Update on Transcatheter Interventions in Adults with Congenital Heart Disease

The field of adult congenital interventions is unique in the world of cardiac catheterization, combining the structural concepts commonly employed in pediatric heart disease and applying them to adult patients, who are more amenable to device intervention as they no longer experience somatic growth. Rapid advances in the field have been made to match the growing population of adult patients with congenital heart disease, which currently surpasses the number of pediatric patients born with congenital heart disease. Many congenital defects, which once required surgical intervention or reoperation, can now be addressed via the transcatheter approach, minimizing the morbidity and mortality often encountered within adult congenital surgeries. In this paper, we aim to provide a focused review of the more common procedures that are utilized for the treatment of adult congenital heart disease patients in the catheterization laboratory, as examples of current practices in the United States, as well as emerging concepts and devices awaiting approval in the future.

Finite Element Analysis and Bench Testing of Ventricular Septal Defect Occluder

Complications after transcatheter closure of the ventricular septal defect (VSD) is significantly associated with the mechanical behaviour of the VSD occluder. This study aims to investigate the effect of structural parameters of the VSD occluder. A mechanical model of the VSD occluder was constructed by theoretical modelling. The mechanical properties of the VSD occluders with different braiding angles (30°, 45°, 60°), materials (nitinol (NiTi), polydioxanone (PDO)) and waist-heights (3 mm, 4 mm) were analysed and validated by bench tests. For the 30°NiTi, 45°NiTi, 60°NiTi and 45°PDO occluders, the bending angles at the waist under 1 mm radial shrinkage were 112°, 121°, 155° and 155°, respectively. And the maximum principal strains at the waist were 16.62%, 8.19%, 1.20%, and 0.66%, respectively. The maximum radial deformations with 0.5 rad axial bending at the waist were 1.73, 1.44, 0.41 and 1.68 mm, respectively. When the occluders were implanted into VSD with the mean thickness of 3.5 mm, high stress appeared at the margin and the contact area, and the area with the 3-mm-occluder was much larger. In conclusion, the 60°NiTi occluder showed better ability to fit the deformation of the defect than the other NiTi occluders, and the 45°PDO occluder performed better under compression conditions but poorly under bending conditions than the 45°NiTi occluder. The choice of the appropriate waist-height is beneficial to eliminate associative complication by reducing the contact stress.

Occlutech® muscular ventricular septal defect device: the first reported human use

Percutaneous closure of muscular ventricular septal defects has been well described and has not attracted the same controversy or scrutiny as perimembranous defect closure. Therefore, the development of specifically designed devices has been limited. We report the first use of the Occlutech® muscular ventricular septal defect device. Does its design add any significant benefit?

Does the technique of interventional closure of perimembranous ventricular septal defect reduce the incidence of heart block?

OBJECTIVE

To describe the difficulties and differing techniques in the transcatheter placement of amplatz ventricular septal defect devices to close perimembranous ventricular septal defects and place these in the context of the expanding literature on ventricular septal defect catheter closure.

BACKGROUND

Surgery remains the established first-line therapy for closure of haemodynamically significant perimembranous ventricular septal defects. Transcatheter techniques appeared to promise a possible alternative, obviating the need for cardiac surgery. However, significant technical and anatomical constraints coupled with ongoing reports of a high incidence of heart block have prevented these hopes from being realised to any significant extent. It is likely that there are important methodological reasons for the high complication rates observed. The potential advantages of transcatheter perimembranous ventricular septal defect closure over surgery warrant further exploration of differing transcatheter techniques.

METHODS

Between August, 2004 and November, 2009, 21 patients had a perimembranous ventricular septal defect closed with transcatheter techniques. Of these, 14 were closed with a muscular amplatz ventricular septal defect device. The median age and weight at device placement were 8 years, ranging from 2 to 19 years, and 18.6 kilograms, ranging from 10 to 21 kilograms, respectively.

RESULTS

There were 25 procedures performed on 23 patients using 21 amplatz ventricular septal defect devices. Median defect size on angiography was 7.8 millimetres, ranging from 4 to 14.3 millimetres, with a median device size of 8 millimetres, ranging from 4 to 18 millimetres, and a defect/device ratio of 1.1, with a range from 0.85 to 1.33. Median procedure time was 100 minutes, with a range from 38 to 235 minutes. Adverse events included device embolisation following haemolysis in one, and new aortic incompetence in another, but there were no cases of heart block. Median follow-up was 41.7 months, with a range from 2 to 71 months.

CONCLUSIONS

Evaluating transcatheter closure of perimembranous ventricular septal defect using amplatz ventricular septal defect devices remains important, if a technically feasible method with low and acceptable complication rates is to be identified. Incidence of heart block may be minimised by avoiding oversized devices, using muscular devices, and accepting defeat if an appropriately selected device pulls through. Given the current transcatheter technologies, the closure of perimembranous ventricular septal defects should generally be performed in children when they weigh at least 10 kilograms.

Pediatric interventional cardiology: 2009

PURPOSE OF REVIEW

Pediatric interventional cardiology has evolved quite dramatically over the past few decades and now, in 2009, the published literature continues to evolve new percutaneous strategies for managing patients with congenital heart disease, both simple and complex. Our goal for this review was to highlight new techniques and the new devices available to the pediatric interventional cardiologist, and to review the outcomes from past endeavors.

RECENT FINDINGS

Manuscripts published in the past year continue to demonstrate innovation; indicating an exciting and increasing experience of transcatheter treatment of septal communications using either new occluder devices or novel techniques. Bioabsorbable devices and percutaneously implanted valves are leading examples of technological improvements and creativity that will ultimately improve patient outcomes while minimizing invasiveness. Reports on procedural outcomes show technically safe early follow-up, with promising mid-term and long-term results for balloon valvuloplasty, balloon atrial septostomy and pulmonary artery stent implantation. As well, fetal and hybrid interventions have become important new arenas for the pediatric interventionist.

SUMMARY

Pediatric interventions have grown far beyond the early stages of the 1980s as mid-term and long-term outcome data are being reported, and many previously insurmountable hurdles have been overcome by developing new strategies and devices.