Subadventitial Advancement of a Mother-and-Child
`Catheter to Allow Successful Recanalization of a
`Complex In-Stent Chronic Total Occlusion:
`Testing the Resistance of the Adventitia
`
`Luciano Candilio, MD(Res)1,2; Satoru Mitomo, MD1; Mauro Carlino, MD1; Antonio Colombo, MD1;
`Lorenzo Azzalini, MD, PhD, MSc1
`
`ABSTRACT: In-stent chronic total occlusion (CTO) represents a challenging lesion subset for percutaneous coronary intervention
`(PCI), and although a true-to-true lumen crossing is the first-line strategy, a subadventitial approach may become necessary.
`Here we describe a case of successful in-stent right coronary artery CTO-PCI performed with subadventitial crossing, crushing of
`the occluded stents, and advancement of a mother-and-child catheter to the distal right coronary artery through the subadven-
`titial space to allow stent delivery. The use of intracoronary imaging in this setting proved crucial to confirm adequate apposition
`of the newly implanted stents and optimal crushing of the occluded stents.
`
`J INVASIVE CARDIOL 2017;29(12):E190-E194.
`KEY WORDS: chronic total occlusion, in-stent restenosis, subadventitial
`
`Chronic total occlusions (CTOs) represent one of the
`
`most challenging lesion subsets for percutaneous
`coronary intervention (PCI), and those secondary
`to in-stent restenosis have historically been associated with
`higher failure rates.1,2 True-to-true lumen crossing, achieved
`by either a wire-based approach or by means of the CrossBoss
`catheter (Boston Scientific), is the optimal strategy to recana-
`lize in-stent CTOs.3 However, this is sometimes impossible to
`achieve, and alternative crossing strategies need to be pursued.
`Subadventitial crossing followed by external crushing of
`the occluded stent has been anecdotally reported as a feasible
`strategy to overcome “uncrossable” in-stent CTOs.4,5 Howev-
`er, in such cases, the occluded stents were rather short, which
`allowed stent delivery with conventional techniques.
`Herein, we describe a case of successful recanalization of
`a CTO due to a long occlusive restenosis in two overlap-
`ping stents in the mid-to-distal right coronary artery (RCA).
`Since true-to-true crossing could not be achieved, subadven-
`titial crossing with subsequent stent crushing was performed.
`However, the extensive length of the crushed stent segments
`prevented advancement of new stents into the distal true lu-
`men. Therefore, a mother-and-child catheter was successfully
`advanced through the subadventitial channel to allow stent
`delivery. Invasive imaging confirmed optimal apposition of
`the newly implanted stents and adequate crushing of the oc-
`cluded stents.
`
`Case Presentation
`A 54-year-old man was admitted for a third attempt at
`RCA-CTO recanalization. He was known to have hyperten-
`sion, dyslipidemia, smoking habit, and significant coronary
`
`artery disease (CAD), having undergone multiple PCIs to the
`three coronary arteries. In particular, he had received multi-
`ple bare-metal stents in his RCA, which were found to be
`occluded 10 years earlier. The patient remained symptomat-
`ic despite optimal medical therapy and myocardial perfusion
`imaging demonstrated inducible ischemia in the inferior wall.
`Two unsuccessful PCIs of the RCA-CTO were performed
`through both antegrade and retrograde approaches.
`The occlusion extended from the ostium to both the
`posterolateral (PL) branch and posterior descending artery
`(PDA), and presented proximal cap ambiguity, multiple focal
`areas of calcification, and a short island of patent vessel (vi-
`sualized through an ipsilateral epicardial collateral from the
`proximal RCA; Mashayekhi type B6) just proximal to two
`overlapping occluded stents in the mid-to-distal RCA (Fig-
`ures 1A and 1B). The Japanese-CTO score was 5.
`In previously failed CTO-PCIs, antegrade true-to-true
`crossing was attempted with multiple guidewires of different
`tip shape, which consistently tracked outside the occluded
`stents in the mid RCA (Figure 1C) due to gross stent under-
`sizing (Figure 2). A retrograde approach was performed via
`ipsilateral epicardial collaterals from the proximal to the mid
`RCA in an attempt to recanalize the proximal segment of
`the occlusion and therefore to facilitate a staged attempt at
`revascularization of the more distal part of the CTO. How-
`ever, vessel calcification and the steep angle between the
`landing of the epicardial collateral and the occluded vessel
`prevented retrograde microcatheter advancement and wire
`externalization (Figure 1D). Therefore, antegrade balloon
`angioplasty of the occluded proximal RCA was performed
`(investment procedure; Figures 1E and 1F).
`
`E190
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`FIGURE 1. First procedure: right coronary artery (RCA) in-stent chronic total occlusion.
`(A) The occlusion is very long, with proximal cap ambiguity, multiple focal areas of cal-
`cification, and a short island of patent vessel just proximal to two overlapping occluded
`stents in the mid-to-distal RCA. (B) Ipsilateral epicardial collaterals (from the proximal
`to the mid RCA), as well as contralateral septal (from the left anterior descending to
`the acute marginal) and epicardial (from the circumflex to the posterolateral) channels
`are visualized. (C) Antegrade true-to-true crossing fails, with wires tracking outside the
`occluded stents in the mid RCA. (D) The retrograde approach through an epicardial
`ipsilateral collateral also fails due to impossibility in overcoming the steep angle, as
`indicated by the arrow. (E) Balloon predilation in the subadventitial space is performed
`(investment procedure). (F) Final result.
`
`For the current procedure, dual
`access was secured via left radial ar-
`tery and right femoral artery with
`7 Fr sheaths. Baseline angiography
`showed similar findings as prior to
`the previous attempt (Figure 3A). The
`retrograde approach was attempted
`with a Turnpike LP microcatheter
`(Vascular Solutions) and a Sion wire
`(Asahi Intecc) via epicardial collater-
`als from the circumflex, to no avail
`due to their extreme tortuosity (Fig-
`ures 3B and 3C).
`An antegrade approach was there-
`fore undertaken with the CrossBoss
`catheter, which tracked outside the
`stents in the mid RCA due to the
`aforementioned
`stent-vessel
`size
`mismatch (Figure 3D). CrossBoss
`wire-redirection was similarly un-
`successful.
`Subsequently, a knuckle wire was
`created with a Fielder FC (Asahi In-
`tecc). Due to difficulty in advanc-
`ing the knuckled wire through the
`subadventitial space in the crushed
`stent area, the Turnpike LP itself was
`knuckled and successfully advanced
`to the distal RCA (Figure 3E). The
`subintimal
`tracking and re-entry
`(STAR) technique was performed
`and the wire crossed into the PL branch (Figure 3F).
`Extensive lesion predilation was then achieved using
`a 2.5 x 20 mm non-compliant (NC) balloon and a
`2.5 x 30 mm semicompliant balloon, with subsequent
`crushing of the occluded stents (Figure 4A). However,
`it was not possible to pass a new stent to the distal
`RCA through the subadventitial space. A 7 Fr Guide-
`Liner mother-and-child catheter (Vascular Solutions)
`was therefore advanced through the channel creat-
`ed in the subadventitial space, outside the occluded/
`crushed stents, using the stepwise repeated distal bal-
`loon anchoring technique7 (Figure 4B; Videos 1 and
`2), with subsequent implantation of five overlapping
`drug-eluting stents (3.0 x 38 mm, 3.5 x 38 mm, 4.0 x
`38 mm, 4.0 x 38 mm, and 5.0 x 12 mm) from the PL
`branch to the ostial RCA. High-pressure postdilation
`was carried out using 3.5 mm, 4.0 mm, 4.5 mm, and
`5.0 mm NC balloons from the distal to the proximal
`segments. Excellent angiographic result was obtained
`(Figures 4C and 4D), and both intravascular ultrasound
`(IVUS) and optical coherence tomography confirmed
`optimal crushing of the occluded stents and expansion
`of the newly implanted stents (Figure 5).
`
`FIGURE 2. Quantitative coronary analysis of the occluded stents with
`relative measurements. Two overlapping stents for a total length of 30
`mm are visualized in the mid-to-distal right coronary artery, with evi-
`dence of gross stent undersizing at the level of the distal part of the
`overlapping segment.
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`vol. 29, no. 12, deCember 2017
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`E191
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`Subadventitial advancement for a complex cto
`
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`The patient was discharged the
`following day on long-term dual-an-
`tiplatelet therapy and was asymptom-
`atic at subsequent follow-up exam.
`
`Discussion
`CTO due to in-stent occlusive
`restenosis represents a particularly
`challenging lesion subset and can be
`secondary to neointima formation,
`neoatherosclerosis, adverse reaction
`to polymer, or stent thrombosis, frac-
`ture, malapposition, or under-expan-
`sion.3,8 Despite potential advantages
`deriving from the use of previously
`implanted stents as a roadmap9 to
`guide through the occluded vessel,
`in-stent CTO-PCI has traditionally
`been associated with lower success
`rates when compared with PCI for
`de novo CTOs.1,2 Inability to wire
`the occlusion is the most frequent
`mechanism of failure of both in-stent
`and native coronary artery CTO-
`PCI; however, balloon-uncrossable
`and balloon-unexpandable
`lesions
`are more frequent with in-stent
`CTO1 due to the resistance offered
`by stent struts in close proximity
`to the guidewire.9 Nevertheless, as
`a result of technical developments
`(lower-profile microcatheters and
`balloons, steerable wires, CrossBoss)
`and the introduction of the hybrid
`algorithm,10 procedural success rates
`of in-stent CTO-PCIs have recently
`become comparable to those for de
`novo CTOs.3,11
`
`FIGURE 4. (A) Subadventitial crushing of
`the occluded stents is performed with
`2.5 mm balloons. (B) A 7 Fr GuideLiner
`is advanced to the distal right coronary
`artery (RCA) through the subadventitial
`space using the stepwise repeated dis-
`tal balloon anchoring technique.7 Five
`drug-eluting stents were
`implanted
`from the posterolateral branch to the
`RCA ostium, with optimal angiograph-
`ic result confirmed with intravascular
`ultrasound imaging (C and D). Note the
`much larger final lumen diameter (C)
`compared with the baseline situation
`shown in Figure 2.
`
`E192
`
`FIGURE 3. Second procedure. (A) Baseline angiography is unchanged from the initial
`attempt. (B) Tortuous epicardial collaterals from the circumflex are accessed (C) with a
`Turnpike LP microcatheter and a Sion wire, to no avail due to extreme tortuosity. (D) The
`CrossBoss tracks outside the occluded stents. (E) The Turnpike LP and a Fielder FC wire
`are knuckled in the subadventitial space and (F) advanced, reaching the true lumen in the
`posterolateral branch (arrow).
`
`The Journal of InvasIve CardIology®
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`Subadventitial advancement for a complex cto
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`candilio, et al.
`
`H MP Com munications
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`FIGURE 5. Intravascular ultrasound and optical coherence tomography showing adequate crushing of the occluded stents and
`optimal expansion and apposition of the newly implanted stents. Arrowheads indicate crushed stent struts.
`
`In particular, the use of the CrossBoss, an over-the-wire
`catheter with a blunt, atraumatic 3 Fr tip, offers the oppor-
`tunity of a quick, safe, within-stent, true-to-true crossing,
`utilizing the “fast-spin” technique.9 However, in the current
`case, we could not manage to engage the CrossBoss into
`the occluded stent, likely due to the lower resistance of the
`subadventitial space compared with the intraplaque plane,
`as well as the gross stent under-sizing. Wire redirection was
`also unsuccessful.
`Alternative techniques, including antegrade-wire esca-
`lation and the retrograde approach through ipsilateral and
`contralateral epicardial collaterals, were attempted to no
`avail. Subadventitial crossing with subsequent crushing,
`which has previously been shown feasible both antegradely5
`and retrogradely,4 appeared the only remaining option to re-
`canalize such a complex occlusion in a severely symptomatic
`patient. An important point of concern is represented by the
`possibility of vessel perforation/laceration from predilation
`underneath the thin adventitial layer and against the resis-
`tant metallic stent. For this reason, some operators advocate
`against performing aggressive stent sizing and postdilation,
`which could, however, lead to subsequent new episodes of
`in-stent restenosis.
`Crucially, experimental evidence indicates that the ad-
`ventitia possesses very high tensile strength compared with
`inner layers,12 thus allowing aggressive manipulation (includ-
`ing rotational atherectomy13) and safe CTO recanalization, as
`long as advancement of wires and other devices takes place
`through a plane that is longitudinal to the vessel main axis.14
`
`In the current case, a large-bore device – a 7 Fr Guide-
`Liner – was advanced through a long subadventitial channel
`from the mid to the distal RCA. To the best of our knowl-
`edge, this is the first description of this technique. This ma-
`neuver became necessary because stent delivery to the distal
`vessel was impossible, despite extensive crushing of the oc-
`cluded stents. Fully expanded balloons in this setting (Figure
`4A) indicated that the underlying mechanism was subadven-
`titial space recoil. Therefore, utilization of a device able to
`prevent collapse of the subadventitial space, such as a moth-
`er-and-child catheter, appeared the best choice. Advancing
`the GuideLiner with the stepwise repeated distal-balloon
`anchoring technique7 (Figure 4B) was crucial to the deliv-
`ery of long stents to the distal vessel, thus avoiding friction
`and interference by the distorted struts of the long, crushed,
`occluded stents. This novel utilization of a mother-and-child
`catheter through a long subadventitial channel following ex-
`ternal crushing of occluded stents confirms the high tensile
`strength of the adventitia.12
`Another important element in the safe and successful per-
`formance of such an aggressive intervention is represented by
`the use of intravascular imaging to confirm optimal apposition
`of the newly implanted stents and adequate crushing of the
`occluded stents. There is solid evidence indicating that com-
`pared to angiography guidance alone, IVUS-guided CTO-
`PCI is associated with better mid-term outcomes, including
`lower incidence of myocardial infarction and target-vessel
`revascularization.15 In the setting of in-stent CTO treated
`with subadventitial crushing of a long segment of occluded
`
`vol. 29, no. 12, deCember 2017
`
`E193
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`Subadventitial advancement for a complex cto
`
`candilio, et al.
`
`H MP Com munications
`Copyright 2017
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`
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`stents, the indication for invasive imaging appears even more
`compelling. However, specific outcome data are lacking due
`to the very low frequency of such procedures, and evidence
`derives from anecdotal case reports.4,5
`
`Conclusion
`We report a challenging case of successful in-stent CTO
`recanalization achieved with an unconventional approach
`represented by the combination of subadventitial crushing
`of occluded stents and the innovative use of a mother-and-
`child catheter through the subadventitial space and along-
`side the crushed stents. Invasive imaging confirmed opti-
`mal apposition of the newly implanted stents. Clearly, the
`techniques described in this article should be considered by
`operators with advanced skills tackling complex cases, and
`when conventional techniques and maneuvers have proved
`unsuccessful.
`
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`12. Teng Z, Tang D, Zheng J, Woodard PK, Hoffman AH. An experimental
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`15. Shin DH, Hong SJ, Mintz GS, et al. Effects of intravascular ul-
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`
`From 1the Division of Interventional Cardiology, Cardio-Thoracic-Vascular Depart-
`ment, San Raffaele Scientific Institute, Milan, Italy; and the 2Department of Car-
`diology, The Hammersmith Hospital, Imperial College London, United Kingdom.
`
`Disclosure: The authors have completed and returned the ICMJE Form for Disclo-
`sure of Potential Conflicts of Interest. Dr Azzalini reports personal fees from Guer-
`bet and grant funds from Acist Medical Systems. The remaining authors report no
`conflicts of interest regarding the content herein.
`
`Manuscript submitted March 30, 2017 and accepted April 20, 2017.
`
`Address for correspondence: Lorenzo Azzalini, MD, PhD, MSc, Division of Inter-
`ventional Cardiology, Cardio-Thoracic-Vascular Department, San Raffaele Scien-
`tific Institute, Via Olgettina 60, 20132 Milan, Italy. Email: azzalini.lorenzo@hsr.it
`
`E194
`
`The Journal of InvasIve CardIology®
`
`Subadventitial advancement for a complex cto
`
`candilio, et al.
`
`H MP Com munications
`Copyright 2017
`For Personal Use Only
`
`
`Page 5
`
`Teleflex Ex. 2136
`Medtronic v. Teleflex
`IPR2020-00135
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