Shapability, memory, and luminal changes in microcatheters after steam shaping: a comparison of 11 different microcatheters

Abstract

Purpose: The purpose of this study was to compare the characteristics of shaped microcatheters, including shapability, durability, and luminal changes.

Materials and methods: Eleven brands of steam-shaped microcatheters and one brand of preshaped microcatheter were evaluated. There were 2 nonreinforced and 10 reinforced devices supported by coils. For evaluation of shapability, the tip angle of 6 samples of each brand were measured after steam-shaping for 20 seconds with a shaping mandrel bent at a 90 degrees or 150 degrees angle. The ability to maintain the shaped angle after guidewire insertion stress (durability) was compared by calculation of the change in the tip angle by using 3 samples of each brand. Luminal change after steam shaping was evaluated by calculation of narrowing rate of the smallest diameter and observation of the surface morphology of the mold of each catheter lumen by using a silicone polymer by means of a fluorescent projection method.

Results: The nonreinforced microcatheters and the fiber-braided microcatheter showed higher shapability than the others. The degree of distal microcatheter straightening with the microguidewire insertion was less pronounced in the preshaped microcatheter and the fiber-braided microcatheter. Spontaneous recovery to the initial tip angle 5 minutes after the guidewire procedure was observed in 10 brands to various degrees (87%-98%). Irregular luminal surface morphology at the angled portion was found in 6 reinforced brands. One nonreinforced catheter and the fiber-braided catheter showed high narrowing rates >6%.

Conclusion: There are differences in shapabilty, durability, and luminal changes of steam shaping in 12 brands of microcatheters. These characteristics could be important factors in catheter choice for endovascular procedures.

Fig 1.

Change of tip angle of a microcatheter. A, Initial tip angle. B, Tip angle following the water bath procedure for 10 minutes. C, Tip angle following guidewire procedure. D, Tip angle following the second water bath for 5 minutes.

Fig 2.

Shapability of small-sized catheters. Although the mean tip angle is increased according to increasing the intended tip angle in all catheters, Fas10 shows the highest shapability.

Fig 3.

Shapability of large-sized catheters. MF and Rg show higher shapability than the others.

Fig 4.

Durability of the shape of small-sized microcatheters. All microcatheters show reduction of tip angle after the microguidewire procedure (GW). The change rates are >10% in Fas 10 and Pg 2.0. At the final calculation, the Fas10 nonreinforced catheter shows high angle-recovery rates. All reinforced microcatheters except for Pg2.0 show similar change rates, <10%. Pg2.0 shows change rates >10% at the final calculation.

Fig 5.

Durability of the shape of large-sized microcatheters. RT and PP show reduction of the tip angle before the guidewire procedure. All microcatheters show reduction of the tip angle following the microguidewire procedure (GW). The change rates are >10% in RT and PP. At the final calculation, RT and PP show high reduction rates and final change rates >10%. PP90 and Rg show low reduction rates throughout the examination. The nonreinforced catheter MF shows the highest angle-recover rate.

Fig 6.

Luminal irregularities at the curved portion of the shaped microcatheters. A, Moderate irregularity (arrows) on the lesser curvature approximately 0.04 mm in peak-to-valley measurement in RT and Rg. B, Mild irregularity (arrows) on the lesser curvature approximately 0.015 mm in peak-to-valley measurement in Ex, Pg2.0, Rb14, and PP. C, Smooth surface on the lesser curvature in the other microcatheters.