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Angioplasty & Stents - Artery Re-narrowing

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Angioplasty & Stents
Risks
Effectiveness
Angioplasty vs. Clot Busters
Angioplasty After Clot Busters
Other Devices
Artery Re-narrowing
Angioplasty for Mild Heart Attack
Choosing a Hospital & Doctor
The Angioplasty Procedure

Why do arteries sometimes renarrow?

Unfortunately, blocked arteries that have been cleared with angioplasty and stenting often renarrow. After the procedure, scar tissue grows over the stent and it becomes embedded in the wall of the artery. Sometimes too much scar tissue grows and the artery renarrows. New desposits of fatty plaque may also contribute to this renarrowing. The medical term for renarrowing is restenosis ( stenosis means narrow in Greek), defined as a regrowth that blocks more than 50% of the artery.

How common is arterial renarrowing?

Between 20% and 50% of people treated with balloon-only angioplasty develop renarrowing of the artery. Because stents remain in the artery to prop it open, there is less risk of renarrowing when stents are used — it occurs in as few as 10% of patients who receive bare metal stents and 5% in those with drug-coated stents .31, 87, 88

Some people are more susceptible to renarrowing—patients with diabetes or smaller blood vessels, for example. Doctors can look for restenosis by performing an angiogram (an X-ray of the blood vessels of the heart). But even if the angiogram shows that a treated artery has renarrowed, it should only be reopened if it is causing problems such as chest pain.

Are women less likely to experience renarrowing?

Some studies find that women treated with angioplasty are less likely to develop renarrowing than men. This seems counterintuitive since women have smaller blood vessels than men and smaller blood vessels are more susceptible to renarrowing. It has been argued that women only appear to develop restenosis less often because they are less likely to be sent for testing. In one study, X-rays of the heart six months after stent placement showed less renarrowing in women than men.89 However, 1 year later women were just as likely as men to need a repeat procedure and to complain of chest pain.

Generally, cleared arteries renarrow within 6 months to a year or else not at all. Blockages that develop after this time are not usually related to the first angioplasty. These blockages may be in a different artery or a different section of the treated artery.

How is renarrowing treated?

If the artery renarrows, you may be treated with a repeat angioplasty or stent placement. Stents are more effective than balloon-only angioplasty at reducing the chances of the artery renarrowing yet again.90 Even though arteries treated with stents in the first instance are less likely to renarrow, when they do, this type of restenosis (called in-stent restenosis) is particularly tricky to treat.

Radiation treatment (called brachytherapy or vascular brachytherapy) is currently the only approved treatment for in-stent restenosis. During brachytherapy, a catheter containing pellets of radiation is threaded into the blocked artery as in angioplasty or cardiac catheterization. This catheter is positioned so that the pellets are placed next to the scar tissue, where they zap it with radiation and clear the artery. The treatment usually lasts about 10 minutes and the radiation exposure is similar to a chest X-ray. Sometimes, a balloon with tiny blades embedded on the surface is used to cut away the scar tissue before radiation treatment. The artery renarrows again in 20% to 25% of patients treated with radiation, requiring further treatment.91 Implanting an additional stent at the same time as radiation treatment appears to do more harm than good.92, 93

Drug-coated stents are also proving effective at treating the renarrowing of arteries that have already been treated with plain metal stents.94, 95



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