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Smaller, Covered Stents Could Increase Safety of Cardiac Repairs

Pediatric Heart News
March 1, 2013

Richard Ringel, MD

Richard Ringel is leading the search for an effective stent for patients with aortic aneurysm related to coarctation of the aorta.

Open surgical repair of aortic coarctation in older pediatric and young adult patients is a serious and invasive procedure involving cardiopulmonary bypass and circulatory arrest—factors that make an endovascular approach attractive.

Over time, patients with repair of coarctation of the aorta by surgery or balloon dilation can develop an outpouching or aneurysm that requires repair or sealing. “The problem is, usually the aortas we’re dealing with are a bit too small for the standard self-expanding covered stents used to repair abdominal aortic aneurysms in adults,” says Johns Hopkins pediatric cardiologist Richard Ringel.

In addition, fibrosis or scarring from earlier surgery and abnormal tissue mean that a self-expanding stent isn’t strong enough to open the narrowing, so a balloon-expandable covered stent is necessary.

Such covered stents would be welcome tools for these and other highrisk therapeutic catheter-based procedures. Ringel is working toward that end as sponsor and principal investigator for three clinical trials aimed at testing the safety of bare metal and covered stents for patients with congenital heart disease. In the Coarctation of the Aorta Stent Trial (COAST), stronger and specially sized bare metal stents were used to repair coarctation of the aorta in late-childhood patients. Two years of data collection are complete, and the acute outcome paper is nearing publication, says Ringel.

In a related trial—the Prevention or Repair of Aortic Wall Injury Associated with Coarctation of the Aorta (COAST II)—Ringel and researchers at more than a dozen sites nationwide are evaluating the safety of specially sized covered stents to repair aortic wall injury that may occur from attempts to repair the problem. “In the United States, there are covered stents in the size needed for the aorta to help repair or prevent aortic wall injury,” says Ringel. The COAST II trial has just reached one year of follow-up.

The third trial, Pulmonary Artery Repair with Covered Stents (PARCS), will be limited to patients undergoing implantation of the Melody transcatheter pulmonary valve and who develop tears during this catheterization. “Once the tear is recognized, the cardiologist can proceed with placement of a covered stent,” Ringel says.

Although the balloon-expandable covered stent being evaluated in these studies is used commonly in Europe and elsewhere, the stents lack FDA endorsement in this country. The stent is a coveted tool here because it “greatly increases the safety of our work,” says Ringel. Even if we don’t plan on using a covered stent and the aorta tears, we’ve only got minutes to avert a disaster. So people would feel much better knowing that they could quickly get a covered stent in to fix the tear.” 

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