Herz 2010 · 35:582–588DOI 10.1007/s00059-010-3387-2Received: 25. Mai 2010Revised: 2. Juli 2010Accepted: 6. September 2010Online publiziert: 22. September 2010© Urban & Vogel 2010

M. Tomasevic · V. Vukcevic · G. Stankovic · D. Orlic · M. OstojicDepartment of Cardiology, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade

Main branch stent deformation following difficult side branch rewiring and balloon dilatation

Rare complication of provisional T stenting

Case study

Stenting of bifurcation lesions remains a challenge in percutaneous coronary in-tervention as it is associated with a lower procedural success rate and higher rate of adverse events during follow-up. Pro-visional T stenting is a widely used strate-gy that may have excellent outcomes and, according to several randomized trials, results are similar or even superior to the systematic two-stent strategy [1, 2, 3].

The major procedural safety challenge in provisional side branch stenting tech-niques is to ensure that the side branch is protected and has a satisfactory final re-

sult with or without stenting. Side branch rewiring, balloon dilatation, and deploy-ing a side branch stent through the side of a main branch stent can be technical-ly challenging and may not be achieved [4]. One possible case scenario, especial-ly when the main branch stent is under-deployed, is side branch rewiring “under-neath” the main branch stent struts, with marked stent deformation during side branch dilatation and creation of a large gap in the proximal main branch and at the ostium of the side branch [5]. It may be unrecognized angiographically during

procedure but may have an important in-fluence on clinical outcome. As a conse-quence, delayed endothelization, persis-tent turbulence, insufficient mechanical scaffolding, and inadequate drug deliv-ery may develop and contribute to high-er incidences of stent thrombosis and re-stenosis in this setting.

We report a case of provisional T stenting with the guide wire re-crossing between the main vessel stent struts and vessel wall in the proximal part of the drug-eluting stent (DES), and balloon

“crushing” of the proximal portion of the main vessel stent, which resulted in sig-nificant restenosis and symptom recur-rence at follow-up.

Case report

A 52-year-old woman with history of hy-pertension, dyslipidemia, obesity, and smoking was admitted to the hospi-tal for scheduled percutaneous coro-nary revascularization of a true bifur-cation lesion in the mid LAD and sec-ond diagonal branch (D2). Both branch-es were wired with Runthrough NS flop-py guidewires (Terumo) and the LAD le-sion was pre-dilated with a Ryujin bal-loon 2.0×20 mm (Terumo) at 12 atm. A 3.0×28 mm Xience V stent (Abbot) was implanted in the mid LAD at a pressure of 12 atm, jailing a wire in the D2. Fol-lowing stenting, pinching of the ostium of the D2 and slow flow in that branch were observed. Guidewire exchange was

Fig. 1 9 Angiographic result following two stent implanta-tion using provision-al T technique, during first procedure, with  optimal angiographic  appearance

582 |  Herz 8 · 2010

difficult and several wires were tried to re-cross into the diagonal branch. Final-ly, a Miracle Bros 3gr (Asahi) was insert-ed and the struts were reopened with a Sprinter 1.5×15 mm balloon (Medtron-ic). Balloon insertion through the struts was also difficult, but after predilatation of the ostium of diagonal branch dissec-tion and slow flow occurred and Nobori stent 2.5×18 mm (Terumo) was implant-ed using the T stenting technique. The side-branch stent was pulled back slight-ly into the LAD to fully cover the ostium of the D2. The main branch was rewired with a wire previously placed in the diag-onal branch. Final kissing balloon infla-tion was performed with Quantum Mav-erick 3.25×20 mm (Boston Scientific) at 8 atm in the LAD and 2.5×18 mm deliv-ery balloon at 16 atm in the D2. An ex-cellent angiographic result was achieved (. Fig. 1).

The patient became symptomatic sev-eral weeks later with typical unstable an-gina. Follow-up angiography 2 months later revealed diffuse although angio-graphically intermediate in-stent reste-nosis in the proximal part of the LAD stent. We, therefore, decided to evaluate the LAD in-stent restenosis with IVUS (ILab Boston Scientific). It was not pos-sible to advance the IVUS catheter across the lesion because of a tight lesion at the proximal stent edge. After lesion predila-tation with a Sprinter RX 1.5×15 mm bal-loon (Medtronic), the IVUS catheter was successfully advanced distal to the LAD stent. IVUS pull-back revealed partial compression of the stent proximal to the bifurcation site against the vessel wall op-posite to the ostium of diagonal branch (. Fig. 2). A large gap without stent struts was visible at the bifurcation side of the vessel. The decision was made to crush the stent proximal to the bifurca-tion with the diagonal branch by a larger balloon and implant a new stent. Balloon angioplasty with Quantum Maverick bal-loons (Boston Scientific) 3.0×15 mm and 3.5×15 mm was performed. Following predilatation, a 3.5×18 mm Cypher se-lect stent (Cordis) was implanted suc-cessfully in the proximal segment LAD at 14 atm. Angiographic result was opti-mal. The 6 month clinical outcome was free of events.

Abstract · Zusammenfassung

Herz 2010 · 35:582–588   DOI 10.1007/s00059-010-3387-2© Urban & Vogel 2010

M. Tomasevic · V. Vukcevic · G. Stankovic · D. Orlic · M. Ostojic

Main branch stent deformation following difficult side branch rewiring and balloon dilatation. Rare complication of provisional T stenting

AbstractCoronary artery bifurcations are one of the largest challenges in interventional cardiolo-gy. Presented is the case of a patient in whom restenosis of a drug-eluting stent (DES) oc-curred as a consequence of guide wire re-crossing between the main vessel stent struts and the vessel wall in the proximal part of DES, and consequential balloon crushing of the proximal portion of the DES. Initially, the complication was not recognized because of a good angiographic result and absence of 

intravascular ultrasound (IVUS) guidance dur-ing the procedure. During the second proce-dure, IVUS analysis explained the mechanism of the DES failure. The problem was solved with the implantation of a new DES.

KeywordsCoronary vessels · Stents · Intravascular  ultrasonography · Coronary restenosis ·  Complications

Deformation eines Hauptaststents nach komplizierter Ballondilatation mittels Seitenast-Rewiring. Seltene Komplikation beim „provisional“ T-stenting

ZusammenfassungKoronararterienbifurkationen zählen zu den größten Herausforderungen der interventio-nellen Kardiologie. Bei dem hier vorgestellten Patienten zeigte sich nach Implantation eines Drug-eluting-Stent (DES) als Komplika-tion nach proximalem Seitenast-Rewiring mit Deformation des proximalen Stentanteils eine unerwartet frühe Restenose aufgrund eines zu proximalen Vorgehens. Wegen ein-er unauffälligen Koronarangiographie und fehlender intravaskulärer Ultraschall (IVUS)-

Kontrolle wurde dies zunächst nicht bemerkt. Im Verlauf der zweiten Intervention aufgrund der Restenose konnte die Ursache für das DES-Versagen mittels IVUS eruiert werden. Zur Implantation eines neuen DES erfolgte eine weitere Intervention.

SchlüsselwörterKoronargefäße · Stents · Intravaskuläre  Sonographie · Koronararterienrestenose · Komplikationen

583Herz 8 · 2010  | 

Fig. 2 9 Angiographic ap-pearance on follow-up with IVUS images: stent compression with two  layers of struts in one side of the vessel wall proximal to the bifurcation site (in-ner layer of struts marked with white arrows and out-er layer marked with black arrows in a), without struts on the opposite side of the vessel up to the bifurca-tion point (b). c Optimal circumferential stent ex-pansion in the LAD seg-ment distal to the bifur-cation site. d Coronary  angiography with cross-sectional levels (A–C)  corresponding to the IVUS images shown in a–c

Discussion

This case illustrates a rare mechanical complication related to side branch dil-atation and stent implantation follow-ing main vessel stenting (provisional T stenting technique). The guidewire and balloon were advanced outside the prox-imal segment of the LAD stent and the balloon was inflated crushing the stent against the vessel wall opposite the bifur-cation ostium. Most probably, the LAD was also rewired behind the struts after predilatation of the diagonal branch and stent deformation was exaggerated dur-ing the final kissing inflation. The IVUS image confirmed no visible stent struts on the one side of the main vessel. As shown in . Fig. 3, a possible explana-tion is that forceful manipulation of a stiff guidewire resulted in passing out-side of an undersized and probably un-derexpanded stent in the LAD.

Marked stent deformation and dis-tortion in the main vessel is possible de-spite the excellent angiographic result af-ter kissing balloon inflation in the treat-ment of a bifurcation lesion. However, the consequences of partial crushing of the LAD stent are incomplete strut ap-position and inadequate scaffolding with creation of areas with low and oscillato-ry shear stress, which could explain the higher incidence of stent thrombosis and restenosis in this setting [6].

IVUS evaluation is very important in assessing potential etiology for DES restenosis, including stent underexpan-sion, stent fracture, stent deformation, stent distortion, non-uniform strut dis-tribution, and subsequent non-uniform drug deposition. Asymmetric strut dis-tribution which impairs homogenous drug delivery is the main reason for more neointimal hyperplasia and diffuse stent restenosis after DES implantation

[7]. A IVUS substudy of the SIRIUS tri-al demonstrated that Cypher stent fail-ure in that trial was due mostly to stent underexpansion at the time of implan-tation [8]. In another study, IVUS was performed in 24 lesions with Cypher re-stenosis and results were compared to a group of 25 nonrestenotic Cypher stents []. That study indicated that the num-ber and distribution of stent struts af-fected the amount of intimal hyperpla-sia after Cypher stent implantation, pre-sumably by affecting the dose of sirolim-us delivered to the arterial wall.

Because stent underexpansion is poorly recognized by angiography, the real incidence of suboptimal stent de-ployment is likely to be underestimated. Indeed, it has been observed that dis-crepancies exist between angiographi-cally defined and IVUS-defined optimal stent deployment regardless of the stent implanted, with the IVUS success rate

584 |  Herz 8 · 2010

Case study

ranging from 13–70% despite successful angiographic results.

Among the possible reasons for sub-optimal stent deployment are (1) the un-dersizing of the stent delivery balloon re-lated to the target vessel, (2) the deploy-ment pressure may not be adequate to deploy the stent optimally and high-pres-sure stent deployment, especially with the current semicompliant balloons, can only in part compensate for the balloon undersizing, and (3) the semicompliant balloon may not be adequate to achieve full stent expansion in arterial segments with heavy plaque burden and increased resistance; thus, the use of a noncompli-ant balloon postdilatation represents a good compromise to achieve adequate stent expansion and symmetry without increasing risk of dissection or rupture of the vessel [10]. We, therefore, believe that IVUS guidance should be recommend-ed in complex bifurcation lesions, espe-cially when technical difficulties or com-

plications occur at any stage of the pro-cedure.

Careful lesion preparation before stent implantation in the main branch of the bifurcation is critical to enhance optimal stent expansion and access to the side branch. In order to optimize side branch access following main vessel stenting, the proximal optimization tech-nique (POT technique) was proposed by Darremont and colleagues [11]. Optimi-zation of the stent deployment proximal to the carina by using a short, half-size larger balloon or a spherical balloon may help to access the most distal strut dur-ing wire exchange. Proximal dilatation is strongly recommended before wire ex-change or when side branch re-crossing is difficult, as in our case, before trying a hydrophilic or stiff guidewire. The jailed wire in the side branch should always be left in place as a marker until complete re-crossing has been performed.

Little data is available on the opti-mal therapeutic strategy of DES resteno-sis, especially when the cause is mechan-ical stent deformation. POBA or repeat DES implantations are acceptable treat-ment options. Based on IVUS evaluation, we decided that completely crushing the distorted segment of LAD stent followed by implantation of new, adequately sized DES and final kissing inflation was the best therapeutic option in our case.

Corresponding addressM. OstojicDepartment of Cardiology, Clinical Center  of Serbia, School of Medicine,  University of BelgradeKoste Todorovica 8, 11000 BelgradeSerbiamostojic2003@yahoo.com

Conflict of interest.  The corresponding author states that there are no conflicts of interest.

Fig. 3 7 The guide-wire and balloon were  advanced outside the proximal segment of the LAD stent during 

side branch rewiring (a),  resulting in stent defor-

mation during balloon in-flation (b) and after final 

 kissing (c)

585Herz 8 · 2010  | 

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