Coronary artery in-stent stenosis persists despite inhibition of the von Willebrand factor--collagen interaction in baboons.

Revascularization techniques, such as angioplasty and stent implantation, frequently lead to restenosis due to the formation of neointima after platelet activation and the concomitant release of various smooth muscle cell mitogenic and attractant factors. We here investigate whether inhibition of initial platelet adhesion after stent implantation can decrease neointima formation in a clinically relevant baboon model of in-stent stenosis using standard treatment with aspirin, clopidogrel and heparin. Inhibition of platelet adhesion was established by administration of the anti-von Willebrand factor (VWF) monoclonal antibody 82D6A3, which inhibits VWF binding to collagen. Administration of 82D6A3 resulted in a complete inhibition of VWF binding to collagen during the first three days after stent implantation. No thrombocytopenia or prolongation of the bleeding time was observed. Our results show that the formation of neointima was not affected in the group of baboons where primary platelet adhesion was abolished with 82D6A3 when compared to the control group. Vascular injury scores were the same in both groups. Inhibition of platelet adhesion during the first three days after stenting, on top of standard treatment with aspirin, clopidogrel and heparin, had no effect on neo-intima formation in a baboon model of in-stent stenosis. During the last decade, attempts to translate seemingly effective therapies based on smaller animal experimentation to the clinic have consistently failed. This study, using a non-human primate model that more closely resembles the clinical situation, presents a model that may be of further clinical interest for studying the prevention of restenosis.

Effectiveness of single detachable COOK coils in closure of the patent ductus arteriosus.

OBJECTIVE: To assess the efficacy and safety of single detachable coils in the closure of PDAs. METHODS: Review of cases in which a single detachable coil was implanted. The diameter of the ampulla was used to select coil size. Diameters of the PDA, ampulla and residual shunts were measured. RESULTS: There were 36 patients with a mean minimal ductal diameter of 2.2 +/- 0.6 mm. Immediately after implantation, 46% of the patients had residual shunts and after 24 hours, only 28%. A final spontaneous closure rate of 94% was observed after 21 months. There was a significant (p < 0.01) difference when minimal PDA diameter of those who had complete closure within 24 hours (median: 2 mm, interquartile range: 1.7-2.3 mm) was compared to those with a residual shunt (median: 2.5 mm, interquartile range: 2.3-3.2 mm). Negligible complications were experienced. CONCLUSIONS: Single Cook detachable coils are effective for PDA closure with a low complication rate if properly selected. There is a high rate of spontaneous closure of trivial residual shunts. In patients with a minimal ductal diameter > or = 2 mm and a residual shunt, more coils may be considered.