Subintimal Space Plaque Modification for “Balloon-Uncrossable” Chronic Total Occlusions

Abstract: Novel techniques for percutaneous revascularization of chronic total occlusions or other complex coronary lesions utilize the subintimal space to safely and efficiently traverse the occluded coronary segment. Antegrade and retrograde dissection reentry is gaining popularity, and is an elegant method to successfully cross coronary chronic total occlusions. We describe a “subintimal space plaque modification” that involves use of antegrade and retrograde dissection reentry techniques to treat “balloon-uncrossable” coronary lesions. 

J INVASIVE CARDIOL 2014;26(10):E133-E136

Key words: chronic total occlusion, percutaneous coronary intervention, balloon uncrossable

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Coronary chronic total occlusions (CTOs) and other complex coronary lesions are commonly found during catheterization of patients with coronary artery disease.^1,2 Recent advances in CTO percutaneous coronary intervention (PCI) techniques, such as the retrograde approach^3-5 and antegrade dissection reentry,^6,7 have been associated with operator willingness to attempt these lesions and improved success rates of CTO-PCI. As more complex lesions are attempted, more “resistant” lesions are encountered, including lesions that cannot be crossed with a balloon after successful guidewire crossing.^8,9 Such lesions may fail to respond to several treatment strategies, such as techniques to enhance guide catheter support or to modify the lesion.^8,10,11 

Subintimal crossing techniques have revolutionized CTO-PCI by increasing procedural success rates.^6,7 We describe the use of antegrade and retrograde subintimal techniques to enable crossing of “balloon-uncrossable” CTOs or other complex lesions, a technique we named “subintimal space plaque modification.”

Case Reports

Case #1. A 76-year-old man with Canadian Cardiovascular Society (CCS) class IV angina despite two antianginal drugs was referred for rotational atherectomy (RA) of a subtotally occluded and heavily calcified mid-right coronary artery (RCA; Figure 1A). The RCA was engaged with an 8 Fr Judkin’s right 4 guide catheter and the lesion was crossed with a soft-tipped polymer jacketed wire (Fielder FC; Asahi Intecc). Despite use of the side-branch anchor technique, none of the available microcatheters (Corsair and Tornus 2.6 [Asahi Intecc] and Finecross [Terumo Corporation]) could be advanced through the lesion to allow exchange for the RA wire (Figure 1B). A second Fielder FC guidewire was used to create a knuckle and dissect around the calcified proximal cap. A 2.5 mm balloon was advanced over this wire to “crush” the proximal cap from the subintimal space (Figure 1C), followed by easy CTO crossing with a Corsair microcatheter (Figure 1D) over the first true lumen wire.  An RA wire was exchanged and RA was performed using a 1.5 mm burr at 180,000 rpm on the true lumen wire after removal of the subintimal wire (Figure 1E). GuideLiner-facilitated stenting (Vascular Solutions) was performed and an excellent final angiographic result (Figure 1F) was obtained. The patient had an uneventful recovery and remains symptom free 1 year later.

Case #2. A 72-year-old woman with CCS III angina despite maximal medical therapy and previous PCI to left anterior descending (LAD) and left circumflex arteries was referred for PCI of an RCA-CTO.  The CTO was relatively short, with a J-CTO score of 1 (Figure 2A). A LIMA and an XB 3.5 6 Fr guide catheter were used to engage the RCA and LAD, respectively. Simultaneous bilateral injections of the LAD and RCA were performed; after angiographic review, we decided that the initial strategy would be antegrade wire escalation, followed by antegrade dissection-reentry and retrograde bail-out, according to the “hybrid” algorithm.¹² A Prowater guidewire (Asahi Intecc) was advanced to the proximal cap over a Finecross microcatheter.  The microcatheter was left in place and the Prowater was exchanged for a Pilot 200 guidewire (Abbott Vascular) that easily crossed the CTO (Figure 2B). Unfortunately, even with the use of a 6 Fr GuideLiner, no balloons or microcatheters could be delivered across the proximal CTO cap (Figure 2C).  The Pilot 200 antegrade wire was left in place and we switched to retrograde approach. A Fielder FC guidewire was advanced through the LAD into a septal branch into the distal RCA, followed by advancement of a Corsair catheter into the distal RCA (Figure 2D). The retrograde Fielder FC guidewire was exchanged for a Pilot 200 guidewire and attempts were made at crossing the CTO segment retrogradely. This wire kept advancing into the subintimal space, and therefore was exchanged for a Confienza pro 12 guidewire (Asahi Intecc), which also entered the subintimal space. We then decided to proceed with retrograde knuckle technique using Fielder XT guidewire (Figure 2E). This retrograde knuckle in the subintimal space modified the proximal cap, enabling delivery of a 1.25 mm Monorail balloon over the antegrade wire through the CTO (Figures 2F and 2G). This lesion was progressively dilated and the RCA was stented with 2.5 x 32 mm and 2.25 x 32 mm Promus Element stents (Boston Scientific), followed by postdilation with a 2.75 mm non-compliant balloon (Figure 1H). The patient had no postprocedural complications and is angina free at follow-up.

Discussion

We describe a novel technique for modifying resistant “balloon-uncrossable” coronary lesions to allow passage of angioplasty balloons and/or microcatheters. We named this technique “subintimal space plaque modification.” In this technique, after successful antegrade guidewire crossing, another guidewire is delivered to the subintimal space adjacent to the resistant lesion, either in the antegrade (Case #1) or retrograde (Case #2) direction. Once the wire is in the subintimal space across the CTO, we modify the lesion “externally” by performing either subintimal balloon angioplasty or advancement of a subintimal knuckle wire. Modification of the lesion by our technique allows passage of balloons and/or microcatheters through these complex resistant lesions, enabling delivery of intracoronary stents.  To the best of our knowledge, this is the first report of this technique in balloon-uncrossable CTO lesions.

During recent years, the technical and procedural success rates of CTO-PCI have improved dramatically, reaching or exceeding 90%.^3,5 There have been significant improvements in equipment and procedural techniques.  One major improvement in technique is the use of the subintimal space to safely, efficiently, and successfully revascularize a CTO.^4,7,12-15 A dissection plane across the CTO is created either antegradely or retrogradely and subsequently reentered distally or proximally, respectively. Antegrade dissection reentry techniques include subintimal tracking and reentry (STAR),¹⁶ limited antegrade subintimal tracking (LAST), and dedicated dissection reentry devices such as CrossBoss and Stingray catheters (Boston Scientific).^7,14 Retrograde dissection reentry techniques include controlled antegrade and retrograde tracking (CART) and reverse CART.^4,6 The use of the subintimal space in these techniques allows safe and rapid crossing of the CTO segment with subsequent reentry into the true lumen, enabling successful delivery of balloons and stents. In our case reports, we illustrate a novel use of the subintimal space.  Instead of using it to traverse the CTO segment, we stay within the CTO segment to modify the lesion externally either with subintimal balloon angioplasty or with a knuckle wire. Doing so enables delivery of balloons and stents over the true lumen guidewire. This is a technique that can be used for resistant balloon-uncrossable and balloon-undilatable lesions when Rotablator rotational atherectomy is not possible due to the inability to pass the RotaWire, or when laser is not possible due to its unavailability in many centers.  This technique uses equipment that is already available in most, if not all, cardiac catheterization laboratories. 

There are several limitations to this technique. It is not always possible to predictably advance a wire into the subintimal space. This technique also requires limited dissection by entering the subintimal space as close as possible to the CTO segment, which can be difficult to purposely achieve. Once subintimal position of the wire is obtained, there is risk of perforation with “external crush” ballooning, so high-pressure inflation should be avoided. Furthermore, careful management of subintimal space is mandatory in order to avoid extension of the subintimal space either proximally or distally, requiring much longer stenting segments than necessary or other treatments of subintimal space hematomas. In all, this technique requires advanced PCI skills — especially with CTO-PCIs — which may not be possible in some labs. For example, if the technique is complicated or unsuccessful, it can be salvaged with distal reentry using the BridgePoint system (Boston Scientific) or reverse CART in a new location. Finally, the use of RA in the setting of dissection should be avoided if possible, but when necessary we recommend using only small burrs (≤1.5 mm) and high rpm (≥180,000).

Conclusion

In summary, subintimal space plaque modification is a novel technique that can be useful in balloon-uncrossable lesions to enable subsequent delivery of balloons and stents.

Acknowledgments. We would to acknowledge Emmanouil S. Brilakis, MD, PhD, for his significant contribution to this paper. 

References

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From the ¹University of Manitoba, Manitoba, Canada; ²St Boniface Hospital, Winnipag, Canada; and ³Saint-Lukes Mid America Heart Institute, Kansas City, Missouri.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Vo reports fees, travel, and honoraria from Boston Scientific. Dr Ravandi reports no disclosures. Dr Grantham reports research and education grants from Boston Scientific, Medtronic, Asahi-Intecc; speaking fees, travel fees, and honoraria from Boston Scientific and Asahi-Intecc.

Manuscript submitted January 23, 2014, provisional acceptance given February 14 2014, final version accepted February 26, 2014.

Address for correspondence: Minh N. Vo, MD, University of Manitoba, 409 Tache Ave, Winnipeg, Manitoba R2H 2A6, Canada. Email: mvo@sbgh.mb.ca