Restenosis Prevention

Stents have dramatically reduced the incidence of stenosis following percutaneous angioplasty. However, they are also known to restenose within months. Prevention of restenosis therefore depends on several factors:

• Accurate stent placement and expansion, which avoids the occurrence of empty spaces for scar buildup
• Use of targeted treatments to reduce neointimal hyperplasia and restenosis, which include:
  • Drug-eluting stents
  • Perivascular delivery which delivers the drug into the space around the artery
  • Delivery catheters
  • Antibody or peptide-linked drugs
  • Gene-based therapies
  • Cell-based therapies
  • Nanoparticle-based drug delivery
• Lifestyle modifications as advised by the cardiologist, including regular exercise, lowering of blood pressure, quitting smoking and cutting down to one drink of alcohol, and a low-fat diet.
• Use of appropriate medication to prevent platelet clots from forming

There are several categories of drugs for restenosis:

• Drugs which inhibit coagulation, such as anticoagulants, antithrombotic agents and antiplatelet agents like clopidogrel and heparin
• Anti-inflammatory agents such as dexamethasone and tranilast
• Drugs which inhibit proliferation and oppose growth factors, such as ACE inhibitors, trapidil, tyrphostin
• Cytostatic drugs which inhibit cell growth, like paclitaxel and rapamycin
• Lipid-lowering agents such as statins
• Antioxidants such as probucol or resveratrol

Vascular brachytherapy

Vascular brachytherapy is another technique used to prevent or treat a restenotic lesion. Here short-range ionizing therapy is used to inhibit neointimal hyperplasia, so as to prevent shrinkage of the arterial lumen after angioplasty. The radiation produces:

• Inhibition of smooth muscle cell proliferation
• Increased number of cells that enter the apoptosis pathway
• Less fibrosis
• Less negative remodeling, or healing which results in a shrunken lumen

Characteristic changes in irradiated vessels include:

• Persistent absence of endothelium over the irradiated part of the vessel
• Fibrin deposition over the bare area
• Inflammatory cell infiltration of the vessel wall

Vascular brachytherapy can be used alone or following angioplasty of a restenotic lesion. This is performed through a special catheter placed for 10 minutes inside the blocked segment, and containing a source of short-term radiation.

References

• http://eurheartj.oxfordjournals.org/content/ehj/21/21/1739.full.pdf
• http://www.radcliffecardiology.com/articles/treatment-stent-restenosis-past-present-and-future?page=9
• http://circ.ahajournals.org/content/105/22/2586.full