Angioplasty

Risks And Possible Complications of Angioplasty

Angioplasty is considered safe and effective, although, as with all medical treatments, there is some risk. In general, possible complications fall into two categories:

• Acute complications – These are complications that occasionally occur during the procedure or immediately afterward.
• Long-term complications – Even when the angioplasty procedure is performed without problems, the artery can narrow again months afterward, causing chest pain to return. This complication is called restenosis.

Acute Complications

Angioplasty is a very safe procedure when performed by experienced cardiologists at top-notch medical centers. In a small percentage of patients, an artery may abruptly close during the procedure, which may trigger a heart attack. A heart attack may also occur if a blood clot is dislodged during angioplasty and completely blocks the artery, cutting off blood and oxygen to the heart.

These complications may or may not require emergency bypass surgery. The death rate among patients who have angioplasty is very tiny, about 0.1% (compared to 1% to 2% for routine bypass surgery).

Restenosis

Restenosis is the most troublesome problem hampering the success of angioplasty. Restenosis is a medical term that refers to the gradual re-narrowing of the artery during several months following the procedure.

• Sometimes, restenosis is caused by blood clots occurring at or near the site of the treatment. Aspirin, heparin, or combinations of anti-clotting drugs are generally used before and after the procedures to try and prevent this.
• Coronary stents that are coated with anti-clotting drugs are now being used in the hope of preventing the immediate formation of blood clots and, over time, restenosis.

Researchers are gaining a better understanding of the restenosis process and experimenting with several different approaches to prevent it. They believe that three complex, interrelated mechanisms are involved.

• Within hours after an angioplasty procedure, the walls of the artery may start to recoil, gradually “caving in” to their original position. This can reduce the channel that was created, sometimes by as much as half.
• Angioplasty, by pressing against the artery wall and creating tiny cracks in the plaque, causes a certain amount of injury to the artery wall. As the body attempts to heal itself, special blood cells that are involved in clotting, called platelets, may accumulate, possibly causing a blood clot.
• Blood clots create a substance, thrombin, that causes the cells of the artery to multiply and new tissue to form. This is a helpful part of the healing process – but, if too much tissue is formed, it can reduce the flow of blood through the artery.

Thanks to an improved understanding of restenosis, several drugs are now being tested to help prevent it.

The reason restenosis occurs is not known, but several conditions increase the risk that the artery will narrow again after angioplasty. These include:

• High blood pressure
• Diabetes
• Angina, both unstable and stable
• Kidney disease requiring dialysis

There is also a theory that procedures affecting blood vessels activate cytomegalovirus (CMV), a herpes virus that is common in older people but is usually dormant. According to this theory, CMV is the factor that allows too many cells to multiply during the artery’s healing process and eventually narrows the artery again.