Are superabsorbers useful for endovascular embolization of saccular aneurysms? An in vitro study.
OBJECTIVE
The authors conducted in vitro evaluation of superabsorber for endovascular embolization of saccular aneurysms.


METHODS
The swelling properties of the superabsorber Sanwet IM-7000 were investigated in various solvents. The material used was granulate (group A: particle size approximately 459 microm; group B: particle size approximately 20 microm) as well as cubes with an edge length of 1 mm prepared from a block. With ascending concentrations of Sanwet IM-7000 held in suspensions made of Lipiodol and 96% ethanol, the injectability was determined using microcatheters (2.1 F/3 F). The behavior of Sanwet IM-7000 as occlusion material for aneurysms was examined in a sacciform glass-model aneurysm.


RESULTS
The granule showed no significant increase in size in Lipiodol and in 96% ethanol, so that they were chosen for catheter measurement. In Lipiodol suspension the maximum fraction of the granulate suitable for injection through a 3 F catheter was 3.2%. In 96% ethanol suspension the maximum fraction of granulate suitable for injection through a 3 F catheter was 0.8%. Suspended in Lipiodol Sanwet IM-7000 showed a moderate swelling in the aneurysm model, whereas the use of 96% ethanol resulted in a pronounced swelling of the granulate (100 vol%) after the 96% ethanol was washed off. Irrespective of the granulate size used, a rinse-off process of the granulate occurred in the model aneurysm at a flow rate above 200 mL x min(-1). Cubes prepared from a block of the base polymerisate of Sanwet IM-7000 showed a delayed increase in size. The final size in 0.9% NaCl solution was reached in the cubes after 220 min, in the granulate already after 20 mins. The cubes displayed a high form stability.


CONCLUSIONS
Due to the substance-related absence of intercorporeal cross-linking and the unpredictable increase in size, embolization of aneurysms using Sanwet IM-7000 granulate is inadvisable at present. In spite of a longer swelling time and because of its form consistency, the use of prepared cubes could provide a reasonable alternative.
Walter
M
M
Department of Neuroradiology, University of Freiburg, Germany.
Schellhammer
F
F
Schumacher
M
M
D000783:Aneurysm / Q000628:therapy*; D001672:Biocompatible Materials; D004621:Embolization, Therapeutic / Q000379:methods*; D066298:In Vitro Techniques; D008422:Materials Testing; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D011673:Pulsatile Flow
D001672:Biocompatible Materials; D011108:Polymers