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Long-term freedom from angina
and ischemic events after coronary artery bypass graft (CABG) surgery
is limited by degeneration of saphenous vein grafts. Vein graft stenosis
may begin within the first year after surgery, but becomes increasingly
prevalent after the first five years following a bypass operation. Stenosis
results from intimal hyperplasia, atherosclerotic plaque build-up, and
graft remodeling similar to that observed in native coronary arteries.
In fact, only 80 percent of vein grafts remain patent five years after
surgery, versus 50 to 60 percent at 7 to 10 years. The outcome is better
with internal mammary grafts. The optimal management of saphenous vein
stenosis is uncertain. Angioplasty for vein graft disease results in even
higher restenosis rates (40 to 70 percent) than seen in native coronary
vessels. Stenting results in lower restenosis rates and is usually used
for vein graft interventions. Re-do CABG may be necessary in certain cases,
however, it is associated with increased perioperative mortality and with
less complete revascularization and control of symptoms when compared
to the first CABG. Stenting are very effective in the treatment of saphenous
vein graft lesions. If restenosis occurs, brachytherapy
may be used to further reduce the restenosis rate.
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A major problem in saphenous vein graft interventions is distal embolization resulting in no-reflow following successful intervention leading to elevated cardiac enzymes and Q non-Q wave myocardial infarctions. This is particularly worrisome in older degenerated grafts. In fact using distal protection devices, plaque debris can be retrieved which would otherwise go distally. In addition, older grafts tend to redevelop ischemia due to new disease in the unstented segment of the saphenous vein graft as well as restenosis.
Revascularization of totally occluded saphenous vein graft is associated with a lower initial success rate and higher complication rate. However, when no other options are available, these can be achieved. Interventionalists at BIDMC have recently started taking a step approach to these totally occluded vein grafts with recanalization, spot stenting, and radiation if restenosis occurs.