In situ fracture of stents implanted for relief of pulmonary arterial stenosis in patients with congenitally malformed hearts

Pulmonary Artery Stent Implantation

Pulmonary artery stent implantation has become integral in the treatment of pulmonary artery stenosis and is probably the most efficacious therapy for these lesions. Advancements in technology involving stent design and the equipment used for stent delivery have made this procedure much safer and more effective. Strategies to mitigate and successfully treat adverse events related to pulmonary artery stent implantation are reasonably well-established. Pulmonary artery stent implantation remains one of the most complex and technically challenging of congenital cardiac interventions.

Economic evaluations of medical devices in paediatrics: a systematic review and a quality appraisal of the literature

BACKGROUND

Although economic evaluations (EEs) have been increasingly applied to medical devices, little discussion has been conducted on how the different health realities of specific populations may impact the application of methods and the ensuing results. This is particularly relevant for pediatric populations, as most EEs on devices are conducted in adults, with specific aspects related to the uniqueness of child health often being overlooked. This study provides a review of the published EEs on devices used in paediatrics, assessing the quality of reporting, and summarising methodological challenges.

METHODS

A systematic literature search was performed to identify peer-reviewed publications on the economic value of devices used in paediatrics in the form of full EEs (comparing both costs and consequences of two or more devices). After the removal of duplicates, article titles and abstracts were screened. The remaining full-text articles were retrieved and assessed for inclusion. In-vitro diagnostic devices were not considered in this review. Study descriptive and methodological characteristics were extracted using a structured template. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) 2022 checklist was used to assess the quality of reporting. A narrative synthesis of the results was conducted followed by a critical discussion on the main challenges found in the literature.

RESULTS

39 full EEs were eligible for review. Most studies were conducted in high-income countries (67%) and focused on high-risk therapeutic devices (72%). Studies comprised 25 cost-utility analyses, 13 cost-effectiveness analyses and 1 cost-benefit analysis. Most of the studies considered a lifetime horizon (41%) and a health system perspective (36%). Compliance with the CHEERS 2022 items varied among the studies.

CONCLUSIONS

Despite the scant body of evidence on EEs focusing on devices in paediatrics results highlight the need to improve the quality of reporting and advance methods that can explicitly incorporate the multiple impacts related to the use of devices with distinct characteristics, as well as consider specific child health realities. The design of innovative participatory approaches and instruments for measuring outcomes meaningful to children and their families should be sought in future research.

Percutaneous pulmonary valve implantation in a patient with a single pulmonary artery and distal narrowing

Percutaneous pulmonary valve implantation is established as a safe and effective method of treating patients with disfunction of right ventricular outflow tract. Modifications of this method allow for an increasingly wider use of this less invasive treatment. We present a staged percutaneous pulmonary valve implantation into a single-branch pulmonary artery in a paediatric patient with tetralogy of Fallot after patch repair.

Ultra-high pressure balloon angioplasty for pulmonary artery stenosis in children with congenital heart defects: Short- to mid-term follow-up results from a retrospective cohort in a single tertiary center

Objective

Balloon angioplasty (BA) has been the treatment of choice for pulmonary artery stenosis (PAS) in children. There remains, however, a significant proportion of resistant lesions. The ultra-high pressure (UHP) balloons might be effective in a subset of these lesions. In this study, we analyzed the safety and efficacy with short- to mid-term follow-up results of UHP BA for PAS in children with congenital heart defects (CHD) in our center.

Methods

This is a retrospective cohort study in a single tertiary heart center. Children diagnosed with PAS associated with CHD were referred for UHP BA. All data with these children were collected for analysis with updated follow-up.

Results

A total of 37 UHP BAs were performed consecutively in 28 children. The success rate was 78.4%. A significantly (P = 0.005) larger ratio of the balloon to the minimal luminal diameter at the stenotic waist (balloon/waist ratio) was present in the success group (median 3.00, 1.64-8.33) compared to that in the failure group (median 1.94, 1.41 ± 4.00). Stepwise logistic regression analysis further identified that the balloon/waist ratio and the presence of therapeutic tears were two independent predictors of procedural success. The receiver operating characteristic curve revealed a cut-off value of 2.57 for the balloon/waist ratio to best differentiate success from failure cases. Signs of therapeutic tears were present in eight cases, all of whom were in the success group. Perioperative acute adverse events were recorded in 16 patients, including 11 pulmonary artery injuries, three pulmonary hemorrhages, and two pulmonary artery aneurysms. During a median follow-up period of 10.4 (0.1-21.0) months, nine cases experienced restenosis at a median time of 40 (4-325) days after angioplasty.

Conclusions

The UHP BA is safe and effective for the primary treatment of PAS in infants and children with CHD. The success rate is high with a low incidence of severe complications. The predictors of success are a larger balloon/waist ratio and the presence of therapeutic tears. The occurrence of restenosis during follow-up, however, remains a problem. A larger number of cases and longer periods of follow-up are needed for further study.

Interventions after Arterial Switch: A Single Low Case-Volume Center Experience

Background and Objectives: With the growing population of arterial switch operation survivors, the rate of late complications associated with the operation is growing as well. The aim of this publication is to share our experience and encourage collaboration between congenital cardiac surgeons and interventional cardiologists in treating late complications after arterial switch operation. Materials and Methods: A retrospective analysis of Vilnius University Santaros Clinics Cardiothoracic Surgery Centre arterial switch operation survivors who underwent additional treatment for late neo-pulmonary artery stenosis and aortic arch obstruction between 1989 and 2019 was conducted. Results: Out of 95 arterial switch operation survivors 14 (15%) underwent 36 reinterventions. The majority were treated for neo-pulmonary stenosis. The median time from arterial switch operation to the first reintervention was 1.4 years (interquartile range, 2 months to 2.4 years). 1, 3, 5, and 10 years intervention-free survival in patients treated for neo-pulmonary stenosis and aortic arch obstruction was 98, 94, 94, and 93% vs. 95, 94, 94, and 93%, respectively. There were no complications associated with redo surgical procedures, while eight patients who underwent catheter-based interventional treatment had treatment-related complications, including one death. Conclusions: Both neo-pulmonary stenosis and aortic arch obstruction (new aortic coarctations or aortic recoarctations) tend to develop in the first decade after an arterial switch operation. Surgical and catheter-based interventional treatment with good results is possible even in a small volume center. Close collaboration of the congenital heart team (congenital cardiac surgeons and interventional cardiologists) in choosing the best treatment option for an individual patient helps to minimize the risk of potential complications.

Pulmonary artery and lung parenchymal growth following early versus delayed stent interventions in a swine pulmonary artery stenosis model

OBJECTIVES

Compare lung parenchymal and pulmonary artery (PA) growth and hemodynamics following early and delayed PA stent interventions for treatment of unilateral branch PA stenosis (PAS) in swine.

BACKGROUND

How the pulmonary circulation remodels in response to different durations of hypoperfusion and how much growth and function can be recovered with catheter directed interventions at differing time periods of lung development is not understood.

METHODS

A total of 18 swine were assigned to four groups: Sham (n = 4), untreated left PAS (LPAS) (n = 4), early intervention (EI) (n = 5), and delayed intervention (DI) (n = 5). EI had left pulmonary artery (LPA) stenting at 5 weeks (6 kg) with redilation at 10 weeks. DI had stenting at 10 weeks. All underwent right heart catheterization, computed tomography, magnetic resonance imaging, and histology at 20 weeks (55 kg).

RESULTS

EI decreased the extent of histologic changes in the left lung as DI had marked alveolar septal and bronchovascular abnormalities (p = .05 and p < .05 vs. sham) that were less prevalent in EI. EI also increased left lung volumes and alveolar counts compared to DI. EI and DI equally restored LPA pulsatility, R heart pressures, and distal LPA growth. EI and DI improved, but did not normalize LPA stenosis diameter (LPA/DAo ratio: Sham 1.27 ± 0.11 mm/mm, DI 0.88 ± 0.10 mm/mm, EI 1.01 ± 0.09 mm/mm) and pulmonary blood flow distributions (LPA-flow%: Sham 52 ± 5%, LPAS 7 ± 2%, DI 44 ± 3%, EI 40 ± 2%).

CONCLUSION

In this surgically created PAS model, EI was associated with improved lung parenchymal development compared to DI. Longer durations of L lung hypoperfusion did not detrimentally affect PA growth and R heart hemodynamics. Functional and anatomical discrepancies persist despite successful stent interventions that warrant additional investigation.

Comparison of pulmonary artery dimensions in swine obtained from catheter angiography, multi-slice computed tomography, 3D-rotational angiography and phase-contrast magnetic resonance angiography

Accurate pulmonary artery (PA) imaging is necessary for management of patients with complex congenital heart disease (CHD). The ability of newer imaging modalities such as 3D rotational angiography (3DRA) or phase-contrast magnetic resonance angiography (PC-MRA) to measure PA diameters has not been compared to established angiography techniques. Measurements of PA diameters (including PA stenosis and PA stents) from 3DRA and non-contrast-enhanced PC-MRA were compared to 2D catheter angiography (CA) and multi-slice computed tomography (MSCT) in a swine CHD model (n = 18). For all PA segments 3DRA had excellent agreement with CA and MSCT (ICC = 0.94[0.91-0.95] and 0.92[0.89-0.94]). 3DRA PA stenosis measures were similar to CA and MSCT and 3DRA was on average within 5% of 10.8 ± 1.3 mm PA stent diameters from CA and MSCT. For compliant PA segments, 3DRA was on average 3-12% less than CA (p < 0.05) and MSCT (p < 0.01) for 6-14 mm vessels. PC-MRA could not reliably visualize stents and distal PA vessels and only identified 34% of all assigned measurement sites. For measured PA segments, PC-MRA had good agreement to CA and MSCT (ICC = 0.87[0.77-0.92] and 0.83[0.72-0.90]) but PC-MRA overestimated stenosis diameters and underestimated compliant PA diameters. Excellent CA-MSCT PA diameter agreement (ICC = 0.95[0.93-0.96]) confirmed previous data in CHD patients. There was little bias in PA measurements between 3DRA, CA and MSCT in stenotic and stented PAs but 3DRA underestimates measurements of compliant PA regions. Accurate PC-MRA imaging was limited to unstented proximal PA anatomy.

Long-term evolution of stents implanted in branch pulmonary arteries

BACKGROUND

Branch pulmonary artery stenosis complicates the management of congenital heart diseases. Surgical branch pulmonary artery angioplasty is associated with a high reintervention rate. As an alternative, percutaneous or intraoperative branch pulmonary artery stents have been implanted to improve efficiency, but long-term evaluations are limited.

AIM

To describe the long-term evolution of branch pulmonary artery stents.

METHODS

We conducted a retrospective cohort study at Tours University Hospital. All stents implanted by surgery or catheterization in branch pulmonary arteries with a minimum follow-up of 12 months and at least one catheterization control were included. The primary endpoint combined cardiovascular mortality, surgical or percutaneous reintervention for stent complication or new stent implantation.

RESULTS

Between 2007 and 2017, 76 stents in 51 patients were included (62 stents implanted by surgery, 14 by catheterization). At implantation, the patients' mean age and weight were 4.7years (interquartile range 4.2years) and 17.3kg (interquartile range 11.0kg), respectively. Mean branch pulmonary artery minimum diameter was 4.1±2.1mm (mean Z-score-4.9±2.9), and mean initial stent diameter was 9.1±3.1mm. During a follow-up of 5.3years (range 0-11.2 years), freedom from primary endpoint was 86.8% (95% confidence interval 79.6-94.8%) at 1 year, 71.5% (95% confidence interval 61.9-82.7%) at 5years and 69.6% (95% confidence interval 59.6-81.2%) at 10 years. We did not identify any factors associated with major adverse cardiovascular events. Among stents without major adverse cardiovascular events, the mean branch pulmonary artery diameter Z-score at last evaluation had increased by +4.8±3.2 compared with the initial diameter (P<0.001). After stent implantation, a median of 2 re-expansions were performed for each stent (range 0-7).

CONCLUSIONS

Stent implantation should offer a good long-term solution for branch pulmonary artery stenosis, although iterative re-expansions are required.

Transcatheter pulmonary valve replacement in pediatric patients

INTRODUCTION

Right ventricular outflow tract (RVOT) dysfunction is common among individuals with congenital heart disease (CHD). Surgical intervention often carries prohibitive risks due to the need for sequential pulmonary valve (PV) replacements throughout their life in the majority of cases. Transcatheter pulmonary valve replacement (tPVR) is one of the most exciting recent developments in the treatment of CHD and has evolved to become an attractive alternative to surgery in patients with RVOT dysfunction.

AREAS COVERED

In this review, we examine the pathophysiology of RVOT dysfunction, indications for tPVR, and the procedural aspect. Advancements in clinical application and valve technology will also be covered.

EXPERT OPINION

tPVR is widely accepted as an alternative to surgery to address RVOT dysfunction, but still significant numbers of patients with complex RVOT morphology deemed not suitable for tPVR. As the technology continues to evolve, new percutaneous valves will allow such complex RVOT patient to benefit from tPVR.

Treatment of Peripheral Pulmonary Artery Stenosis

Peripheral pulmonary artery stenosis (PAS) is an abnormal narrowing of the pulmonary vasculature and can form anywhere within the pulmonary artery tree. PAS is a congenital or an acquired disease, and its severity depends on the etiology, location, and number of stenoses. Most often seen in infants and young children, some symptoms include shortness of breath, fatigue, and tachycardia. Symptoms can progressively worsen over time as right ventricular pressure increases, leading to further complications including pulmonary artery hypertension and systolic and diastolic dysfunctions. The current treatment options for PAS include simple balloon angioplasty, cutting balloon angioplasty, and stent placement. Simple balloon angioplasty is the most basic therapeutic option for proximally located PAS. Cutting balloon angioplasty is utilized for more dilation-resistant PAS vessels and for more distally located PAS. Stent placement is the most effective option seen to treat the majority of PAS; however, it requires multiple re-interventions for serial dilations and is generally reserved for PAS vessels that are resistant to angioplasty.

Branch Pulmonary Artery Valve Implantation Reduces Pulmonary Regurgitation and Improves Right Ventricular Size/Function in Patients With Large Right Ventricular Outflow Tracts

OBJECTIVES

The authors sought to assess the intermediate-term effects of percutaneous placed valves in the branch pulmonary artery (PA) position.

BACKGROUND

Most patients with large right ventricular outflow tracts (RVOTs) are excluded from available percutaneous pulmonary valve options. In some of these patients, percutaneous branch PA valve implantation may be feasible. The longer-term effects of valves in the branch PA position is unknown.

METHODS

Retrospective data were collected on patients with significant pulmonary regurgitation who had a percutaneous branch PA valve attempted.

RESULTS

Percutaneous branch PA valve implantation was attempted in 34 patients (18 bilateral and 16 unilateral). One-half of the patients were in New York Heart Association (NHYA) functional class III or IV pre-implantation. There were 2 failed attempts and 6 procedural complications. At follow-up, only 1 patient had more than mild valvar regurgitation. The right ventricular end-diastolic volume index decreased from 147 (range: 103 to 478) ml/m² to 101 (range: 76 to 429) ml/m², p < 0.01 (n = 16), and the right ventricular end-systolic volume index decreased from 88.5 (range: 41 to 387) ml/m² to 55.5 (range: 40.2 to 347) ml/m², p < 0.01 (n = 13). There were 5 late deaths. At a median follow-up of 2 years, all other patients were in NYHA functional class I or II.

CONCLUSIONS

Percutaneous branch PA valve implantation results in a reduction in right ventricular volume with clinical benefit in the intermediate term. Until percutaneous valve technology for large RVOTs is refined and more widely available, branch PA valve implantation remains an option for select patients.

A review: Percutaneous pulmonary artery stenosis therapy: state-of-the-art and look to the future

Stenosis, or narrowing, of the branches of the pulmonary artery is a type of CHD that, if left untreated, may lead to significant complications. Ideally, interventions to treat stenosis occur before significant complications or long-term sequelae take place, often within the first 2 years of life. Treatment depends on specifics of the condition, the presence of other malformations, and age of the child. Research and recent innovation to address these shortcomings have provided physicians with safer and more effective methods of treatment. This has further continued to push the ceiling of pulmonary arterial stenosis treatment available for patients. Despite continuous advancement in angioplasty - such as conventional and cutting balloon - and stenting, each treatment method is not without its unique limitations. New technological developments such as bioresorbable stents can accommodate patient growth and pulmonary artery stenosis treatment. As more than a decade has passed since the review by Bergersen and Lock, this article aims to provide a contemporary summary and investigation into the effectiveness of various therapeutic tools currently available, such as bare metal stents and potential innovations including bioresorbable stents.

Pulmonary artery interventions after the arterial switch operation: Unique and significant risks

BACKGROUND

In the modern era, results of the arterial switch operation (ASO) for transposition of the great arteries are excellent. However, because of the LeCompte maneuver, there may be a propensity for development of pulmonary artery stenosis. We encountered atypical complications of pulmonary artery stenting in patients after the ASO, including aorto-pulmonary fistula and coronary compression.

METHODS

We performed a 10-year retrospective review of catheterizations performed in patients after ASO in our institution with a focus on adverse events.

RESULTS

Diagnostic and interventional catheterizations were performed in 47 patients. In 29 patients, 37 interventional procedures performed, which included pulmonary artery angioplasty and/or stenting. In this group, there were five major adverse events (14%), including three aorto-pulmonary fistulae and one coronary artery compression among patients having stent implantation or stent redilation. In addition, there were 6/37 (16%) intended stent procedures, which were aborted because there appeared to be high-risk of significant adverse events.

CONCLUSIONS

This review suggests that percutaneous intervention on pulmonary artery stenosis after ASO has high-risk and should be undertaken advisedly. Prior thorough evaluation of coronary arteries is mandatory as coronary reimplantation sites may be adjacent to sites of pulmonary artery stenosis. Furthermore, if pulmonary artery stent implantation or stent redilation is contemplated, the risk of stent fracture and possible AP fistula should be recognized. Primary use of reinforced covered stents should be considered.

Bilateral branch pulmonary artery valve implantation in repaired tetralogy of fallot

BACKGROUND

Transcatheter, bilateral branch pulmonary artery (PA) valve implantation is a novel treatment for patients with severe pulmonary insufficiency and oversized right ventricle (RV) outflow tract. There is scarce data on efficacy and safety of this approach.

METHODS

This was a retrospective study of 8 patients with repaired tetralogy of fallot (TOF) who underwent bilateral branch PA valve implantation. Demographics, echocardiography, cardiac catheterization, and axial imaging data were reviewed. Variables were compared by a paired sample t-test.

RESULTS

All patients were adult sized (weight 43-99 kg) with oversized RV outflow tract not suitable for conventional transcatheter pulmonary valve implantation. Staged bare metal PA stenting followed by valve implantation (interval 3-5 months) was technically successful in 7 patients with one stent embolization. In another patient, proximal stent migration prevented placement of bilateral pulmonary valve stents. There were a total of 14 valved branch PA stents placed (Melody valve n = 9, Sapien XT n = 2, Sapien 3 n = 3). In the 7 patients undergoing successful branch pulmonary valve placement, at median follow up of 10 months (range 3 months to 6 years), 13 (93%) valves had none/trivial insufficiency on echocardiography. Prevalve and postvalve implantation cardiac magnetic resonance imaging in five patients showed significant reduction of indexed RV end-diastolic volume (152 ± 27 to 105 ± 15 mL/m² , P < .001).

CONCLUSIONS

Transcatheter, bilateral branch PA valve implantation was technically feasible with satisfactory efficacy and safety in patients with repaired TOF, severe pulmonary insufficiency, and oversized RV outflow tracts. Elimination of pulmonary insufficiency with this method resulted in reduced RV end-diastolic volume. This approach can be offered as an alternative to surgery, particularly in patients considered high risk for standard surgical placement and who are not candidates for the newer self-expanding valve prosthesis for placement in RV outflow tracts larger than 30 mm diameter.

Consequences of an early catheter-based intervention on pulmonary artery growth and right ventricular myocardial function in a pig model of pulmonary artery stenosis

OBJECTIVE

To determine the consequences of an early catheter-based intervention on pulmonary artery (PA) growth and right ventricular (RV) myocardial function in an animal model of branch PA stenosis.

BACKGROUND

Acute results and safety profiles of deliberate stent fracture within the pulmonary vasculature have been demonstrated. The long-term impact of early stent intervention and deliberate stent fracture on PA growth and myocardial function is not understood.

METHODS

Implantation of small diameter stents was performed in a pig model of left PA stenosis at 6 weeks (10 kg) followed by dilations at 10 (35 kg) and 18 weeks (65 kg) with intent to fracture and implant large diameter stents. Hemodynamics, RV contractility, and 2D/3D angiography were performed with each intervention. The heart and pulmonary vasculature were histologically assessed.

RESULTS

Stent fracture occurred in 9/12 and implantation of large diameter stents was successful in 10/12 animals with no PA aneurysms or dissections. The final stented PA segment and distal left PA branch origins equaled the corresponding PA diameters of sham controls. Growth of left PA immediately beyond the stent was limited and there was diffuse fibro-intimal proliferation within the distal left and right PA. RV contractility was diminished in the intervention group and the response to dobutamine occurred uniquely via increases in heart rate.

CONCLUSIONS

Early stent intervention in this surgically created PA stenosis model was associated with improved growth of the distal PA vasculature but additional investigation of PA vessel physiology and impact on the developing heart are needed.

Transcatheter Pulmonary Valve Replacement: Current State of Art

PURPOSE OF REVIEW

The past couple of decades have brought tremendous advances to the field of pediatric and adult congenital heart disease (CHD). Percutaneous valve interventions are now a cornerstone of not just the congenital cardiologist treating patients with congenital heart disease, but also-and numerically more importantly-for adult interventional cardiologists treating patients with acquired heart valve disease. Transcatheter pulmonary valve replacement (tPVR) is one of the most exciting recent developments in the treatment of CHD and has evolved to become an attractive alternative to surgery in patients with right ventricular outflow tract (RVOT) dysfunction. This review aims to summarize (1) the current state of the art for tPVR, (2) the expanding indications, and (3) the technological obstacles to optimizing tPVR.

RECENT FINDINGS

Since its introduction in 2000, more than ten thousands tPVR procedures have been performed worldwide. Although the indications for tPVR have been adapted earlier from those accepted for surgical intervention, they remain incompletely defined. The new imaging modalities give better assessment of cardiac anatomy and function and determine candidacy for the procedure. The procedure has been shown to be feasible and safe when performed in patients who received pulmonary conduit and or bioprosthetic valves between the right ventricle and the pulmonary artery. Fewer selected patients post trans-annular patch repair for tetralogy of Fallot may also be candidates for this technology. Size restrictions of the currently available valves limit deployment in the majority of patients post trans-annular patch repair. Newer valves and techniques are being developed that may help such patients. Refinements and further developments of this procedure hold promise for the extension of this technology to other patient populations.

Intentional Fracture of Maximally Dilated Balloon-Expandable Pulmonary Artery Stents Using Ultra–High-Pressure Balloon Angioplasty

Background—

Treatment with endovascular stents has become increasingly common for the management of vascular stenosis in congenital heart disease. The use of stents in smaller patients has been tempered by concerns about the potential for stent expansion to accommodate somatic growth. One solution to limited stent diameter is the intentional fracture of maximally dilated stents, which can be accomplished using ultra–high-pressure (UHP) balloons.

Methods and Results—

This retrospective cohort study compared procedural characteristics and adverse events between a cohort of patients with branch pulmonary artery (PA) stents who underwent stent fracture using UHP balloons and control patients who underwent UHP redilation of previously placed PA stents without stent fracture between 2004 and 2014. Two control patients were selected for every case. Thirty-three PA stents were fractured in 31 patients with a median of 10 years after initial stent placement. The median balloon:waist ratio was 1.17 (1–1.71), and the median inflation pressure was 20 (8–30) atm. There were significant reductions in pressure gradient after angioplasty, with no difference in postangioplasty gradients between cases and controls. There were no major PA complications in the stent fracture group and no difference in the number of adverse events between the 2 groups.

Conclusions—

In this small series, PA stent fracture using UHP balloon angioplasty was feasible and did not result in major complications although predictors of successful fracture were not identified. Intentional fracture with UHP balloon angioplasty may be considered when treating stents that have become restrictive despite maximal dilation.

Prestenting for prevention of melody valve stent fractures: A systematic review and meta-analysis

INTRODUCTION

The role of right ventricular outflow tract (RVOT) prestenting in the prevention of Melody valve stent fractures (SFs) is not well defined. We aimed to perform a systematic review and meta-analysis comparing the incidence of SF in Melody valve transcatheter pulmonary implants with and without prestenting.

METHODS

PubMed, EMBASE, and Cochrane Central were searched for studies that reported the incidence of SF in Melody valve transcatheter pulmonary implants stratified by the presence or absence of RVOT prestenting. Subgroup analyses were performed for (1) SF associated with a loss of stent integrity and (2) SF requiring reintervention.

RESULTS

Five studies and 360 patients were included, of whom 207 (57.5%) received prestenting. Follow-up ranged from 15 to 30 months. SF were significantly reduced in the prestenting group (16.7%) when compared to no prestenting (33.5%) (odds-ratio [OR] 0.39; 95%CI 0.22-0.69). Patients who received prestenting also had a lower incidence of (1) SF associated with loss of stent integrity (OR 0.16; 95%CI 0.05-0.48) and (2) SF requiring reintervention (OR 0.15; 95%CI 0.02-0.91).

CONCLUSION

Our findings suggest that stenting of the RVOT prior to Melody valve implantation is associated with a reduction in the incidence of SF and fracture-related reinterventions.

Iatrogenic aortopulmonary communications after transcatheter interventions on the right ventricular outflow tract or pulmonary artery: Pathophysiologic, diagnostic, and management considerations

OBJECTIVES

To investigate the spectrum, etiology, and management of traumatic aortopulmonary (AP) communications after transcatheter interventions on the pulmonary circulation.

BACKGROUND

An iatrogenic AP communication is an unusual complication after balloon pulmonary artery (PA) angioplasty or stenting, or transcatheter pulmonary valve replacement (TPVR). However, with the increasing application of transcatheter therapies for postoperative PA stenosis and right ventricular outflow tract (RVOT) dysfunction, including percutaneous pulmonary valve replacement, consideration of the etiology, diagnosis, and management of this problem is important for interventional cardiologists performing such procedures.

METHODS AND RESULTS

We present three new cases, as well as gross anatomy and histopathology data, related to AP communications after PA interventions. We also review the literature relevant to this topic. Including these new cases, there have been 18 reported cases of iatrogenic AP communication after transcatheter interventions on the PAs or RVOT, primarily patients with transposition of the great arteries who underwent PA angioplasty after an arterial switch operation, or after TPVR in patients who had undergone a Ross procedure. The likely cause of such defects is PA trauma plus distortion of the neo-aortic anastomosis resulting from angioplasty or stenting of the RVOT or central PAs, with subsequent dissection through the extravascular connective tissue and into the closely adjacent vessel through the devitalized tissue at the anastomosis.

CONCLUSIONS

Cardiologists performing PA or RVOT interventions should be aware of the possibility of a traumatic AP communication and consider this diagnosis when confronted with suggestive signs and symptoms.

Initial use of endothelial progenitor cells capturing stents in paediatric congenital heart disease

INTRODUCTION

Stenosis, mediated by neointimal hyperplasia and thrombosis, is a major limiting factor in successful stent implantation. The introduction of a stent, coated in its endoluminal surface by antihuman CD34 antibodies with endothelial progenitor cell-capturing properties, opens the possibility of promoting a rapid and normal functioning coverage by endothelium and thus avoids both an excessive cell proliferation within stent and the need for long-term dual antiplatelet therapy. These stents, developed for adult coronary artery disease, have not yet been implanted in children or in those with congenital heart disease.

OBJECTIVE AND METHODS

In this paper, we describe the implantation of Genous® stents in three children with cyanotic congenital heart disease and obstructed systemic-to-pulmonary shunts. We describe the use of this stent and address its potential feasibility in paediatric congenital heart disease.

RESULTS

To maintain the patency of two modified Blalock-Taussig shunts and one ductus arteriosus, four Genous® stents were implanted in three infants with cyanotic heart disease. All procedures were immediately successful, with resolution of stenosis and improvement in transcutaneous oxygen saturation from 66% ± 3.6% to 92% ± 2.6%. In the follow-up, one stent had no occlusion; however, the remaining two had partial occlusion after 5 and 5.5 months, which were successfully managed with balloon dilatation preceding elective definitive surgical correction.

CONCLUSION

In our preliminary experience, we demonstrated that Genous® stent implantation was feasible in infants with complex congenital heart disease. Additional studies with larger samples and longer follow-up are required to confirm the potential benefits of this technology in this clinical setting.

Pulmonary artery stents in the recent era: Immediate and intermediate follow-up

BACKGROUND

Long-term follow-up after stent dilation of native and acquired pulmonary artery stenosis is scarce in the pediatric population. Most cohorts include a myriad of anatomies and associated conditions.

METHOD

In order to establish objective performance criteria, we performed a retrospective review of all patients who underwent unilateral pulmonary artery stenting in biventricular physiology at three centers from June 2006 to June 2011.

RESULTS

Fifty-eight patients received 60 stents with Palmaz Genesis stent used most commonly (78%). Average age at implantation was 10.4 ± 10.3 years and weight 31.6 ± 21.8 kg. The immediate success rate was 98%, with improvement in minimal diameter from 5.1 ± 2 cm to 10.6 ± 3 cm (P < 0.01). There were 10 complications (7 major and 3 minor) and no acute mortality. One-year follow-up studies were available in 48 patients (83%), including echocardiogram (60%), catheterization (28%), MRI (29%), and lung perfusion (31%). Follow-up echocardiogram showed mild increase in stent gradient, from 5.7 ± 6.7 mm Hg post-procedure to 17.1 ± 11.7 mm Hg. Follow-up catheterization showed no significant change in minimal stent diameter (8.8 ± 2.6 to 7.8 ± 2.3 mm), gradient (7.7 ± 8.4 to 12.6 ± 12.2 mm Hg), or right ventricular pressures (43.7 ± 9 to 47.7 ± 10.5 mm Hg). Nine patients (16%) underwent scheduled stent redilation over a period of 12 days to 25 months.

CONCLUSION

In conclusion, stent implantation shows excellent immediate and 1-year follow-up results with maintenance of improved caliber of the stented vessel and lowered right ventricular systolic pressures.

Postmarketing trials and pediatric device approvals

BACKGROUND

Medical devices can be useful in a variety of diseases, but few devices have been specifically approved for use in children. The 2007 Pediatric Medical Device Safety and Improvement Act was passed to stimulate pediatric device development. The current state of trial evidence underpinning the approval of pediatric devices remains poorly described.

METHODS

We identified all high-risk (ie, class III) devices approved through the premarket approval or humanitarian device exemption pathways for therapeutic use in children between 2008 and 2011. We collected key information on clinical trial design (randomization, blinding, controls, and types of end points) as well as age distribution of trial participants. We also identified US Food and Drug Administration (FDA)-mandated postmarketing trials.

RESULTS

Twenty-two devices were approved for use in children via the premarket approval pathway and 3 via the humanitarian device exemption pathway. Twenty-two (88%) qualified as pediatric despite minimum approval ages of ≥18 years (the FDA Center for Devices and Radiologic Health considers patients 18-21 years old as pediatric). Most devices were approved on the basis of nonrandomized (59%), open-label (68%) studies with surrogate effectiveness end points (86%). Overall, 21 (84%) devices were not studied in any patients <18 years of age. Postmarketing studies were mandated by the FDA for 19 (76%) devices, although only 3 (18%) required enrollment of pediatric patients.

CONCLUSIONS

Most high-risk pediatric devices are approved on the basis of trials in patients ≥18 years old, with few pediatric patients exposed to the devices before market availability. Few postmarketing studies require additional study in pediatric patients.

A 10-year single-centre experience in percutaneous interventions for multi-stage treatment of hypoplastic left heart syndrome

OBJECTIVES

The purpose of this paper is to report our 10 years of experience of interventional treatment of patients with hypoplastic left heart syndrome and to focus on the frequency, type, and results of percutaneous interventions during all the stages of palliation, considering the different techniques, devices, and complications.

BACKGROUND

Constant progress in surgical treatment of congenital heart defects in the last decade has significantly improved the prognosis for children with hypoplastic left heart syndrome. However, morbidity and mortality remain relatively high. Modern interventional procedures complement or occasionally replace surgical treatment.

METHODS

Between January, 2001 and December, 2010, 161 percutaneous interventions were performed in 88 patients with hypoplastic left heart syndrome. Patients were divided into four groups: (a) before the first surgical treatment including hybrid approach, (b) after first-stage Norwood operation, (c) after second-stage bidirectional Glenn operation, and (d) after third-stage Fontan operation.

RESULTS

Percutaneous interventions resulted in statistically significant changes in pulmonary artery pressures, vessel diameters, and O2 saturation. Complications occurred in 4.3% of interventions and were related mainly to stent implantation in stenosed pulmonary arteries.

CONCLUSIONS

Percutaneous interventions may result in haemodynamic stability and reduction in the number of operations. They may result in significant changes in pulmonary artery pressures, vessel diameters, O2 saturation, with a low rate of complications, which are mainly related to stent implantation in the pulmonary arteries.

Effect of interventional stent treatment of native and recurrent coarctation of aorta on blood pressure

The aim of this study was to describe the clinical impact of management of coarctation of the aorta by transcatheter stent placement in the context of longer term management of systemic hypertension. In the long term, poor outlook associated with untreated coarctation of the aorta is likely to relate to uncontrolled systemic hypertension. Transcatheter stent placement to treat native and recurrent coarctation of the aorta is an established therapy in adolescents and adults. There remains confusion about longer term outcomes, particularly the relation between procedural success and improvement in blood pressure (BP) control. Improvement in lifelong systemic BP control after transcatheter stent placement remains unproved. Forty patients underwent transcatheter stent placement over a 10-year period (2001 to 2010) at the Yorkshire Heart Centre. The average age at the time of procedure was 25 years (range 14 to 57). There was a reduction in peak systolic gradient across the coarcted segment from 25 to <10 mm Hg in 35 of 39 patients. After stent placement, there was a significant improvement in systolic BP control at early and later follow-up (mean 155 mm Hg before the procedure and 134 mm Hg at 2.81-year follow-up, p <0.0001). There was 1 early procedural adverse event (stent embolization) and 1 late adverse event (lower limb claudication). In conclusion, transcatheter stent placement for the management of aortic coarctation is associated with a reduction in systolic BP that is maintained over the medium term. A significant minority of patients remain significantly hypertensive, and the best management strategy for this group of patients remains unclear.

Clinical and stent-related outcomes after transcatheter or operative placement of bare-metal stents in the ventricular septum or subvalvar systemic outflow tract

BACKGROUND

Stenting of the systemic ventricular outflow tract and creation or enlargement of a ventricular septal defect using stents are potential therapeutic options in rare patients with congenital heart disease who develop significant ventricular hypertension due to outflow obstruction. These stents may be at increased risk of fracture because of exposure to cyclic compressive stresses. The objective of this study was to evaluate the safety and efficacy of this intervention and to determine the incidence of stent fracture and other adverse outcomes after placement of intraventricular or interventricular stents for this indication.

METHODS AND RESULTS

Between 1992 and 2010, 27 patients underwent bare-metal stent placement in the ventricular septum or subvalvar systemic outflow tract, using 1 of the following 3 delivery approaches: (1) percutaneous (n=18), (2) intraoperative (n=8), and (3) hybrid (n=1). The median ventricular-to-aortic systolic pressure ratio decreased from 1.7 (1.3-2.6) to 1.1 (0.9-1.8) (P<0.001). Survival free from surgical reintervention for outflow obstruction was 92% at 1 year and 66% at 3 years. Stent fracture was diagnosed in 11 patients (41%) a median of 2.6 years (0.03-7.8 years) after stent placement and was always associated with recurrent obstruction. Survival free from diagnosis of stent fracture was 84% at 1 year and 73% at 3 years. Other adverse events included complete heart block (n=2) and increased atrioventricular valve regurgitation requiring surgical intervention (n=2).

CONCLUSIONS

Transcatheter, intraoperative, or hybrid stenting of the ventricular septum or systemic outflow tract is feasible and effective in the short term. Stent fractures were common during follow-up and associated with recurrent obstruction.

Stent Fracture, Valve Dysfunction, and Right Ventricular Outflow Tract Reintervention After Transcatheter Pulmonary Valve Implantation

Background—

Among patients undergoing transcatheter pulmonary valve (TPV) replacement with the Melody valve, risk factors for Melody stent fracture (MSF) and right ventricular outflow tract (RVOT) reintervention have not been well defined.

Methods and Results—

From January 2007 to January 2010, 150 patients (median age, 19 years) underwent TPV implantation in the Melody valve Investigational Device Exemption trial. Existing conduit stents from a prior catheterization were present in 37 patients (25%, fractured in 12); 1 or more new prestents were placed at the TPV implant catheterization in 51 patients. During follow-up (median, 30 months), MSF was diagnosed in 39 patients. Freedom from a diagnosis of MSF was 77±4% at 14 months (after the 1-year evaluation window) and 60±9% at 39 months (3-year window). On multivariable analysis, implant within an existing stent, new prestent, or bioprosthetic valve (combined variable) was associated with longer freedom from MSF ( P <0.001), whereas TPV compression ( P =0.01) and apposition to the anterior chest wall ( P =0.02) were associated with shorter freedom from MSF. Freedom from RVOT reintervention was 86±4% at 27 months. Among patients with a MSF, freedom from RVOT reintervention after MSF diagnosis was 49±10% at 2 years. Factors associated with reintervention were similar to those for MSF.

Conclusions—

MSF was common after TPV implant in this multicenter experience and was more likely in patients with severely obstructed RVOT conduits and when the TPV was directly behind the anterior chest wall and/or clearly compressed. A TPV implant site protected by a prestent or bioprosthetic valve was associated with lower risk of MSF and reintervention.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00740870.

Balloon Angioplasty and Stenting of Branch Pulmonary Arteries

Background—

Pulmonary artery (PA) balloon angioplasty and/or stenting (PA rehabilitation) is one of the most common procedures performed in the cardiac catheterization laboratory, but comprehensive and consistently reported data on procedure-related adverse events (AE) are scarce.

Methods and Results—

Data were prospectively collected using a multicenter registry (Congenital Cardiac Catheterization Project on Outcomes). All cases that included balloon angioplasty and/or stent implantation in a proximal or lobar PA position were included. Multivariate analysis was used to evaluate for independent predictors of AE and need for early reintervention. Between February 2007 and December 2009, 8 institutions submitted details on 1315 procedures with a PA intervention. An AE was documented in 22% with a high severity (level 3 to 5) AE in 10% of cases. Types of AE included vascular/cardiac trauma (19%), technical AE (15%), arrhythmias (15%), hemodynamic AE (14%), bleeding via endotracheal tube/reperfusion injury (12%), and other AE (24%). AE were classified as not preventable in 50%, possibly preventable in 41%, and preventable in 9%. By multivariate analysis, independent risk factors for level 3 to 5 AE were presence of ≥2 indicators of hemodynamic vulnerability, age below 1 month, use of cutting balloons, and operator experience of <10 years. Reintervention during the study period occurred in 22% of patients undergoing PA rehabilitation.

Conclusions—

PA rehabilitation is associated with a 10% incidence of high-level severity AE. Hemodynamic vulnerability, young age, use of cutting balloons, and lower operator experience were significant independent risk factors for procedure-related AE.

Endovascular stent placement is an acceptable alternative to reoperation in selected infants with residual or recurrent aortic arch obstruction

OBJECTIVE

To describe endovascular stent placement in infants as a technically feasible option in circumstances where surgery is considered less favorable.

BACKGROUND

Endovascular stent placement has become established as a first line therapy for native coarctation of the aorta or recoarctation in older children where stents capable of expansion to adult size can be placed safely. Surgery remains the therapy of choice in infants and young children. The management of aortic arch obstruction in infants is, however, frequently complicated by complex anatomy or clinical condition that may make surgery or further surgery an unattractive option. There is little reported data and the implications thereof of transcatheter stent placement in aortic arch obstruction in infants.

METHODS

Between August 2004 and November 2009, 11 patients had aortic arch obstruction treated with endovascular stent placement. The median age and weight at first stent placement was 46 days (range 3-399 days) and 4 kg (range 1.4-8 kg), respectively. In 10 patients, surgical intervention preceded transcatheter stent placement. Four had complex aortic arch obstruction and seven had recoarctation.

RESULTS

Reduction in peak systolic gradient to <10 mm Hg was achieved in seven of 10 patients with an improvement in aortic artery diameter to >90% of adjacent aorta in all. The diameter of the arch obstruction increased from a median of 1.60 to 4.90 mm (P = 0.001) and the peak systolic gradient from 45 mm Hg to 8 mm Hg (P < 0.0001). Adverse events occurred in two patients one who required further surgical revision and a second who required placement of a second stent. The median follow up was 3.60 years (range 0.4-5.5 years) with two patients having died at 1.34 and 1.42 years poststent placement. Of the nine patients alive, six have since undergone further angioplasty at a median time interval of 0.77 years (range 0.17-2.76 years). Long-term complications occurred in none.

CONCLUSIONS

Endovascular stent placement in infants is technically feasible with good results achievable even in small babies. It should be considered as a therapeutic option in complex cases when surgical alternatives are less favorable.

Fracture and dislocation of a pulmonary stent after cardiac massage

Following a Glenn procedure, a stent was implanted into the pulmonary artery to relieve stenosis. After the procedure, the patient developed bradycardia and became asystolic. Resuscitation was successful following cardiac massage, but subsequent catheterization revealed the stent to be broken in two, with shift of the distal fragment. The two parts were stabilized and connected by implantation of an additional CP stent.