The introduction of stents helped restore blood flow to patients who had clogged arteries (atherosclerosis) – without surgery.
Stephen G. Ellis, MD, Section Head of Invasive/Interventional Cardiology in Cleveland Clinic’s Robert and Suzanne Tomsich Department of Cardiovascular Medicine, is studying a new innovation in stenting called bioabsorbable scaffolds (stents).
What are stents?
Stents or scaffolds are small tubes that are inserted into narrowed arteries to support artery walls and keep the blood vessels open.
A brief history of stents
Stents (scaffolds) were first introduced in the early 1990s as a tool in interventional cardiology. They helped make angioplasty (the first breakthrough treatment for atherosclerosis (clogged blood vessels)) safer and more effective.
Drug eluting stents were introduced in the early 2000s. They have a polymer coating on top of the metal skeleton of the stent. The coating exudes a drug that prevents scar tissue from forming and reclogging the artery.
Drawbacks in current designs
- Metal stents provided a sturdy structure that kept treated blood vessels open, but sometimes the blood vessels narrowed again (restenosis) after a few months.
- Drug eluting stents successfully reduced short-term restenosis, but restenosis rates remained a concern over the long term (a year or more). And the formation of blood clots on the stents caused problems.
- All metal stents are permanent and rigid, so stented blood vessels lose their natural capacity to expand under certain conditions (like exercise).
About bioabsorbable scaffolds
Bioabsorbable scaffolds are also stents designed to support blood vessel walls, but they are made out of special materials (similar to those used in “dissolving” sutures) that will eventually break down and decompose after their work is done.
Bioabsorbable stent technology is still in its experimental phase. Many questions remain, such as how long the scaffold needs to remain intact and how sturdy or how delicate the structure needs to be.
The hope for bioabsorbable scaffolds is that they might help:
- Solve the problem of restenosis
- Avoid the problem of clot formation
- Avoid the need for long-term anti-clotting medication
- Avoid chronic, inflammatory processes, which are triggered by the continued presence of a foreign body (metal stent)
- Avoid a permanent, rigid “cage” that encases blood vessels and hinders their ability to flex and expand
“Initial data suggests that the scaffold provides comparable efficacy and safety compared to current generation stents, but that needs to be confirmed in larger populations and whether or not it offers long-term benefits remains to be determined,” says Dr. Ellis.