Pulmonary Artery Branch Stenosis Alleviates Pulmonary Valve Insufficiency in a Swine Model of Repaired Tetralogy of Fallot
Introduction: Pulmonary insufficiency-induced right ventricular volume overload in adults with repaired tetralogy of Fallot (TOF) is associated with reduced exercise tolerance, ventricular arrhythmias and sudden cardiac death. Studies have shown that the severity of pulmonary insufficiency (PI) predicts these symptoms. There has been indirect evidence that pulmonary artery branch stenosis (PABS) exacerbates PI in adults with repaired TOF. However the impact of treatment of PABS on PI has not been evaluated.
Hypothesis: Relief of unilateral PABS in the setting of PI alleviates the severity of PI.
Methods: Newborn piglets (n=9) underwent pulmonary valve resection with transannular patch and left pulmonary artery (LPA) banding. Between 10 to 16 weeks later, a cardiac catheterization was performed with hemodynamic evaluation and stenting of the banded LPA. Immediately prior to catheterization, and then 1 week following intervention, a cardiac MRI was performed. MRI data obtained included main and branch pulmonary arterial forward and reverse flow, and right and left ventricular volume.
Results: Six animals survived the protocol. At time of catheterization, the LPA had a discrete stenosis, with a mean gradient of 11.6 mmHg (range 9 –16.1) across the banded region. The mean diameter of the LPA at the banded region was 3.4 mm (range 3.1– 4.2) and 10.8 mm distally (range 9.6 –14) at baseline, compared with a mean right pulmonary artery diameter of 20.2 mm. The banded region was stented to a mean diameter of 10.4 mm (range 8 –12.6). The main pulmonary artery regurgitant fraction (RF) at baseline was a mean of 38.2%; after stenting of the LPA, the RF decreased to 29.6% (p=0.02). Flow into the LPA improved in all animals, from a mean of 12.2% of total at baseline to 33.6% following stenting (p<0.01). While the total RF decreased following LPA stenting, the branch pulmonary arterial RF did not change significantly for either pulmonary artery. Right ventricular volume did not change significantly after stenting of the LPA.
Conclusions: In the setting of unilateral PABS, stenting alleviates the severity of PI in an animal model of repaired TOF. Though clinical studies are required, these findings should be considered in decisions regarding treatment of PABS after repair of TOF.