Impressive Progress In Interventional Cardiology - From 1st Balloon Inflation To First Bioabsorbable Stent

Main Category: Cardiovascular / Cardiology
Article Date: 15 May 2006 - 8:00 PDT

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When pioneering interventional cardiologists introduced angioplasty and stenting more than 20 years ago, few could have imagined that, one day, severely diseased coronary arteries would be propped open virtually end-to-end with tubular metal scaffolding. Fewer still could have envisioned how to dismantle that mesh support system once the artery healed.

Dr. Richard S. Stack, professor emeritus of medicine at Duke University, Durham, NC, had that vision. Today, during the Society for Cardiovascular Angiography and Interventions (SCAI) 29th Annual Scientific Sessions in Chicago, Dr. Stack will trace the evolution of interventional cardiology from inflation of the first angioplasty balloon to implantation of the first bioabsorbable stent, in a Founders' Lecture entitled, "How Can You Get Out of a Full-Metal Jacket?"

"It's been an amazing story. It's incredible to see how far we've come in 20 years," said Dr. Stack, who is also president of Synecor, a company that develops new medical technology, including the bioabsorbable stent.

In the early days of percutaneous transluminal coronary angioplasty (PTCA), each procedure took three to four hours to complete, and fully one in 20 patients suffered a heart attack in the catheterization laboratory. There was little an interventional cardiologist could do, other than rush the patient to surgery.

Introduction of the steerable guidewire made PTCA easier to do and shortened procedure times. Development of the perfusion catheter meant that interventional cardiologists could re-establish blood flow to the heart and stabilize patients in case of a sudden arterial blockage.

Bare metal stents and new anti-clotting medications reduced the chances of sudden arterial closure. However, stents proved vulnerable to clogging with scar tissue and other debris months after implantation, a complication known as restenosis.

Drug-eluting stents, introduced just a few years ago, markedly reduce the risk of restenosis. These stents have quickly become a mainstay of interventional therapy, but their use to treat large segments of the coronary circulation has created new challenges.

"Over the years, we have been in a relentless pursuit to re-establish blood flow through the coronary artery," said Dr. Stack. "Today, because coronary artery disease is also relentless, patients end up collecting a 'full metal jacket' of drug-eluting stents."

A metal-clad artery poses problems should the patient ever need bypass surgery. Implanted metal also makes it impossible to use increasingly powerful noninvasive imaging techniques, such as multislice computed tomography and magnetic resonance imaging, to evaluate the health of the artery.

Enter bioabsorbable stents, experimental devices that have recently been implanted in humans for the first time. Bioabsorbable stents have all the strength of a metal stent, and can even release drugs into the artery to prevent restenosis. The big difference: Once the artery is healed, the bioabsorbable stent is engulfed by the arterial wall and dissolves into carbon dioxide and water, returning the artery to its natural state.

"A conventional metal stent is like having a broken arm and never getting the cast removed," Dr. Stack said. "Once the artery heals, you don't need the stent."

The Founders' Lecture is an annual tradition at the SCAI Annual Scientific Sessions. It was established to honor the pioneers of invasive/interventional cardiology and founders of SCAI.

Headquartered in Bethesda, Md., the Society for Cardiovascular Angiography and Interventions is a 3,400-member professional organization representing invasive and interventional cardiologists. SCAI's mission is to promote excellence in invasive and interventional cardiovascular medicine through physician education and representation, and advancement of quality standards to enhance patient care. SCAI was organized in 1976 under the guidance of Drs. F. Mason Sones and Melvin P. Judkins. The first SCAI Annual Scientific Sessions were held in Chicago in 1978.

Kathy Boyd David
jdavid62@juno.com
Society for Cardiovascular Angiography and Interventions
http://www.scai.org