study comparing two methods of expanding stents placed in legs of diabetics with peripheral vascular disease

Conditions: PERIPHERAL VASCULAR DISEASE

Summary: despite recent advances in stent technology and its widespread application in the treatment of peripheral vascular disease (pvd), incidences of partial or complete blockage of stent lumen (in-stent restenosis) due to in growth of cells (neo-intimal proliferation) is unacceptably high. in diabetics with long superficial femoral artery (sfa) lesions, in-stent restenosis rates are higher than in non-diabetics. consequently interventional techniques that curtail in-stent restenosis have to be explored. cryoplasty is a stent expansion method in which a balloon is expanded using pressurized nitrous oxide gas. as the nitrous oxide expands in the balloon it cools the surroundings to about -10 degrees c. this induces programed death (apoptosis) of the smooth muscle cells in arterial wall. the investigators hypothesize that cryoplasty, by inducing an apoptotic smooth muscle cell response, when applied to post-dilation of nitinol self-expanding stents in the superficial femoral artery (sfa) of diabetics, would lead to decreased in-stent restenosis due to decreased neointimal proliferation.

the pre-recruitment process would identify diabetics who have life-style limiting claudication in their legs. based on the physicians decision such patients may have to undergo a peripheral vascular intervention of the sfa, with placement of self-expanding nitinol stents. if such a decision is made, the patient will be randomized to either cryoplasty balloon post-dilation of the stent or to conventional angioplasty balloon post-dilation after obtaining informed consent. at one year, in segment (stent + 10 mm beyond its proximal and distal edges) peak systolic velocity by duplex ultrasound will be measured in all subjects to assess the rate of binary restenosis defined as a \> or = 2.5 times increase in peak systolic velocity (primary endpoint). a 6 month resting ankle brachial index, and binary restenosis may be assessed as a secondary endpoint of the study.

Eligibility criteria:
inclusion criteria: * diabetics, insulin or non-insulin dependent above 21 years of age * able to provide an informed consent * life expectancy \> 1 year * presenting with with moderate claudication (rutherford stage 2), severe intermittent claudication (rutherford stage 3), chronic critical limb ischemia with pain while the patient was at rest(rutherford stage 4), or chronic critical limb ischemia with ischemic ulcers/gangrene(rutherford stage 5/6) * placement of \> 5 mm in diameter self-expanding nitinol stent in the sfa, with at least 1 vessel infra-popliteal runoff * placement of \> 60 mm in length self-expanding nitinol stent in the sfa, with at least 1 vessel infra-popliteal runoff exclusion criteria: * serum creatinine of \>= 2.0 mg/dl * presence of iodinated contrast allergy * presence of allergy to aspirin and plavix * pregnancy * relative or absolute contraindication for anticoagulation * history of allergy to angiomax and unfractionated heparin or heparin induced thrombocytopenia (hit) * white blood count \< 3000; platelet count \< 100000, and baseline hemoglobin \< 10 g/dl * absence of brisk at least 1 vessel infra-popliteal runoff to the foot * left ventricular ejection fraction \< 25% * relative or absolute contraindication for anticoagulation

Keywords: diabetes peripheral vascular disease (pvd) superficial femoral artery (sfa) cryoplasty restenosis