Guidewire

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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The ability to cross an atherosclerotic lesion with a coronary guidewire depends upon both the performance characteristics of the giudewire and the skill of the operating physician. This chapter discusses the technique of crossing an atherosclerotic lesion with a coronary guidewire.

It is a good general practice to use the same coronary guidewire for the majority of cases. In doing so, the operator becomes very familiar with the behavior characteristics of the wire, and becomes very sensitive to any changes in the behavior of the wire. In general, a flexible wire with a floppy tip that does not have a hydrophilic coating is a good choice as a workhorse guidewire. 90% of lesions should be able to be crossed with this workhorse guidewire.

• For the majority of lesions, create a curve at the tip of the guidewire which is roughly the length of the diameter of the vessel proximal to the lesion.
• If you are attempting to cross a total occlusion the tip of the guidewire should be left straighter or with a minimal bend.

• Adjust the guide so that it is more coaxial with the lumen of the artery
• Use a balloon, transit, ultrafuse or twin pass catheter to direct the wire in a more favorable direction
• Modify the bend at the tip of the wire. In tortuous segments, a more proximal secondary bend approximating shape the artery may be required
• Change the wire

• Avoid bending or buckling the wire. Buckling or bending of the wire can be a sign of a subintimal position.
• Never push a wire if you feel undue resistance.
• A ventricular premature beat could be a suggestion that the wire is too dital or has perforated the artery. Check the position of the wire in the presence of PVCs.
• If the patient goes into sustained ventricular tachycardia, check the position of the wire but do not lose wire position if at all possible.
• Be vigilant for coronary perforation when hydrophilic wires are used.
• Once you cross with the hydrophilic wire consider switching out for a non-hydrophilic wire.
• If there is a suspicion of a perforation, then an emergent Echo should be performed immediately while the patient is on the table.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

To go back to the main page on Guidewires, click here.

The use of coronary guidewires can be associated with perforation of the epicardial coronary artery, entrapment of the wire in the vessel, wire fracture and detachment or embolization of the wire tip. This chapter discusses the management of these complications ^[1][2][3]

Coronary perforations are uncommon (< 1%) complications of percutaneous coronary intervention (PCI) and are associated with significant morbidity and mortality rates. ^{[4] [5] [6] [7] [8]} Coronary perforations are infrequent in patients undergoing balloon angioplasty (0.1%) compared with patients undergoing atheroablative therapy (1.3%; P< 0.001) ^{[9] [10]} Perforation due to coronary guidewires may present late after the procedure.

The use of hydrophilic wires and wires in which the court extends to the tip are wire characteristics associated with perforation. Lesions with the highest risk of perforation include chronic total occlusions.

Perforation is an angiographic diagnosis. It appears as a small extraluminal extravasation of blush in the distribution of the target vessel. Care should be taken to routinely visualize the distal extent of the vessel following PCI to exclude the presence of a wire perforation. Emergency echocardiography should be performed to rule out the presence of a pericardial effusion or pericardial tamponade.

The prognosis following coronary perforation depends on the extent of extravastion into the pericardium ^[11].

The following classification scheme has been developed based on angiographic appearance of the perforation:

• Type I perforations including an extraluminal crater without extravasation
• Type II perforations containing pericardial or myocardial blushing
• Type III perforations having a ≥ 1 mm diameter with contrast streaming; and cavity spilling ^[12].

Shown below is perforation of the right coronary artery during PCI: {{#ev:youtube|sFSKnzL1kp0}}

• Class I perforations were associated with no deaths and cardiac tamponade in 8% of patients.
• Class II perforations were associated with no deaths and cardiac tamponade in 13% of cases
• Class III perforations were associated with death in 19% and cardiac tamponade in 63% of patients ^[13].

Initial management strategies include:

1. Prolonged balloon inflation: For this reason it is often wise for a cardiac catheterization laboratory to have perfusion balloons in a range of sizes available.
2. Reversal of anticoagulation: This would included administration of protamine to reverse heparin and administration of platelets if abciximab has been administered.
3. In refractory cases, polytetrafluoroethylene covered stents (stent grafts) can be used to seal the perforation ^{[14] [15]} .
4. The administration of platelets can be considered to reverse the effects of antiplatelet agents.
5. The administration of protamine can be considered to reverse the effects of unfractionated heparin. Protamine will also partially reverse the antithrombotic effect of enoxaparin if this antithrombin was used.
6. Other techniques include coil embolization, the injection of clotted blood, the use of gel foam and the injection of thrombin at the site of the perforation.

Approximately one third of cases of PCI-associated coronary artery perforation require emergent cardiac surgery.

A pseudolesion is a stenosis that appears in an artery after the coronary gidewire is placed in the artery.

Pseudolesions appear in tortuous sections of vessels that have been straightened out by the guidewire. Tortuous right coronary arteries and left internal mammary arteries are at risk for pseudolesion formation.

A pseudolesion must be distinguished from a dissection or coronary spasm.

A pseudolesion will usually disappear if the wire is withdrawn to the distal edge of the lesion and the vessel is allowed to assume its normal shape. Sometimes replacement of a stiff wire with a more flexible floppy wire eliminates that pseudolesion. In addition, either a microcatheter or a balloon catheter can be placed distal to the lesion and this will sometimes eliminate the pseudolesion. If the balloon kinks at the site of vessel tortuosity, then it can be hard to reintroduce the wire. A pseudolesion should completely disappear after the wire is withdrawn from the coronary artery.

Pseudolesions should not be stented or dilated!

In some cases pseudolesions may cause hemodynamic compromise and ischemia. Inadvertent stenting of pseudolesions by overzealous interventional cardiologists.

Guidewire entrapment is more likely to occur in the following scenarios:

• In the presence of calcified vessels (for example the RCA)
• Repeated use of the same wire for multiple interventions
• Repeated attempts at crossing the same lesion multiple times with the same wire
• Two wires may become entrapped when the “buddy wire” technique is used
• Crossing fresh stent struts

• One technique is to advance a small profle balloon or a small caliber catheter (transit catheter) to the “attachement” site and pull back gently. Care must be taken not to cause perforation when advancing the small profile balloon.
• When a second or “buddy wire” gets trapped between a stent and the vessel wall gentle traction can be used to free the wire from the stent. The coating of the tip may “deglove” and be left behind. This technique may result in wire tip embolization.
• The entangled wire can be “pushed and pasted” against the vessel wall with another stent.
• Surgery may be required retrieve the entrapped guidewire.

Risk factors for guidewire entrapment and fracture include the presence of a calcified lesion, the performance of bifurcation stenting and prolonged procedures in which the guidewire is manipulated extensively.

Care should be taken to remove the guidewire from the body very slowly so as to not result in distal embolization of the wire tip. If resistance is felt as the wire is being pulled back, further investigation should be made as to whether the wire is entrapped in a stent strut or other structure.

• If the embolized tip is small and cannot be retrieved, a stent can be used to “push and paste” it to the vessel wall.
• For large or long pieces of embolized tip that cannot be retrieved or in the setting of thrombosis, surgery may be required.

There are several devices that can be used to snare the fragment.

• The Amplatz Gooseneck Microsnare manufactured by eV3 Incorporated, Plymouth Minnesota: This device is made up of three loops measuring 2, 4, and 7 mm. The device the device is contained in advanced via a 2.3 French microcatheter and the loop used to lasso the guidewire extends from this. Once the guidewire is ensnared, the loop is withdrawn from the body and this closes the loop ensnaring the guidewire.
• The EnSnare Triple Loop Device: In this device, there are three loops each oriented at hundred 120° from the other.
• The X Pro Micro Elite Snare: This device also has loops of 2, 4 and 7 mm.
• The Alligator Retrieval Device made by Chestnut Medical Technologies Incorporated of Menlo Park California: This device is made up of jaws that are attached to the tip of a wire. The 4 jaws of this device close when a 0.021 inch micro catheter is advanced.

In the largest published series of eight patients, there were no complications among the five patients in whom the guidewire could be snared and removed. In the other three patients, the guidewire was retained inside of a chronic total occlusion.^[16]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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There are several performance characteristics of coronary guidewires that make them effective. These desirable performance characteristics are described below.

The tip of a coronary guidewire must be curved and must be able to be turned or “torqued” to follow the course of the vessel down which it is being placed.

A coronary guidewire must be capable of being readily advanced around curves in the coronary arteries, and must have sufficient strength or support to allow devices to likewise go around these curves in the coronary artery.

The tip of the guidewire must be able to be pointed in different directions by the operator to change directions, to go into sidebranches, to cross asymmetric or eccentric lesions, to avoid stent struts and to go around corners and bends in the coronary artery. When the operator rotates the guidewire outside the body, the ability of the guidewire to translate this motion into a similar motion at the tip is called torquability. This is the ability of the coronary guidewire to transmit rotational forces from the operators hand to the tip and the optimal performance is for this rotation of the coronary guidewire to be translated to the tip in a one-to-one fashion. The operator will often use his hand to twist or maneuver the wire, however, the torquability of the wire may be further improved by the use of a “torquer” or a “pin vise” or “steering tool”.

The support of coronary guidewire refers to the ability of the coronary guidewire to allow a bulky device to track through bends in the coronary artery and to be to be delivered across the blockage without buckling or kinking of the wire. If the operator is attempting to advance a balloon or stent down the artery, and if the guiding catheter backs out of the coronary artery and if the guidewire also works its way from a distal position to a proximal position and backs out of the body, then this may be a sign of a “lack of guidewire support”. Calcified and tortuous right coronary arteries often require guidewires that offer improved support to maneuver a balloon or a stent to a distal lesion in the right coronary artery.

Flexibility refers to the ability of the coronary guidewire to bend with direct pressure. The flexibility of the wire is determined mainly by the distance from the tip of the central core to the distal tip of the wire. Flexibility is an important performance characteristic that minimizes vascular trauma.

Stiffness of the guidewire depends upon the diameter, trackability and torque control of the guidewire. Stiffer wires give better torque control and straighten the vectors of forces pushing the wire, balloon or a stent. Stiff quagmires may allow devices to be delivered through tortuous and calcified vessels with greater ease. A stiffer wire can be useful in crossing chronic total occlusions as well as when delivering a stent or balloon in a straight segment and can work against delivering a stent or balloon in a tortuous or an angulated segment. Stiffer wires are more likely to cause pleating artefacts and also slice through the intima in a “cheese cutter” effect. This “cheese cutter” effect has been observed with the “Iron Man” wire.

Tactile feedback refers to the “feel” of the wire tip’s behavior as perceived by the operator. Tactile feedback is better appreciated with coil tipped wires, whereas polymer tipped wires it may be minimal or absent, making inadvertent perforation, dissection or subintimal diversion into a plaque more likely.

Malleability refers to the ability of the coronary guidewire to be shaped or bent without breaking.

Radio-opacity refers to the visibility of a coronary guidewire under fluoroscopy and cineangiography. It is a critical characteristic of the guidewire so that the leading tip of the guidewire can be identified. Platinum at the end of the wire provides radio-opacity to the tip. One of the limitations of increased radio-opacity or visibility throughout the length of the guidewire is that the guidewire may mask the presence of a tear or dissection in the artery.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

To go back to the chapter on Guidewires, click here.

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Crossing guide wires

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• PT
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• ATW™All Track Wire
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• Steer it Deflecting Tip Guidewire E-1

• CINCH® QR Extension Wire
• EASY TWIST® Torquing Device

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