Kissing Balloon Technique within a 5 Fr Guiding Catheter
Using 0.010 Inch Guidewires and 0.010 Inch Guidewire-
Compatible Ball

Percutaneous coronary intervention (PCI) devices have been getting smaller, especially guide catheters. In the 1990s, an 8 Fr guide catheter was necessary for stent implantation in a simple coronary lesion. At present, a 6 Fr guide catheter is frequently used for drug-eluting stent (DES) implantation in Japan. Recent studies have shown that a 5 Fr guide catheter is effective for the majority of noncomplex, selected cases.^1–5 While small guide catheters are superior to large catheters in terms of a lower complication rate at the approach site,^6,7 a 5 Fr guide catheter has some limitations. For example, a 5 Fr guide catheter does not accept an Atlantis SR Pro (Boston Scientific Corp., Natick, Massachusetts) intravascular ultrasound (IVUS) catheter because the IVUS catheter is too large for the inner lumen of a 5 Fr guide catheter. However, the same IVUS catheter can pass through a 5 Fr guide catheter if the guidewire size is 0.010 inch.
The kissing balloon technique (KBT) is a basic method for dilating bifurcation lesions.^8,9 In the 1990s, it required an 8 Fr guide catheter that would accept 2 balloons.¹⁰ We recently performed the KBT through a 6 Fr guide catheter using small outer-diameter balloons. However, it is still impossible to perform the KBT through a 5 Fr guide catheter, even with the use of the 0.010 inch guidewires and any small balloon catheters. Smaller outer-diameter balloons are necessary if the KBT is to be performed through a 5 Fr guide catheter.
We report here the characteristics of a new balloon with a smaller outer diameter. The key technological advancement that now allows the use of small-diameter balloons was the reduction of the guidewire lumen, which is now a suitable diameter of 0.010 inch. We also report on an animal experiment using a porcine model and a clinical case of the use of a 5 Fr guide catheter to perform the KBT.

Materials and Methods

Ikazuchi-10 balloon. The Ikazuchi-10 PTCA balloon system is compatible with a 0.010 inch guidewire and consists of a regular rapid-exchange balloon catheter component (Figure 1B) (Kaneka Medics, Tokyo, Japan). While a traditional ACS 10 balloon is shown in Figure 1A, the Ikazuchi-10 is smaller than the ACS 10. In this system, every part is smaller than the conventional 0.014 inch-compatible product (Table 1). The maximum outer diameter of this balloon is 2.1 Fr, though it is 2.4 Fr with the smallest 0.014 inch-compatible balloons. Consequently, it is possible to pass 2 balloons over 2 wires through a 5 Fr guide catheter (Figure 1C). We compared the balloon profiles used in the present study to other balloons based on catalog data provided by the manufacturers.
In vitro experiments for trackability. Trackability was measured using a handmade curved coronary artery model. A 6 Fr JL 3.5 Sherpa NX guide catheter (Medtronic Inc., Minneapolis, Minnesota) was inserted and a 0.010 inch Slender 01 guidewire (Japan Lifeline, Japan) was passed into the curved portion of the left anterior descending artery (LAD) model. The 1.5 mm x 15 mm Ikazuchi-10 balloon was advanced with a constant mechanical pressure of 5 mm/second by a motor drive with a push-pull gauge that indicates the pressure automatically.¹¹ The model was filled with water at 37^°C.
Other 0.014 system balloons (1.5 mm x 15 mm) were used as controls: Ottimo-Ex (Kaneka, Japan), Maverick 2 (Boston Scientific), Crosssail (Guidant) and Ryujin Plus (Terumo, Japan). The experiment was repeated 3 times for each catheter.
Animal experiments. We performed an animal experiment in order to determine whether the KBT would be possible through a 5 Fr guide catheter in vivo. The animal protocol conformed to national and local regulations on animal experimentation.

Two juvenile LWD pigs weighing 38 and 40 kg were studied. Anesthesia was induced with xylazine and maintained with inhaled isoflurane. A nonferrous 6 Fr sheath was placed percutaneously in the femoral artery. The animals were anticoagulated with a 200 IU/kg bolus of heparin followed by an infusion of 50–100 IU/kg/hour. We used two types of 0.010 inch guidewires: a coil-type guidewire (Athlete Slender 01, Japan Life Line, Tokyo, Japan) and a hydrocoated guidewire (Athlete Eel Slender Japan Life Line, Tokyo, Japan).

Results
Balloon profiles. Table 1 lists the balloon catheter profiles. Note that these are not our measurements, but datafrom the catalog provided by the manufacturer. The balloon outer diameter, distal shaft and mid-shaft diameters were significantly smaller than other catheters that are considered the best performing balloon catheters at present. Figure 1 shows the catalog data for ACS 10 balloons that were commercially available in the 1990s compared to the Ikazuchi-10 balloon.
In vitro experiments for trackability. We tested the trackability of balloon catheters using the coronary artery model. The force required to advance the Ikazuchi-10 balloon was significantly lower than that required for the other 0.014 inch balloon catheters, probably because of the smaller outer diameter (Figure 2).
Animal experiments. We performed the KBT in the circumflex (CX) coronary artery of the swine using a 5 Fr guide catheter (Heartrail II, Terumo, Tokyo, Japan), 0.010 inch Athlete Slender 01 guidewires and Ikazuchi-10 balloon catheters. Two parallel balloons on 0.010 inch guidewires smoothly passed into the CX bifurcation (Figure 3A). The two balloons were simultaneously inflated to mimic the KBT (Figure 3B). We tested the KBT in both the CX artery and left anterior descending artery in each swine. In all four tests, parallel Ikazuchi-10 balloons on 0.010 inch guidewires passed into the bifurcations very smoothly.
Case report. An 82-year-old male was admitted to our hospital because of unstable angina. Coronary risk factors were hypertension, hyperlipidemia and current smoking. The patient was conscious and no murmurs or rales were heard. Edema was not found. The chest X-ray showed mild congestion and the electrocardiogram revealed no ST changes at rest. Blood tests showed no abnormalities. Coronary angiography showed a 90% diameter stenosis at the proximal right coronary artery (RCA), a 75% diameter stenosis in the left main artery (LM), a 90% stenosis in the proximal CX and a 99% stenosis in the distal CX artery. We chose a combination of off-pump bypass surgery without sternotomy and PCI to treat the patient’s left main and triple-vessel disease because of his advanced age (> 80 years). Coronary artery bypass graft surgery (CABG) was successfully performed by grafting the left internal mammary artery to the left anterior descending artery (LAD). His chest pain persisted despite successful bypass surgery. Thus, we performed PCI for the remaining stenoses 2 weeks after the CABG.
Coronary angiography showed an intact internal mammary artery, a 90% diameter stenosis in the proximal RCA, a 75% diameter stenosis in the LM, a 90% stenosis in the proximal CX, and a 99% stenosis in the distal CX (Figures 4A and B). Furthermore, there was a large diagonal branch between the LM stenosis and 75% stenosis in the mid-segment of the LAD proximal to the internal thoracic artery graft anastomosis. We performed PCI of the RCA and CX including the protected LM using a 5 Fr system to avoid access site complications. We determined that the KBT was necessary for the LM stenosis because of the large diagonal branch.
A 5 Fr sheath was inserted at the right femoral artery and a 5 Fr guide catheter (Heartrail-2 FL4.0, Terumo) with an inner diameter of 0.059 inch was inserted into the left coronary artery. Heparin (5,000 IU) was administered intravenously.
Two types of 0.010 inch guidewires were inserted into the LAD and left CX: an Athlete Slender 01 (Japan Life Line) and an Athlete Eel Slender (Japan Life Line), respectively. The KBT was performed using two 2.5 x 15 mm Ikazuchi-10 balloons at the LM bifurcation for predilatation (Figure 4C).

A 3.0 x 23 mm Cypher^™ stent (Cordis Corp., Miami Lakes, Florida) was implanted from the LM to the CX, crossing over the LAD. After deploying the stent, we recrossed the guidewire to the LAD through the stent struts, and the KBT was performed using two 2.5 x 15 mm Ikazuchi-10 balloons for postdilatation (Figures 4 D and E). The 5 Fr guide catheter accepted 2Ikazuchi-10 balloons that were used to perform the KBT. While in vitro data reported a longer inflation and deflation time with the Ikazuchi-10, there were no problems during this KBT. After successfully treating the LM lesion, a 3.0 x 18 mm Cypher stent was deployed in the distal CX, and two 3.5 x 23 mm Cypher stents were deployed in the RCA through a 5 Fr guide catheter (FR 3.5, Heartrail 2; Terumo). There were no complications during PCI, and the patient’s angina disappeared after the procedure.

Discussion
We report a case of a protected LM artery treated with a 5 Fr guide catheter. This is not the first case of PCI for LM disease with a 5 Fr guide,¹² however, it is the first report of the KBT performed through a 5 Fr guide catheter. At present, the Ikazuchi-10 is the only balloon that can be used in the KBT through a 5 Fr guide. Furthermore, the ability to pass the Ikazuchi-10 balloon catheter is better than that offered by any other balloon catheter in vitro because it has the smallest outer diameter.
Another benefit of a 0.010 inch guidewire is the ability to pass an IVUS catheter through a 5 Fr guide catheter. Using a 0.014 inch guidewire, a 5 Fr guide catheter accepts a Terumo IVUS (Terumo) and Virtual Histology (Volcano Therapeutics, Rancho Cordova, California), but not an Atlantis SR Pro (Boston Scientific), the only IVUS catheter with a motorized pullback system. Using a 0.010 inch guidewire, it is possible to pass all of the IVUS catheters through a 5 Fr guide catheter.
Transradial intervention (TRI) is another way to reduce complications aside from using a small guide catheter.13– 15 TRI reduces access site complications,^16,17 hospital stay, total hospital costs and improves quality of life.¹⁸ A 5 Fr guide catheter is also useful for TRI because a small-sized guide catheter reduces radial artery occlusion.^19–21 Thus, a 5 Fr system is useful both for transfemoral and transradial interventions.
There are currently some limitations with the 0.010 system. The balloon has a longer inflation and deflation time and a weak shaft structure due to its small shaft diameter. The 0.010 guidewire (Athlete Slender 01 or Athlete Eel Slender) has weaknesses such as bending easily and poor trackability. While the 0.010 system has not been available long enough for routine clinical use, we believe that using smallsized devices in PCI is an important future direction in interventional cardiology.
In conclusion, we report the characteristics of the Ikazuchi-10 balloon and a case report of the KBT performed through a 5 Fr guide catheter. The 0.010 system can be used to facilitate PCI with a 5 Fr guide catheter. Further studies are necessary, however, to prove the efficacy and safety of this slender device before it is adopted for routine use in PCI.

References
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