phosphorus-radioisotopes and Carotid-Artery-Thrombosis

Beta radiation prevents recanalization after coil embolization. We sought to determine the effects of varying coil caliber, length, activity of 32P per centimeter of coil or per volume, and spatial distribution of coils on recanalization.. We studied the angiographic evolution of 81 canine maxillary, cervical, and vertebral arteries implanted with a variety of nonradioactive (n=29 arteries) or radioactive (n=52) devices. We compared 1- or 2-caliber 0.015 or 0.010 coils ion-implanted or not with 3 different activity levels (0.05 to 0.08, 0.06 to 0.12, 0.18 to 0.32 microCi/cm) of 32P and totaling 4, 8, and 16 cm in length for the same arterial volume. We also compared inhibition of recanalization by beta radiation delivered by stents, after coil occlusion proximal to or within the stent, with that delivered by coils placed within nonradioactive stents. We finally studied the angiographic evolution of canine lateral wall carotid aneurysms treated with 1 or 2 stents of various activity levels positioned inside the parent artery across the neck. Animals were killed at 4 and 12 weeks for macroscopic photography and pathological examination.. All arteries (29 of 29) occluded with nonradioactive devices were recanalized, while 49 of 52 arteries (94%) implanted with 32P devices were occluded at 4 weeks. All aneurysms treated with stents, radioactive or not, demonstrated residual filling of the sac or of channels leading to the aneurysms at follow-up angiography at 4 weeks.. The recanalization process found in the canine arterial occlusion model is minimally affected by coil caliber, number, and length or packing density. Beta radiation reliably inhibits this process, but thrombosis is an essential condition for the efficacy of a radioactive coil strategy.

Topics: Aneurysm; Animals; Arterial Occlusive Diseases; Arteries; Beta Particles; Carotid Artery Diseases; Carotid Artery Thrombosis; Carotid Artery, Common; Combined Modality Therapy; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Drug Implants; Embolization, Therapeutic; Endothelium, Vascular; Equipment Design; Maxillary Artery; Neck; Phosphorus Radioisotopes; Radiotherapy Dosage; Recurrence; Single-Blind Method; Stents; Vertebral Artery

The effect of bonding of heparin, via a glutaraldehyde-stabilized ionic complex, on the early thrombogenicity of polyurethane (PU) and expanded polytetrafluoroethylene (PTFE) (Gore-tex) as well as covalent bonding of heparin on PTFE was studied in vivo. Grafts 6 cm long and 4 mm in diameter were placed in the carotid arteries of sheep and perfused for 4 hours at 25 ml/min in order to accelerate thrombus formation. The thrombogenicity was determined by calculation of the percent of the luminal surface free of thrombus and patency. In addition, 32P-labelled platelet accumulation was determined in some of the grafts. The stabilized ionic bonding of heparin significantly reduced the early thrombogenicity of PU but had little effect on PTFE grafts; but the thrombogenicity of the latter was markedly decreased following covalent bonding of heparin. A regional distribution of platelet accumulation was found with the distal anastomoses showing the highest platelet deposition. By choice of an appropriate method of heparinization, a significant reduction of the thrombogenicity of PU and PTFE grafts was achieved.

Topics: Animals; Blood Vessel Prosthesis; Carotid Arteries; Carotid Artery Thrombosis; Female; Heparin; Isotope Labeling; Male; Phosphorus Radioisotopes; Platelet Count; Polytetrafluoroethylene; Polyurethanes; Sheep; Thrombosis