Congenital Pulmonic Valve Dysfunction Treated With SAPIEN 3 Transcatheter Heart Valve (from the COMPASSION S3 Trial)

Heart Valve Replacement in Children: Homografts to Partial Heart Transplantation

Congenital valvular abnormalities in pediatric patients represent a complex surgical problem that carries with it significant morbidity and mortality. Repair of native valves may not always be feasible, leading to requisite surgical intervention. This has led to the development of mechanical valves, bioprosthetic valves, homografts, stented valves, the Ross operation, and finally, the ultimate development of partial heart transplantation. Each technique carries with it potential benefits and limitations. A comprehensive literature search in concert with expert opinion was completed. This yielded a total of 35 applicable references, with the goal to describe the indications, benefits, and risks associated with each approach. Pediatric patients present a unique problem when considering intervention for irreparable valvular abnormalities. Each technique provides a unique opportunity for mitigation of extant pathology but carries with it potential for risks that are inherent to the approach and must be considered. Partial heart transplant is the only technique which provides the opportunity for definitive valvular replacement in pediatric patients. Although each technique does provide an opportunity to resolve congenital valvular disease, the development of partial heart transplantation is a revolutionary technique that is unique in its ability to grow with the patient. The remaining techniques, at a minimum, require further intervention as the patient grows and develops. Although the literature is clear that there are a variety of options available to surgeons, there is only 1 which can resolve congenital valvular disease with 1 operation.

Delivery systems for transcatheter therapies of congenital heart disease

INTRODUCTION

Delivery systems are crucially important for the implantation of medical devices in patients with congenital heart disease. However, very little data is available comparing the advantages and disadvantages of the various delivery systems.

AREAS COVERED

This article describes the delivery systems and methods used for delivery of atrial septal occluder devices, ventricular septal occluder devices, devices to occlude patent arterial ducts, and transcatheter pulmonary valves. Delivery systems are compared relating to prepping and loading, positioning of the delivery sheath/catheter, deployment, ability to recapture and reposition, as well as device release.

EXPERT OPINION

For most ASD/VSD/PDA occluder devices, the basic delivery mechanism has changed very little over the preceding 20 years. Future modifications may focus on meaningful modifications to the cable systems that reduce stiffness and improve angulation at the connection to the device. Over the next 5-10 years, it is expected to see significant changes to delivery systems used for transcatheter pulmonary valve implantation, that result in improvements in the ability to recapture and reposition self-expandable transcatheter valves during the deployment process, combined with kink resistant sheaths that facilitate easy tracking across often complex right ventricular outflow tracts.

Standardized Bench Test Evaluation of Biomechanical Characteristics of Stents Used in Right Ventricular Outflow Tract Revalvulation

PURPOSE

Pre-stenting of the right ventricular outflow tract (RVOT) is commonly performed before percutaneous pulmonary valve implantation (PPVI), to relieve obstruction, prevent valved stent fractures, and provide a landing zone. This study aimed to evaluate the biomechanical characteristics of the stents currently used to perform pre-stenting of the RVOT.

METHODS

We assessed five commercially available stents: Cheatham-Platinum Stent ("CP Stent"), AndraStent XL, AndraStent XXL, Optimus XL, and Optimus XXL. Following stent deployment at nominal pressure, radial and longitudinal elastic recoils and radial resistance were measured. The bending stiffness of the stents crimped onto the balloons was also evaluated.

RESULTS

Three samples were tested for each stent. Our study showed no significant difference between the stent platforms in terms of radial elastic recoil, which was relatively low (< 10%). The longitudinal elastic recoil was also low for all the devices (< 5%). Significant differences were observed in radial resistance (P < 0.001). CP Stent and AndraStent XL exhibited the highest radial resistances. The bending stiffnesses of the stents crimped on their balloons were significantly different (P < 0.00001). Optimus XL and XXL were more flexible than the other stents.

CONCLUSION

This study highlights the significant differences between the stents currently used in RVOT pre-stenting. Stents with good radial resistance are preferred, especially for calcified vessels, and flexibility is crucial for tortuous vessels. We proposed an algorithm for selecting the most suitable stent according to the need for radial force and flexibility, which will help inform clinicians considering RVOT revalvulation.

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.

Catheter-based Interventions in Tetralogy of Fallot Across the Lifespan

Surgical treatment of tetralogy of Fallot (TOF) involves surgical relief of right ventricular outflow tract (RVOT) obstruction and closure of ventricular septal defect. However, some patients may require staged palliation before surgical repair. This traditionally was achieved only with surgery but recently evolved to include catheter-based techniques. RVOT dysfunction occurs inevitably after the surgical repair of TOF and, depending on the surgical approach, manifests as either progressive stenosis, regurgitation, or a combination of both. This predisposes the individual to repeated RVOT interventions with the attendant risks of multiple open-heart surgeries. The advent of transcatheter pulmonary valve replacement has reduced the operative burden, and the expansion of transcatheter pulmonary valve replacement device platforms has widened the type and size of RVOT anatomies that can be treated. This review will discuss the transcatheter therapies available throughout the lifespan of the patient with TOF.