By Jana Soeldner Danger
A new type of stent that is absorbed by the body after supporting an artery previously blocked with plaque may eventually replace traditional metal stents. Memorial Regional and Holy Cross hospitals are currently among about 60 medical centers around the country testing the devices.
The absorbable stents, which have been used for three years in Europe, are made of carbon-based polymers. As do traditional metal stents, they support a cleared artery during the healing period, which is usually about three months. Then, unlike permanent stents, they begin to gradually disappear as the artery wall absorbs them.
Studies suggest that the absorbable stents may reduce the risk of clotting and allow the affected artery to return more closely to its original condition, says Dr. Luis Tami, medical director of interventional cardiology at the Memorial Cardiac and Vascular Institute in Hollywood. They may also reduce the need for anticoagulants.
“Normal arteries dilate and contract naturally as the body needs them to,” Dr. Tami says. “When a metal stent is put in place, it stays there forever and the artery opening always remains the same. With the absorbable stent, the artery may be able to heal and recover normal function.”
“I think this will be the next big thing in stents,” says Dr. Joshua Purow, primary investigator of the study at Holy Cross. “There probably will still be a role for metal stents, but if these turn out to have the same value, then the absorbable stents probably will at some point replace them.”
During a stent procedure, a doctor uses a wire to insert a balloon catheter, with a collapsed stent over it, to the narrowed area of an artery. The doctor then inflates the balloon to open the artery. The stent also expands and locks into place to keep the artery open.
In the early years of stents, there were problems with the formation of scar tissue and clotting. Today, stents contain drugs that prevent scar tissue, and patients typically take anticoagulants, or blood thinners, for extended periods of time. “The problem of clotting is now very rare,” Dr. Tami says.
But anticoagulants have their own side effects, such as prolonged bleeding, dizziness, muscular weakness and hair loss. An advantage of the absorbable stents is that they may reduce the time that a patient needs to take these drugs.
Also, because traditional metal stents remain in the body, they may interfere with modern imaging procedures, such as MRI and CT scanning, for the rest of a patient’s life. “A metal stent can also complicate things if a patient needs a bypass later on,” Dr. Tami says.
It’s too early to say for sure whether the absorbable stents will do everything doctors hope they will do. “It’s difficult to predict,” says Dr. Purow. “In the past we’ve seen a lot of technology that looked promising and turned out to have no value. But our biggest hope is that the vessel an absorbable stent is placed in will return to the function of a more normal vessel.”
“We want to make sure the study is well done so it can answer all the questions we have,” Dr. Tami says. “And we know that the techniques will continue to improve. It’s a field that’s highly dynamic.”