approch to bifurcation lesion

APPROACH TO BIFURCATION LESIONS

DR SRIDHAR BABU

WHAT IS BIFURCATION LESION?

APPROACH TO BIFURCATION LEISONS


A ( approach) – between proximal MB & SB.

It defines difficulty in accessing side branch. If this angle more can be ↓ by guide wire insertion, which facilitates SB access after MB stenting.

B ( between) – between the two distal branches. If it small independently predicts SB occlusion after MB stenting

Possible locationsLAD – diagonal LCX – obtuse marginalRCA – PDALMCA bifurcation


INCIDENCEAccount for 16% PCI

Procedural complications – 9%

Restenosis as high as 36%

Lower initial success rate


Technical problemsDifficulty in access to the side branch

Plaque shift

Lesion recoil

Ineffective lumen expansion

High periprocedural complication rate

Sub optimal immediate and long term results

Risk of side branch occlusion


Anatomical Considerations

Y-angulation precise stent placement with complete ostial coverage is often difficult or geometrically impossible.


The outer walls of bifurcation points are subjected to diastolic flow reversal, which leads to oscillatory shear stress.

Oscillatory (as versus laminar) shear stress is less efficient in stimulating eNOS.

Monocytes bind more avidly to areas of oscillatory shear than to areas subjected to linear shear.

oscillatory shear stress is proatherogenic

The shear stress hypothesis

Hsiai, T.K et al ATVB 2001; 21: 1770



Classification of bifurcation lesions

Limitations of Medina classificationDoes not take into account

1. Length of disease in the ostium of the SB2. Length of the LMCA before the bifurcation3. Trifurcation4. Vessel angulation 5. no differentiation is made between a normal

segment (lesion free segment) and a <50% lesion

6. presence of calcifications is not identified


Mohaved classificationMohaved classification

Movahedclassification


PROVISIONAL SIDE BRANCH STENTING

Provisional stenting versus elective double vessel stenting


Major adverse cardiac event (MACE) and TLR incidence in randomized trials comparing 1-stent (1S) with 2-stent (2S) strategies.


MAIN BRANCH RESTENOSIS RATE AFTER DES


SIDE BRANCH RESTENOSIS RATE


BASIC PRINCIPLES

Ramifications of coronary tree follow minimal energy cost in providing myocardial blood flow.

Relation between 3 diameters is simplified by Finet.

Dprox = (Ddistal + Dside) x 0.678.


OPTIMAL VIEW

SB ostium is rarely visualized from 2 orthogonal views, and may be explored from single angle called working view.

For LMCA – RAO or LAO view with caudal inclination.

For LAD – D : AP with marked cranial angulations.

For LCx – OM : slight LAO or RAO with caudal angulations.

For distal RCA : AP with cranial angulations.


Guide selection

A 6-F guiding catheter can be used if the operator performs a provisional stenting technique .

Techniques such as the T, the reverse crush, and the step crush can all be used with a 6-F guiding catheter.

The modified T technique requires at least a 7-F guiding catheter.

Culottes, Y, V techniques require at least 8-F guiding catheters


ONE OR TWO GUIDEWIRES ?GUIDEWIRE IN EACH BRANCH - improve patency of SB

after MB stenting. It also good marker of SB origin in case of SB occlusion

after MB stenting. It can also be used to reopen SB by pushing balloon over

jailed guide wire.

Best way to avoid SB occlusion – select MB stent diameter according to distal MB diameter in order to avoid carina shifting.

Wire modifies angle A – thus facilitates guide wire exchange, balloon & stent advancement.

TULIP – study use of one wire while starting the procedure is a predictor of SB treatment failure.


BIFURCATION LESION – a)STENT SIZE ACCORDING TO DISTAL MB REFERNCEb) STENT SIZE ACCORDING TO PROXIMAL MB REFERENCE RESULT IN CARINA SHIFT


CARINA IS USUALLY FREE OF ATHEROMA – risk of side branch occlusion is mainly because of carina shifting ( rather plaque shifting), when MB stent size distal to bifurcation is too large.

when a wire is needed in the SB?

1) the SB has a narrowing at its ostium. 2) the MB has severe stenosis with a large

plaque burden and the SB originates with an angle of <45°.

3) the ostium of the SB deteriorates after pre-dilatation of the MB.


SHOULD WE PREDILATE SB LESION OR NOT?

Kissing balloon predilatation is not recommended because of risk of extensive dissections in unstented segments.

Predilatation of MB left to discretion of operator based on type of lesion.

Predilatation of SB is subject of controversy – better avoid.

DRAWBACKS - Because while dilating ostium dissection may develop prevents access to SB across stent struts of MB stent.


PROXIMAL OPTIMISATION TECHNIQUE ( POT )

Provides solution to under deployment of proximal MB stent.

Carried out by short bigger NC balloon just proximal to Carina.

Changes the orientation of SB Ostium facilitating the insertion of guide wire, Balloon & if necessary stent in the SB, as well as projection of stents in the SB Ostium.

POT is useful in especially in bifurcation lesion with large SB.


IS KBI NEEDED AFTER SINGLE STENT DEPLOYMENT ?

KBI allows SB ostium treatment & apposition of MB stent struts on SB ostium.

It also enables correction of stent distortion & inadequate apposition.

Drawbacks : Procedural complexity , stent ovalisation, proximal dissection.

Final KBI is strongly recommended after complex technique with two stents, remains controversial in case of single stent.


HOW TO CARRY KBI APPROPRIATELY ?Step 1: Insert a free wire in SB through struts of the MB stent,

if possible closest to the carina.

Pre shaping of MB wire, utilisation of POT , use of hydrophilic or more rigid wire & orientable micro catheter may help.

Hydrophillic wires should not be jailed.

In persistent difficulties advancement & subsequent inflation of very small balloon over jailed wire may restore flow & help in crossing.

Step 2 : After insertion of free wire in SB, jailed wire must be withdrawn.

Step 3: Selection of Balloons – Diameter must match 2 distal branches. Balloons must be sufficiently short & use of NC balloons to ↓ dissection.


Characteristics of bifurcations with difficult SB accessCAG predictors - severe calcifications, severe stenosis with a large plaque burden in the proximal

MV, tortuosity in the proximal MV limiting guide wire manipulations,

severe stenosis of the SB ostium(TIMI flow <3) . Distal bifurcation angle - is an important issue in terms of

access to SBs.SB wiring is usually easy when angle is < 70°, while access

more difficult if angle > 70°, and can be particularly difficult when it exceeds 90°.

Natural distribution 80±27° for LAD/LCX, 46±19° for LAD /D1, 48±24° for LCX/OM1 & 53±27° for PDA/PLA, respectively.


Primary side branch wiring – non complex SB access

J tip angle(L1) is usually modulated according to the side branch take off angle.

Length of tip(L2) is usually adjusted according to diameter of the main vessel lumen.


It is usually advisable to wire the branch which appear more difficult to do.


Complex side branch access

When the problem is a distal wide angle ( LCx take-off from LMCA), a useful solution is to shape the tip with a wide smooth bend or with a double bend (later is being more practical when the SB lesion is tighter).

when the SB take-off is ≥ 90 ° & the stenosis is sub-occlusive -

Ante grade wiring, by pushing the wire directly into the SB. Pullback wiring.

Other methods for complex SB are - “reverse wire” & Venture catheter.


Anterograde in MEDINA 1,1,1 (Wide angle & sub occlusive SB)

Pullback wiring in MEDINA 1,1,1


Reverse wiring in 0,0,1 with extreme angle > 150

SB wiring with VENTURE


Side branch re-wiring after MB stent implantationThe success in SB rewiring is the key point of bifurcation

interventions.

Now commonly accepted best way is to wire the side branch by using a pullback rewiring technique.

Important is to obtain a curve sufficiently wide to let the wire scratch the MV stent struts.

When difficulty in rewiring changing either the shape of the guide wire's tip or the guide wire in favor of stiffer or more hydrophilic ones.

Rewiring site may influence the type of MBstent distortion after SB dilation, as crossing of the distal side cells of the MB stent is associated to better ostium scaffolding & ↓ need of SB stenting.


When are two stents needed? Intention to treat

SB when they are relatively large in diameter (>2.5 mm) & territory of distribution.

Have severe disease that extends well beyond the ostium (≥ 10-20 mm).

Have an unfavorable angle for re-crossing after MB stent implantation.


1)ProvisionalMainvessel stenting ± sidebranch angioplasty(Provisional) T-stenting, TAP, REVERSE INTERNAL CRUSH, REVERSE CULOTTE.

2) elective Culotte-stenting Crush technique (reverse crush) T TECHNIQUE AND TAP V STENTING Y STENTING(SKS technique)

Stenting of Bifurcation Lesions


DEFINITION OF PROVISIONAL SIDE BRANCH STENTING

Main objective is focusing on MB, while maintaining the SB patency.

Strategy is to deploy stent from proximal to distal segment of MB.

In some cases, stent is deployed from proximal segment of MB to SB also called as inverted provisional technique.

Advantages –

because of open nature optimally MB & Bifurcation are dealt with single stent.

When necessary 2nd stent can be used for SB with culotte or T stenting technique.

Procedure can be carried with 6F guiding catheter.


RELETIVE SIMPLICITY .

REQUIRING SINGLE STENT IN 80-90% OF CASES &

RESULTING IN SIMILAR OUTCOME COMPARED WITH MORE COMPLX STRATEGIES MADE THIS METHOD GOLD STANDARD.

EVEN FOR THE LM STENTING AS BY SYNTAX DATA.

Drawbacks – Difficulty in ensuring permanent access to SB. Potential problems in recrossig stent struts towards the SB in

implanting 2nd stent in the SB after stenting the MB.


Provisional stenting of Bifurcations:

place a stent in the MB postdilate the MB stent at high pressure

place a wire into the SB

results are evaluated

dilatation of the SB and kissing balloon inflation


Double stenting techniques which are certainly more complex, time consuming & expensive than provisional stenting.

None of the RCT’s studies showed a clear advantage for routine double stenting over a provisional strategy.

Other side of coin is patients with complex bifurcation anatomy such as large SBs with severe disease extending more than a few mm from the ostium were not well represented in these trials.

There is still a need for an individualized approach to bifurcation PCI & that 2 stents are still needed in 20-30% of true bifurcations .


elective double vessel stenting


The culotte technique

The culotte technique It provides near-perfect coverage of the carina & SB ostium

at the expense of an excess of metal covering in proximal MB.

Best immediate angiographic result & theoretically it may guarantee a more homogeneous distribution of struts & drug .

Can be used in all bifurcation lesions irrespective of bifurcation angle.

Open-cell stents are preferred when the SB diameter is >3 mm.

Disadvantages – Complexity in the rewiring of both branches through the

stent struts, Not advisable if both branches are dissected after

predilatation.


Culotte technique Not advisable when there is large

discrepancy in vessel size between the proximal MB and the SB because the proximal segment of the SB stent will not attain good apposition to the vessel wall of the proximal MB .

Conventional practice - challenged in the Nordic Stent Technique Study, where the authors recommended stenting of the MB first to avoid acute closure of the MB.

This approach guarantees patency of the MB



The crush technique

The crush technique (SB stent crushed by the MB stent)

immediate patency of both branches is assured & therefore it should be applied in conditions of instability or when the anatomy appears complex.

should be avoided in wide angle bifurcations. Only SB has to be re-wired & not both branches as in culotte

technique.

The crush technique has evolved and is nowadays performed with less stent protrusion into the MB (i.e., mini-crush) & mandatory 2-step FKI.

crush” technique can therefore be considered as a sort of simplified

“culottes” technique

The mini-crush may be associated with more complete endothelialisation and easier re-crossing of the crushed stent.


1. Inability to wire the SB. Make Sure That The Wire Is Directed Towards

The Distal Part But Not The Proximal Part. If The Primery Guide Wire Failes Try Hydrophilic

Wires. If They Also Fail Consider Tapered Tip Wires(MIRACLE).

2. INABILITY TO PASS BALOON IN TO SB. USE COMPLIANT MONORAIL 1.5 MM BALOON. IF FAILS REWIRE SB THROUGH A DIFFERENT

SITE AND RE ATTEMT BALOON CROSSING. IF FAILS THEN USE FIXED WIRE BALOON

SYSTEMS.

Potential failure modes of crush and suggested solutions


REVERSE CRUSH TECHNIQUEmain reason for

performing the “reverse crush” is

to allow an opportunity for provisional SB stenting


Step crush

The final result is basically similar to the one obtainedwith the “standard crush” technique, with the only differencebeing that each stent is advanced and deployed separately so that a 6 F guide may be used.


Dk crush

In the DK crush, kissing balloon (KB) inflation is performed after crushing the SB stent with a balloon.

This technique facilitates access to the SB in addition to optimising stent apposition at the SB ostium.


T- and modified T-techniques

The T-technique is the most frequently utilised to crossover from provisional stenting to stenting the SB and is most suited to bifurcations where the angle between the branches is close to 90°.

associated with the risk of leaving a small gap between the stent implanted in the MB and the one implanted in the SB.

In majority T-stenting technique is performed after MB & provisional SB stenting for a suboptimal result or flow-limiting dissection in the SB.



modified T-technique


V technique

SKS TECHNIQUE


V & simultaneous kissing stent (SKS) techniques

• Advantages –

Access to both branches is always preserved during the procedure with no need for rewiring any of the branches.

V-stenting is relatively easy and fast.(ideal in emergencies).

• V-stenting is ideal for Medina 0,1,1 bifurcations with a large proximal MB that is relatively free from disease & with a <90° distal angle.

• Reserve this technique for patients with a short LMCA free from disease & critical disease of both the LAD and LCX ostia.


LIMITATIONS –

balloon barotrauma to the proximal MB.

If a proximal stent is needed almost always the risk of leaving a small gap.

final kissing inflation is performed there is no need to re-cross any stent.

Generally try to limit the length of the new carina to < 5 mm.


2011 ACCF/AHA/SCAI Guideline for PCI


Favourable features for provisional stenting in unprotected LMCA

inSignificant stenosis at the ostial LCX with MEDINA 1,1,0 or 1,0,0

Large size of LCX with >2.5mm in diameter

Right dominant coronary systemNarrow angle with LADNo concomitant disease in LCXFocal disease in LCX


UNFavourable features for provisional stenting in unprotected LMCA

significant stenosis at the ostial LCX with MEDINA 1,1,1; 1,0,1 or 0,1,1.

Diminutive LCX with <2.5mm in diameter

Left dominant coronary systemWide angle with LADConcomitant disease in LCXDiffuse disease in LCX


L.M.C.A. BIFURCATION STENTING


IVUS in bifurcation stenting

Determining anatomic configuration, selecting treatment strategy & assessing final result are key factors in bifurcation lesion treatment that may have a significant impact on acute and long-term outcomes.

Furukawa et al demonstrated that side branches showing at IVUS diffuse plaque around the ostium with >50% stenosis were at higher risk for occlusion.

SB occlusion was uncommon (<10%) after PCI if no plaque was present at the side branch ostium.

Important role in the decision-making process when treating a distal LMCA bifurcation stenosis.


IVUS guidance for bifurcation lesion PCI IVUS can select the appropriate stent size and length as

well as guiding the most appropriate technique.

Helpful in optimally expand the stent avoiding stent under-expansion, malapposition, incomplete lesion coverage & overstretch of stent diameter.

“Incomplete crushing”, defined as incomplete apposition of side branch or main vessel stent struts against the main vessel wall proximal to the carina, was found in > 60% of lesions – mechanism for high restenosis rate.

Therefore, optimisation of the result in the side branch is still the goal even in the DES era


Impact of IVUS guidance on outcomePark et al in 758 pts - non-LMCA bifurcation lesions : IVUS-

guided stenting significantly ↓ very late stent thrombosis in the DES group, while it did not have any effect on TLR.

Stent under-expansion, incomplete lesion coverage, edge dissections & longitudinal plaque shifting, which likely contribute to DES thrombosis are often missed by CAG & are detected by IVUS.

MAIN-COMPARE registry in LMCA lesions - undergoing PCI of the LMCA, 77.5% were treated with IVUS guidance.

3-year outcome showed a strong trend towards a lower mortality risk with IVUS guidance group.


FFR in bifurcation stenting

Bifurcation lesion is very unique as it is the only lesion in which stenting is not better than angioplasty & even angioplasty is not better than a “leave it alone” strategy.

CAG evaluation overestimates the functional severity of jailed SB lesions in every step of the provisional strategy for bifurcation lesions.

FFR-guided provisional side branch intervention strategy is feasible & effective.

Functional status of jailed SB lesions after DES implantation does not change significantly during follow-up.


CAG evaluation is more difficult for bifurcation lesions due to vessel overlap, angulations, stent struts across SB & image foreshortening.

It is technically difficult to perform IVUS or OCT in jailed SB lesions.

FFR can be easily measured in bifurcation lesions both before & during intervention.

CAUTION - When FFR is measured for SB ostial lesions, the influence of proximal & distal lesions should be considered.

If there is a significant proximal stenosis, FFR

overestimates the severity of SB ostial lesion. In contrast, FFR underestimates the lesion severity when

there is a significant distal SB lesion.APPROACH TO BIFURCATION LEISONS

Is there a need for dedicated bifurcation devices?

Limitations of conventional bifurcation stenting MV stent distortion by side accessSide branch and wire jailingSide branch accessibilityLimitations in re-wiring, re-ballooning and

stenting of SBFKI with danger of dissectionWire crossings Incomplete coverage of bifurcational areaComplexity, duration and contrast and X ray

exposureAPPROACH TO BIFURCATION LEISONS

Conclusion

Bifurcation stenosis pose a technical problem.

The complexity of the lesion treatment lies in SB.

Potential reasons for 1 Y or 2ry failure in stenting the SB are :

Presence of gap between the 2 stents Carina/ Plaque shifting from MB Injury to SB ostium- excessive balloon artery

ratio


approch to bifurcation lesion

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