Wiring





Goal : To advance a guidewire through and distal to the target coronary lesion in the most efficient way and without causing a complication and to provide an adequate platform to support balloon, stent and other equipment delivery.


Similar to use of a guide catheter, wire insertion is essential for performing PCI and/or lesion assessment through coronary imaging or physiology. Obtaining optimal guide catheter support, as outlined in Sections 9.5.8.1.1-9.5.8.1.6, can facilitate wiring.


Wiring occurs in nine steps.



Step 1. Determine whether a microcatheter is needed



Goal:


To facilitate guidewire advancement to the desired coronary location, as well as guidewire exchanges.



How?


A microcatheter can significantly facilitate guidewire handling and should be considered in any complex lesion, such as highly tortuous lesions, near-occlusive lesions and chronic total occlusions (CTOs). If a decision is made to use a microcatheter, the guidewire should be inserted together with the microcatheter, bypassing the need to use the introducer needle (step 4 of this section).


There are five main microcatheter categories: large, small, angulated, dual-lumen, and plaque modification, as discussed in detail in Section 30.6 . Use of a microcatheter for navigating through tortuosity is discussed in Section 8.6 , for use in CTOs in Chapter 21 : Chronic Total Occlusions, and for wiring the side branch of bifurcation lesions in Chapter 16 : Bifurcations ( Section 16.2.8 ).


If a microcatheter is not available an over-the-wire balloon could be used instead, but it has limitations (balloons are stiffer and more likely to kink and the marker of small balloons is at the middle, hence the location of the balloon tip can be hard to determine). On the other hand, over-the-wire balloons cost significantly less than microcatheters.



Step 2. Guidewire selection



Goal:


To select a guidewire capable of advancement to the desired location while minimizing the risk of complications. The various guidewire types are discussed in Section 30.7 .



How?




  • 1.

    Noncomplex lesions: workhorse guidewire ( Section 30.7.1 ).


  • 2.

    Tortuous lesions:




    • Option 1: use advanced workhorse guidewires, such as composite core (such as Sion blue), dual core (such as Samurai), or nitinol (such as Runthrough, TurnTrac, Versaturn, Minamo) guidewires.



    • Option 2: use soft tip guidewires with hydrophilic tip coating, such as the Sion, Suoh 03, and Samurai RC.



    • Option 3: use soft, nontapered polymer-jacketed guidewire (such as Sion black, Pilot 50, Fielder FC, or Whisper)



    • Guidewires with higher tip load and hydrophilic coating or polymer jacket carry higher risk of complications, such as dissection or perforation, and should only be used if standard workhorse guidewires fail to advance to the desired coronary segment. Such guidewires should subsequently be exchanged for a workhorse guidewire for balloon and stent delivery. If polymer jacketed guidewires are used for equipment delivery the position of their tip should be monitored constantly to minimize the risk of distal wire perforation.



  • 3.

    CTOs are discussed in Chapter 21 : Chronic total occlusions and in the Manual of CTO Interventions . CTOs are different from other coronary lesions, as the initial wire choice is usually a polymer-jacketed, tapered tip guidewire. Stiff, highly penetrating guidewires (both polymer-jacketed and nonpolymer jacketed guidewires) are also often used.


  • 4.

    More than one guidewire may be needed for crossing a lesion: for example, a workhorse guidewire may be needed for reaching the target lesion and a polymer-jacketed guidewire for crossing it. If it is anticipated that >1 guidewire will be required, use of a microcatheter is recommended to facilitate wire exchanges and enhance wire manipulation.


  • 5.

    After a lesion is crossed with a polymer-jacketed or stiff tip guidewire, the guidewire should be changed (using a microcatheter or over-the-wire balloon) for a workhorse guidewire, a highly supportive guidewire (such as Grand Slam, Iron Man, Wiggle wire), or an atherectomy guidewire such as the Rotawire Floppy or Rorawire extra support for rotational atherectomy ( Section 19.9.5.3 , Section 30.10.1.1.3 ) or ViperWire Advance or ViperWire Advance Flex Tip for orbital atherectomy ( Section 19.9.6.2 , Section 30.10.2.3 ) if atherectomy is planned. Guidewire exchanges using a microcatheter are best performed using the trapping technique ( Section 8.9.2.1 ).




Step 3. Shape the guidewire tip



Goal:


To shape the wire tip in the optimal way for advancing it to the desired coronary artery location.



How?


Some wires are preshaped, obviating the need for shaping the tip, but at the same time limiting the options for customizing the guidewire tip shape.


The shape of the tip depends on the target vessel size and on lesion and vessel angulation: for example, big bends should be used for big vessels and small bends for small vessels ( Fig. 8.1 ). In general the distal bend should be smaller than the diameter of the target vessel. Sometimes different bends may be required for wiring a complex lesion, such as CTOs: for example, one bend may be needed to reach to the target lesion and another bend to cross the lesion. Sometimes placing 2 bends (a proximal bend that is usually larger and a distal bend that is usually smaller) can improve the guidewire reach in larger vessels and vessels with angulated ostia).




Figure 8.1


Different wire bends are required for different tasks. For example, during CTO PCI, entering a septal branch requires a large bend (panel A), whereas crossing the septal requires a small bend (panel B).


Shaping the guidewire tip is best performed by advancing the guidewire tip through the introducer and bending it with a finger from the other hand ( Fig. 8.2 , panel A). Another technique is to compress the guidewire between a finger and the introducer needle and stretch it ( Fig. 8.2 , panel B). Advancing the guidewire through the introducer allows formation of small bends with high accuracy, however may also lead to fracture of the wire core, especially with nitinol guidewires, such as the Runthrough that should only be shaped with the needle that it comes packaged with.




Figure 8.2


How to shape the guidewire tip. Placing small bends is best achieved by advancing the guidewire through the introducer and bending it at the tip (panel A). Large bends can be formed by “sliding” the side of the introducer against the wire (panel B), but this may cause wire deformation.

Reproduced with permission from Brilakis ES. Manual of coronary chronic total occlusion interventions. A step-by-step approach. 2nd ed. Cambridge, MA: Elsevier; 2017 ( Figure 4.7 ).



What can go wrong?




  • 1.

    Excessive guidewire bending


    Causes:




    • Forceful or excessive wire manipulation.



    • Removing the guidewire from its hoop by pulling it from the tip.



    Prevention:




    • Use the introducer for shaping wire tip.



    • Do not hold the tip of the guidewire while removing it from the hoop.



    • Initially create a small bend and subsequently change it if it fails to advance. It is always possible to create additional bend(s) on the guidewire, but it can be hard to remove them.



    Treatment:




    • If the wire cannot be reshaped, it may need to be discarded and another guidewire used.





Step 4. Insert the guidewire into the guide catheter



Goal:


To insert the guidewire into the guide catheter through the hemostatic valve of the Y-connector.



How?


The guidewire tip is withdrawn into the introducer needle. The introducer needle is inserted into the hemostatic valve, followed by guidewire advancement. If the guidewire tip has a large bend, it may need to be back loaded into the introducer.


Alternatively, the guidewire can be preloaded into a microcatheter or over-the-wire balloon, the tip of which is then inserted through the hemostatic valve.



What can go wrong?




  • 1.

    Guidewire tip deformation



Causes:




  • Guidewire tip not fully withdrawn into the introducer needle.



  • Guidewire enters side arm of the Y-connector.



  • Guidewire comes in contact with devices in the guide catheter, such as guide catheter extensions, balloons or stents.



Prevention:




  • Ensure that guidewire tip is not protruding from the tip of the introducer needle or the microcatheter.



  • Do not force the guidewire against resistance.



  • Ensure that the introducer is advanced all the way through the Y-connector.



  • Remove other devices from the guide catheter whenever possible.



  • Use fluoroscopy when advancing guidewires through the proximal collar of guide catheter extensions.



Treatment:




  • Exchange the guidewire for a new one (if the damaged guidewire cannot be reshaped).




Step 5. Advance the guidewire to the tip of the guide catheter



Goal:


To advance the guidewire to the tip of the guide catheter



How?


The guidewire is advanced to the tip of the guide catheter. Fluoroscopy is used to check the guidewire position.


Some guidewires, such as the BMW (Abbott Vascular), have length markers on their shaft at 90 and 100 cm from the tip, that can be used to minimize use of fluoroscopy during wire advancement. It is important, however, to know the length of the guide catheter (the guidewire will exit sooner when used in a 90 cm long as compared with a 100 cm long guide catheter). Caution should be used when wiring through side hole guide catheters, as the guidewire can exit through the side hole, instead of the catheter tip ( Fig. 8.3 ).




Figure 8.3


Wire advancement through the side hole of a multipurpose catheter ( arrow ).



What can go wrong?



Inadvertent advancement into the coronary artery


The guidewire may be advanced into the coronary artery inadvertently or during contrast or saline injections without fluoroscopy guidance, which may lead to dissection, perforation, or loss of guide catheter position.


Causes:




  • Too distal guidewire advancement.



Prevention:




  • Careful monitoring of the position of the guidewire tip.



  • Some guidewires (such as the BMW), have a proximal marker that can help prevent too distal advancement.



  • The torquer can be tightened on the guidewire at approximately 90 cm from the guidewire tip to prevent excessive guidewire advancement.



Treatment:




  • Do NOT remove the guidewire (sometime the guidewire enters the intended branch).



  • Contrast injection to check guidewire position, followed by guidewire redirection, if needed.




Guidewire tip deformation


Causes:




  • Advancement through a guide catheter extension.



  • Advancement past balloons/stent previously inserted in the guide catheter.



  • Advancement through side holes of the guide catheter ( Fig. 8.3 ).



Prevention:




  • Remove guide extensions and/or balloons or stents before inserting another guidewire.



  • If this is not feasible, guidewire advancement through the collar of the guide extension or past balloons/stents should be done under fluoroscopy without forcing the wire.



  • Balloons can be advanced into the coronary artery while advancing additional wires through the guide catheter; the baloon is then retracted into the guide catheter once wire advancement is completed.



  • Use a dual lumen microcatheter: the monorail lumen of the dual lumen microcatheter is advanced over the initially placed guidewire, followed by insertion of the new guidewire through the over-the-wire lumen. Alternatively, an aspiration thrombectomy catheter can be used ( Section 20.9.6 , Section 30.12 ). The trapping technique ( Section 8.9.2.1 ) is then used to remove the dual lumen microcatheter.



Treatment:




  • Attempt to reshape the guidewire tip.



  • If reshaping fails, the guidewire is discarded and a new guidewire is used.




Step 6. Advance the guidewire from the tip of the guide catheter to the target lesion



Goal:


To advance the guidewire from the tip of the guide catheter to the target lesion.



How?


The guidewire is advanced from the guide tip to the lesion under fluoroscopic guidance with intermittent contrast injections. A still frame image of the coronary anatomy can be used as reference to assist with guidewire advancement and minimize the need for contrast injections. Another way to guide wiring is the dynamic roadmap that is available in some X-ray systems.


Advancing the wire: general principles (they apply to steps 6–8)



View selection


For wiring the LAD or circumflex, a caudal view is used initially to enter from the left main into the LAD or circumflex. Subsequent wiring of the LAD is easier using the RAO cranial or AP cranial view, whereas wiring of the circumflex/obtuse marginal is easier in the RAO caudal or LAO caudal views.


For wiring the RCA the LAO view is used to advance to the distal vessel, followed by LAO or AP cranial to wire into the PDA or the right posterolateral branch.



Use of a torquer


Use of a torquer improves wire control, but may not be necessary for simple lesions. This is a matter of preference and experience.



Pushing versus turning


The two key movements of a guidewire are pushing/withdrawing and rotation. Various combinations of push and turn are employed, depending on the vessel and lesion morphology.



Underhand versus overhand and using both hands


This is a matter of personal preference, but the authors prefer underhand holding of the wire as it allows easier wire manipulation. For complex lesions (such as CTOs) many (right-handed) operators advance or withdraw the wire using the left hand and rotate it using the right hand.



Keep tip free


Keeping the wire tip free is important for both (1) succeeding in advancing the wire to the desired location, and (2) minimizing the risk of vessel injury. If the tip goes “under a plaque,” aggressive advancement may lead to vessel dissection and possibly tip entrapment. If the wire tip movement becomes restrained, the wire should be withdrawn and readvanced. Alternatively, the wire can be left in place with a second wire advanced next to it (parallel wiring).



Reference image, intermittent injections and orthogonal views to visualize wiring progress


Having a stored reference image can facilitate guidewire advancement. Moreover, intermittent contrast injections are key for determining the wire position and need for adjustment. Injecting a small amount of contrast usually suffices to visualize the wire position. For chronic total occlusion interventions injecting from the contralateral coronary artery or bypass graft is often required to determine guidewire position and is one of the key principles of CTO crossing. Orthogonal projections are also important to confirm that the guidewire is in the desired location, especially when complex lesions (such as CTOs, tortuous lesions, overlapping side branches, etc.) are being wired.



Looping the wire tip is OK


Forming a loop at the wire tip can be both an effective and safe wiring strategy, especially after crossing the area of stenosis. A knuckled guidewire may in some cases advance more easily through tortuous coronary segments without entering into side branches. A knuckled guidewire is also less likely to cause perforation from inadvertent too distal advancement, but if it does occur, the perforation will be larger as compared with guidewire tip exit only. The knuckle should be kept small and not allowed to extend beyond the radiopaque portion of the wire. Knuckles should be avoided at the tip of highly supportive guidewires, such as the Grand Slam and Iron Man ( Section 30.7.4 ).



Change if tip damaged


Sometimes the guidewire tip may get deformed, especially if advanced through tortuosity or caught in a small branch. In such cases continued manipulation of the damaged guidewire is less likely to be successful and carries higher risk of complications. The guidewire should be changed, ideally using a microcatheter and the trapping technique ( Section 8.9.2.1 ).



Escalate–de-escalate


This is a standard CTO crossing technique, but also applies to non-CTO lesions. If non-workhorse guidewires are used to cross the lesion (e.g., polymer-jacketed guidewires, such as Fielder FC, Sion black, or Pilot 200) they should be exchanged for a workhorse guidewire after lesion crossing before proceeding with balloon, stent and other equipment delivery.



If multiple guidewires are used—keep them organized


If multiple guidewires are used, for example, when treating bifurcation lesions, it is important to keep track of which wire is where. One approach is to separate them with towels, with the wire in the most superior branch as visualized in the X-ray screen being in the top and the wire in the most inferior branch in the bottom ( Fig. 8.4 ). Another option is to use different color guidewires, slightly bend the back end of the side-branch guidewire, or use a torquer on the proximal end of one of the wires.


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