Animal experimental studies on the influence of flow restriction on thrombogenicity of the Palmaz stent via 111indium marked thrombocytes

The purpose of this experimental study in dogs is to evaluate the influence of restricted flow on the thrombogenicity of balloon-expandable intravascular stents (Palmaz type). We implanted 24 Palmaz stents in the femoral artery of mongrel dogs. 12 dogs experienced a 75% flow restriction by means of an artificial stenosis distal to the start in the outflow tract. We used 111In labelled thrombocytes as a marker for thrombus detection within the stent. The results presented demonstrate that there is no considerable risk of thrombus formation if the stent is implanted into vessels with good outflow tracts and therefore high blood flow velocities within the stent. Under conditions of highly impaired flow, a 68% rate of stent occlusion occur if no anticoagulation therapy is performed. After i.v. administration of 100 IU/kg body weight of heparin the occlusion rade drops to zero. It can be concluded that even under low-flow conditions as a result of a restricted outflow tract situation the Palmaz stent can be implanted without any risk of stent occlusion as long a sufficient anticoagulation protocol is maintained. (orig.)