In-Stent Anchoring Facilitates Balloon Delivery for Final Kissing

ABSTRACT: Kissing-balloon inflation has been developed for percutaneous bifurcation interventions to improve outcomes and reduced angiographic (re)stenosis. However, this procedure is sometimes technically challenging due to inability to deliver the side-branch (SB) balloon across the structure of the main vessel stent(s). The balloon anchoring technique is reported to enable equipment delivery through complex lesions. However, the most important limitation is injury at the site of balloon inflation. In this paper, we describe an improved in-stent anchoring technique to facilitate balloon delivery to SB and at the same time avoid intimal injury.

J INVASIVE CARDIOL 2014;26(6):E66-E69

Key words: coronary artery disease, endovascular therapy, bifurcation

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Bifurcation lesions are the most frequently approached coronary lesions and represent a technical challenge for the interventional cardiologist. In comparison to other percutaneous coronary interventions (PCIs), bifurcations still have lower rates of procedural success and higher rates of clinical and angiographic restenosis even in the drug-eluting stent (DES) era.¹ Kissing-balloon (KB) inflation has been deeply investigated and variably recommended to optimize stent apposition, correct stent deformation or distortion, reduce the angiographic side branch (SB) (re)stenosis and improves outcomes.^2,3 However, KB is potentially difficult with a rate of success that varies between 64%-92% due to inability to advance the SB balloon across the main vessel (MV) stent structure.^4-7 On occasion the operator may not be able to regain access to the SB, which is associated with a suboptimal final result and worse outcome.

Balloon-anchoring techniques are commonly used to enhance the support of guiding catheter during inflation of a balloon in the SB and subsequently facilitate the equipment delivery to chronic occlusion lesions.^8-10 However, potential endothelial denudation, plaque rupture, and most importantly, dissection and acute occlusion could occur at the site of balloon inflation.^10,11

In this paper, we offer a previously undescribed improved in-stent anchoring technique to facilitate balloon delivery as well as avoid possible vascular injury, suggesting a safe and effective method to increase the success rate of final KB inflation.

Case #1. A 56-year-old male with unstable angina was referred for PCI of a mid left anterior descending (LAD) diffused lesion (90% stenosis) (Figure 1A). A 6 Fr JL4.0 guide was used and the lesion was predilated with a 2.5 x 18 mm balloon. A 3.0 x 28 mm sent implantation in the mid LAD (using the crossover technique) caused severe stenosis in the ostium of the first diagonal branch (D1) and sudden chest pain (Figure 1B). Then, the D1 was immediately rewired with a 0.014〞Whisper wire. However, we were unable to advance a 1.5 x 15 mm balloon into the D1, even with buddy wires. Thus, a 3.0 x 12 mm non-compliant balloon was positioned between the ostium of the D1 and the distal edge of the LAD stent (anchored zone). Then, we inflated the 3.0 x 12 mm balloon with 12 atm (anchoring in the LAD stent) to enhance the support of the guiding catheter. At the same time, the 1.5 x 15 mm balloon was advanced and successfully crossed the LAD stent cell into the D1 (Figure 1C). Finally, the KB inflation technique was applied to the bifurcation (Figure 1D).

Case #2. A 61-year-old male with chest pain was referred for PCI with a bifurcation lesion of the left circumflex (LCX) and third obtuse marginal branch (OM3) (Figure 2A). A 7 Fr JL4.0 guide was used and the lesions were wired with Balance Middle Weight (BMW) wire. The crush technique was performed according to previous methods (Figures 2B, 2C, 2D).¹¹ The LCX and OM3 stents were deployed in sequence. After rewiring the LCX, we were unable to deliver a 1.5 mm balloon across the OM3 stent structure into the LCX. In order to increase the guiding support, a 3.5 x 9 mm non-compliant balloon was located in the anchored zone of the OM3 stent (between the ostium of the LCX and the distal edge of the stent). Then, we dilated the 3.5 x 9 mm balloon with 12 atm for “in-stent anchoring,” and at the same time advanced a 1.5 x 15 mm balloon into the LCX, respectively (Figure 2E). Sequential high-pressure (16 atm) dilation was performed with a 2.75 mm balloon in the LCX and 3.5 mm balloon in the OM3. At last, final KB inflation was finished, indicating a good angiographic result (Figure 2F).

Discussion. The balloon-anchoring technique was first reported in 2003 to facilitate equipment delivery to chronic total occlusion lesions and has gained popularity in clinical use. Up to now, two variations of anchoring approach (coaxial and SB anchoring) have been described to facilitate equipment movement.^8-11 However, use of the present anchoring technique has defects. The first and most important limitation is injury at the site of balloon inflation.^10,11 The second is that lower inflation pressure (<6 atm) is preferred to avoid potential injury, which may contribute to insufficient guiding support.

However, in this paper, the balloon is inflated in the anchored zone, where the intima is covered and protected by the stent. Thus, there is no risk of vessel dissection and serious injury when high-inflation pressure (12 atm) was performed. Meanwhile, the balloon could advance since the anchored balloon didn’t block the SB. We did use lower inflation pressure (6 atm) for successful equipment delivery in tortuous lesions in order to avoid dissection and possible vascular occlusion (unpublished data). However, carina, plaque shift, and presence of stent struts in the ostium are the leading obstacles to balloon delivery during bifurcation intervention. These obstructions were mainly caused by mechanical extrusion and are more difficult to cross. Therefore, we directly used high inflation pressure to ensure sufficient guide support.

In this paper, a 1.5 mm balloon was successfully recrossed into the SB through multiple layers of stent material after in-stent anchoring; more importantly, no angiographic dissection or thrombus were detected in the MV. These initial results indicate that in-stent anchoring is an effective and safe technique to facilitate balloon delivery for final KB.

Furthermore, we suggest this improved technique as the first-line method for SB balloon delivery in the setting of severe ostial SB stenosis for two reasons: (1) No additional equipment is needed for in-stent anchoring. Therefore, it may shorten operation time to try this handy technique in case KB is necessary. (2) If the in-stent anchoring technique fails, it is likely complementary with other techniques, such as use of smaller balloons, microcatheters, buddy wire, or Glider balloon. That’s also the reason we didn’t use 1-1.25 mm balloons or microcatheters prior to the anchoring technique.

However, there are also some pitfalls with this technique: (1) A preimplanted stent is necessary. (2) A short, non-compliant balloon is recommended because it is easy to be positioned and covered by the stent. (3) A guiding catheter ≥6 Fr  is needed for two balloon catheters to operate together. (4) Although the coronary artery is transiently blocked by anchored balloon dilation (for <30 seconds), the interruption of blood flow may also cause an uncomfortable sensation.

Step-by-step description of in-stent anchoring technique (Figure 3). First, the MV and SB are wired (Figure 3A). Second, an obvious stenosis appears in the ostium of the SB after MV stent implantation (Figure 3B). Third, a 1.5 mm balloon is recommended as the first choice and is unable to advance across the MV stent structure into the SB (Figure 3C). Fourth, a short, non-compliant balloon, size-matched 1:1 to the stent size, is accurately positioned in the “anchored zone” of the MV stent (between the ostium of the SB and the distal edge of the stent) (Figure 3D). Fifth, the in-stent balloon is inflated (usually at high pressure) and the operator pulls the balloon and both wires as an anchor; at the same time, the SB balloon is pushed through the MV stent structures (Figure 3E). Sixth, the in-stent balloon is deflated to recover MV blood flow and withdrawn to the bifurcation. Kissing-balloon dilation was performed according to previous methods (Figure 3F).¹³ The key point of this technique is to accurately position the MV balloon in the anchored zone, where the inflated balloon will leave access to the SB opening and won’t injure the MV outside the stent. Therefore, a short, non-compliant balloon is recommended because it is easy to be positioned and covered by the MV stent.

The proximal optimization technique (POT) relates to a method of expanding the stent proximal to the bifurcation carina, using a short oversized balloon. This technique is recommended by the European Bifurcation Club to facilitate recrossing of SBs.¹² However, the POT technique is useful in the presence of a large SB diameter. It is difficult to accurately position the POT balloon in cases with severe ostial SB stenosis and the technique may involve high risk of SB occlusion after inflation. Therefore, we didn’t try POT prior to the anchoring technique.

Other studies have also been investigated to facilitate delivery of interventional equipment: use of deep insertion of the guiding catheter into the coronary artery;¹⁴ use of extra-supportive wires and buddy-wire technique;¹⁵ and mother-and-child technique.¹⁶ The Glider (TriReme Medical) is a dedicated balloon designed for crossing through struts of deployed stents toward a SB. A recent study of this new balloon catheter concluded that this unique bail-out device offers an effective rescue strategy for recrossing stent struts during complex bifurcation stenting.¹⁷ However, in-stent anchoring is simple and readily available, ensures better balloon delivery than buddy wire, and is safer than deep insertion and the mother-and-child guiding technique.

Study limitations. First, it was reported that carina shift, not plaque shift, is the major mechanism of SB compromise induced by stent expansion.¹⁸ Furthermore, several studies have confirmed the ability of optical coherence tomography to offer guidance during wire recrossing during PCI in bifurcations and to reduce strut malapposition.^19,20 Intravascular ultrasound (IVUS) evaluation of an SB ostium from the MV is only moderately reliable.²¹ For an accurate assessment of the SB ostium, direct imaging is necessary to pull back the IVUS catheter from the SB.²² However, SB pullback (LCX) was available in only 50% pre-stenting and 40% post stenting due to technical difficulty, which may be realistic in clinical practice.²¹ In this study, we couldn’t cross into the SB with an IVUS catheter in this setting of severe compromise; therefore, we didn’t have accurate information regarding why the balloon was unable to pass through the SB (for example, carina shift, presence of stent struts in the ostium, or plaque shift). Second, inadvertent placement of the wire under the struts of the proximal stent prior to the bifurcation could be dangerous. Intravascular imaging should be used to ascertain that the wire is indeed crossing through the SB osmium. Also, use of POT in the MV, ideally performed before recrossing to the SB, is quite helpful to avoid insertion of the wire below the structures. Third, lower inflation pressure is suggested when using the traditional anchoring technique. Theoretically speaking, this may achieve weaker anchoring effect, but would provide less risk. However, we didn’t compare the safety and efficiency of different inflation pressures (<10 atm). Hopefully, future studies will provide answers to this question.

Conclusion. In-stent anchoring is a safe and effective balloon delivery technique for final kissing. However, more cases are needed to provide further verification and evaluation.

References

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From the Cardiovascular Disease Research Center, Xinqiao Hospital, Third Military Medical University, Chongqing, China.

Funding: This study was supported by grants from  the Third Military Medical University (2010XLC28).

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 8, 2013, provisional acceptance given September 27, 2013, final version accepted November 26, 2013.

Address for correspondence: Prof Xiaohui Zhao or Yaoming Song, MD, 183 Xinqiao Street, ShapingBa District, Chongqing, 400037 China. Email: zxhwn@tmmu.edu.cn or sym551342002@126.com