Coronary stenting with a new, radiopaque, balloon-expandable endoprosthesis in pigs.

Abstract

Background. Intracoronary stents may be effective when used as "bail-out" devices for acute complications after percutaneous transluminal coronary angioplasty. Furthermore, preliminary reports have demonstrated some promising results with stents with regard to the reduction of restenosis. Several stent devices are available for preclinical and clinical evaluation. The use of these stainless-steel stents has been limited by poor visibility during fluoroscopy and thrombogenicity during the first days to weeks after implantation. We therefore investigated the immediate and short-term effects on arterial patency of a new, radiopaque, balloon-expandable coil stent in normal coronary arteries of pigs.Methods and Results. In 10 animals, a stent was placed in two of the three epicardial coronary arteries. During the implantation procedure, the animals received heparin; after the procedure, no antithrombotic drugs were administered. After 1 week (five animals and 10 stents) or 4 weeks (five animals and 10 stents), repeat angiography was performed, followed by pressurefixation of the coronary arteries for light and electron microscopic examination. Angiographic analysis revealed that all stented coronary segments were patent and without signs of intraluminal defects. Scanning electron microscopy showed complete endothelial covering of all stents within 7 days. Light microscopy showed a reduced tunica media locally under the stent wires, which resulted from exerted pressure. The neointima on top of the stent wires measured 56 ,m (range, ,um) after 1 week and 139 ,um (range, 84-250 jum) after 4 weeks.Conclusions. Results from this study show that this radiopaque endoprosthesis can be safely placed in normal coronary arteries of pigs. After 4 weeks, all stents were patent and there was no need for additional antithrombotic treatment, whereas neointimal proliferation was limited.

Frontiers in Interventional Cardiology

“…The metal composition and characteristics of the stent surface may also be important for the performance of the implanted stent. [93][94][95][96][97][98][99][100][101][102] Another factor that must be considered when assessing stent design is the mode of delivery: self-expanding versus balloon-expandable. The currently available self-expanding stents are configured as a slotted tube (Radius) or as a wire mesh (Wallstent) and are composed of either nitinol (Radius) or stainless steel (Wallstent).…”

Mechanical features andin vivo imaging of a polymer stent

“…The protocol was approved by the Committee on experimental animals of the Erasmus University. After anaesthesia and under sterile conditions an arteriotomy of the left carotid artery was performed and a 9F introduction sheath was placed as described earlier [6,10]. After administration of 5000 IU of heparin sodium, an 8F catheter was advanced to the infrarenal abdominal aorta.…”

“…Results from uncontrolled clinical studies with stainless steel stents in the coronary circulation indicate, however, that these devices are prone to (sub)-acute thrombotic occlusion and do not eliminate the incidence of restenosis, although they reduce its occurrence [2][3][4][5]. In animal experiments coronary stents composed of tantalum proved to be less thrombogenic than stainless steel stents [6]~but the initial results after implantation in patients showed no detectable advantage of tantalum [7]. Applying a polymer coating to metal stents proved effective in reducing the thrombogenicity of these devices in experimental animals [8].…”

Do stents interfere with the densitometric assessment of a coronary artery lesion?

“…The prosthesis is crimped onto a deflated polyethylene angioplasty balloon and the maximal diameter of the balloon after inflation determines the ultimate size of the prosthesis after implantation [ 5 ] .…”