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Why do arteries close back off after angioplasty
surgery?
Despite the creation of several devices to treat narrowing within the arteries of the
heart, cardiologists have been challenged to find the ideal solution which will
permanently prevent the recurrence of plaque formation within the coronary artery. The
re-development of this blockage, commonly known as restenosis, following a
"balloon" procedure to treat the narrowing is well documented and can occur
within several months following the surgery.
In early studies, restenosis appeared to occur in about one-third of the patients who
had such a procedure done. Today it is recognized that the restenosis rate following
balloon angioplasty may reach up to 50%. If restenosis is prevented within the first six
months following initial treatment, the likelihood of recurrence after that time is
somewhat low, although still possible.
"No single culprit has been identified as causing these recurrences. There is an
element of elasticity of the artery, itself, involved in many of these lesions, so that
almost immediately following the surgery the opening narrows somewhat. There is also a
complicated process involving microscopic build-up of material within the arterial wall,
as well as regrowth of plaque with scar tissue, with possible development of a blood clot
on the scar tissue.
Fortunately for most patients, complete blockage is somewhat unusual following a
balloon procedure, thus the rate of heart attack in this group of patients is relatively
low. Particularly when patients are informed of this possibility and instructed that
symptoms such as recurrent chest pain are important signals not to be ignored. Follow-up
testing with a treadmill study or a nuclear medicine stress test during the first six
months following a balloon procedure can help identify patients in the early stages of
restenosis. However, it should be noted that many patients with recurrent blockage
experience no symptoms of chest pain.
In addition, it is important following any balloon procedure to maximize the
possibility that restenosis will not occur. This can be done through diet modification and
medications to reduce or eliminate specific risk factors. Patients who continue to smoke
heavily following balloon angioplasty, as well as patients who have continuing high
cholesterol levels seem to have a somewhat higher recurrence rate.
If restenosis should occur, there are additional options which can be undertaken,
including a metallic scaffold-like apparatus known as a stent. Much investigation is being
carried out to evaluate the effectiveness of a stent laden with different hormones or
other substances, designed to prevent restenosis when placed within the artery.
Anti-growth factor agents and other more sophisticated approaches are also being studied
experimentally.
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