Experimental Evaluation of Embolic Effect: Pure Glue and Glue-Tungsten Mixture

PURPOSE: For the occlusion of a high-flow fistula, glue is an effective embolic agent. In order to visualize glue fluoroscopicaolly, we demonstrated the different embolic effect of pure glue and a glue-tungsten mixture. MATERIALS AND METHODS: A flow phantom model consisted of a circulating pump (Simon varistaltic pump, Manostat Corporation, U.S.A.) connected to a tygon tube (S-50-HL, Norton Performance Plastic Corporation, U.S.A.); flow was maintained by saline at about 4ml/sec. The tygon tube (4.8mm inner diameter) was cut to a length of 60cm; a Y-connector was fitted to the end of its inflow tract and a gauze filter to the end of the outflow tract. A microcatheter was introduced through the Y-connector into the proximal portion of the tube. 1.0cc of pure glue and 0.25g glue-tungsten mixture were each injected rapidly, three times, and in order to observe flow status within the tygon tube, ink was injected. The shape of the glue cast and the pattern of flow arrest were observed and the length of the cast was measured. In an animal experiment, 0.5cc glue with or without tungsten powder was rapidly injected into the brachial artery of the pig and angiographic findings were compared before and after injection. RESULTS: In the flow phantom experiment, the injection of pure glue resulted in complete flow arrest within the tygon tube; the length of the cast was 7cm. Another injection resulted in incomplete flow arrest and a cast lengthof 16cm. A further injection resulted in the complete passage of glue into the gauze filter, and complete flow arrest. An injection of glue-tungsten mixture resulted in incomplete flow arrest, and a cast length of 30cm; in two other injections, glue-tungsten mixtures passed the tygon tube and gauze filter without flow arrest. In the animal experiment, pure glue resulted in complete in complete flow arrest with minimal distal migration of the glue cast. In contrast, glue-tungsten mixture resulted in incomplete flow arrest or distal migration of the cast, with minimal collateral development. CONCLUSION: Pure glue resulted in complete flow arrest within a short distance of the catheter tip. In contrast, a glue-tungsten mixture tended to result in incomplete flow arrest and more distal migration than was the case with pure glue. In a high-flow vascular lesion, a glue-tungsten mixture therefore appears to result in more distal migration than pure glue without tungsten.

Evaluation of Characteristics of Cyanoacrylate-Lipiodol Mixtures Injected in the Different Flow Layers

PURPOSE: To observe the pattern of glue cast formation when glue was injected into the different fow layersof a flow phantom, and to demonstrate the effect in an animal experiment. MATERIALS AND METHODS: A flow phantom model consisted of a circulating pump (Simon varistaltic pump, Manostat Corporation, U.S.A.) connected via a tygon tube with a specially designed glass tube. Flow of about 4ml/sec was maintained by saline. The glass tube consisted of (1) a small-caliber (2.4-3.2mm inner diameter) straight inflow portion (feeder), (2) a round, larg-caliber portion (nidus), and (3) a medium-caliber (6.7mm inner diameter) straight outflow portion (vein). Glue mixed with Lipiodol (glue: Lipiodol=1:1-3:1) was loaded into a 1cc syringe and slowly injected through a microcatheter ; cast formation along the glass tube was observed. The feeder and nidus portions were injected twelve times and the shape of the cast was compared. In an animal experiment, glue at various concentrations was used to stop rapid flow through a surgically-constructed arteriovenous fistula in porcine carotid artery. RESULTS: When mixture was injected into the straight inflow portion (1), it formed a cast along the wall of the glass tube, with a large cast in the nidus portion. Further injection caused enlargement of the cast in the nidus, but no change in the wall of the inflow portion. When mixture was injected into the nidus portion (2) of the glass tube, a cast formed continuously within the nidus. In the animal experiment, rapid injection of glue at a high conentration staunched flow through the arteriovenous fistula. CONCLUSION: Glue-Lipiodol mixture can be injected slowly and continuously under the surface of the polymerized glue cast which forms along the wall or slow flow portion (nidus) of the glass tube in an experimental flow phantom. However, the effect did not appear during rapid flow in the animal arteriovenous fistular model in which only rapid injection of glue which was either pure or at a glue concentration of more than 75% was effective.