Coronary stents.

As early as 1912, endovascular support devices were tried in canine aortas to maintain luminal patency in various conditions. Stents were introduced into clinical practice in 1986 to treat abrupt closure and to prevent restenosis after angioplasty. In 1994, two major randomised trials have confirmed that stenting after PTCA does indeed reduce the incidence of restenosis as well as other events such as myocardial infarction and emergency surgery. Numerous different stents are now in use: self expanding and balloon expandable stents, stainless steel stents and tantalum stents, flexible and articulated stents, and more recently heparin-coated stents. All stents are foreign bodies and may induce spasm and thrombosis. Meticulous drug treatment helps to reduce the side-effects of stents. New designs with improved fluid dynamics and optimal conformability are now being successfully tested. Polymer stents have not fulfilled their expectations. Optimal implantation strategy-aiming at an absolutely perfect primary result with no residual narrowing, absence of dissections and complete stent expansion--has dramatically reduced the complication rate after stenting as well as the need for heavy anti-coagulation. Stents have revolutionised the practice of transluminal techniques and hold great promise as local drug delivery devices.