Recommendations on stent manufacture, implantation and utilization

The neologism ‘stent’ has irrevocably entered the English medical vocabulary as a noun as well as a verb. It allegedly dates back to the English dentists Charles T. Stent (1807–1885) and his sons Charles R. Stent (1845– 1901) and Arthur H. Stent (1859–1900) who used to support poorly aligned teeth with a special apparatus. Others have traced the word back to the 14th century. The first mention of the word stent in the (non-dentistry) medical literature can be found in a paper on reconstruction of the biliary duct in dogs in 1954. Charles Dotter employed the term stent for vascular implants in 1983 when he presented the first clinical experience with a percutaneously implanted vascular endoprosthesis based on prior canine experiments in 1969. As a further development to heat-expandable stents, Maass published animal data in 1983 and 1984 on mechanically self-expanding stents for use in peripheral arteries. In 1985, a spring-loaded self-expanding stent was described by Gianturco’s group, followed by the first balloonexpandable stent by Palmaz and a self-expanding mesh-stent by Rousseau and Sigwart. In 1987 the first animal studies on coronary stenting were published . The first human implantation using the self-expanding mesh-stent or Wallstent was carried out by Puel on 28 March 1986. Its initial development had been hampered by several problems. First, the risk of subacute thrombotic coronary artery closure several days after the procedure emerged as a novel, stent-specific hazard prompting complex anticoagulation regimens, associated with increased bleeding and prolonged hospital stays. Second, shortly after the clinical introduction of the stent, Medinvent (the Swiss firm producing the Wallstent) became part of the American Pfizer company. Pfizer had been beset by major difficulties with a heart valve of their subsidiary Shiley, and thus proceeded with extreme caution in launching the stent because it was felt to be another implantable device potentially necessitating a later callback campaign. Following the unavailability of the Wallstent, the Palmaz–Schatz, the Gianturco– Roubin and the Wiktor stents developed concurrently, but were only available to selected centres under strict research regulations. Third, the limitation of stenting to acute and threatening occlusions after coronary angioplasty yielded early success and complication rates that were not always competitive with those of routine angioplasty. Insufficient consideration was given to the fact that the stent much improved the otherwise dismal outcome of these patients, and randomized studies were lacking. Fourth, other new devices, such as the laser, rotational ablation, and directional atherectomy, frequently utilized in low-risk situations in contrast to the stent, appeared to many as more attractive as they did not require prolonged and enforced anticoagulation. The sobering accounts on the first roughly 100 patients with a coronary stent fraught with all the adverse risk factors enumerated above, amplified by an explicit editorial, all but extinguished the flickering flame of stent enthusiasm in 1991. It was not until several years later that the common error of looking at the stent as just another new device for coronary angioplasty was first challenged and then corrected by the results of well designed randomized trials. These trials, initiated by Serruys and his colleagues from the Benestent group, proved that primary stent implantation in elective cases could reduce angiographic restenosis rates and improve the patient’s clinical outcome, as compared with balloon angioplasty. Eventually, following the lead of Colombo and others, the implantation technique was improved by focusing on full expansion, adequate deployment of the stent using intravascular ultrasound, and by the use of simplified and more effective anticoagulation protocols. Since then, the stent has gained ground at an incredible speed. In 1995 it was used in most coronary angioplasty procedures at leading centres and in 30–60% of all cases at other centres. Over 20 stent