Initial Characterization of Ikari Guide Catheter for Transradial Coronary Intervention

ABSTRACT: Ikari is a new guide catheter for transradial intervention (TRI) that produces stronger back-up force by utilizing an unfavorable angle between the subclavian and brachiocephalic arteries. We report the initial results of the Ikari guide catheter based on the experience of a single center. Six operators performed a total of 102 coronary interventions for 91 patients using the Ikari guide catheter, while 101 interventions were performed with the transfemoral approach (TFI) during the same period. A left Ikari catheter was used in 63 procedures, and a right Ikari catheter was used in 39. The success rate for the procedure was 97% with a 6 French Ikari catheter. All failures were due to tortuous brachiocephalic arteries. For the Ikari procedure, the average fluorescence time was 14.5 ± 9.5 minutes and the dye volume used was 153 ± 53 ml; these results were equal to or better than those of TFI during the same period (20.1 ± 12.2 minutes and 184 ± 61 ml, respectively). These preliminary data suggest that an acceptable success rate can be achieved in TRI using appropriate guides, such as an Ikari catheter.

Key words: Judkin’s catheter, percutaneous coronary intervention

Several factors may make transradial intervention (TRI) superior to transfemoral intervention (TFI). TRI is more convenient for patients, carries a lower risk of bleeding and shortens hospital stay. However, TRI has not been widely performed probably because of the weak back-up support of guide catheters. We hypothesize that this is due to an angle between the subclavian and brachiocephalic arteries that causes a reverse bend on the guide catheter. Guide catheters designed for transfemoral approach may not work if they are used with a reverse bend in the middle of the catheter. We previously reported a novel guide catheter for a right upper limb approach, which utilized the disadvantageous angle of operation to generate back-up support. The “Ikari” catheter was designed in 1995, published in 1998 and became commercially available in 2002. In this report, we describe our initial results with the use of the Ikari catheter. Methods Ikari catheters. The Ikari catheters are shown in Figure 1. At present, the 6 French (Fr) Heartrail shaft has an inner lumen of 0.071 inches (Terumo, Tokyo, Japan). The mechanism whereby the Ikari catheter operates is based on our hypothesis that the lower back-up support in the upper limb approach is due to a different route of approach used by the guide catheters. The biggest difference is the angle between the right subclavian and the brachiocephalic arteries, which causes a reverse angle on the guide catheters. Judkins catheters designed for TFI are inappropriate to fit this angle. Therefore, we incorporated the reverse angle in the design of the guide catheter (Figure 2). At present, the Ikari left (IL) catheter is available in three sizes, designated IL 3.5, IL 4.0 and IL 4.5. These represent lengths that correspond to the reverse side of the aorta to the left coronary ostium, and are the same sizes as Judkins catheters. IL 4.0 is the regular size. The Ikari R (IR) catheter has four sizes, designated IR 1.5, IR 2.0 and IR 2.5. These correspond to lengths of the distal tips. The first choice is usually IR 1.0 or IR 1.5. When the tip length is longer, the back-up is stronger but more difficult to engage. In the Ikari left catheter, the actual length of each site is 0.8 cm at the first short distal line. At the second straight line, the length is 1.1 cm for IL 3.5, 1.3 cm for IL 4.0 and 1.5 cm for IL 4.5. The length is 1.1 cm at the third straight line and 5.9 cm at the fourth straight line. In the IR catheter, the length of each site for the distal straight line is 1.0 cm (IR 1.0), 1.3 cm (IR 1.5), 1.8 cm (IR 2.0) and 2.3 cm (IR 2.5). The length is 1.0 cm at the second angled line and 6.0 cm at the third straight line. Study design and PCI procedure. This single-center, non-randomized study includes consecutive cases between April and September 2002 where the Ikari guide was used. All patients suitable for the right radial approach were included in this study. In addition, all cases were included when the Ikari guide was considered as the first choice for the right brachial or left radial approaches. Exclusion criteria were: negative Allen’s test; radial artery diameter less than 2.5 mm; hemodialysis; or patient preference for femoral approach due to radial pain during prior catheterization. Although the first choice of guide was Ikari during this period, other guides were used as the first choice in 4 cases because of a protocol error. A 6 Fr sheath (M-coat sheath, Terumo) was inserted via the right radial artery. If the guide catheter did not fit, the catheter was changed to another size Ikari. If an alternately sized Ikari did not work, the catheter was changed to other shapes and then larger guide catheters were used. If none of the catheters worked, then the approach site was changed to the femoral artery. Results Patient and lesion characteristics. The average age of the patients was 64 years, and 81% were male. Target lesions were 63 left, 38 right and 1 vein graft. Type B2 and C lesions accounted for 50% of all lesions. The rate of chronic total occlusion was 8% (Table 1). A typical case is shown in Figure 3. Procedure. The right upper limb approach was used in 94% of the procedures. Small radial arteries or negative Allen’s tests were encountered in 23% of the cases and therefore right radial artery puncture was avoided. A left radial approach was used in 5% of the cases and a brachial approach with puncture method was used in 18% of the cases. During this time, there were no puncture failures of the radial artery. Although the Ikari was originally designed for the right upper limb approach, it also worked when used via the left upper limb (6% of the patients). Six operators used the Ikari during this period, and 29% of the PCI cases were performed by 3 beginners with no prior TRI experience. Stent implantation was performed in 69% of the cases. We performed cutting balloon or regular balloon to treat in-stent restenosis without brachytherapy, because brachytherapy is not presently available in Japan. There was no difficulty inserting stents or cutting balloons because the Ikari guide has an adequately sized lumen. Catheter size. IR 1.0 and IR 1.5 catheters were selected for 49% and 44% of the cases, respectively. IR 1.0 was suitable for lesions that had a short distance between the ostium and the first angle. IL 4.0 was used for 71% of all left coronary arteries. Many operators preferred a left 3.5 for use in TRI; however, the Ikari left 4.0 is the regular size, which is the same size as the left Judkins used for a transfemoral approach. Success. The PCI success rate using 6 Fr Ikari catheters was 97%. Average fluorescence time was 14.5 ± 9.5 minutes, and average volume of dye was 153 ± 53 ml. During the same period, a total of 101 TFI procedures were performed. The average fluorescence time for TFI was 20.1 ± 12.2 minutes and the average volume of dye was 184 ± 61 ml. These data were similar to or better than those for transfemoral interventions at our institution. All of the chronic total occlusions were successfully treated. There were three failures, which were due to tortuous subclavian and brachiocephalic arteries. In these situations, we inserted a 0.035´´ guidewire inside the guide catheter. However, the catheters could not be controlled. In all 3 cases, we changed the guide catheter to a 6 Fr Brite tip Judkins (Cordis Corporation, Miami, Florida). However, the control problem persisted. In 1 case, the guide was successfully changed to a 7 Fr Brite tip via the radial artery. In the other two cases, success was achieved in the end with a 6 Fr TFI. PCI was successful in all of the cases when engagement was successful. None of the cases where M-coat sheaths were used showed complicated spasm or pain of the radial artery. Skin blisters were observed in 14% of cases in which Stepty P (Nichiban, Tokyo, Japan) was used for hemostasis. In one case, the radial pulse was lost in the chronic phase. Discussion In this study, the initial results of the 6 Fr Ikari guide catheter were considered acceptable by the 6 operators, including the 3 beginners. TRI is more convenient for the patient, since it carries a lower risk of bleeding and shortens hospital stay. However, TRI has limitations, such as difficulty to puncture, limited availability of catheter sizes and less back-up support of guide catheters. One of the major reasons that TRI has not been widely used is the weak back-up support of guide catheters. This is because many operators use the Judkins catheter for TRI even though Judkins catheters are designed for the transfemoral approach. Therefore, there is need for a new guide catheter specialized for TRI. If the left radial approach is used, many femoral guide catheters have enough back-up support. However, the left radial approach is sometimes difficult because of the traditional design of the catheter laboratory, which is another major reason that many operators have not adopted TRI. The Ikari guide seemed to generate enough back-up support for TRI because deep engagement was necessary in only 1% of the cases, and this may be as low as the incidence in 6 Fr TFI. All failed cases were due to tortuous subclavian arteries. Furthermore, another catheter (Brite tip) was not able to engage in these cases. The success rate of the Ikari guide (97%) may be acceptable in this “real world” situation. Choosing Ikari catheter size. For left catheterization, the size is the same as Judkins. If JL 4 is considered suitable in angiography, the same size Ikari, IL 4, should be chosen. This is because Ikari left has basically the same shape except for the area of the brachiocephalic angle. However, it is completely different from Voda left, which requires one size smaller catheter. For right catheterization, we suggest IR 1.5 as the first choice, but IR 1.0 should be considered when the lesion is located in the proximal right coronary artery or a small-sized aorta. Ikari right has a longer distal tip and has more back-up force. If extremely strong back-up is necessary, such as in cases of chronic total occlusion, we suggest IR 2.0 or IR 2.5. To avoid occlusion by guide catheter, an IR with side-holes should be considered, especially in small right coronary arteries. In this study, we could not analyze the rate of learning because beginner operators achieved a 100% success rate. The Multicenter registry in Japan shows that success rates for beginners, intermediates and experts are 95%, 97% and 98%, respectively (unpublished data). This may suggest that a learning curve exists. However, a 95% success rate in beginner operators may be acceptable for TRI. TFI using a hemostasis device shortens hospital stay compared to manual compression, suggesting that it may be compatible with TRI. However, the cost of the hemostasis device and the risk of infection cannot be ignored. If the back-up support of the guide catheter is the same for TRI and TFI, then TRI may be a safer and more cost-effective approach. Study limitations and conclusions. This was a retrospective and observational study, and we could not quantify back-up support of the catheter nor compare other catheters for TRI. Our data suggest that the Ikari catheter can be one of the candidates for use as a standard guide in TRI. Wider application of TRI may be possible with use of the Ikari guide catheter.