Stent-induced intimal hyperplasia: are there fundamental differences between flexible and rigid stent designs?

PURPOSE To evaluate possible differences in neointimal development resulting from overdilation of rigid versus flexible vascular stents. MATERIALS AND METHODS Twelve vascular sheaths were placed bilaterally through femoral arteries in six swine. After angiographic measurement, 12 stents (six flexible and six rigid) were balloon expanded to 8-mm diameters in 12 6-mm iliac arteries (approximately 30% overdilation). All stents were similar in surface area, gauge, and type of wire (tantalum). The primary difference was longitudinal flexibility (low hoop strength) versus rigidity (high hoop strength). Stents were studied with angiography and intravascular ultrasound 5 weeks after implantation. The animals were killed, and the stented segments were removed and examined histologically. RESULTS Rigid stents maintained larger diameters than flexible stents: mean, 6.52 mm versus 5.82 mm (mean difference, 0.70; standard deviation [SD], 0.47; confidence interval [CI], +/- 0.49; P < .05). In addition, rigid stents developed a thicker, eccentric neointimal reaction relative to flexible stents: mean 1.08 mm versus 0.74 mm (mean difference, 0.338; SD, 0.315; CI, +/- 0.331; P < .05). CONCLUSION Rigid stents maintain larger diameters over the long term relative to flexible stents when overdilated in normal swine arteries. However, a thicker neointima develops within the lumen of rigid stents at follow-up (greater late loss).

[1]  R. Günther,et al.  Iliac and femoral artery stenoses and occlusions: treatment with intravascular stents. , 1989, Radiology.

[2]  J. Blanc,et al.  Constrictive perivenous mesh prosthesis for preservation of vein integrity. Experimental results and application for coronary bypass grafting. , 1986, The Journal of thoracic and cardiovascular surgery.

[3]  K Amplatz,et al.  Nonsurgical placement of arterial endoprostheses: a new technique using nitinol wire. , 1983, Radiology.

[4]  P. Serruys,et al.  Directional atherectomy for treatment of restenosis within coronary stents: clinical, angiographic and histologic results. , 1992, Journal of the American College of Cardiology.

[5]  S Glagov,et al.  Cyclic stretching stimulates synthesis of matrix components by arterial smooth muscle cells in vitro. , 2003, Science.

[6]  U. Mödder,et al.  Renal artery stenosis: preliminary results of treatment with the Strecker stent. , 1991, Radiology.

[7]  Spencer B. King,et al.  Restenosis After Coronary Angioplasty: Potential Biologic Determinants and Role of Intimal Hyperplasia , 1989 .

[8]  G. Becker.  Intravascular Stents: General Principles and Status of Lower‐Extremity Arterial Applications , 1991, Circulation.

[9]  M. Dake,et al.  Tantalum balloon-expandable stent: in vivo swine studies. , 1993, Journal of vascular and interventional radiology : JVIR.

[10]  K. Hausegger,et al.  Iliac artery stenting--clinical experience with the Palmaz stent, Wallstent, and Strecker stent. , 1992, Acta radiologica.

[11]  P. Serruys,et al.  Relative Risk Analysis of Angiographic Predictors of Restenosis Within the Coronary Wallstent , 1991, Circulation.

[12]  P. Doubilet,et al.  The cost of underutilization. Percutaneous transluminal angioplasty for peripheral vascular disease. , 1984, The New England journal of medicine.

[13]  J. Palmaz,et al.  Expandable intraluminal graft: a preliminary study. Work in progress. , 1985, Radiology.

[14]  C M Gibson,et al.  Generalized model of restenosis after conventional balloon angioplasty, stenting and directional atherectomy. , 1993, Journal of the American College of Cardiology.

[15]  D. Liermann,et al.  Expandable tubular stents for treatment of arterial occlusive diseases: experimental and clinical results. Work in progress. , 1990, Radiology.

[16]  C. Dotter,et al.  Transluminally-placed coilspring endarterial tube grafts. Long-term patency in canine popliteal artery. , 1969, Investigative radiology.