Marker alignment for Guglielmi detachable coil embolization: practical considerations.

BACKGROUND AND PURPOSE Aneurysm embolization is not without risk: numerous technical aspects are considered before, during, and after the procedure. The purpose of this study was to show the position of the detachment zone of a Guglielmi detachable coil (GDC) with respect to the catheter tip for various microcatheters and marker alignments. METHODS Six types of commonly used microcatheters were tested (Excel-14, Excelsior, FasTracker-10, Prowler-10, Prowler-14, and Rebar-14). First, the catheter markers and the distance from the catheter tip to the distal end of the proximal and distal markers of each catheter were compared. Second, the coil maker was aligned with the catheter marker. Third, the distal 3 cm of the microcatheter was modified by random shaping, with or without steaming. Last, marker alignment was tested with resterilized microcatheters (ethylene oxide gas sterilization). RESULTS The length of the catheter marker and the distance between the catheter tip and the distal end of the proximal and distal catheter markers varied among the microcatheters. Sometimes, they varied even within the same microcatheter type. When a GDC was advanced until the proximal end of the marker on the delivery wire was exactly distal to the proximal catheter marker, the coil detachment zone was positioned at approximately 1.0 to 1.5 mm outside the catheter tip. Steaming or shaping of the distal 3 cm of the microcatheters resulted in the GDCs protruding more from the catheter tip. Resterilization also had an effect of marker distance shortening. Microcatheters were easily stretched by usual handling, such as removing a shaping mandrel from the catheter tip. CONCLUSION Our study shows that proper marker alignment is influenced by many factors, including microcatheter type, steaming, shaping, sterilization, and manual handling.