Morphologic Changes of the Pulmonary Arteries after Stent Implantation on Branch Pulmonary Artery Stenosis: Impact of Pulmonary Insufficiency

PURPOSE: Intravascular stent implantation for the treatment of postoperative branch pulmonary artery(PA) stenosis has been used successfully. However, the cross sectional area of contralateral branch PA does not regress in spite of the successful dilation of the stenotic branch PA after stent implantation. We analyzed the morphologic and hemodynamic factors on the size of branch PA after successful stent implantation. METHODS: The subjects in our study were 23 children who had undergone stent implantaion from Jan. 1995 to Jul. 2002 in the Division of Yonsei Pediatric Cardiology. We evaluated the cross sectional area index(CSAI) of branch PA before and after stent implantation at follow-up catheterization. We also investigated factors such as residual pulmonary stenosis, pulmonary regurgitation(PR), systolic pressure of right ventricle, and lung perfusion scan. RESULTS: The CSAI of the RPA without stenosis changed from mean 238+/-17 mm2/BSA to mean 249+/-20 mm2/BSA(P=0.47), but didn't regress. The CSAI of the LPA with stenosis was increased effectively by stent implantation from the mean 102+/-12 mm2/BSA to mean 125+/-11 mm2/BSA(P< 0.05). At follow up after stent implantation, the CSAI of PA is correlated with the residual PR fraction after stent implantation. CONCLUSION: In a group with increased residual PR, CSAI of RPA was found to be significantly increased between the pre- and post-stages of stent implantation. So, we suspect that the pulmonary regurgitation remaining after right ventricle outlet tract(RVOT) dilatation surgery is correlated with the increase in CSAI of RPA.

Early Results of Stent Implantation in Branch Pulmonary Artery Stenosis after Tetralogy of Fallot Repair

PURPOSE: Pulmonary artery stenosis is mainly complicated by aortopulmonary shunt or total correction of tetralogy of Fallot(TOF). Results of surgical angioplasty are poor and the success rate of balloon angioplasty is 53-72%. Endovascular stents have been applied to these lesions. The purpose of this study is to evaluate the early results of stent implantation in postoperative pulmonary artery stenosis in TOF. METHODS: Nineteen children with postoperative pulmonary artery stenosis were selected and balloon-expandable stent implantation was attempted between May 1994 and Feb 2000. For assessment of the results of stent implantation, the intraluminal diameter and the pressure gradient across the narrowest point were measured, as were the ratio of a right ventricle and aorta pressure, and a radionuclide lung perfusion scan was done before and after the procedure. RESULTS: Nineteen stents were implanted in 19 children, aged 2.3 years to 25,5 years. The increase of vessel diarneter ranged from 5.0+/-1.4mm to 10.7+/-2.1mm, pulmonary perfusion ratio from 16.7+/-5.3% to 29.2+/-10.0% and pressure gradients from 28.0+/-18.0 to 11.0+/-11.0mmHg with stent implantation. The systolic pressure ratio of the right ventricle and aorta decreased from 0.55+/-0.16 to 0.45+/-0.14. All above changes were statistically significant. Implantation failure occurred in 1 case and complications arose in 4 cases. CONCLUSIONS: The success rate of stent implantation is 94.296. Stent implantation is an effective and safe treatment method for postoperative pulmonary artery stenosis of TOF in short-term follow-up.

Experience of Stent Implantation in Branch Pulmonary Artery Stenosis of the Congenital Heart Disease

PURPOSE: Branch pulmonary artery stenosis remains a clinically challenging lesion. Results of surgical angioplasty are rarely rewarding, and balloon angioplasty is not uniformly successful. So, endovascular stent has been applied recently to these lesions. But this new modality has not been fully evaluated. The aim of this study is to evaluate the short-term result of stent implantation in postoperative branch pulmonary artery stenosis. METHODS: In selected 17 children with postoperative branch pulmonary artery stenosis, balloon-expandable stent implantation were attempted between Aug. 1993 and Feb.1996. They all had Tetralogy of Fallot except one with ventricular septal defect and pulmonary atresia and had been underwent total correction. For assessment of results of stent implantation, intraluminal diameter ratio (LPA/RPA) and pressure gradient across the narrowest point were measured, and radionuclide lung perfusion scan was done before and after the procedure. RESULTS: Fifteen stents were successfully implanted in each 15 children, aged 3.4 years to 12.7 years. The average ratio of vessel diameter (LPA/RPA) on angiogam increased from 0.49+/-0.15 to 0.96+/-0.18, pulmonary perfusion fraction from 25.6+/-6.1 to 38.9+/-9.9% and pressure gradients from 19.0+/-8.5mmHg to 7.4+/-6.0mmHg with stent placement. All changes were statistically significant. There were no fever, transfusion requirement, femoral artery thrombosis, and transient bradycardia during the procedure. Implantation failure was two cases. Failure was due to displacement of stent to distal pulmonary artery. CONCLUSIONS: Success rate of stent implantation is 88%. Effective relief of stenosis is accomplished in 93%. Stent implantation is effective and safe modality for postoperative branch pulmonary artery stenosis in short-term follow-up.