This is certainly an exciting time to be a congenital interventional cardiologist. No doubt the later part of the 20th century laid the foundation for the new millennium; however, since the centennial celebration, several milestone events have already occurred and the future looks as bright as ever. In late 2001, the Amplatzer Atrial Septal Occluder System®, became the first device ever to receive US Food and Drug Administration (FDA) approval for the secundum atrial septal defect (ASD) closure indication. It currently remains the only FDA-approved device for this indication.At the same time, this device was also FDA-approved for closure of Fontan fenestrations. Nearly simultaneously in 2001 came the FDA approval of the CardioSEAL Septal Occluder System® for the high-risk muscular ventricular septal defect closure indication. This highly specific approved indication has been expanded with the frequent 'off-label' use of this non-self-centering septal occluder for closure of small- to moderate-sized secundum ASDs as well as a host of other, less common indications. A clinical trial of a new-generation septal occluder called the BioSTAR™ has recently been launched, with bioabsorbable, drug-eluting implant technology. Device closure of the patent foramen ovale (PFO) in the setting of cryptogenic stroke is currently being evaluated in the Randomized Evaluation of Recurrent Stroke Comparing PFO Closure to Established Current Standard of Care Treatment (RESPECT) trial and the CLOSURE 1 trial. Also, PFO closure device trials are likely to expand into evaluation of PFO closure in the treatment of migraine headaches, particularly those with apreceding aura.
Another milestone came in mid-2003 with the FDA approval of the Amplatzer Duct Occluder® for closure of the patent ductus arteriosus (PDA).This device is the first and, so far, only to be approved for the PDA closure indication.With its availability, PDA closure is now one of the most commonly performed congenital heart interventions. Consequently, patients no longer require surgical PDA ligation other than the premature infant. Additional devices in the short pipeline include devices to close perimembranous ventricular septal defects and muscular ventricular septal defects, which will eventually make it unnecessary for patients with these relatively common congenital heart defects to undergo highly invasive open-heart surgery for correction.
Stenting of large diameter arteries and veins in the treatment of congenital heart defects has become the first line of definitive treatment over the past several years. New second- and third-generation stents have improved overall results, particularly with more predictable stent deployment, smaller delivery profiles, and lower intra-procedural complications. Stents such as the Palmaz Genesis and the Palmaz XL, as well as the Intrastent DS, have broadened the size and variety of vessel pathologies that are treatable. These second-generation balloon-expandable large diameter stents have more flexibility for enhanced maneuverability through complex and smaller radius catheter courses (smaller hearts), high radial hoop strength, and less shortening throughout their expansion range. These improved stents enable the interventional cardiologist to place large diameter-range stents in younger patients with the prospect that the stents will stay in place until adulthood, only requiring further balloon expansion to adjust for vessel/patient growth. Improved balloon technology has played an equally important role in improved large vessel stenting results.
More recently, a number of covered stent graft platforms have become available for the treatment of peripheral vascular disease. It is hoped that larger diameter versions of these covered stents will soon become available, particularly for the treatment of native and post-operative recurrent aortic coarctation. Magnetic resonance imaging (MRI)-compatible covered-stent grafts, such as the Cheatham Platinum Covered Stent, have been used to a limited extent in the US and will be formally evaluated in upcoming clinical trials. The use of three-dimensional (3-D) realtime MRI to direct interventional procedures, instead of X-ray fluoroscopy, is currently under investigation in a select few centers and could become widespread. If so, there will be a significant need for MRI-compatible interventional devices and catheter platforms for safe use in the MRI environment.
Finally, the near future holds promise for a new era of 'hybrid procedures' combining the attributes of open cardiac surgery exposure and the discreteness of catheter-based technologies. A whole new generation of catheter-based devices, such as nitinol flow limiters, implantable valves, and bio-degradable drug-eluting device platforms, will likely play a crucial role. No doubt the future will be exciting for the interventional cardiologist who treats congenital heart disease.