Stent implantation for relief of pulmonary artery stenosis: immediate and short-term results

Bioresorbable PPDO sliding-lock stents with optimized FDM parameters for congenital heart disease treatment

Stent implantation has been a promising therapy for congenital heart disease (CHD) due to better efficacy. Compared to permanent metal stents, bioresorbable polymer stents have shown a great advantage in accommodating the vascular growth of pediatric patients, but the application is still limited due to inferior radial strength. Here, bioresorbable poly(p-dioxanone) (PPDO) sliding-lock stents for CHD treatment were fabricated by fused deposition modeling (FDM). The effects of FDM processing parameters, including nozzle temperature, bed temperature, layer thickness, and printing speed, on the mechanical properties of PPDO parts were investigated to optimize the processing condition to enhance the radial strength of stents. Finite element analysis (FEA) was also used to evaluate the mechanical properties of stents. PPDO sliding-lock stents fabricated under optimized FDM parameters showed radial strength of 3.315 ± 0.590 N/mm, superior to benchmark commercial metal stents. Radial strength curve and compression behavior of PPDO sliding-lock stents were investigated. Results of FEA exhibited that strut width, shape of the mesh cell and surface coverage ratio had an impact on the compression force of PPDO sliding-lock stents. PPDO sliding-lock stents fabricated with optimized FDM parameters show favorable mechanical performance and meet the requirement of CHD treatment.

Stent angioplasty of narrowed right ventricular outflow conduits and pulmonary arteries consistently reduces right ventricular systolic pressures and delays subsequent surgeries

Objectives

Narrowed right ventricular (RV) outflow conduits and pulmonary arteries (PA) increase RV pressures and warrant interventions. Stent angioplasty is an alternative to more morbid redo-surgery in developing countries. We evaluate the efficacy and safety of stenting and assess need for redo-surgical reinterventions on midterm follow-up after stent angioplasty.

Methods

Patients who underwent conduit, main PA and bilateral branch PA stenting for elevated RV pressures were analyzed retrospectively. Success was defined as 20% reduction in RV pressures or RV-aortic pressure ratio; 50% reduction in gradients or 50% increase of luminal diameter. Procedural results, complications and need for redo surgeries on follow-up were assessed.

Results

Among 60 patients aged 1–46 years, 57 were post-operative patients, who needed stenting at a median period of 48 months after surgery. Stenting succeeded in 98% and reduced RV pressures from 105.42 ± 28.39 mmHg to 54.46 ± 16.89 mmHg. Direct major procedural complications in five (8%) patients included procedural failure in one, stent migration in three and lung hemorrhage in one. None of the stented conduits needed a surgical change on a follow-up ranging 3–120 months. Following bilateral PA stenting in twenty-four patients, only two needed a repeat open-heart surgery during follow-up ranging 3–108 months. Catheter reinterventions on follow-up included elective percutaneous pulmonary valve implantation in nine patients and stent redilation in seven patients.

Conclusions

Stent angioplasty was safe and effective. Surgery was postponed in all stenosed conduits. Elective redilation of stents after bilateral PA stenting may be needed for somatic growth; but open-heart repeat surgeries can be avoided in a majority.

Adult Congenital Interventions in Heart Failure

Congenital heart disease (CHD) is the most common birth defect, occurring in approximately 0.8% to 1.0% of neonates. Advances in medical and surgical therapies for children with CHD have resulted in a growing population of patients reaching adulthood, with survival rates exceeding 85%. Many of these patients, especially if managed inappropriately, face the prospect of future complications including heart failure and premature death. For adults with uncorrected or previously palliated CHD, percutaneous therapies have become the primary treatment for many forms of CHD. In this article, we discuss the role of transcatheter interventions in the treatment of adults with CHD.

Single-center outcome analysis comparing reintervention rates of surgical arterioplasty with stenting for branch pulmonary artery stenosis in a pediatric population

Although catheter-based intervention is generally accepted as the treatment of choice for branch pulmonary artery (PA) stenosis, there are no data directly comparing both the need for reintervention and time to reintervention in patients undergoing transcatheter stenting versus surgical arterioplasty. We compared children who underwent surgical branch pulmonary arterioplasty and branch PA stent placement between January 2008 and May 2012 at a single tertiary center. Need for reintervention and mean time to reintervention were assessed using chi-square and independent sample Student t test. Thirty-seven patients were included (surgery n = 18, stent n = 19). Mean weight at initial intervention was 11.3 ± 8.8 kg for surgical and 20.1 ± 15.5 kg for stent (p = 0.041). Intervention was performed on the left PA in 17 patients, the right PA in 12 patients, and both PAs in 8 patients. Five patients had undergone previous intervention. On mean follow-up of 807 ± 415 days, 50% (9 of 18) of the surgery cohort and 5.3% (1 of 19) of the stent cohort required reintervention (p = 0.002). In all but one case reintervention was catheter-based. Mean time to reintervention for the surgery cohort was 272 ± 162 days and for the single stent cohort it was 150 days. When comparable age and weight groups were analyzed, reintervention was still more common in the surgery cohort (p = 0.007). Children undergoing surgical branch pulmonary arterioplasty are more likely to require reintervention than those undergoing stent placement.

Medium and long-term outcomes after bilateral pulmonary artery stenting in children and adults with congenital heart disease

Percutaneous stenting of branch pulmonary arteries (PAs) has become an important interventional therapy in the complete management of congenital heart disease. Few data exist on long-term outcomes for patients requiring placement of bilateral stents. This study aimed to determine the medium- to long-term outcomes after bilateral stenting of branch PAs in patients with congenital heart disease. A retrospective study analyzed all procedural and follow-up data on patients undergoing bilateral PA stenting during a single procedure. From October 2001 to May 2012, 26 patients underwent bilateral PA stenting (total of 62 stents). The mean age of these patients was 9.5 ± 12 years, and their mean weight was 27 ± 19 kg. The mean procedural time was 191 ± 67 min, and the mean fluoroscopy time was 50 ± 29 min. The mean gradient across the right pulmonary artery decreased from 35 ± 22 to 11 ± 12 mmHg (p < 0.001). The left pulmonary artery gradient decreased from 32 ± 17 to 10 ± 12 mmHg (p < 0.001), and the right ventricle to descending aorta pressure ratio decreased from 71 ± 18 % to 46 ± 13 % (p < 0.001). Intraprocedural adverse events were encountered in four patients (1 small PA dissection, 2 intraprocedural arrhythmias, and 1 first-degree burn on the thigh). The mean follow-up period was 41 ± 23 months. Two deaths occurred. Further interventions were required for 12 patients. Bilateral PA stenting is effective and safe, with an instantaneous significant decrease in pressure gradients. The need for reintervention is common, so continued follow-up assessment is warranted.

How we approach peripheral pulmonary stenosis in Williams-Beuren syndrome

Williams-Beuren syndrome is associated with supravalvar aortic stenosis and peripheral pulmonary artery stenosis in the majority of affected individuals. Among patients in whom surgery for supravalvar aortic stenosis is contemplated, stenosis of the branch pulmonary arteries is common. For asymptomatic patients with subsystemic right ventricular pressure, the natural history is favorable and no intervention is necessary. For patients with important proximal branch pulmonary artery, stenoses patch arterioplasty can be accomplished at the time of surgery for supravalvar aortic stenosis. For patients with important peripheral pulmonary stenosis, preoperative catheter-based therapy is indicated. Surgical repair of peripheral pulmonary stenosis is indicated when preoperative intervention is unsuccessful and can include a combination of patch arterioplasty as well as intraoperative application of catheter-based techniques. This report will address the approach to this lesion with catheter-based approaches, surgical approaches, and their combination.

Surgery Insight: current advances in percutaneous heart valve replacement and repair

Several advances have been made in interventional cardiology, particularly in the field of valvular heart disease. Among the procedures for which technologies are available, percutaneous replacement of the pulmonary and aortic valves, and percutaneous repair of the mitral valve, via annuloplasty or the Alfieri method, are the best known. Along with the excitement generated by these new subspecialties, however, there has also been skepticism. In this article we focus on the current innovations that have been applied to the procedures in humans, and discuss the advantages and disadvantages of the different strategies.

Successful dilatation of left pulmonary artery stenosis by stent implantation through a modified Blalock-Taussig shunt in an infant with pulmonary atresia and ventricular septal defect

We successfully implanted a coronary stent via a modified Blalock-Taussig shunt to relieve stenosis of the left pulmonary artery in an infant with pulmonary atresia and ventricular septal defect. The placement of a flexible coronary stent via a modified Blalock-Taussig shunt is a safe and feasible catheter intervention for the treatment of infants with hypoplastic pulmonary arteries.

The CP stent--short, long, covered--for the treatment of aortic coarctation, stenosis of pulmonary arteries and caval veins, and Fontan anastomosis in children and adults: an evaluation of 60 stents in 53 patients

OBJECTIVE

To evaluate the feasibility and usefulness of the Cheatham platinum (CP) stent in a broad spectrum of lesions.

METHODS

Retrospective analysis of 60 implanted CP stents (11-80 mm lengths, 12 covered) between September 2001 and March 2004.

PATIENTS

53 patients aged 2.5-68 years (median 17 years). Body weight ranged from 12-95 kg (median 52 kg). Thirty six patients had aortic (re)coarctation; seven of them had functionally interrupted aortic arches. Thirteen patients had pulmonary artery stenosis and four had stenosis of caval veins or conduits in a total cavopulmonary connection (TCPC).

RESULTS

Arterial pressure gradients dropped from 33 mm Hg (range 20-80 mm Hg) to 5 mm Hg (range 0-10 mm Hg) and pressure gradients in TCPC or caval veins dropped from 4 mm Hg (range 4-20 mm Hg) to 0 mm Hg (range 0-3 mm Hg). All stents were placed in the target lesion without complications. Three stent fractures without clinical instability were noted.

CONCLUSIONS

The CP stent is suitable for the treatment of vessel stenosis in congenital heart diseases from childhood to adulthood. Whether these good results will be stable in the long term needs to be investigated.

First successful implantation of a biodegradable metal stent into the left pulmonary artery of a preterm baby

Stent implantation in the youngest patients with a congenital heart disease implicates limitations concerning further vessel growth, the need of staged redilation, and later surgical removal. The search to overcome these restrictions led to open stent designs, with a wide adaptability to the vessel growth and recently to the development of bioabsorbable stent materials. A preterm baby born at 26 weeks of gestation was referred to our clinic following inadvertent ligation of the left pulmonary artery. Despite efficient debanding, the left lung perfusion was absent. Implantation of a biodegradable 3 mm magnesium stent was performed in a hybrid procedure when the baby weighed 1.7 kg. Reperfusion of the left lung was established and persisted throughout the 4-month follow-up period during which the gradual degradation process of the stent completed. Additional interventions, should they become necessary, seem not to be limited. Despite the small size of the baby, the degradation process was clinically well tolerated. The mechanical and degradation characteristics of the magnesium stent proved to be adequate to secure reperfusion of the previously occluded left pulmonary artery. Bioabsorbable stents with different diameters may help develop new strategies in the therapy of vessel stenosis in pediatric patients.

Feasibility and safety of immediate perioperative implantation of intravascular stents in cavopulmonary pathways

Fontan-type procedures are widely used for palliation of patients with many forms of a functional univentricular heart. An ideal Fontan circuit should be free of any distortion or stenosis. The use of stents for the treatment of stenotic and hypoplastic vessels is well established in pediatric cardiac practice. We report the successful use of endovascular stents during the immediate postoperative period in patients undergoing cavopulmonary anastomoses.

The efficacy and safety of stent redilatation in congenital heart disease

OBJECTIVES

To assess the extent of neointimal proliferation and the safety and efficacy of stent redilatation in patients with stents implanted for aortic coarctation or branch pulmonary artery stenosis.

DESIGN

Retrospective observational study.

SETTING

Tertiary referral centre.

PATIENTS AND INTERVENTIONS

Of 60 patients with Palmaz stents, 12 with coarctation and 12 with branch pulmonary artery stenosis (with 21 stented sites) underwent recatheterisation and stent redilatation.

RESULTS

Neointimal thickening > 1 mm was detected in six of the 12 coarctation stents and at nine of the 21 stented sites in branch pulmonary arteries (five of which had been overdilated at implantation). Eight of the coarctation stents were electively underdilated at implantation. Coarctation stent redilatation increased median (range) lumen diameter from 9.2 (6.3-11.1) mm to 11.7 (9.8-14.1) mm (p = 0.002), decreased gradient from 10.5 (0-20) mm Hg to 0.5 (0-15) mm Hg (p = 0.008), and increased the ratio of stent diameter to descending aorta diameter from 0.66 (0.38-1.02) to 0.85 (0.52-1.2) (p = 0.008). Pulmonary artery stent redilatation increased lumen diameter from 6.9 (3.8-13.5) mm to 8.8 (4.8-14.1) mm (p < 0.001), decreased gradient from 24 (2-62) mm Hg to 12 (0-29) mm Hg (p < 0.001), and increased the ratio of stent diameter to diameter of distal pulmonary artery from 0.66 (0.44-1.5) to 0.86 (0.48-1.88) (p = 0.001). Dilatation of one peripheral pulmonary artery stent resulted in rupture of the vessel distal to the stent.

CONCLUSIONS

Neointimal proliferation is precipitated by overdilating stents at implantation. Redilatation using balloons matched to distal vessel diameter increases stent lumen size, but may not optimise vessel diameter. Redilatation is effective whether the indication for redilatation is a resistant stenosis at implantation, underexpansion at implantation, neointimal proliferation, or relative stenosis caused by growth.

IntraStent double-strut LD: collapse and recoil following use in postoperative stenoses

We describe the use of the Intratherapeutics IntraStent in two postoperative patients, its collapse and recoil following deployment, and subsequent transcatheter correction.

Interventional catheterization management of perioperative peripheral pulmonary stenosis: balloon angioplasty or endovascular stenting

There is limited reported experience of catheterization therapy for peripheral pulmonary stenosis (PPS) at a surgical site in the early postoperative period. We reviewed the clinical course of patients undergoing interventional catheterization for PPS at a surgical site < 7 weeks after surgery. Successful dilation (SD) was defined as > 50% increase in predilation diameter. From 1984 to 2000, 17 patients had 19 proximal pulmonary arteries dilated 1 to 46 (median 8) days postoperatively. Median age and weight were 3.1 year and 12.7 kg. Three arteries were initially occluded. Seventeen arteries had initial BD with postintervention imaging available in 15; 8 arteries had SD. The arterial diameter increased from 3.9 +/- 2.6 to 5.5 +/- 2.8 mm (P < 0.001). Nine of these arteries had stents placed with diameter increasing to 8.7 +/- 3.7 mm (P < 0.001 compared with post-BD diameter). Stents increased the diameter in all arteries and made four of four failed BD successful. In the two most recent procedures, stents were placed without prior BD with diameter increasing from 1.3 to 9 mm and 8.2 to 14 mm. A stent was placed in 1 of 7 arteries prior to 1993 and in 10 of 12 arteries thereafter (P < 0.004). Three patients prior to 1995 had catheterization-related deaths secondary to vessel rupture after BD. BD produces SD in approximately one-half of the procedures but is associated with mortality. Stent placement increases vessel diameter substantially more than BD alone. Stents reduce the acute complication rate and avoid early reoperation in this patient group.

Balloon dilation angioplasty of peripheral pulmonary stenosis associated with Williams syndrome

BACKGROUND

Experience of balloon dilation of peripheral pulmonary stenosis (PPS) in Williams syndrome (WS) is limited.

METHODS AND RESULTS

Catheterizations in all patients with WS undergoing therapy for PPS from 1984 to 1999 were reviewed. Criteria for successful dilation included an increase >50% in predilation diameter and a decrease >20% in ratio of right ventricular (RV) to aortic (Ao) systolic pressure. Median age and weight were 1.5 years and 9.5 kg. There were 134 dilations during 39 procedures in 25 patients. The success rate for initial dilations was 51%. In multivariate analysis, successful dilation was more likely (1) in distal than in central pulmonary arteries (P=0.02), (2) if the balloon waist resolved with inflation (P=0.001), and (3) with larger balloon/stenosis ratio (P<0.001). RV pressure was unchanged after dilation (96+/-30 versus 97+/-31 mm Hg), primarily because of failure to enlarge central pulmonary arteries. The Ao pressure increased (102+/-14 versus 109+/-19 mm Hg, P=0.03), and the RV/Ao pressure ratio decreased (0.97+/-0.34 versus 0.91+/-0.30, P=0.05). Aneurysms developed after 24 dilations (18%) and were not related to balloon/stenosis ratio. Balloon rupture in 12 dilations produced an aneurysm in all 7 cases when rupture was in a hypoplastic segment. Three patients died, none from pulmonary artery trauma, and all before 1994.

CONCLUSIONS

Mortality occurred early in our experience. Despite successful dilation of distal pulmonary arteries, there was modest initial hemodynamic improvement, mainly because of persistent central pulmonary artery obstruction. A serial approach of distal dilations followed by surgical repair of proximal obstruction may be a rational and successful therapy.

Pulmonary artery trauma due to balloon dilation: recognition, avoidance and management

OBJECTIVES

We reviewed the management and outcome of patients experiencing pulmonary artery (PA) trauma during balloon dilation (BD).

BACKGROUND

Balloon dilation of the PA is important in the management of peripheral pulmonary stenosis. Successful BD requires a controlled tear of the PA; excessive tearing can produce complications ranging from pseudoaneurysms to rupture and death. The incidence and optimum management for such complications are unreported.

METHODS

All records of patients who underwent branch PA dilation between June 1984 and October 1997 were reviewed; those with a significant complication were analyzed.

RESULTS

Of 1,286 catheterizations in 782 patients, PA trauma (excluding isolated pulmonary edema and PA aneurysms) was identified in 29 catheterizations in 26 patients. Tears occurred distal to the area of stenosis in most cases (62%). Intensive medical management, with and without catheter directed therapy, was employed. The damaged PA was successfully coil embolized in five patients, four of whom survived; temporary balloon occlusion did not prevent death in two patients. There were six deaths from pulmonary hemorrhage. A case control analysis demonstrated that PA trauma was significantly associated with pulmonary hypertension.

CONCLUSIONS

Pulmonary artery trauma associated with BD occurs mostly distal to the site of narrowing, is associated with underlying pulmonary hypertension and is frequently (5/12 or 42%) fatal in those with unconfined tears. Intensive management strategies as well as attention to distal balloon position may reduce incidence and mortality. Coil occlusion of the damaged PA appears to be a valuable strategy to prevent fatal hemorrhage.

Early and intermediate-term complications of self-expanding stents limit its potential application in children with congenital heart disease

OBJECTIVES

We report on the early and intermediate-term follow-up results of self-expanding Wallstent (Schneider, Switzerland) implanted in children with congenital heart disease.

BACKGROUND

The inherent shortcomings of balloon-expandable stents prompted the trial of an alternative stent.

METHODS

Twenty patients underwent 22 implantations of 25 self-expanding Wallstents between December 1993 and June 1997 in two institutions. The mean age and weight were 10.8+/-4.5 years and 30.5+/-14.2 kg, respectively. The patients were divided into two groups: 1) Group I comprised 17 patients with pulmonary arterial stenoses, 2) Group II comprised four patients with venous stenoses (one belonged to both groups). Sixteen patients underwent recatheterization at a median of 5.8 months (range 0.5 to 31, mean 8.1 months) after stenting. Hemodynamic and angiographic changes after the interventional procedures and complications were documented.

RESULTS

All the stents were successfully deployed in the intended position. In Group I, the narrowest diameter of the stented vessel increased from 4.1+/-1.5 to 8+/-2 mm (95% increase, p < 0.0001) while the systolic pressure gradient across decreased from 24.6+/-15.8 to 12.1+/-11.4 mm Hg (51% decrease, p = 0.001). In Group II, the dimensional changes of the narrowest segment increased from 4.3+/-0.5 to 7.5+/-0.4 mm (75% increase, p = 0.003), and the pressure gradient reduced from 5.0+/-2.9 to 0.9+/-1.0 mm Hg (82% decrease, p = 0.04) across the stented venous channel. Distal migration of two optimally positioned stents occurred within 24 h of implantation. At recatheterization, significant neointimal ingrowth (>30% of the expanded diameter) was noted in 7 (28%) of the 25 implanted stents. This responded poorly to balloon dilation. Predisposing factors for the neointimal ingrowth included stents of smaller diameter (<9 mm) and longer period after implantation.

CONCLUSIONS

Self-expanding Wallstent could be deployed easily and safely to relieve vascular stenoses in children. The complications of distal migration, significant neointimal ingrowth and its unyielding design to overdilation limit its application to this patient group.

A technique to prevent newly implanted stent displacement during subsequent catheter and sheath manipulation

We describe a novel technique to prevent the displacement or migration of a newly implanted stent as a consequence of any subsequent catheter and sheath manipulation during the same catheterization procedure. The technique involves reinflation of the dilation balloon within the stent immediately after implant followed by advancing the long delivery sheath carefully over the balloon as the balloon is slowly deflated within the stent. The technique was used successfully in 78 stents in 30 patients without stent dislodgment or migration.

Simultaneous stent implantation for coarctation of the aorta and closure of patent ductus arteriosus using the Amplatzer duct occluder

We report on a 13-year-old girl with coarctation of the aorta and patent ductus arteriosus who underwent successful simultaneous stent implantation for the coarctation and catheter closure of the ductus using an Amplatzer duct occluder.

[Experience with Palmaz stent in pulmonary branch stenosis]

INTRODUCTION AND OBJECTIVES

Since 1989, the balloon expandable Palmaz stent (Johnson & Johnson Interventional Systems) has been used for the treatment of congenital heart disease. This study reports the results and the technique used for its implantation in native and post surgical retraction pulmonary branch stenosis.

MATERIALS AND METHODS

From february 1995 to june 1996, we have performed this technique in 11 symptomatic children/adolescents with pulmonary branch stenosis, the mean age was 11 +/- 2 years. Fourteen procedures were made and 16 stents were implanted. The mean condition of the patients was: 7 with tetralogy of Fallot after a previous complete correction, 1 with Noonan syndrome and a surgically corrected atrial septal defect, 1 with pulmonary trunk aneurysm and a previous surgical correction for pulmonary valve and branch stenosis, 1 with pulmonary atresia and an intact septum who underwent a surgical valvotomy and posterior percutaneous valvuloplasty with a good ventricular development, and final was a tricuspid atresia with a previous Waterston anastomosis which produced a stenosis at the right pulmonary branch who underwent a modified Fontan operation with the result of a severe stenosis at the medial and inferior right pulmonary artery. The branch ostium was affected in five cases, and in one case with diffuse hypoplasia of the right branch, the stenosis was at both sites. The stenosis was native in nine cases and post surgery in the other five (2 Waterston, 1 Blalock-Taussig, 1 Fontan). We used the right and/or left femoral vein in all cases except two, in which we used the internal jugular vein. We followed the technique reported by the Boston-Houston experience, with an extra stiff guide and Mullins sheath towards the site of the stenosis.

RESULTS

The procedure was effective in all cases except one. The mean pulmonary branch and balloon diameter was 11 +/- 3 mm and 14 +/- 2 mm, respectively, rate 1.2. The stenosis diameter rose from 4.8 +/- 1 to 11 +/- 2 mm (p < 0.001) with a percentage fall from 63 +/- 5 to 2 +/- 1% (p < 0.001). The pressure gradient fell from 30 +/- 5 to 5 +/- 1 mmHg (p < 0.001) and the right ventricle systolic pressure fell from 77 +/- 6 to 48 +/- 3 mmHg (p < 0.01). The mean followup was 10 +/- 3 months, a symptomatic and pulmonary perfusion improvement was seen. After 8 +/- 4 months, we evaluated six patients/nine stents with angiography, and we excluded thrombosis, aneurysms and occlusion of lobar or segmental branches. One case had a proximal stent re-stenosis as it did not cover the whole stenosis, so a new stent was implanted. Three patients/four stents underwent redilatation getting a slightly higher diameter than previously.

COMPLICATIONS

One patient had a stent migration and he underwent surgical stent retrieval.

CONCLUSIONS

Implantation of the Palmaz stent is a useful procedure for the treatment of native or post-operative pulmonary stenosis. It is possible to apply it to hypoplastic and ostial pulmonary stenosis. We confirm the effectiveness of redilatation at mid term.