Transcatheter Pulmonary Valve Implantation in Congenital Heart Diseases: Current Advances and Future Prospectives

Pulmonary disfunction is frequent in repaired congenital heart diseases. Both pulmonary regurgitation and pulmonary stenosis are possible complications over time. In the past, the surgical approach was the only feasible management but exposed the patient to a redo-surgery with its consequent risks. Nowadays, the development of novel devices and techniques has made possible a transcatheter pulmonary valve implantation. The Melody Transcatheter Pulmonary Valve (TPV) (Medtronic Inc., Minneapolis, MN, USA) and the Edwards Sapien XT and S3 Transcatheter Heart Valve (Edwards Lifesciences LLC, Irvine, CA, USA) are balloon-expandable valvular bioprostheses approved for pulmonary position. Venus P-Valve (Venus Medtech, Shanghai, China) and Harmony TPV (Medtronic Inc., Minneapolis, MN, USA) are self-expandable pulmonary valves. Alterra Adaptive Prestent (Edwards Lifesciences LLC, Irvine, CA, USA) is an hourglass self-expandable stent that reduces the size of large right ventricular outflow tracts, creating a suitable landing zone to implant an Edwards Sapien S3 THV 29 mm. Novel stents and percutaneous valves are being planned and experimented with to widen the field of transcatheter approach. The aim of this review is to describe both the current approaches, strategies, and techniques as well as the future perspective to deal with the patients with significant pulmonary stenosis and/or regurgitation.

A Novel Modification of the Melody Valve in a Short Right Ventricle-Pulmonary Artery Conduit: A Case Report

Pulmonary insufficiency often follows the surgical repair of tetralogy of Fallot, leading to adverse outcomes. Young patients with short right ventricle-pulmonary artery conduits are at risk of pulmonary artery branch occlusion when a traditional Melody valve (Medtronic) is used. We report a novel case of a folded Melody valve implanted with a simultaneous stent in a pediatric patient to address challenges posed by a short right ventricle-pulmonary artery conduit.

Transcatheter Pulmonary Valve in Congenital Heart Disease

Over the last 2 decades, experience with transcatheter pulmonary valve replacement (TPVR) has grown significantly and has become an effective and reliable way of treating pulmonary valve regurgitation, right ventricular outflow (RVOT) obstruction, and dysfunctional bioprosthetic valves and conduits. With the introduction of self-expanding valves and prestents, dilated native RVOT can be addressed with the transcatheter approach. In this article, the authors review the current practices, technical challenges, and outcomes of TPVR.

Melody transcatheter pulmonary valve replacement: a single-center case series in Southeast Asia

BACKGROUND

Studies of transcatheter pulmonary valve replacement (TPVR) with the Melody valve have demonstrated good clinical and hemodynamic outcomes. Our study analyzes the midterm clinical and hemodynamic outcomes for patients who underwent Melody valve implantation in Southeast Asia.

METHODS

Patients with circumferential conduits or bioprosthetic valves and experiencing post-operative right ventricular outflow tract (RVOT) dysfunction were recruited for Melody TPVR.

RESULTS

Our cohort (n = 14) was evenly divided between pediatric and adult patients. The median age was 19 years (8-38 years), a male-to-female ratio of 6:1 with a median follow-up period of 48 months (16-79 months), and the smallest patient was an 8-year-old boy weighing 18 kg. All TPVR procedures were uneventful and successful with no immediate mortality or conduit rupture. The primary implant indication was combined stenosis and regurgitation. The average conduit diameter was 21 ± 2.3 mm. Concomitant pre-stenting was done in 71.4% of the patients without Melody valve stent fractures (MSFs). Implanted valve size included 22-mm (64.3%), 20-mm (14.3%), and 18-mm (21.4%). After TPVR, the mean gradient across the RVOT was significantly reduced from 41 mmHg (10-48 mmHg) to 16 mmHg (6-35 mmHg) at discharge, p < 0.01. Late follow-up infective endocarditis (IE) was diagnosed in 2 patients (14.3%). Overall freedom from IE was 86% at 79 months follow-up. Three patients (21.4%) developed progressive RVOT gradients.

CONCLUSION

For patients in Southeast Asia with RVOT dysfunction, Melody TPVR outcomes are similar to those reported for patients in the US in terms of hemodynamic and clinical improvements. A pre-stenting strategy was adopted and no MSFs were observed. Post-implantation residual stenosis and progressive stenosis of the RVOT require long term monitoring and reintervention. Lastly, IE remained a concern despite vigorous prevention and peri-procedural bacterial endocarditis prophylaxis.

Current status of transcatheter intervention for complex right ventricular outflow tract abnormalities

Various transcatheter interventions for the right ventricular outflow tract (RVOT) have been introduced and developed in recent decades. Transcatheter pulmonary valve perforation was first introduced in the 1990s. Radiofrequency wire perforation has been the approach of choice for membranous pulmonary atresia in newborns, with high success rates, although complication rates remain relatively common. Stenting of the RVOT is a novel palliative treatment that may improve hemodynamics in neonatal patients with reduced pulmonary blood flow and RVOT obstruction. Whether this option is superior to other surgical palliative strategies or early primary repair of tetralogy of Fallot remains unclear. Transcatheter pulmonary valve replacement has been one of the biggest innovations in the last two decades. With the success of the Melody and SAPIEN valves, this technique has evolved into the gold standard therapy for RVOT abnormalities with excellent procedural safety and efficacy. Challenges remain in managing the wide heterogeneity of postoperative lesions seen in RVOT, and various technical modifications, such as pre-stenting, valve ring modification, or development of self-expanding systems, have been made. Recent large studies have revealed outcomes comparable to those of surgery, with less morbidity. Further experience and multicenter studies and registries to compare the outcomes of various strategies are necessary, with the ultimate goal of a single-step, minimally invasive approach offering the best longer-term anatomical and physiological results.

Simultaneous Stenting With Edwards SAPIEN Transcatheter Pulmonary Valve Replacement

Background

Prestenting of the landing zone for transcatheter pulmonary valve replacement (TPVR) with a balloon-expandable valve can dilate a stenotic right ventricular outflow tract (RVOT), prevent paravalvar leak (PVL), and protect against conduit tear. Simultaneous stenting (SS) with the Melody valve has been described, but to our knowledge, SS with a SAPIEN valve has not been reported. We report our experience with this novel technique.

Methods

A retrospective chart review of patients who underwent TPVR at Rady Children's hospital and UCSD Medical Center was performed. Patients were included if they had underwent SAPIEN TPVR with SS. Rationale for stent choice was a bare metal stent to relieve long-segment stenosis and covered stents to prevent PVL or to protect against conduit tear.

Results

A total of 17 cases were identified. The majority of RVOTs were transannular patches (n = 9, 56%), with a minimum diameter of 19.6 ± 5.2 mm, and the most common valve placed was an Edwards SAPIEN 26.0 mm (n = 10, 59%). All SAPIEN valves placed were of the S3 generation. The procedure was successful in all patients, with no conduit tears. Minor complications occurred in 3 patients (17.6%).

Conclusions

Simultaneous stent deployment with a SAPIEN TPVR is an alternative 1-step technique for patients who require prestenting. SS simplifies the procedure, has low complication rates, and offers the benefits of a longer landing zone and decreased PVL.

Transcatheter Pulmonary Valve Replacement: A Review of Current Valve Technologies

Transcatheter pulmonary valve replacement was first performed by Dr Philip Bonhoeffer, who implanted a Medtronic Melody valve in a human in 2000. Over the past 2 decades, there have been many advances in transcatheter pulmonary valve technology. This includes the use of the SAPIEN transcatheter heart valve in the pulmonary position, modifications and refinements to valve implantation procedures, and development of self-expanding valves and prestents to treat large diameter native or patched right ventricular outflow tracts. This article reviews the current transcatheter pulmonary valve technologies with a focus on valve design, screening process, implant procedure, and clinical outcomes.

Piggyback mounting for stent and valve deployment during percutaneous pulmonary valve implantation

OBJECTIVES

We report our experience in simultaneously implanting multiple stents and valves mounted on a single balloon before and during transcatheter pulmonary valve placement.

BACKGROUND

Heterogeneity and complexity of the right ventricular outflow tract (RVOT) may complicate stent deployment when preparing a landing zone for transcatheter pulmonary valve implantation.

METHODS

Retrospective analysis of patients from Children's Hospital of Colorado, USA; and Oslo University Hospital, Norway, undergoing transcatheter pulmonary valve replacement that had at least two stents mounted on a single balloon, deployed in the RVOT.

RESULTS

Over a 42-month period, a total of 50 subjects from the two centers met inclusion criteria for the study. Subjects were predominantly male (58%), and the median age was 17 years (4-78 years). In six subjects (12%), there was need for prestenting with use of the double or triple stent piggyback technique. Forty subjects (80%) had a Melody ™ TPV implanted. In 45 cases (90%), one or more stents were mounted over the pulmonary valve using its delivery system, either the Ensemble for the Melody™ TPV or the Edwards Commander for the SAPIEN 3 THV. Thirty-seven subjects (74%) had one stent mounted and eight subjects (16%) had two stents mounted over the pulmonary valve for simultaneous deployment. No complications related to this technique were reported.

CONCLUSIONS

The piggyback technique aims to simplify and facilitate adequate conduit preparation and valve insertion by minimizing manipulation across the outflow tract and decreasing the risk of stent distortion, misalignment, and embolization.

Early multicenter experience of Melody valve implantation in India

Background

Transcatheter valves provide a safe and effective alternative to surgery for treating dysfunctional right ventricular outflow tracts (RVOTs). We present our early multicenter experience of percutaneous pulmonary valve implantation (PPVI) using Melody valve (Medtronic Inc., Minneapolis, MN).

Methods

Patients with stenosed conduits or degenerated bioprosthetic valves in RVOT with combined stenosis and regurgitation were evaluated for suitability of Melody valve implantation. After undergoing an initial structured training, PPVI using Melody transcatheter pulmonary valve (TPV) was guided by an approved proctor. Conduits were serially dilated and prestented with careful coronary interrogation, and bioprosthetic valves were dilated with high-pressure balloons. Clinical and echocardiographic follow-up was performed at 6 monthly intervals.

Results

Fifteen patients (three females) aged 23.1 ± 9.5 years in NYHA Class II-III underwent Melody TPV implantation in four Indian centers. The underlying anatomy comprised surgically implanted bioprosthetic valves for pulmonary regurgitation (n= 5), conduit repair for pulmonary atresia (n = 4), Rastelli repair (n = 3), truncus (n = 1), and Ross procedure (n = 2). Twelve patients had more than one previous surgery. Doppler gradient decreased from 74.2 ± 21.5 mmHg to 10.2 ± 4.5 mmHg after the PPVI. At a median follow-up of 14 months (1-39 months), all the patients were in NYHA Class I with echocardiographic gradients of 8 ± 5.7 mmHg with no evidence of pulmonary regurgitation. There were no major procedural adverse events or deaths.

Conclusions

Our early experience shows encouraging results of the PPVI program in India with proctored case selection and meticulous planning. It also confirms the safety and efficacy of Melody TPV for treating dysfunctional RVOT in postoperative patients.

Procedural technique for hybrid pulmonary valve replacement in infants and small children

OBJECTIVES

Hybrid approach to pulmonary valve replacement (PVR) in the paediatric population has been reported, although data in infants and small children are limited. Several strategies are now possible. The aim of this study is to review our hybrid PVR strategy in a complex patient cohort, outlining a variety of approaches employed in our centre.

METHODS

We performed a retrospective review of infants and small children who underwent hybrid PVR between May 2017 and April 2019 in a single tertiary cardiology centre. Medical records were reviewed to ascertain demographic, clinical and outcome data.

RESULTS

Ten patients with a median (interquartile range) age of 1.5 years (1.1-1.9) and weight of 8.8 kg (8-10.6) were managed with hybrid pulmonary valve insertion. Eight patients had perventricular approach (4 sternotomy and 4 subxiphoid) and 2 patients had surgically sutured valve. Six patients underwent cardiopulmonary bypass for associated lesions. Three had insertion of the valve into conduits and 7 were deployed into native right ventricular outflow tracts. The pulmonary valve was successfully inserted in all 10 patients with no mortality. Postprocedural complications included paravalvar leak in 2 patients, suspected endocarditis in 1 patient who developed early valve regurgitation and wound infection in 1 patient.

CONCLUSIONS

Several approaches to hybrid PVR may be employed in small children with a high success rate. Follow-up studies are required to evaluate longer term durability of these approaches compared to standard surgical replacement.

Melody Valve Fracture Causing Mitral Stenosis: Novel Solution for Transapical Valve-in-Valve

The use of Melody valves in the mitral position has been introduced in clinical practice. Stent fracture is a recognized complication of Melody valve implantation in the pulmonary position; however, reports in the mitral position are rare. We present the case of an 8-year-old boy in whom complete fracture of the proximal stent struts occurred, causing acute severe mitral stenosis, and in whom urgent hybrid transapical Melody valve implantation in the fractured Melody valve was performed successfully using a novel modified technique. This modification simplified the implantation, led to reduced time of the procedure, and minimized hemodynamic instability.

Right ventricular outflow tract prestenting with AndraStent XXL before percutaneous pulmonary valve implantation

BACKGROUND

The indications for percutaneous pulmonary valve implantation (PPVI) have been extended to include large dysfunctional right ventricular outflow tracts (RVOTs). Prestenting of the RVOT is commonly performed before PPVI in order to ensure a stable landing zone. The AndraStent XXL (AndraMed GmbH, Reutlingen, Germany), a cobalt-chromium stent with semi-open cell design, has unique mechanical properties in this indication but is no longer available in France.

AIMS

To assess the efficiency of AndraStent XXL before PPVI.

METHODS

In this retrospective multicentre cohort study, 86 AndraStents XXL were implanted in 77 patients in 6 centres.

RESULTS

PPVI was indicated mainly for pulmonary regurgitation (75.3%) in native or patched RVOT (88.3%). The stents were manually mounted on balloon catheters and delivered through sheaths using a conventional femoral approach. PPVI was performed successfully in 97.4% of patients after successful prestenting, generally during the same procedure (77.9%). There were no deaths associated with stent implantation, and four patients experienced five complications, mainly stent embolization, including one requiring surgery. Neither stent fracture nor dysfunction were observed in any patient during a mean follow-up of 19.2±8.7months. Stent analysis showed an excellent maximal stent expansion (97.1%) regardless of balloon size. A 22.3%±3.4 stent shortening with a 30mm balloon was observed.

CONCLUSIONS

Implantation of large cobalt-chromium AndraStent XXL stents is efficient for prestenting before PPVI.

Percutaneous pulmonary valve implantation (PPVI) in non-obstructive right ventricular outflow tract: limitations and mid-term outcomes

BACKGROUND

Percutaneous pulmonary valve implantation (PPVI) has been established as a safe and effective alternative to surgery treating patients with a failing pulmonary valve conduit. Nevertheless, the majority of patients in need of a valve have a native, non-obstructive right ventricular outflow tract (RVOT). The current approved stent-valves have a balloon-expandable design. Pre-stenting of the RVOT to create a landing zone and also protect the valve stability is usually mandatory; large, non-obstructive RVOTs need pre-stenting to reduce the RVOT-diameter for a balloon-expandable valve implantation.

METHODS

A retrospective study design was used to analyze the medium-term outcome after PPVI in a series of 26 patients with native or reconstructed RVOT.

RESULTS

PPVI was successfully performed in all, but 1 (96%). Within the follow-up of a minimum of 2 years, the percutaneous implanted valves remained competent; a significant pressure gradient was not detected. Furthermore, no PPVI-related complications such as endocarditis, migration or stent fractures were observed. The electrocardiogram at rest, in particular the QRS duration remained unchanged immediate post-PPVI as well as at medium-term follow-up of 24 months. However, ventricular arrhythmias were documented in 3 patients (11.5%); all patients were successfully treated with antiarrhythmic drugs, utilizing metoprolol. A trial of an invasive catheter based RVOT-ablation in one remained unsuccessful; pre-stented RVOT did not allow a successful intervention.

CONCLUSIONS

Medium-term follow-up showed excellent results of the mechanical valve function. PPVI utilizing balloon-expandable stent-valves in a native RVOT remains an off-label use. Despite our encouraging results, advanced manipulations of the patched or native RVOT might be associated with significant ventricular arrhythmias. There is a need for less invasive RVOT reduction devices.

SAPIEN valve for percutaneous transcatheter pulmonary valve replacement without "pre-stenting": A multi-institutional experience

OBJECTIVES

To describe a multicenter experience of percutaneous transcatheter pulmonary valve replacement (TPVR) using the Edwards SAPIEN S3 valve without the use of a prior stent ("pre-stenting").

BACKGROUND

The SAPIEN S3 and XT valves have durable cobalt-chromium stent frames which may allow for TPVR in large diameter dysfunctional right ventricular outflow tracts (RVOTs) without pre-stenting the landing zone.

METHODS

A retrospective review was performed of all patients with Congenital Heart Disease and dysfunctional RVOT who underwent TPVR using the SAPIEN valve without the use of a pre-stent. Imaging data, procedural elements, and clinical follow-up data were collected to evaluate short and intermediate-term results.

RESULTS

Fifty-seven patients underwent percutaneous placement of the SAPIEN valve in the pulmonary position without the use of pre-stenting. The anatomical substrate varied: native RVOTs (n = 41), conduits (n = 10), and bioprosthetic valves (n = 6). There were no cases in which the valve could not be implanted and no cases of valve embolization or misplacement. On follow-up (range 1 month to 2.2 years, median 5.3 months), no patients had significant obstruction or regurgitation around the valve. There were no frame fractures. There were no procedural deaths. Major complications included severe aortic compression (n = 1) requiring surgical explantation and tricuspid valve injury requiring surgical intervention (n = 2).

CONCLUSIONS

This limited multi-institutional experience demonstrates that the SAPIEN valve can be used for TPVR without the use of a pre-stent without medium-term risk of frame fracture, paravalvar leak, or embolization. Longer term follow-up is required to fully assess this method.

Pulmonary Valve Regurgitation: Neither Interventional Nor Surgery Fits All

Introduction: PV implantation is indicated for severe PV regurgitation after surgery for congenital heart defects, but debates accompany the following issues: timing of PV implantation; choice of the approach, percutaneous interventional vs. surgical PV implantation, and choice of the most suitable valve. Timing of pulmonary valve implantation: The presence of symptoms is class I evidence indication for PV implantation. In asymptomatic patients indication is agreed for any of the following criteria: PV regurgitation > 20%, indexed end-diastolic right ventricular volume > 120-150 ml/m2 BSA, and indexed end-systolic right ventricular volume > 80-90 ml/m2 BSA. Choice of the approach: percutaneous interventional vs. surgical: The choice of the approach depends upon the morphology and the size of the right ventricular outflow tract, the morphology and the size of the pulmonary arteries, the presence of residual intra-cardiac defects and the presence of extremely dilated right ventricle. Choice of the most suitable valve for surgical implantation: Biological valves are first choice in most of the reported studies. A relatively large size of the biological prosthesis presents the advantage of avoiding a right ventricular outflow tract obstruction, and also of allowing for future percutaneous valve-in-valve implantation. Alternatively, biological valved conduits can be implanted between the right ventricle and pulmonary artery, particularly when a reconstruction of the main pulmonary artery and/or its branches is required. Hybrid options: combination of interventional and surgical: Many progresses extended the implantation of a PV with combined hybrid interventional and surgical approaches. Major efforts have been made to overcome the current limits of percutaneous PV implantation, namely the excessive size of a dilated right ventricular outflow tract and the absence of a cylindrical geometry of the right ventricular outflow tract as a suitable landing for a percutaneous PV implantation. Conclusion: Despite tremendous progress obtained with modern technologies, and the endless fantasy of researchers trying to explore new forms of treatment, it is too early to say that either the interventional or the surgical approach to implant a PV can fit all patients with good long-term results.

Interventional Cardiology for Congenital Heart Disease

Congenital heart interventions are now replacing surgical palliation and correction in an evolving number of congenital heart defects. Right ventricular outflow tract and ductus arteriosus stenting have demonstrated favorable outcomes compared to surgical systemic to pulmonary artery shunting, and it is likely surgical pulmonary valve replacement will become an uncommon procedure within the next decade, mirroring current practices in the treatment of atrial septal defects. Challenges remain, including the lack of device design focused on smaller infants and the inevitable consequences of somatic growth. Increasing parental and physician expectancy has inevitably lead to higher risk interventions on smaller infants and appreciation of the consequences of these interventions on departmental outcome data needs to be considered. Registry data evaluating congenital heart interventions remain less robust than surgical registries, leading to a lack of insight into the longer-term consequences of our interventions. Increasing collaboration with surgical colleagues has not been met with necessary development of dedicated equipment for hybrid interventions aimed at minimizing the longer-term consequences of scar to the heart. Therefore, great challenges remain to ensure children and adults with congenital heart disease continue to benefit from an exponential growth in minimally invasive interventions and technology. This can only be achieved through a concerted collaborative approach from physicians, industry, academia and regulatory bodies supporting great innovators to continue the philosophy of thinking beyond the limits that has been the foundation of our specialty for the past 50 years.