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Ask the doctor: Does a collapsed stent need fixing?

Ask the doctor

Does a collapsed stent need fixing?

Q. About 10 years ago, after being unexpectedly short of breath a few times, my brother had a stent put in during an angioplasty procedure. He has been fine since. During a routine visit to his cardiologist, he was told he had a blockage in the vicinity of the stent. A CT scan showed that the stent had collapsed but blood was passing through arteries around the stent. Both my brother's doctor and a cardiologist he saw for a second opinion said the stent cannot be replaced and, since my brother isn't having any symptoms, told him not to worry about it. This doesn't sound right to me. Shouldn't a stent be replaced if it is defective?

A. Although most stents work like they're supposed to, the technology isn't foolproof. Occasionally, a stent doesn't open completely during implantation, making it more likely that problems will develop later. A more common problem is blockage of the stent caused by the body's healing response. The blockage can be partial or total.

Once a stent is placed in a coronary artery, it can't be taken out. Cardiologists can perform procedures to reopen a problematic stent, and sometimes even put a new stent inside an older one, but removal isn't an option.

If a stent is going to become blocked, it usually happens soon — within days or months of implantation. Your brother's case is interesting because the CT scan showed a problem 10 years later. CT scans — even the superfast new ones — don't have the accuracy to show fine details of a stent. With the injection of an x-ray dye, though, they can show how much blood, if any, is flowing through the area.

It sounds like your brother's stent has completely blocked (occluded) the artery, and new blood vessels have grown around the outside of the stent to compensate for the blockage. This is called collateral circulation (see figure). If this is the case, then his doctors are correct. Trying to open up the stent or put in a new one offers him no benefit — it won't alleviate any symptoms like chest pain or breathlessness, since you say he isn't having any problems. And it would expose your brother to the small but real risks that come with this procedure.

Collateral vessels make new connections A network of tiny blood vessels (called collateral circulation) can provide alternate routes around a blocked artery. The new vessels grow and stretch out toward existing arteries or other new blood vessels. By linking different parts of the same artery or different arteries, these new vessels reroute blood around the blockage.

Your brother's heart probably doesn't care that the old stent is blocked, since the new vessels appear to be working just fine. The most important thing for him to focus on now is keeping these new arteries, and the rest of his old ones, in good health. That way he shouldn't need any more stents down the road.

— Richard Lee, M.D. Associate Editor, Harvard Heart Letter

Last updated:	November 27, 2006