Bifurcations






Bifurcation algorithm


( Fig. 16.1 )




Figure 16.1


Algorithm for approaching coronary bifurcation lesions. MV, main vessel; SB, side branch; PCI, percutaneous coronary intervention; TAP, T and protrusion; DK crush, double kissing crush.



Does the side branch need to be preserved?


This depends on the size of the side branch (SB) (usually branches <2 mm in diameter do not need to be preserved) and the supplied myocardial territory. If a decision is made to preserve the SB, it must be decided whether to simply wire the SB to help preserve patency during provisional stenting of the main vessel (MV), or whether to perform an upfront dedicated two-stent bifurcation percutaneous coronary intervention (PCI) strategy. To help decide this, it is necessary to assess the likelihood of SB occlusion after MV stenting.



What is the likelihood of SB occlusion?


The likelihood of SB occlusion depends on:



  • 1.

    Location of disease (Medina classification , Fig. 16.2 ).




    Figure 16.2


    The Medina classification of bifurcation lesions. The first number describes the proximal main vessel (PMV), the second number the distal main vessel (DMV), and the third number the side branch (SB). 1 signifies ≥50% diameter stenosis, whereas 0 signifies <50% diameter stenosis.


  • 2.

    Severity of SB disease.


  • 3.

    Lesion morphology (calcification, thrombus, length). Use of intravascular imaging can help with lesion morphology assessment.


  • 4.

    Bifurcation angulation (extreme angles may be challenging to wire).




If a provisional stenting strategy (Section 16.2.10.1) is implemented, is the SB compromised after MV stenting?


If an important SB becomes compromised after MV stenting (TIMI flow<3, diameter stenosis>70%, or NHLBI dissection B or more), efforts should be made to restore flow. The risk of SB compromise is reduced by sizing the MV stent according to the diameter of the distal MV. Balloon angioplasty often suffices to restore or improve flow in the SB, but sometimes SB stenting may be necessary.



What is the SB angulation?


The SB angulation is key for selecting the optimal two-stent bifurcation stenting strategy (either primary or in case of SB compromise after MV stenting).


For angulations between 70°–90° T-stenting ( Section 16.2.10.2 ) or T and Protrusion (TAP, Section 16.2.10.3 ) are usually used.


For angulation <70°, double kissing crush (DK crush) ( Section 16.2.10.5 ), culotte ( Section 16.2.10.6 ), and reverse crush ( Section 16.2.10.4 ) are commonly used, with DK crush being the preferred strategy in most cases.



Medina 0.1.1


V-stenting ( Section 16.2.10.7 ) can be performed in Medina 0.1.1 bifurcations.



Need for emergency stenting


When emergency stenting is needed and access to both MV and SB needs to be maintained, simultaneous kissing stents (SKS, Section 16.2.10.8 ) can be used. However, subsequent treatment and equipment delivery can be very challenging after SKS, due to formation of a long stent neocarina. SKS should not be performed in non-emergent bifurcation PCI.



Bifurcation PCI: step-by-step



Preparation


Planning for bifurcation PCI is performed as discussed in Chapter 1 : Planning. Some bifurcation stenting techniques, such as V-stenting and SKS require at least 7 French guide catheters (that have large enough lumen to accommodate two stents).



Monitoring


Monitoring for bifurcation PCI is performed as discussed in Chapter 2 : Monitoring.



Pharmacology


Pharmacology is as discussed in Chapter 3 : Medications.


Periprocedural anticoagulation for bifurcation PCI is similar to standard PCI.


Prolonged dual antiplatelet therapy should be considered in patients who have low risk of bleeding, as bifurcation stenting has been associated with increased risk of stent thrombosis.



Access


Arterial access is described in Chapter 5 : Coronary and Graft Engagement.


Radial or femoral access are both acceptable for bifurcation stenting, depending on patient anatomy, lesion complexity, and operator experience. For highly complex cases, femoral access may provide optimal support.



Engagement


Goal : To engage target vessel with a guide catheter that will provide optimal support and facilitate performance of the various steps of bifurcation stenting.


How to ?



  • 1.

    Coronary engagement is covered in detail in Chapter 5 : Coronary and Graft Engagement.


  • 2.

    Guide catheter type: supportive guide catheters are preferred (AL for the right coronary artery and EBU or XB for the left main).


  • 3.

    Guide catheter size: Most coronary bifurcation techniques can be performed through 6 French guide catheters (except for V-stenting and SKS deployment which need at least 7 French guide catheters). However, it is much easier to pass two pieces of equipment (in particular, previously used angioplasty balloons) through a larger guide catheter. A larger guide catheter also provides more support and facilitates troubleshooting in case of difficulties during the procedure.




Angiography


Performing coronary angiography is described in detail in Chapter 6 : Coronary Angiography.


For bifurcation lesions angiography should be performed in angulations that allow optimal separation of the MV and the SB, to facilitate wiring and placement of the stents as well as the stent crush, if applicable.



Selecting target lesion(s)


This is performed as described in detail in Chapter 7 : Selecting Target Lesion(s).



Wiring


Performing coronary wiring is described in detail in Chapter 8 : Wiring.


Wiring of both MV and SB should be performed in most cases, unless the SB is too small or does not have any significant disease. Standard workhorse wires ( Section 30.7.1 ) are preferred for both the MV and SB.


If SB wiring is challenging, the following techniques can be used (Section 8.6.8):


A. Wire-based options




  • Create secondary bend on the wire.



  • Use a hydrophilic-coated or polymer-jacketed guidewire ( Section 30.7.2 ).



  • Reversed guidewire technique ( Chapter 8 : Wiring, Section 8.6 ) .


    B. Microcatheter options



  • Use of big ( Section 30.6.1 ) or small ( Section 30.6.2 ) microcatheters improves wire support and allows changing the shape of the wire tip without losing wire position.



  • Angulated microcatheters (such as Venture, Swift NINJA, and Supercross, Section 30.6.3 )



  • Dual lumen microcatheter (such as TwinPass Torque and Sasuke, Section 30.6.4 ).


    C. Modify MV



  • With balloon angioplasty (possibly with use of plaque modification balloons) or atherectomy (carries risk of SB occlusion).



The distal position of the MV and SB wires should be constantly monitored, as too distal migration could cause perforation. If polymer-jacketed guidewires were used for wiring they should be replaced for a workhorse guidewire before performing lesion preparation and stenting.



Lesion preparation


Lesion preparation is described in detail in Chapter 9 : Lesion Preparation.




  • Preparation of the MV lesion should be done in all cases, as it facilitates stent sizing, stent delivery, and stent expansion.



  • Preparation of the SB should generally be avoided when provisional stenting is done, as it may lead to SB dissection, necessitating stenting.



  • Preparation of the SB (and the MV) should be routinely performed when two-stent techniques are planned.



Intravascular imaging/physiology is performed as described in Chapter 12 : Coronary Physiology and Chapter 13 : Coronary Intravascular Imaging. Intravascular imaging can be very useful for determining the size and length of the MV and SB lesions and for determining the need for atherectomy or other forms of lesion preparation.




  • Atherectomy : Atherectomy can be challenging in coronary bifurcation lesions, because only one guidewire (the atherectomy wire) can be in the treated coronary artery during atherectomy. The other guidewire is traditionally removed prior to atherectomy to prevent wire fracture. However, in case of dissection of the non-wired vessel, rewiring can be challenging. If it is highly desirable to not remove the second wire the following techniques could be used:



Solutions for keeping in place both the MV and SB wires during atherectomy :




  • Advance atherectomy device (burr or crown) through a guide extension (if the lesion that requires atherectomy is at the proximal SB or the distal portion of the MV). The guide extension is placed over the atherectomy wire only, isolating the burr or crown from the other wire. This requires a 7 French guide catheter (with a 6 French guide catheter extension) which can accommodate a 1.25 mm rotational atherectomy burr or the 1.25 mm orbital atherectomy crown. An 8 French guide catheter with a 7 French guide catheter extension can accommodate a 1.5 mm rotational atherectomy burr.



  • Use a microcatheter over the nonatherectomy wire to protect it: a smaller microcatheter, such as the Finecross should be used to minimize the risk of microcatheter damage. If multiple atherectomy runs are performed, the microcatheter should be slowly moved during atherectomy runs to minimize damage of the same portion of the microcatheter ( Fig. 16.3 , CTO PCI Manual case 136 ). This requires an 8 French guide catheter. Alternatively, atherectomy can be performed leaving the SB wire in place, accepting a low risk of guidewire damage.




    Figure 16.3


    Perforation of a Finecross microcatheter used to protect the side branch guidewire while performing orbital atherectomy on the main vessel guidewire.



  • Use laser atherectomy.




Stenting



Provisional stenting


See online video : “How to do provisional stenting”


Background : Provisional stenting is the preferred and easiest technique for most bifurcation lesions, if technically feasible without posing significant risk of compromising a significant SB. If the severity of disease at the SB ostium is unclear, hemodynamic assessment or intravascular imaging should be considered.


Goal : Deploy a stent in the MV without compromising the SB.


How ?


Preparation :




  • Wiring : both MV and SB should be wired if the SB is important and there is risk of occlusion ( Fig. 16.4 ).




    Figure 16.4


    Provisional bifurcation stenting: wiring both main vessel and side branch.



  • Lesion preparation : balloon angioplasty is usually done in the MV, but is in most cases avoided in the SB, as it may lead to SB dissection necessitating stenting.




Provisional stenting steps





  • Step 1. Deliver MV stent ( Fig. 16.5 )




    Figure 16.5


    Provisional bifurcation stenting: a stent is delivered in the main vessel and positioned across the bifurcation.


    Tips:




    • The diameter of the MV stent should match the diameter of the distal MV ( Fig. 16.6 ), but should also be able to be expanded to the size of the proximal MV [using the proximal optimization technique (POT)] to achieve full apposition. Knowledge to the individual stent post dilatation limits ( Fig. 10.1 ) is necessary to avoid excessive stent deformation. The MV stent length should be enough to allow use of a balloon for POT (≥6 mm if 6 mm balloons are available).




      Figure 16.6


      Why the stent should be sized to match the distal true lumen, followed by POT. If the stent is sized based on the proximal MV diameter, the SB may become occluded and perforation or dissection can occur in the distal MV.




  • Step 2. Deploy MV stent, jailing the SB guidewire ( Fig. 16.7 )




    Figure 16.7


    Provisional bifurcation stenting: main vessel stent deployment.


    Jailing of the SB wire is recommended in any bifurcation stenting procedure when the SB needs to be preserved for the following reasons :



    • 1.

      The jailed guidewire helps keep the SB open; also in case of occlusion, it acts as a marker of the SB position, facilitating rewiring attempts.


    • 2.

      The jailed guidewire facilitates reaccess to the SB by favorably altering the angle of the bifurcation for recrossing.


    • 3.

      The jailed guidewire provides anchoring that facilitates seating of the guide catheter, and increases support for equipment advancement in subsequent bifurcation PCI steps; and


    • 4.

      In extreme situations, a low profile balloon (or torquable microcatheter) can be advanced over the jailed guidewire and inflated to urgently rescue the SB.



    Several guidewire types (workhorse, with hydrophilic coating, or polymer-jacketed, Section 30.7 ) can be jailed. There has been controversy about whether polymer-jacketed guidewires should be jailed or not due to risk of stripping the polymer during wire withdrawal, potentially causing distal embolization. In one microscopy-based study of jailed guidewires, only 2 of 115 polymer-coated guidewires showed mild damage while 55% (63 of 120) of the non-polymer-coated guidewires were damaged, with two showing internal fracturing . The length of the jailed guidewire appeared to be a factor contributing to the degree of guidewire damage and wiring the SB was quicker when a polymer-coated guidewire was used . On the other hand, distal embolization of the polymer jacket material was detected downstream of stented coronaries in 10% of autopsied hearts in one study (not in the setting of guidewire jailing) .


    Tips and tricks:




    • Before jailing, partially withdraw the SB guidewire, so that the radiopaque portion of the SB guidewire is closer to the carina making the wire more visible. However, do not jail across the radiopaque portion of the guidewire, as this may increase the risk of guidewire fracture.


      Step 3. Perform POT ( Fig. 16.8 )




      Figure 16.8


      Illustration of POT (proximal optimization technique). POT is performed by inflating a short balloon in the portion of the stent proximal to the carina. The goal of POT is to optimize deployment of the MV stent proximal to the carina, and is especially important in cases with significant MV diameter discrepancy proximal and distal to the carina. Moreover, POT increases the stent strut diameter, facilitating distal wire crossing.


      Tips and tricks:



    • The diameter of the balloon used for POT should match the diameter of the proximal MV.



    • The length of the balloon used for POT should be equal or shorter to the MV stent length proximal to the carina. Since the shortest balloon length currently available is 6 mm, the length of the MV stent should be enough to allow at least 6 mm and ideally 8–10 mm of stent proximal to the carina after placement.



    • The distal marker of the balloon used for POT should be placed at the carina. Too distal placement may increase the risk for compromising the SB, whereas too proximal placement will not allow optimal expansion of the MV stent next to the SB ostium.



    • If the balloon length is shorter than the MV stent length proximal to the carina, multiple inflations will be needed, changing the position of the balloon. If the balloon is longer than the MV stent length proximal to the carina, it will injure the MV proximal to the stent, increasing the risk of restenosis.




Step 4. Assess SB ( Fig. 16.9 )




Figure 16.9


Provisional bifurcation stenting: assessment of the side branch after MV stenting.


Is the SB compromised?


How to assess the SB after MV stenting :


Antegrade flow : if antegrade flow is decreased or absent, the SB is compromised. Significant disease at the SB ostium or placement of an oversized stent in the MV (or use of an oversized POT balloon) increase the likelihood of SB compromise.


Luminal stenosis : The severity of the SB stenosis can be assessed visually, although visual interpretation frequently overestimates the severity of SB stenosis.


Physiologic assessment : Coronary physiology can be used (in nonculprit lesions for acute coronary syndromes) to determine whether the SB is ischemic post stenting .


Intravascular imaging : Intravascular imaging (IVUS or OCT) can also be used to determine the severity of the SB ostial stenosis.


Step 4a. No SB compromise : procedure done !


Step 4b. Yes, SB is compromised but not occluded :



  • 1.

    The SB is rewired through the MV stent ( through a distal strut ) ( Fig. 16.10 )




    Figure 16.10


    Provisional bifurcation stenting: side branch rewiring after MV stenting (rewiring is performed through a distal strut, i.e., closer to the carina).


    The reason for distal strut rewiring is that is provides better scaffolding of the SB ostium ( Fig. 16.11 )




    Figure 16.11


    Proximal versus distal crossing in side branch. This figure shows the importance of distal cell recrossing close to the carina after main vessel stenting. Recrossing wire through the strut closest to the carina showed better scaffolding of the side branch ostium than proximal recrossing that pushes the struts inward toward the main vessel lumen. The white arrow indicates location of wire recrossing and its effect on side branch scaffolding.

    Reproduced with permission from Sawaya FJ, Lefevre T, Chevalier B, et al. Contemporary approach to coronary bifurcation lesion treatment. JACC Cardiovasc Interv 2016;9:1861–78. Copyright Elsevier.


    Tips and tricks:




    • Some operators use the MV wire for rewiring the SB (so as to avoid substent wiring with a new guidewire), however in our practice we usually use a new wire for SB rewiring.



    • Some operators advance the guidewire that will be used for SB rewiring through a microcatheter. Once the SB is crossed, the microcatheter is advanced into the SB to facilitate subsequent balloon advancement into the SB.



    • To ensure a distal strut crossing, pass the wire distal to the bifurcation, then point the wire tip toward the SB. Gently pull the wire back and watch for the wire tip to drop toward the SB, then advance the wire through the stent strut.



    • Confirmation of guidewire crossing through a distal strut can be obtained using OCT.



  • 2.

    The jailed wire is removed ( Fig. 16.12 )




    Figure 16.12


    Provisional bifurcation stenting: removal of the jailed guidewire.



Challenge: Difficulty removing the jailed guidewire.


Solutions:



  • 1

    Do NOT pull hard! Apply gentle constant traction instead. Pulling hard may lead to guidewire fracture and/or unraveling, possibly requiring emergency cardiac surgery . Also, pulling the guidewire hard may cause deep intubation of the guide catheter that could lead to guide catheter induced dissection.


  • 2

    Advance a small balloon or microcatheter all the way to the area of guidewire entrapment, and then gently withdraw.


  • 3

    Advance a small balloon all the way distally and inflate to free up the entrapped guidewire. Repeat POT should be performed afterwards.


  • 4

    Rotation of the entrapped guidewire using a torquer may help.


  • 5

    Before jailing a guidewire, ensure that the tip is straight, as subsequent withdrawal of a guidewire with a loop at the tip may be more challenging as the guidewire can become entangled with the deployed stent (PCI Manual cases 33 , 88 ). Avoid jailing long guidewire segments.


Feb 4, 2021 | Posted by in CARDIOLOGY | Comments Off on Bifurcations
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