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J Thorac Cardiovasc Surg 2009;138:382-389
© 2009 The American Association for Thoracic Surgery

Congenital Heart Disease

Relief of branch pulmonary artery stenosis reduces pulmonary valve insufficiency in a swine model

^a Division of Pediatric Cardiology, Department of Pediatrics, Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, Pa
^b Division of Cardiothoracic Surgery, Department of Surgery, Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, Pa

Received for publication October 20, 2008; revisions received January 12, 2009; accepted for publication February 16, 2009.

^_* Address for reprints: Christopher J. Petit, MD, Texas Children's Hospital, Section of Cardiology, 6621 Fannin St, MC–19345 C, Houston, TX 77030. (Email: cjpetit{at}texaschildrenshospital.org).

Objective: We sought to determine the impact of relieving branch pulmonary artery stenosis on pulmonary valve insufficiency and right ventricular function. Long-standing pulmonary insufficiency causes progressive right ventricular dilatation, leading to decreased right ventricular function. Adults with pulmonary insufficiency are at risk of decreased exercise tolerance, arrhythmias, and sudden cardiac death. Branch pulmonary artery stenosis frequently occurs in these patients, and the presence of branch stenosis may exacerbate valve insufficiency.

Methods: Neonatal piglets (n = 7) underwent surgery to create pulmonary insufficiency and left pulmonary artery stenosis. At 3 months of age, the animals underwent baseline cardiac magnetic resonance imaging followed by stenting of the left pulmonary artery. A repeat magnetic resonance imaging scan was performed 1 week after intervention. Magnetic resonance imaging evaluation included (1) velocity mapping to assess the forward and reverse flow at the main, left and right pulmonary arteries, and aorta; and (2) volumetric assessment of the right ventricle.

Results: Left pulmonary artery flow increased from 14.5% to 36.3% of total net flow after stenting (P < .01). Pulmonary regurgitation decreased from 38.7% to 27.4% (P < .02). Right ventricular ejection fraction improved from a median of 53.5% to 58.2% after stenting (P < .01). Cardiac index improved from a median of 2.7 to 3.5 L/min/m² (P = .01).

Conclusion: Relief of branch pulmonary artery stenosis reduces insufficiency and improves right ventricular systolic function in this animal model. This supports the practice of aggressive intervention in patients with branch pulmonary artery stenosis and pulmonary insufficiency.