Acute coronary artery occlusion complicates 2-12% of the balloon angioplasty procedures, and despite repeat angioplasty, emergency surgical revascularization is often necessary. We report our initial experience with the emergency implantation of endoluminal stents for acute vessel closure after coronary balloon angioplasty. Nine patients received one stent, and two patients received two stents during the study period. Implantation was technically successful in all patients; there were no deaths, no myocardial infarctions as evidenced by Q wave on the electrocardiogram, and no need for emergency surgery. One additional patient, not satisfying the study inclusion criteria, died 16 hours after stent implantation from left ventricular failure and intractable arrythmias. Two patients in the study group had a moderate creatinine phosphokinase rise during the first 48 hours after implantation. During a median follow-up period of 3 months (range, 1-20 months), there have been no deaths and no need for elective coronary bypass surgery. One patient required emergency recanalization 3 months after implantation because of acute occlusion of the stented segment with limited myocardial infarction. Six patients have undergone control angiography, and none has developed chronic restenosis within the stented segment. For selected patients, coronary artery stenting appears to be a promising alternative to emergency bypass surgery after acute vessel occlusion during balloon angioplasty.

A new type of endovascular prosthesis was inserted in 28 animals and evaluated for several factors, including thrombogenicity, tendency to migrate, critical implant zones, and incorporation into the vascular wall. The new prosthesis is a woven, multifilament structure of stainless steel alloy; its inherent elastic, self-expanding characteristics hold it against the vessel walls. Forty-seven endoprostheses (3-5 mm in diameter, 15-50 mm long) were percutaneously implanted with either a 6-F introducer sheath, a coaxial 9-F catheter, or a 0.014-inch (0.036-cm) guide wire into the femoropopliteal, coronary, carotid, and renal arteries and iliac veins. Anticoagulant or platelet antiaggregating agents were not used before or after implantation. Angiographic and histologic analyses showed that the prosthesis had a very low thrombogenicity when it was well adapted to the native vessel diameter and that it was incorporated into the vessel wall by a new intima by the 3d week after implantation. No migration occurred, and branch vessel flow was preserved even in those vessels in which ostia were traversed by the prosthesis. This prosthesis has potential for clinical application in the treatment of postangioplasty restenoses, particularly in the coronary arteries.

A new pattern of metallic intravascular stent has been experimentally and clinically tested. When the stent is percutaneously placed through a six french introducer, it is held against the vessel wall by its natural elastic properties. In 28 animals, 47 stents of different sizes (from 3 to 5 mm of luminal diameter and from 1.5 to 5 cm of length) have been implanted in the femoro-popliteal (16), the coronary (20), the carotid (3) and the renal arteries (5) and in 3 femoral veins. Angiographic and histological results have shown the stent's low thrombogenicity when it is well fit to the vessel's caliber. Moreover, they have shown its incorporation to the vessel wall by intimalisation as early as the third week after its implantation. The collateral vessels which covered by the stent remain permeable. At the end of this experimentation, 10 implants have been achieved in 8 patients (4 recurrences of iliac stenosis and 6 femoral stenosis). The angiographic results show the perfect tolerance of the organism at 6 months. This good tolerance is revealed by a thin intraluminal border which does not change the artery's diameter. This confirms the experimental results. The permeability is good except for two patients who had an obliteration after one month (one iliac and one femoral obliteration).