Modified Mother-Child Technique Using a Buddy Wire

ABSTRACT: For percutaneous coronary intervention, 6 Fr guiding catheters are the current standard. However, when treating complex coronary lesions, stent delivery is sometimes difficult with a 6 Fr system because of limited back-up support. Several strategies have been proposed in order to overcome this disadvantage, including active/passive guiding-catheter support, wire support, and the anchor-balloon technique. The 4-in-6 mother-child technique is one of the most effective techniques to deliver stents into complex lesions. In the present study, we introduced a new technique in which a second guidewire was used as a buddy wire in combination with the 4 Fr mother-child technique in a case in which stent delivery via the standard 4-in-6 technique failed.

J INVASIVE CARDIOL 2014;26(5):E52-E53 

Key words: interventional cardiology, stenting, new techniques

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Delivery of stents into complex coronary lesions, such as calcified, bent, or diffuse lesions, is sometimes difficult because in such cases, the guide catheter provides poor back-up force. The 4-in-6 mother-child technique is used for delivery of stents to complex coronary lesions.^1,2 This technique showed success in >90% of cases in which the conventional technique had failed to deliver the stents. However, for the remaining ~10% of extremely complex cases, stent delivery requires additional technical solutions. More recently, we proposed a modified 4-in-6 technique to deliver stents using a second guidewire for side-branch protection.³ In the present study, we used this second guidewire as a buddy wire4 to advance the stent and stabilize the child catheter in a case of failed stent delivery employing the standard 4-in-6 technique. Here, we report our experience with this case. To our knowledge, this is the first report describing this novel technique for delivering stents to complex coronary lesions.

Case Report. The patient was a 68-year-old woman with electrocardiographic abnormality. A 6 Fr extra back-up 3.25 Taiga guiding catheter (Medtronic, Inc) was engaged into the left coronary artery via the radial artery. Angiography at baseline showed severe narrowing of the left anterior descending (LAD) artery (Figure 1A, open arrow). After a Runthrough Hypercoat guidewire (Terumo Corporation) was crossed to the LAD, the lesion was predilated with a 2.0 × 15 mm Sprinter Legend balloon (Medtronic, Inc). However, a 2.25 × 24 mm Promus Element stent (Boston Scientific) could not pass the lesion because of severe calcification and bending. Therefore, a standard 4-in-6 technique was used to deliver the stent. The Y-connector was detached from the 6 Fr guiding catheter and attached to the child catheter. The latter was then advanced through the hemostatic valve attached to the 6 Fr guiding catheter. Despite the use of the anchor-balloon technique, the child catheter could not pass the lesion and was therefore placed at the proximal part of the lesion (Figure 1B, arrow). Although several attempts of the 4-in-6 technique were made, delivery of the Promus Element stent remained unsuccessful. In addition, every time the stent was advanced, the child catheter came out proximally (Figure 1C, arrow). A different stent (2.5 x 20 mm Tsunami; Terumo Corporation) and a different child catheter (Cokatte; Asahi Intecc), which might have better crossing ability, were also used, but the outcome did not change.

Finally, the buddy-wire technique was attempted in combination with the 4-in-6 technique. The second guidewire (Runthrough Hypercoat) was advanced through the space between the mother and child catheters. When this second guidewire was positioned as a buddy wire (Figure 1D, arrow heads), the child catheter could be advanced a little bit further (Figure 1D, arrow), and the Tsunami stent easily passed the lesion. Notably, during stent advancement, the child catheter remained stationary. After the Tsunami stent was implanted in the mid-LAD, the Promus Element stent was implanted in the proximal LAD. Since the second diagonal branch showed filling delay with ST elevation, kissing-balloon dilatation was subsequently performed using a 2.0 mm Sprinter Legend balloon and a 2.0 mm Mini Trek balloon (Abbott Vascular). Although the first diagonal branch also showed filling delay, the patient was asymptomatic and no associated electrocardiographic change was noted; therefore, this branch was not touched. 

Discussion. Treatment of calcified and/or bent lesions is often difficult and is associated with failure of stent delivery. We previously reported that the 4 Fr mother-child technique is useful in such cases of failed stent delivery.¹ In the case presented in this report, however, delivery of the coronary stent was difficult even with the 4-in-6 technique. Therefore, we attempted a modified 4-in-6 technique using a buddy wire.

Placement of a second guidewire, the so-called buddy-wire technique, has been considered a safe and effective approach for successful stent delivery.⁴ In the present case, we employed this technique in combination with the 4-in-6 technique and successfully delivered the stent. The mechanisms underlying the success of stent delivery provided by the buddy wire may include: (1) straightening of the lesion; (2) improved support for device tracking; (3) improved positioning of the child catheter; and (4) stabilization of the child catheter.

At present, 4 Fr child catheters are produced by two manufacturers, namely, Terumo and Asahi Intecc. The outer diameter of the Cokatte catheter from Asahi Intecc is slightly larger than in the Kiwami catheter from Terumo (1.50 mm and 1.43 mm, respectively). Therefore, only the 4 Fr child catheter from Terumo can be used for this modified 4-in-6 technique using a buddy guidewire. However, the 4 Fr child catheter from Terumo is not currently available in certain countries, including the United States.

It should also be mentioned that the 4-in-6 technique with the second guidewire can be performed using a 6 Fr guiding catheter with a wide inner diameter (ID). For example, Taiga from Medtronic (ID = 0.072 inches) is suitable for this technique. Heartrail from Terumo and Launcher from Medtronic (ID = 0.071 inches) can also be used, but a small amount of friction may be noted. Guiding catheters with an ID of 0.070 or less are not recommended for this technique.

Conclusion. In conclusion, the 4-in-6 mother-child technique with a buddy wire appears to be a useful and promising approach for treating complex lesions after failed stent delivery.

 References

1. Takeshita S, Shishido K, Sugitatsu K, et al. In vitro and human studies of a 4F double-coaxial technique ("mother-child" configuration) to facilitate stent implantation in resistant coronary vessels. Circ Cardiovasc Interv. 2011;4(2):155-161.
2. Takeshita S, Takagi A, Saito S. Backup support of the mother-child technique: technical considerations for the size of the mother guiding catheter. Catheter Cardiovasc Interv. 2012;80(2):292-297.
3. Shishido K, Takeshita S, Tanaka Y, Saito S. The 4 Fr mother-child technique with side-branch protection for treatment of complex bifurcation lesions. EuroIntervention. 2012;8(5):634-637.
4. Burzotta F, Trani C, Mazzari MA, et al. Use of a second buddy wire during percutaneous coronary interventions: a simple solution for some challenging situations. J Invasive Cardiol. 2005;17(3):171-174.

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From the Department of Cardiology, Nagasaki Municipal Hospital, Nagasaki, Japan.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted August 26, 2013, provisional acceptance given September 9, 2013, final version accepted October 18, 2013.

Address for correspondence: Satoshi Takeshita, MD, FACC, Department of Cardiology, Nagasaki Municipal Hospital, 6-39 Shinchi, Nagasaki 850-8555, Japan. Email: stake@muse.ocn.ne.jp