[Stent implantation for relief of pulmonary artery branch stenosis].

OBJECTIVE: Branch pulmonary artery stenosis is one of the common congenital heart disease. Stent implantation to relieve branch pulmonary artery stenosis (BPAS) is an alternative to failed surgical or balloon angioplasty. The aim of this study was to explore the indication, methods and complications of using balloon expandable stent placement to treat branch pulmonary artery stenosis, and evaluate the results of stent implantation in the treatment of branch pulmonary artery stenosis.

METHOD: From August 2005 to December 2012, 19 patients underwent an attempt at stent implantation. The median age of those patients was 9.1 years (range 4.0-15.0 years). The median weight was 31.7 kg (range 17.0-60.5 kg); 14/19 patients underwent post surgical repair of tetralogy of Fallot, one patient received post surgical repair of pulmonary atresia with ventricular septal defect, one patient underwent post surgical repair of pulmonary atresia with intact septum, one with native left BPAS, and one was after surgical repair of aortopulmonary window and the other truncus arteriosus. CP stent and NuMED Balloon-in-Balloon catheter were selected according to digital subtracted angiography measurements. After checking for correct position by angiography, the inner balloon and outer balloon was inflated successively to expand the stent to desired diameter. Statistical analysis was performed with the unpaired Student t test.

RESULT: A total of 26 stents were implanted successfully in 19 patients. The systolic gradient across the stenosis fell from a median of (36.0 ± 18.3) to (3.8 ± 3.4) mmHg (P < 0.01, 1 mmHg = 0.133 kPa) and the diameter of the narrowest segment improved from (6.0 ± 1.9) to (11.6 ± 3.1) mm (P < 0.01). The right ventricle to aortic pressure ratio fell from 0.68 to 0.49 (P < 0.01). Complications included the following: two stents were malpositioned in the right ventricular outflow tract and one balloon ruptured when dilated the hole of the stent. No other complications occurred. All patients were followed up for 6 months to 6.0 (2.5 ± 1.8) years. One patient underwent stent re-dilation in order to accommodate somatic growth two years later.

CONCLUSION: Balloon expandable stents are safe and effective in relieving BPAS. Stent implantation should be considered the treatment of choice for most patients with BPAS. Stents placed into growing children will require further dilation to keep up with normal somatic growth. Intermediate and long-term follow up studies have shown excellent results after further dilation over time.