Wiring

8.1.1

Goal:

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

8.1.2

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.

8.2.1

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 .

8.2.2

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 ).

8.3.1

Goal:

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

8.3.2

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).

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.

8.3.3

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.

8.4.1

Goal:

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

8.4.2

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.

8.4.3

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).

8.5.1

Goal:

To advance the guidewire to the tip of the guide catheter

8.5.2

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 ).

8.5.3

What can go wrong?