Ultra-small Catheter Shaping Method with a Sheath Dilator: Usefulness for Coil Embolization of Cerebral Aneurysms

Objective: We devised a method to readily create an ultra-small shape at the microcatheter tip using a sheath dilator. In the present study, we introduce the creation method and report its usefulness. Methods: For mandrel formation, 7 Fr. or 4 Fr. sheath dilators were used. 1) A small, round loop was prepared by rolling a mandrel on a sheath dilator. 2) The mandrel with an ultra-small loop was inserted into the tip of a straight-type microcatheter. 3) The microcatheter tip was heated using a heat gun. 4) The mandrel was removed from the microcatheter tip. Using the catheter which has ultra-small shaped tip, coil embolization was performed. Results: The mandrel loop diameter was 3 mm when a 7 Fr. sheath dilator was used. It was 2 mm when a 4 Fr. sheath dilator was used. It was possible to create various ultra-small shapes, such as J, S, and pigtail shapes, at the catheter tip. Ultra-small shaped catheters were used to treat 25 cerebral aneurysms. In all patients, catheters could be readily guided into the aneurysms, and their stability after insertion was favorable. Conclusion: The ultra-small catheter shaping method with a sheath dilator facilitated the creation of various ultra-small shapes measuring 2–3 mm in diameter at the microcatheter tip.