A 6-Fr Guiding Catheter (Slim Guide^®) for Use with Multiple Microdevices

Summary

A modified technique is required in patients with wide-necked aneurysms whose treatment by the single microcatheter technique is difficult. We developed a 6-Fr guiding catheter (Slim Guide^®) that features a large lumen (0.072 inch) for performing the modified technique. To evaluate the usefulness of Slim Guide^® we carried out experiments using three types of 6-Fr guiding catheter.

In experiment 1, the shaft hardness and kink resistance were compared among three different guiding catheters (Slim Guide^®, Launcher^®, Envoy^®). In experiment 2, we inserted a microballoon catheter and a microcatheter into the three different guiding catheters and recorded the maximal infusion pressure. In experiment 3, we inserted 13 different types of microdevices into the three different guiding catheters and evaluated the resistance of the microdevices.

Although the shaft of the Slim Guide^® was softer than that of the other two guiding catheters, its kink resistance was comparable. The maximal infusion pressure was significantly lower than with Launcher^® or Envoy^® catheters. Furthermore, with Slim Guide^®, in 136 of 143 microdevice combinations examined (95.1%) there was no resistance; this was true for 125 (87.4%) and 116 (81.1%) combinations using the Launcher^® - and the Envoy^® guiding catheters, respectively. There was a significant difference between Slim Guide^® and the other two guiding catheters with respect to their accommodation of double microsystems (p<0.05).

Although the inner diameter of Slim Guide^® is slightly larger than of the other two guiding catheters, it significantly increased the combination of microdevices that could be used for the coil embolization of difficult aneurysms.

Introduction

There have been remarkable advances in the treatment of intracranial aneurysms by endovascular coil embolization. However, it remains difficult to address wide-necked aneurysms or aneurysms with a large neck-to-fundus ratio by embolization using detachable coils and single-microcatheter methods. Coil migration or coil protrusion into the parent artery has been reported ^1-3. Among modified techniques to treat difficult aneurysms is the double microcatheter technique; it introduces two microcatheters into the aneurysm. This method facilitates the simultaneous positioning of two coils and assessment of their stability before detachment ⁴. Another is the balloon-assisted technique where a small balloon-occlusion microcatheter protects the parent vessel during the deployment of coils in the aneurysm ^5-9. Endovascular stents that bridge the aneurysmal neck facilitate the deposition of coils without parent artery occlusion ¹⁰.

It is necessary to introduce guiding catheters larger than 7-Fr or two guiding systems (5- or 6-Fr) in procedures involving two devices (e.g. two microcatheters, a microcatheter plus a microballoon catheter, a microcatheter plus a stent delivery microcatheter). As this raises the risk of disturbing the parent artery during endovascular treatment, the development of a single guiding system with a large lumen allowing for the passage of two microdevices was desirable. We developed a 6-Fr guiding catheter (Slim Guide^®) that facilitates the performance of techniques requiring more than one microdevice. We introduced different microcatheters and microballoon systems into different 6-Fr guiding catheters and report the usefulness of Slim Guide^®.

Materials and Methods

We developed the Slim Guide^® guiding catheter in collaboration with Medikit Co. Ltd. (Tokyo, Japan) and performed a series of comparison experiments using three types of 6-Fr guiding catheter (Slim Guide^®, Medikit, 0.072” lumen; Launcher^®, Medtronic, MN, 0.071” lumen; Envoy^®, Codman, MA, 0.070” lumen). The Slim Guide^® and Envoy^® guiding catheters are made of polyamide, the Launcher^® is made of polyamide and polyurethane. All feature a stainless steel blade and polytetrafluoroethylene in the inner layer.

Experiment 1

Shaft hardness and kink resistance

We cut each guiding catheter to a length of 10 cm from the tip and affixed the devices on two props of a fulcrum spaced 45 mm apart. We pushed the central part of the device at a speed of 150 mm/min using a digital force gauge (DPX-5TR; IMADA, Toyohashi, Japan) (Figure 1). We measured the maximum pressure (in Newtons) when the catheter was bent and recorded the mean value and standard deviation (SD) from five identical tests. We also determined the shaft hardness of each guiding catheter.

We then placed the devices on digital vernier calipers (CD-20; Mitutoya, Kawasaki, Japan) and while engaging the vernier calipers we measure the distance (mm) between both termini when the guiding catheter was bent (Figure 2). We recorded the mean value and SD from 5 identical tests. The distance between the termini was evaluated to determine the kink resistance of each guiding catheter.

Figure 1.

Shaft hardness was measured using a digital force gauge.

Figure 2.

The distance (mm) between both termini when the guiding catheter was bent was measured using digital vernier calipers.

Experiment 2

Infusion pressure using three types of guiding catheter and double microsystems

We evaluated the infusion pressure using three types of 6-Fr guiding catheter under the condition of double microsystem insertion. We inserted a 6-Fr introducer (25 cm, Medikit) in the right femoral artery of a blood vessel model (V-PREP Catheterization Training Simulator, Model V-4^®; IWASAKI, Osaka, Japan) (Figure 3) and navigated the guiding catheter. Its tip was placed in the right common carotid artery; its proximal end was connected to a double-Y-type connector (MX336^®; SHEEN MAN, Osaka, Japan). Then we perfused the guiding catheter with a glycerin water solution (36°C) to mimic the flow of human blood and inserted two microdevices simultaneously. One was a microballoon catheter (4×7 mm, HyperForm^®, eV3, Irvine, CA, USA) and the other an Excelsior SL-10^® microcatheter (Stryker Neurovascular, Fremont, CA, USA). After introducing the different guiding catheters harboring two microdevices we injected contrast medium (Iopamidol^®, 300 mgI/mL; Schering, Osaka, Japan, 1-5 ml/s) with an auto-injector (Angiomat ILLUMENA^®; Liebel-Flarsheim, OH, USA) and recorded the maximal infusion pressure at each injection volume/s. We recorded the maximal infusion pressure at the highest infusion volume rate and calculated the mean value and SD from five identical test injections. To examine differences we subjected the maximal infusion pressure to the χ square test; differences of p<0.05 were considered significant.

Figure 3.

The blood vessel model used in our study.

Experiment 3

Passage of different microsystems in the three types of guiding catheter

Using the same blood vessel model as in experiment 2, we inserted one microdevice with the aid of a microguide wire into each of the three types of guiding catheter. We then evaluated the degree of resistance at the insertion of a second microdevice. Two interventional neurosurgeons (YK, YO) recorded resistance as absent, slight, and strong. The impossibility of passage was also recorded. These evaluations involved the introduction of different combinations of microdevices into the three types of guiding catheter (Table 1). When the guiding catheter allowed the introduction of two microdevices, the device inserted last was connected to a digital push-pull gauge (Model RX-5^®, Aikoh Engineering, Tokyo, Japan) and pulled at a constant of 10 cm/s. We recorded maximal resistance (in Newtons) in the course of three push-pull procedures and the mean resistance value. To examine differences among the three types of guiding catheter we subjected the maximal infusion pressure to the χ square test; differences of p<0.05 were considered significant.

Table 1.

The various microdevices used in our experiments.

Microdevice	Size (distal/proximal)	Manufacturer
Hyper Form® (4 mm × 7 mm)	2.5F / 2.8F	eV3, Irvine, CA, USA
Hyper Form® (7 mm × 7 mm)	3.0F / 2.8F	eV3, Irvine, CA, USA
Excelsior SL-10®	1.7F / 2.4F	Stryker Neurovascular, Fremont, CA, USA
Excelsior SL-10® (S type)	1.7F / 2.4F	Stryker Neurovascular, Fremont, CA, USA
Excelsior SL-10® (45 degree)	1.7F / 2.4F	Stryker Neurovascular, Fremont, CA, USA
Excelsior 1018®	2.0F / 2.6F	Stryker Neurovascular, Fremont, CA, USA
Excelsior 1018® (S type)	2.0F / 2.6F	Stryker Neurovascular, Fremont, CA, USA
Excel 14®	1.9F / 2.4F	Stryker Neurovascular, Fremont, CA, USA
FasTracker 10®	2.0F / 2.6F	Stryker Neurovascular, Fremont, CA, USA
Renegade®	2.5F / 3.0F	Stryker Neurovascular, Fremont, CA, USA
PROWLER 10®	1.7F / 2.3F	Cordis, Bridgewater, NJ, USA
PROWLER 14®	1.9F / 2.3F	Cordis, Bridgewater, NJ, USA
PROWLER PLUS®	2.3F / 2.8F	Cordis, Bridgewater, NJ, USA
Resistance was subjectively evaluated and recorded as absent (double circle), slight (single circle), and strong (triangle). The impossibility of passing 2 microdevices inside the guiding catheter was also recorded (×). -: not performed. To measure maximal resistance (in Newtons) we used a digital push-pull gauge (lower section)

Results

Experiment 1

The shaft hardness was 1.80 ± 0.09 N for the Slim Guide^®, 2.63 ± 0.04 N for the Envoy^®, and 2.63 ± 0.06 N for the Launcher^® guiding catheter; the shaft of the Slim Guide^® was softest. The distance between the two termini when the guiding catheter was bent was 18.10 ± 0.13 mm, 20.95 ± 0.55 mm-, and 18.15 ± 1.04 mm for the Slim Guide^®, Envoy^®, and Launcher^®, respectively. Although kink resistance was lowest with the Slim Guide^®, it was not significantly different from that of the other two guiding catheters.

Experiment 2

The maximal infusion pressure (PSI) for the three types of guiding catheter at injection rates of 1-5 ml/s is shown in Figure 4. It increased as the injected volume/s increased. There was an inverse correlation between the lumen size of the guiding catheter and the infusion pressure. Starting at 3.0 ml/s, there was a significant difference between the guiding catheter with the largest lumen (Slim Guide^®) and the other guiding catheters (p<0.05).

Figure 4.

Maximal infusion pressure (PSI) recorded for the 3 types of guiding catheter. The values are the mean and standard deviation. Black circle: Envoy^®, black triangle: Launcher^®, black square: Slim Guide^®, *p < 0.05.

Experiment 3

We examined 143 microdevice combinations introduced into the three guiding catheters. With the Envoy^®, no resistance was recorded for 116 combinations (81.1%) (Table 2); this was true for 125 (87.4%) combinations using the Launcher^® guiding catheter (Table 3). With Slim Guide^®, no resistance was produced in 136 of 143 microdevice combinations (95.1%) (Table 4). There was a significant difference between the Slim Guide^® and the other two guiding catheters with respect to their accommodation of double microsystems (p<0.05).

Table 2.

Passage of various combinations of microdevices in the Envoy^® guiding catheter.

First microdevice
Second microdevice		PROWLER 10	SL-10	SL-10 45	SL-10 S type	PROWLER 14	Excel 14	Excelsior 1018	Excelsior 1018 S type	FasTracker 10	PROWLER PLUS	Renegade	HyperForm (4*7 mm)	HyperForm (7*7 mm)
	PROWLER 10	⦾ 0.08	⦾ 0.08	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.07	⦾ 0.09	⦾ 0.12	⦾ 0.08	⦾ 0.16	⦾ 0.18	⦾ 0.09	⦾ 0.10
	SL-10	⦾ 0.08	⦾ 0.08	⦾ 0.09	⦾ 0.12	⦾ 0.11	⦾ 0.09	⦾ 0.13	⦾ 0.15	⦾ 0.10	⦾ 0.26	⦾ 0.20	⦾ 0.12	⦾ 0.23
	SL-10 45	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.09	⦾ 0.10	⦾ 0.08	⦾ 0.08	⦾ 0.10	⦾ 0.09	⦾ 0.12	⦾ 0.18	⦾ 0.10	⦾ 0.15
	SL-10 S type	⦾ 0.07	⦾ 0.08	⦾ 0.09	⦾ 0.09	⦾ 0.12	⦾ 0.11	⦾ 0.12	⦾ 0.13	⦾ 0.10	⦾ 0.15	⦾ 0.22	⦾ 0.1	⦾ 0.17
	PROWLER 14	⦾ 0.08	⦾ 0.08	⦾ 0.10	⦾ 0.10	⦾ 0.10	⦾ 0.11	⦾ 0.13	⦾ 0.15	⦾ 0.11	⦾ 0.15	⦾ 0.23	⦾ 0.12	⦾ 0.18
	Excel-14	⦾ 0.10	⦾ 0.13	⦾ 0.11	⦾ 0.12	⦾ 0.13	⦾ 0.08	⦾ 0.15	⦾ 0.18	⦾ 0.14	⦾ 0.21	⦾ 0.22	⦾ 0.13	⦾ 0.75
	Excelsior 1018	⦾ 0.13	⦾ 0.16	⦾ 0.09	⦾ 0.10	⦾ 0.10	⦾ 0.14	⦾ 0.18	⦾ 0.20	⦾ 0.20	△ 0.62	×	△ 1.23	×
	Excelsior 1018 S type	⦾ 0.15	⦾ 0.18	⦾ 0.12	⦾ 0.15	⦾ 0.15	⦾ 0.16	⦾ 0.21	⦾ 0.22	⦾ 0.23	△ 0.70	×	△ 1.46	×
	FasTracker 10	⦾ 0.15	⦾ 0.16	⦾ 0.15	⦾ 0.16	⦾ 0.19	⦾ 0.18	⦾ 0.22	⦾ 0.25	⦾ 0.23	○ 0.32	×	△ 1.83	×
	PROWLER PLUS	⦾ 0.10	⦾ 0.13	⦾ 0.12	⦾ 0.14	⦾ 0.13	⦾ 0.14	○ 0.40	○ 0.46	○ 0.38	×	×	×	×
	Renegade	⦾ 0.18	⦾ 0.21	⦾ 0.18	⦾ 0.19	⦾ 0.23	⦾ 0.23	×	×	×	×	×	×	×
	HyperForm (4*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
	HyperForm (7*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
Resistance was subjectively evaluated and recorded as absent (double circle), slight (single circle), and strong (triangle). The impossibility of passing 2 microdevices inside the guiding catheter was also recorded (×). -: not performed. To measure maximal resistance (in Newtons) we used a digital push-pull gauge (lower section).

Table 3.

Passage of various combinations of microdevices in the Launcher^® guiding catheter.

First microdevice
Second microdevice		PROWLER 10	SL-10	SL-10 45	SL-10 S type	PROWLER 14	Excel 14	Excelsior 1018	Excelsior 1018 S type	FasTracker 10	PROWLER PLUS	Renegade	HyperForm (4*7 mm)	HyperForm (7*7 mm)
	PROWLER 10	⦾ 0.05	⦾ 0.05	⦾ 0.04	⦾ 0.05	⦾ 0.06	⦾ 0.10	⦾ 0.08	⦾ 0.06	⦾ 0.08	⦾ 0.08	⦾ 0.11	⦾ 0.13	⦾ 0.15
	SL-10	⦾ 0.08	⦾ 0.07	⦾ 0.06	⦾ 0.08	⦾ 0.08	⦾ 0.11	⦾ 0.10	⦾ 0.12	⦾ 0.08	⦾ 0.12	⦾ 0.12	⦾ 0.15	⦾ 0.18
	SL-10 45	⦾ 0.06	⦾ 0.07	⦾ 0.06	⦾ 0.07	⦾ 0.07	⦾ 0.08	⦾ 0.07	⦾ 0.09	⦾ 0.08	⦾ 0.12	⦾ 0.10	⦾ 0.10	⦾ 0.13
	SL-10 S type	⦾ 0.06	⦾ 0.08	⦾ 0.06	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.10	⦾ 0.11	⦾ 0.10	⦾ 0.13	⦾ 0.11	⦾ 0.12	⦾ 0.16
	PROWLER 14	⦾ 0.08	⦾ 0.08	⦾ 0.06	⦾ 0.07	⦾ 0.08	⦾ 0.10	⦾ 0.09	⦾ 0.11	⦾ 0.10	⦾ 0.14	⦾ 0.13	⦾ 0.13	⦾ 0.18
	Excel-14	⦾ 0.06	⦾ 0.06	⦾ 0.06	⦾ 0.05	⦾ 0.07	⦾ 0.07	⦾ 0.06	⦾ 0.08	⦾ 0.06	⦾ 0.10	⦾ 0.20	⦾ 0.11	⦾ 0.14
	Excelsior 1018	⦾ 0.06	⦾ 0.07	⦾ 0.06	⦾ 0.05	⦾ 0.08	⦾ 0.10	⦾ 0.06	⦾ 0.07	⦾ 0.10	⦾ 0.17	×	○ 0.32	×
	Excelsior 1018 S type	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.08	⦾ 0.10	⦾ 0.11	⦾ 0.12	⦾ 0.12	⦾ 0.12	⦾ 0.18	×	○ 0.35	×
	FasTracker 10	⦾ 0.06	⦾ 0.08	⦾ 0.06	⦾ 0.06	⦾ 0.08	⦾ 0.07	⦾ 0.07	⦾ 0.08	⦾ 0.10	⦾ 0.11	×	⦾ 0.11	⦾ 0.25
	PROWLER PLUS	⦾ 0.08	⦾ 0.10	⦾ 0.08	⦾ 0.10	⦾ 0.11	⦾ 0.23	⦾ 0.27	⦾ 0.28	⦾ 0.28	×	×	×	×
	Renegade	⦾ 0.08	⦾ 0.11	⦾ 0.10	⦾ 0.10	⦾ 0.13	⦾ 0.24	○ 0.46	×	×	×	×	×	×
	HyperForm (4*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
	HyperForm (7*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
Resistance was subjectively evaluated and recorded as absent (double circle), slight (single circle), and strong (triangle). The impossibility of passing 2 microdevices inside the guiding catheter was also recorded (×). -: not performed. To measure maximal resistance (in Newtons) we used a digital push-pull gauge (lower section).

Table 4.

Passage of various combinations of microdevices in the Slim Guide^® guiding catheter.

First microdevice
Second microdevice		PROWLER 10	SL-10	SL-10 45	SL-10 S type	PROWLER 14	Excel 14	Excelsior 1018	Excelsior 1018 S type	FasTracker 10	PROWLER PLUS	Renegade	HyperForm (4*7 mm)	HyperForm (7*7 mm)
	PROWLER 10	⦾ 0.04	⦾ 0.04	⦾ 0.06	⦾ 0.05	⦾ 0.05	⦾ 0.05	⦾ 0.08	⦾ 0.06	⦾ 0.05	⦾ 0.07	⦾ 0.07	⦾ 0.06	⦾ 0.06
	SL-10	⦾ 0.04	⦾ 0.05	⦾ 0.05	⦾ 0.06	⦾ 0.05	⦾ 0.05	⦾ 0.06	⦾ 0.07	⦾ 0.06	⦾ 0.08	⦾ 0.08	⦾ 0.05	⦾ 0.06
	SL-10 45	⦾ 0.04	⦾ 0.05	⦾ 0.06	⦾ 0.05	⦾ 0.05	⦾ 0.05	⦾ 0.08	⦾ 0.04	⦾ 0.04	⦾ 0.07	⦾ 0.07	⦾ 0.05	⦾ 0.08
	SL-10 S type	⦾ 0.04	⦾ 0.05	⦾ 0.05	⦾ 0.06	⦾ 0.04	⦾ 0.06	⦾ 0.06	⦾ 0.08	⦾ 0.07	⦾ 0.08	⦾ 0.09	⦾ 0.06	⦾ 0.07
	PROWLER 14	⦾ 0.08	⦾ 0.06	⦾ 0.06	⦾ 0.08	⦾ 0.06	⦾ 0.07	⦾ 0.06	⦾ 0.05	⦾ 0.05	⦾ 0.13	⦾ 0.08	⦾ 0.10	⦾ 0.10
	Excel-14	⦾ 0.05	⦾ 0.06	⦾ 0.06	⦾ 0.07	⦾ 0.05	⦾ 0.07	⦾ 0.06	⦾ 0.06	⦾ 0.06	⦾ 0.07	⦾ 0.11	⦾ 0.08	⦾ 0.10
	Excelsior 1018	⦾ 0.06	⦾ 0.08	⦾ 0.08	⦾ 0.08	⦾ 0.08	⦾ 0.07	⦾ 0.07	⦾ 0.05	⦾ 0.08	⦾ 0.10	⦾ 0.17	⦾ 0.07	⦾ 0.13
	Excelsior 1018 S type	⦾ 0.07	⦾ 0.07	⦾ 0.08	⦾ 0.06	⦾ 0.08	⦾ 0.08	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.11	⦾ 0.20	⦾ 0.08	⦾ 0.22
	FasTracker 10	⦾ 0.05	⦾ 0.04	⦾ 0.04	⦾ 0.04	⦾ 0.06	⦾ 0.05	⦾ 0.05	⦾ 0.05	⦾ 0.06	⦾ 0.07	⦾ 0.16	⦾ 0.08	⦾ 0.09
	PROWLER PLUS	⦾ 0.08	⦾ 0.08	⦾ 0.12	⦾ 0.11	⦾ 0.11	⦾ 0.09	⦾ 0.15	⦾ 0.16	⦾ 0.11	⦾ 0.11	×	×	×
	Renegade	⦾ 0.09	⦾ 0.07	⦾ 0.08	⦾ 0.08	⦾ 0.11	⦾ 0.14	⦾ 0.19	⦾ 0.15	⦾ 0.21	×	×	×	×
	HyperForm (4*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
	HyperForm (7*7 mm)	―	―	―	―	―	―	―	―	―	―	―	―	―
Resistance was subjectively evaluated and recorded as absent (double circle), slight (single circle), and strong (triangle). The impossibility of passing 2 microdevices inside the guiding catheter was also recorded (×). -: not performed. To measure maximal resistance (in Newtons) we used a digital push-pull gauge (lower section).

Discussion

The development of detachable coils has led to marked improvements in the endovascular treatment of intracranial aneurysms, particularly saccular aneurysms with small necks ¹. However, in aneurysms with a large neck (diameter >4 mm) or an unfavorable neck-to-fundus ratio (>0.7), stable occlusion using detachable coils and a single microdevice remained difficult. To embolize these aneurysms, advanced methods such as the double microcatheter- and the balloon assist technique must be applied.

The simultaneous introduction of two microcatheters in an aneurysm allows the positioning and stability-assessment of two coils before their detachment and their side-by-side placement in the aneurysmal orifice. The lattice formed by coil loops facilitates the bridging of the aneurysmal neck, decreases the risk of coil herniation through the neck, and allows the safe deposition of subsequent coils ^4,11,12. The balloon-assisted or neck-remodeling technique is an adjunctive approach that consists of placing a balloon microcatheter at the neck of the aneurysm before microcatheterization of the dome and coil deployment into the aneurysm ⁹. Temporary balloon inflation during coil deployment obliterates the neck, thereby preventing coil herniation into the parent vessels ^6,7,13.

Access for the two microdevices can be obtained by introducing a guiding catheter larger than 7-Fr via a single groin site or by placing two guiding catheters (5- or 6-Fr) via separate groin sites. However, in many patients with vertebrobasilar artery aneurysms the dominant vertebral artery is too small for the introduction of a 7-Fr guiding catheter or two guiding catheters and may elicit complications such as thrombo-embolic events or flow disturbance in the parent artery. Therefore, there was a need for a single guiding system with a large inner lumen that can accommodate two microdevices. We found no reports on the use of a 6-Fr guiding catheter in the performance of double microdevice techniques indicating that the catheter provided sufficient space for intraoperative roadmapping and angiography.

The 6-Fr Slim Guide^® facilitates employment of the double microdevice technique. Its outer diameter is 6-Fr; its lumen is 0.072 inch and thus larger than of Launcher^® (0.071 inch) and Envoy^® (0.070 inch) guiding catheters. According to Luzardo et al. ¹⁴, balloon-assisted coiling through a single 6-Fr guiding catheter (Envoy^®) was possible, but they noticed a slight increase in friction between the microcatheter and the guiding catheter that did not interfere with the execution of any procedures. Although the Slim Guide^® is slightly larger than the other guiding catheters we used, it offers several advantages. In experiment 2, its infusion pressure was lower at injection volumes exceeding 3.0 ml/s, suggesting that despite the simultaneous introduction of two microdevices, a higher contrast volume can be delivered than is possible with the other guiding catheters and that sharp images can be acquired for angiography and roadmapping during aneurysmal embolization procedures. In addition, Slim Guide^® increased the possible combinations of introduced microdevices. When we used Envoy^® or Launcher^® devices as guiding catheters and the microballoon catheter as the microdevice, we did not need to introduce the Excelsior^® or Fas-Tracker 10^® microcatheter as a second microdevice. Both microdevices were accommodated by the Slim Guide^®.

We were concerned that an increase in the inner lumen of the guiding catheter would result in a decrease in the shaft hardness and kink resistance. The results of experiment 1 showed that although the shaft of the Slim Guide^® was softer than of Envoy^® and Launcher^®, its kink resistance was comparable. Therefore, the characteristic features of the Slim Guide^® are its greater flexibility compared to the other two 6-Fr guiding catheters and its comparable kink resistance.

Although the use of double microdevices rendered the treatment of wide-necked aneurysms safer and increased the range of treatable aneurysms, their introduction via conventional guiding catheters raises the risk of eliciting thrombo-embolic complications. Our preliminary experiments suggest that Slim Guide^®, whose lumen is larger than that of conventional guiding catheters, may reduce these risks and that the Slim Guide^® may be useful for the treatment of selected patients with aneurysms whose embolization by conventional techniques is difficult. Elsewhere ¹⁵ we reported the results of our clinical trial of the Slim Guide^®. With the Slim Guide^® the risks inherent in the use of advanced techniques to address aneurysms that pose treatment challenges may be decreased.

Conclusions

The inner diameter of Slim Guide^® is slightly larger than that of the other two guiding catheters we used in these experiments (Launcher^®, Envoy^®). Although the Slim Guide^® is more flexible than the other two guiding catheters, its kink resistance was comparable. The use of Slim Guide^® significantly increases the combination of microdevices that can be used for the coil embolization of difficult aneurysms.