Experimental study of loop shape using 0.025-inch ERCP guidewires (with videos).

Duct penetration by the guidewire sometimes occurs during endoscopic retrograde cholangiography, which might lead to adverse events such as acute pancreatitis. To prevent duct penetration, making a loop shape with the guidewire might provide a useful technique. The aim of this experimental study was thus to evaluate which types of guidewire can most easily form a loop shape. This experimental study evaluated six guidewires (0.025-inch, angle type): MICHISUJI; VisiGlide 2; Jagwire; Pathcorse; RevoWave-α UltraHard 2; and M-through. Flexibility of the tip, shaft stiffness, and the ability to form a loop were evaluated for each type in an ex vivo model. Deformation behavior was also recorded on video, and factors suitable for making a loop shape in each guidewire were evaluated.  Flexibility and stiffness of each guidewire differed significantly. During an experimental study regrading deformation behavior before forming a loop shape, maximum load was lower for MICHISUJI (6.8 g) than for other guidewires (Jagwire [11.3 g], M-through [12.9 g], VisiGlide 2 [12.9 g], Revowave [21 g], and Pathcorse [25.4 g]). Mean time required to achieve a loop shape was as follows: MICHISUJI, 6.2 seconds; M-through, 8.7 seconds; VisiGlide 2, 11.0 seconds; and Revowave, 7.1 seconds.  In conclusion, characteristics of flexibility and stiffness among guidewires were significantly different in the ex-vivo study. In the experimental study regrading deformation behavior until achieving a loop shape, maximum load also differed. To evaluate whether guidewires easily form a loop shape, clinical study is needed.