Simple and Reproducible Microcatheter Shaping Method for Coil Embolization of Medially-directed Paraclinoid Internal Carotid Artery Aneurysms

Abstract

Objective: It is important to guarantee intra-aneurysmal stability of microcatheters during coil embolization. We developed a simple and reproducible microcatheter shaping method for medially-directed paraclinoid internal carotid artery aneurysms.

Methods: An injection needle cap was used to make a smooth curve on the mandrel, which was first wound around the back end of the cap to create a primary curve. Next, a secondary curve was created using near the tip of the cap. Thus, a two-dimensional (2D), pigtail-shaped mandrel with a two-stage curve was created. The pigtail-shaped mandrel was inserted from the tip of a straight microcatheter and heat-shaped using a heat gun. Lastly, a microcatheter having a curve whose tip was approximately 6 mm longer than that of the preshaped J was created. We evaluated the ease of navigating the microcatheter into the aneurysm and its stability during coil embolization.

Results: In all, 34 consecutive medially-directed paraclinoid internal carotid artery aneurysms were treated using the shaped catheters. It took 50-300 seconds (intermediate value: 90 seconds) from inserting the microcatheter with a microguide wire to navigate and place it into an aneurysm. There were no cases that required reshaping of the microcatheters during navigation into the aneurysm. There were no cases that resulted in kickback of the microcatheters from the aneurysm during coil placement, and microcatheter stability was good until the end of the procedure. In all, 12 cases required the balloon-assisted technique and three cases required stent-assisted coiling. The angiographic outcomes immediately after embolization were as follows: 25 cases (73.5%) with complete occlusion; 3 cases (8.8%) with dome filling; and 6 cases (17.6%) with a neck remnant. There were no perioperative complications.

Conclusion: The shaping method with a pigtail-shaped mandrel using an injection needle cap is simple and reproducible, and is useful for medially-directed paraclinoid internal carotid artery aneurysms.

Keywords: catheter shaping; coil embolization; internal carotid artery; paraclinoid aneurysm.

Fig. 1. Winding a mandrel around the back end of the 18-G needle cap to create a primary curve (A and C). Next, winding a mandrel near the tip of the 18-G needle cap to create a secondary curve (B and D). Two-dimensional and two-stage curves, such as a pigtail, are easily created (E). Inserting the pigtail-shaped mandrel from the tip of the straight microcatheter (F) and holding it over the heat gun (G).

Fig. 2. A mandrel is formed into a pigtail-like shape to make a curve of sufficient length at the tip of the preshaped J microcatheter, and then the mandrel is inserted from the tip of the straight microcatheter (A). When the mandrel is removed from the tip of the microcatheter after heat shaping, a microcatheter with a longer tip curve than the preshaped J microcatheter is created (B).

Fig. 3. Angiography shows a medially-directed paraclinoid ICA aneurysm, and a balloon catheter has already been placed (A and D). The microcatheter placed in the aneurysm has two support points (arrows), with the ICA wall opposite to the aneurysmal neck and the wall of the carotid siphon (B and E). The aneurysm has disappeared on postoperative angiography (C and F). ICA: internal carotid artery

Fig. 4. Angiography shows a medially-directed paraclinoid ICA small aneurysm (A and D). The microcatheter placed in the aneurysm has two support points (arrows) with the ICA wall opposite to the aneurysmal neck and the wall of the carotid siphon (B and E). The aneurysm has disappeared on postoperative angiography (C and F). ICA: internal carotid artery

Fig. 5. The yellow line has only one support point, and the tip cannot reach the aneurysmal dome sufficiently, whereas the blue line has two support points (red circles), and the tip is sufficiently inserted into the aneurysmal dome (A). The tip of the microcatheter removed after coil embolization demonstrates a 3D shape according to the vascular shape (B and C).