Choosing the Right Guidewire: The Key for a Successful Revascularization

Abstract

Even though frequently less considered, the guidewires are the most fundamental tools to track throughout the vessels, to cross stenoses or occlusions, and to be able to deliver the desired therapy to the selected vessel. In this chapter entitled “Choosing the Right Guidewire: The Key for a Successful Revascularization,” the following issues will be thoroughly described: how the guidewires are built and why it is so important to be aware of it; why are there so many different guidewires; what are the possible applications for each guidewire; how to choose the right guidewire in every situation; techniques to cross a stenosis and a chronic total occlusion.

1. Introduction

Even though frequently less considered, the guidewires are the most fundamental tools to track throughout the vessels, to cross stenoses or occlusions, and to be able to deliver the desired therapy to the target lesion of a given vessel. A thorough knowledge of how they are built and in what way this impacts on their specific characteristics and applications is crucial for any vascular specialist who wishes to succeed. In fact, considering the vast number of options, a correct choice and utilization of a guidewire can frequently be the difference between success and failure of a revascularization, avoiding many possible complications that can jeopardize the final result.

2. General characteristics

2.1 Length

The selection of a guidewire with a correct length can be very relevant to adequately reach and treat the target vessel. For this decision, distance from the access to the vessel to be treated and the shaft length of the sheaths and catheters to be used (either if it is a diagnostic catheter, a balloon catheter, or a delivery device of a stent or a stent graft) needs to be considered. In fact, this apparently less relevant subject may threaten the entire procedure.

Depending on the manufacturer, guidewires can range from 80 to 450 cm. Additionally, some guidewires may allow the connection of an extension during the procedure. This is particularly the case when a coronary guidewire is used as it is designed for rapid exchange devices.

There is a trick that can help in extreme circumstances and as bailout option only. During the removal of a catheter from inside the patient, it is possible to connect an inflation syringe device to the guidewire port of the catheter, just after losing the guidewire, and inflate inside the port, which will keep the guidewire in place. It is crucial to perform this maneuver under fluoroscopy as the guidewire may move forward and the external tip can even migrate and be lost inside the patient.

2.2 Diameter

Even if there are several diameters available, the most commonly used guidewires to cross stenoses and occlusions in peripheral arteries have 0.014″, 0.018″, or 0.035″ in diameter. At this point, it will be relevant to recall the relation between the different units used in endovascular devices, as so: 1 French (F) = 1/3 millimeter = 0.013 inches. It is quite obvious that the thicker the guidewire, the stiffer it is and the more support it allows, even if the core material of it is also very relevant for those properties.

They are several factors that someone should keep in mind when choosing the diameter of a guidewire:

• The vessel(s) to be tracked. The smaller the vessels to be tracked, the smaller the guidewire should be. For instance, in the iliac arteries or in the aorta, the guidewires usually used are 0.035″ in diameter, as it is when a crossover at the aortic bifurcation is necessary. In tibial vessels, 0.018″ or 0.014″ guidewires are usually the preferred diameters and in the delicate foot arteries, the 0.014″ guidewires are the rule. Another issue is the distance from the access to the target vessel(s). Logically, the longer the distance, the more support will be needed and the thicker the guidewire will need to be.

• The target vessel(s). As for the vessels to be tracked, the smaller the vessel, the thinner the guidewire should usually be.

• The kind of lesion(s) to be treated (stenosis versus occlusion). Even if occlusions are usually more difficult to cross, some stenoses can be particularly challenging. In fact very tight heavily calcified stenoses may initially allow the passage of a thicker guidewire, but can preclude the crossing of catheters with the corresponding caliber. In these situations, a downsizing of the guidewire diameter is required. For instance, in tibial vessels of diabetic patients, particularly those with end-stage renal disease, calcified stenoses can be crossed with a 0.018″ guidewire, but frequently, the balloon catheter is not able to cross impelling the change to a 0.014″ system (Figure 1).

• The devices planned to be used and their respective platform.

• The support needed to deliver the intended devices.

• The operator’s preference. In many instances, several guidewires with different diameters can be used. This will depend on the experience of the operator with a particular guidewire or the institutional availability. Most of the times, there is no right or wrong as long as the aim of the intervention is successfully fulfilled.

Figure 1.

A, B—Anterior tibial artery with very calcified and tight stenoses. C—Posterior tibial artery of the same patient (diabetic and on hemodialysis). The stenoses were successfully crossed and treated with angioplasty with a 0.014″ guidewire.

2.3 Stiffness

There is no clearly accepted nomenclature that can reproductively relate a word or a group of words to the stiffness of a guidewire. As so, it is possible to find several guidewires with the label stiff, extra stiff, super stiff, or even ultra-stiff, without any objective information of its real stiffness. Flexural modulus is an engineering parameter related to a wire’s resistance to bending (Figure 2). This measure is rarely displayed on the guidewire packaging or within the catalog [1]. Yet, it represents an objective method to quantify the stiffness of a guidewire.

Figure 2.

Generically, the guidewire is supported at two points that are equidistant to a third point where a vertical force is applied. The force needed to bend the guidewire to a given extent determines its stiffness.

This property is more frequently used to describe the body of the guidewire, but its use in the description of the tip of the guidewire can be very useful too. The stiffer the body of a guidewire is, the more support it will allow to deliver the intended endovascular devices to the target vessel. On the other end, a higher stiffness of the body reduces the ability of the guidewire to track the vessel tree. Concerning the tip, a higher stiffness increases the penetration capacity, but also turns the tip more aggressive to vessel wall increasing the risk of dissection or perforation.

2.4 Trackability

It represents the capacity of a guidewire to navigate through the arterial tree, especially through curves of tortuous vessels. As so, floppier guidewires have a better trackability than stiffer guidewires.

2.5 Crossability

It characterizes the ability of a guidewire to easily cross a lesion without buckling or kinking. Several features of the guidewire can optimize this capacity, depending on whether it is a stenosis or a chronic total occlusion.

2.6 Pushability

Pushability can be defined by the percentage or amount of a given forward force applied to the proximal end of the guidewire that is transmitted to the distal end of the guidewire. Usually, the stiffer and broader the guidewire, the more pushability it gives. This characteristic is particularly relevant in crossing long and/or calcified chronic total occlusions, either in an intraluminal or subintimal way.

2.7 Torqueability

Torqueability represents the ability to apply a given rotational force at the proximal end of the guidewire and have that force transmitted efficiently and with the less delay possible, to achieve proper control of the distal tip. This feature is very relevant to determine the path of the guidewire and, consequently, to navigate inside the arterial tree (for instance, to go from the popliteal artery to the anterior tibial artery without a curved catheter) or to cross lesions. Torqueability is very dependent on the material used in the core and the distance from the access to the tip of the guidewire. As an example, guidewires with a stainless-steel core lose most their torqueability when used in a crossover fashion.

3. Composition

A basic knowledge of the engineering aspects of the guidewire technology is quite relevant to understand more thoroughly how a given guidewire is expected to behave in different conditions.

A guidewire has essentially four major components (Figures 3 and 4):

1. the body;

2. the tip;

3. the cover of both the body and tip;

4. the final coating of both the body and tip.

Figure 3.

Basic composition of a guidewire.

Figure 4.

A—Spring coils design. B—Guidewire with a complete polymer jacket and coating. C—Hybrid covering.

3.1 Core

A guidewire has a core that goes all the way through the body and finishes at the tip, where it may or may not reach the end of the guidewire (Figure 5). The core can be made of nitinol (alloy of nickel and titanium), stainless steel, or another metallic alloy. Nitinol allows more flexibility, memory (ability to maintain the original shape), and resistance to bending. Stainless steel increases the stiffness of the guidewire, but is less resistant to bending, so it is easier to irreversibly kink a guidewire with a stainless-steel core than a guidewire with a nitinol core. Other alloys will provide intermediate characteristics. Some guidewires may also have hybrid cores with stainless steel in the body and nitinol in the tip. In addition to its composition, its thickness straightforwardly corresponds to its stiffness: the thicker the core, the greater the stiffness and support. Therefore, the core is decisive for the behavior of the guidewire concerning its stiffness, torqueability, pushability, and trackability.

Figure 5.

A, B, C—Core-to-tip design. The core taper is longer and segmented in B and C. D – Shaping ribbon design.

3.2 Tip

There are essentially two main inner designs concerning the tip (Figure 5):

• the core finishes at the end of the tip in a variable tapered format (core-to-tip design) [2]. In this configuration, the tip has more pushability and torque, a higher penetration capacity, and a better tactile feel (see below). On the other hand, the tip is more prone to inadvertently perforate a vessel, to prolapse to an undesired vessel during tracking the arterial tree (Figure 6A) and to be irreversibly damaged (especially if the core is made of stainless steel). The length of the core taper and its configuration in a continuous or segmented design will enhance or attenuate the enumerated characteristics (Figure 5A–C).

• The core does not reach the end of the tip (shaping ribbon design) [2]. With this configuration, the end of the tip is wrapped in a small flexible metal ribbon, providing the continuity of the guidewire (Figure 5D). This design provides a less aggressive and flexible tip, less prone to prolapse (Figure 6B), easier to shape, though at the cost of a less tip torque control.

Figure 6.

A—A guidewire with a core-to-tip design has more difficulties in tracking the arterial tree and can prolapse to an undesired vessel. B—A guidewire with a shaping ribbon design tracks the intended vessel much more easily. Arrows indicate the natural direction of each guidewire.

The outer diameter of conventional guidewires is usually the same throughout its length. However, in more dedicated devices, the tip has a progressive reduction of the diameter (tapered tip design—Figure 7), going, for instance, from 0.014″ to 0.009″ [2]. This characteristic increases the penetration capacity but turns the tip much more aggressive and prone to vessel perforation. These guidewires are almost exclusively utilized in chronic total occlusions and should be handled with extreme care.

Figure 7.

An example of a tapered tip design.

3.3 Cover

The core of the guidewire is usually covered either by coils or by a polymer component (Figure 4). When all the core is surrounded only by spring coils (spring coils design), it enhances tactile feel (see below), but adds friction when navigating the arterial tree, reducing trackability. However, this additional friction tends to stabilize the wire distally to the target lesion, making the guidewire less prone to move backward or forward. On the other hand, a polymer jacket along all the guidewire including the tip provides a very smooth surface improving trackability at the cost of losing tactile feel. Some guidewires have a hybrid covering or polymer covering all the body but leaving the coils of the tip naked, also referred to as “sleeves” [3]. This configuration allows good trackability of the body maintaining tactile feel mostly intact.

3.4 Coating

Most of contemporary guidewires have a thin hydrophilic or hydrophobic coating applied at the final manufacturing process (Figure 4). Hydrophilic coating (e.g., polyethylene oxide or polyvinyl pyrolidone) needs water to be activated and to become slippery, but once wet, it allows an extremely low coefficient of friction [4]. As a result, it makes vessels easier to track and stenoses simpler to cross but leads to a decreased tactile feel, increasing the risk of dissection or perforation. Paradoxically, if a guidewire with hydrophilic coating gets dry, it loses lubricity and can get stuck, for instance, inside a catheter. Conversely, hydrophobic coatings (e.g., polytetrafluoroethylene or silicones) do not require water for activation [4]. As their name indicates, they repel water and create a smooth, “wax-like” surface [3]. Hydrophobic coating reduces friction but leads to a less slippery guidewire with enhanced tactile feel. Frequently, hydrophobic coatings are applied to guidewire bodies to facilitate movement inside plastic catheters [4]. Nevertheless, both coatings can coexist in a single guidewire, allowing their respective specific characteristics to be present either at the tip or throughout the body. In some configurations, even the tip can have both coatings, for instance, hydrophobic at the end for tactile feel and tip control purposes and hydrophilic intermediate segment for smooth crossing. Moreover, both hydrophilic and hydrophobic coatings may chafe or degrade with use [4]. This can account for the deterioration in wire performance at times noted during long procedures, particularly when wires are working through areas of severe tortuosity and friction or after numerous device exchanges [4]. This can even lead the guidewire to get fixed inside the catheter, forcing both devices to be removed as one piece, jeopardizing the therapy of the targeted vessel.

4. Specific characteristics

Even though, they are common to all guidewires used in endovascular procedures, the characteristics that will be discussed here are much more relevant in the 0.014″ and 0.018″ guidewires.

4.1 Tactile feel

It reports to the ability of a guidewire in transmitting tactile information from its tip to the hands of the interventionist. Even though it is a relatively subjective property, the possibility of the interventionist to feel the behavior of the tip when tracking vessels or crossing lesions (e.g., the tip goes freely or finds resistance) can help avoiding complications and improving results.

There is an inverse relationship between lubricity and tactile feel (Figure 8). Moreover, specific features can enhance tactile feel such as the core-to-tip design and the spring coil design.

Figure 8.

Components combination influencing the relationship between lubricity and tactile feel.

4.2 Tip load

The tip load represents the stiffness of the tip and is defined by the force needed to deflect to bend the tip 2 mm when the wire is fixed 10 mm above its end (Figure 9). It is a quite well-defined and reproducible parameter and therefore a comparable property. But as it is expressed in grams, it can generate confusion making some to think that the guidewire has effectively added weights at the tip. The tip load of the 0.014″ and 0.018″ guidewires utilized in peripheral interventions can range from 0.5 up to 35 g or more. The higher the tip load, the more aggressive the tip is. The lower it is, the softer and atraumatic it is.

Figure 9.

Tip load test.

4.3 Penetration capacity

The penetration capacity can be defined by the perpendicular force exerted over a defined area (i.e., pressure). It will depend on the tip load and the profile of the tip. For the same tip load, a guidewire that has a tapered tip will have a much higher penetration capacity than a more conventional nontapered tip. Additionally, adding a catheter (either a balloon catheter or a support catheter) very close to the end of the tip also adds penetration capacity as it prevents the tip to bend.

4.4 Shape, shapeability, and shape retention

Most of the 0.035″ guidewires used in peripheral interventions come in a preshaped format from the manufacturer. The more common available shapes are straight, angled, and J-shaped. The latter is the least traumatic. As so, it can be the best guidewire to use to deliver the intended devices to a target vessel. It can also be quite useful in tracking throughout a previously placed patent stent because the tip will not get stuck in the struts of the stent, neither will go between the stent and the vessel wall. Straight tips are more adequate to cross occlusions and angled tips to track vessels and to cross stenoses.

On the other hand, the vast majority of the 0.014″ and 0.018″ guidewires available for peripheral purposes comes in a straight shape and needs to be shaped. As so, shapeability characterizes the capacity of the guidewire tip to be angulated and shaped by the interventionist and shape retention represents its ability to maintain the intended shape over time [3]. These properties depend on the tip design and materials. Accordingly, a core-to-tip design with a core made of stainless steel is particularly easy and accurate to be shaped, but almost impossible to be reshaped. Conversely, nitinol core makes the tip more difficult to be shaped because it tends to return to its original form (memory) but is more reshapeable.

The tip of the GW can be shaped using the puncture needle (for moderately angulated curves), with the non-cutting edge of the blade (for sharp angulations) or with the inserter (for both) (Videos 1 and 2, https://bit.ly/3jPF7aj).

The desired shape depends on the primary purpose the guidewire will be used (Figure 10). Moderately angled continuous curves are very useful to track throughout the artery tree or to select a target vessel (Figure 10A). Several sharp angulations may help in selecting arteries with an acute takeoff such as the anterior tibial artery (Figure 10B). A very short sharply angled curve (usually no more than 1 mm) is intended to perform forceful and well-controllable drilling (Figure 10C).

Figure 10.

Tip shaping. A—Moderately angled continuous curve. B—Two sharp angles. C—Very short sharply angled curve.

5. Guidewire selection

An accurate knowledge of the discussed characteristics of each guidewire will permit the proper choice for every specific situation and also to create an adequate local laboratory portfolio. In practice, a vascular interventionist will rather need to thoroughly master a relatively small number of guidewires, instead of scarcely knowing many.

The purpose of guidewires in a peripheral procedure can be summarized as:

• getting to the target vessel;

• crossing the target lesion;

• give support to deliver the intended devices to the target lesion in a safely way.

Most of the interventionists have one or two “workhorse” guidewires, which are the guidewires that will be chosen to initiate the procedure and get to the target vessel. Their common characteristics are: good trackability and torqueability to navigate throughout the arterial tree, correct body stiffness to deliver catheters and sheaths to the intended vessel, and a tip as atraumatic as possible. They can also be used as an initial approach to the target lesion.

One additional aspect to take into account when choosing a guidewire is the catheter that will be also used. As such, for stenoses and some occlusions in larger vessels, such as the iliac arteries, an angled diagnostic or support catheter can be preferred to guide the tip of the guidewire to the center of the vessel, avoiding a subintimal track. Meanwhile, a straight support catheter or a balloon catheter would be the primary option for most of the stenoses and for occlusions in smaller vessels such as the tibial arteries.

5.1 Basic rules for guidewire manipulation

One of the best friends of a vascular interventionist is the torquer (Figure 11). It is the most proper manner to control the orientation of the guidewire tip. Therefore, its utilization is of utmost relevance in tracking difficult anatomies or in crossing challenging lesions (for instance, if the drilling technique is to be employed).

Figure 11.

Example of a torquer.

After having crossed the target lesion, the guidewire should be advanced very smoothly to the distal segment of the vessel. Confirmation through contrast injection that the true lumen has been reached after crossing the lesion is a basic but essential step. If a guidewire with a very aggressive tip was used to cross the lesion, it should be replaced by a much safer guidewire with good body stiffness for support (frequently the initial workhorse guidewire is adequate for this intent), sometimes after having shaped the tip as a loop (J-shaped like). During the delivery of the intended devices to the target lesion, it is of paramount importance to avoid inadvertent retraction of the guidewire, particularly after a complex crossing step and to prevent back and forth or shaking motion of the guidewire. That is why the tip of the guidewire should be on sight at almost all times. In summary, the two goals are: to secure the access to the target vessel and lesion; to avoid any trauma to the distal intact vessels.

5.2 Crossing the target lesion

The opening “workhorse” guidewire can be used in an initial attempt to cross the target lesion. Nevertheless, in many circumstances, a more dedicated guidewire will be required.

5.2.1 Crossing a stenosis

To cross a stenosis, it is perceptibly fundamental to stay intraluminal. For that purpose, the guidewire does not need to have increased stiffness, pushability, or penetration capacity. The tip should probably be hydrophilic as tactile feel is less relevant in those situations, and this can also improve the crossability of the guidewire. The tip is typically shaped in soft curve (Figure 10A), to be directed to the opposite direction of the stenosis. Specifically in tibial vessels, a 0.014″ guidewire can be preferable as in the case showed in Figure 1.

5.2.2 Crossing a chronic total occlusion

A chronic total occlusion is generally defined as an occluded artery of 3 months duration or longer [5]. When the vascular interventionist faces a chronic total occlusion, the best guidewire is obviously the one that successfully crosses the lesion. Nevertheless, there are several issues to consider in an attempt to cross a chronic total occlusion:

• The target artery. In fact, some arteries can be quite challenging to recanalize. For instance, an occlusion of the anterior tibial artery from its origin is, most of the times, very challenging to cross anterogradely because of the difficulty to engage the ostium. In those circumstances, adjuvant retrograde approach can be very helpful.

• The length of the occlusion. Longer occlusions are more difficult to cross and involve additional struggle to keep the guidewire in an intraluminal track. Moreover, the guidewire should have a stiffer body to support the crossing of a balloon or a support catheter, and it can also frequently require segmental pre-dilatations.

• The associated calcification. Depending on its length, location (entry point of the occlusion and/or in its core), and whether it is concentric or eccentric, calcification can greatly complicate the crossing of an occlusion or the reentry after a subintimal path. It also increases the risk of complications such as perforations or ateroembolization. On another hand, medial calcification can occasionally help in defining the limits of the vessel and consequently can guide the interventionist to stay intraluminal.

• Visible run-off. As a rule, the end of the chronic total occlusion should be clearly defined. Nevertheless, in some instances, such as in tibial vessels with very poor collateralization, it may not be initially adequately outlined and only appears after having crossed the occlusion.

5.2.3 Sliding technique

This technique is particularly indicated for engaging softer chronic total occlusions with microchannels [6]. It is frequently the first approach. For that intent, the initial “workhorse” guidewire with a soft hydrophilic tip and a body with some stiffness can be the option as reduced surface friction enhances passage through the chronic total occlusion core. The tip should initially be shaped in a single, long shallow bend (Figure 10A), and movement consists of simultaneous smooth tip rotation and gentle probing. But during the crossing, the interventionist should stay vigilant, as the guidewire has reduced tactile feel and typically advances with minimal resistance, frequently resulting in inadvertent entry to the subintimal space [7].

5.2.4 Drilling technique

If the sliding technique fails after a few attempts (one should not insist on this technique as it is easy to create several subintimal tracks that will jeopardize a desirable intra-luminal crossing), then the drilling technique should be tried. In this technique, a guidewire with a core-to-tip design with an uncovered tip should be preferred to enhance tactile feel. The tip is bended in a very short extension (Figure 10C) and clockwise and counterclockwise rotations of the guidewire are performed while the tip is pushed modestly against the chronic total occlusion (Figure 12). The important issue in this technique is that one does not push the guidewire very hard. Placing the balloon or the support catheter very close to the tip increases the penetration capacity. If the tip of the guidewire does not advance any more with gentle pushing, it is by far better to exchange for a stiffer tip and body guidewire, rather than continue pushing. If one pushes the wire hard, it will easily go into the subintimal space. Yet, when a stiffer guidewire is used, it may be difficult to perceive whether the tip has been engaged in the true or in a false lumen inside the chronic total occlusion. The movement of the tip may help in distinguishing one from the other. Typically, when the guidewire is in the subadventitial space, the tip budges markedly. Tactile feel from the guidewire during pullback can also aid as true lumen usually offers higher resistance. This technique has an increased risk of perforation, especially when using stiff tips guidewires [7].

Figure 12.

Drilling technique. Adapted from [7].

5.2.5 Penetrating technique

The penetration technique comes next if the drilling technique does not succeed or when the interventionist has a chronic total occlusion with very calcified cap. In this technique, the preferred guidewires have a very aggressive tip (core to-tip design, uncovered tapered tip, with increased tip load, and a subsequent high penetration capacity) and a relatively stiff body. The tip shape is essentially straight, and a less rotational tip motion and a more direct forward probing is used in comparison to the drilling technique (Figure 13). Again, placing the balloon or the support catheter very close to the tip increases the penetration capacity and reduces the propensity of the tip to bend. Additionally, the distal target must be clearly identified and careful monitoring of the progressive guidewire advancement should be done. The guidewires employed in this technique should not be used to deliver the intended devices to the target lesion as the tip can easily damage the distally intact vessels. It is a technique with a particularly augmented risk of complications [7].

Figure 13.

Penetrating technique. Adapted from [7].

5.2.6 Subintimal technique

It is usually the last technique to be employed, even if it can be a first option in specific situations such as very long chronic total occlusions. For this technique, a guidewire with a stiff body and a soft short tip with hydrophilic coating is usually preferable. The short tip allows a short loop. After having created the loop, the guidewire is advanced to the end of the occlusion. To reenter into the true lumen, the loop has to be undone. Sometimes, the guidewire needed to be exchanged to a guidewire with a reduced diameter (if the initial guidewire was not a 0.014″ guidewire), with an uncovered tip (to increase the tactile feel and reduce the tendency to stay in the subintimal space that a hydrophilic tips has), a good torqueability, and an angled shaped tip (to be able to direct this one to the true lumen). Sometimes moving the balloon or the support catheter and the guidewire as one can be very useful (Video 3, https://bit.ly/3jPF7aj and Figure 14). If the loop, during the crossing, becomes too large, it means that most certainly, a perforation has occurred. In these situations, the guidewire should be retracted and an another subintimal track should be pursued.

Figure 14.

A, B—Initial angiogram showing a long occlusion of the anterior tibial artery. C—Confirmation that the true lumen has been reached after a subintimal crossing of the occlusion (Video 3, https://bit.ly/3jPF7aj). D—Final result.

5.2.7 Retrograde access

When the antegrade approach is not successful, a retrograde puncture may be required. Retrograde puncture of the popliteal artery is usually not a big issue. However, at below-the-knee level, since arteries are quite small and fragile and frequently the tibial or peroneal artery to be punctured is the unique artery to the foot, extreme care must be the rule. As so, after having performed the puncture with a 21G needle (either guided by ultrasound or by X-ray), a guidewire is to be engaged inside the artery. To avoid additional injury to the artery, the devices introduced in it should be kept at the strict minimum. That why usually it is most preferable to initially advance only the guidewire without any catheter or sheath (Figure 15). Therefore, the guidewire to be chosen needs to have a hydrophilic stiff body due to the lack of a sheath, the relevance of having adequate torqueability to guide the tip and to perform the snaring of the guidewire, and a potential need for an additional catheter if the guidewire does not reach the true lumen or the same subintimal track made anterogradely. A 0.018″ diameter guidewire is probably the best option as it is still a delicate guidewire, but with more support than a 0.014″ guidewire. The tip should be soft and most probably hydrophilic to track easily the punctured vessel retrogradely. As no sheath should usually be introduced, hard push on the guidewire can lead to irreversible kinging of its body, which can jeopardize the intervention.

Figure 15.

After a retrograde puncture of the peroneal artery, a guidewire was inserted in it lumen, without any sheath or catheter.

5.2.8 Pedal plantar loop technique

This technique consists in creating a loop with the guidewire from the anterior tibial artery to the posterior tibial artery, or the reverse, through the foot vessels [8, 9]. The most common pathway is through dorsalis pedis artery, deep plantar artery, deep plantar arterial arch, lateral plantar artery, and posterior tibial artery. Indications for this technique are similar to the retrograde access. However, it can be performed when no distal vessels are available for puncture, being also less invasive. Moreover, this technique can improve the outflow for tibial arteries.

However, complications related to foot vessels manipulation can precipitate a serious worsening of the ischemic condition. Taking this into account, the guidewire to be chosen to this technique needs to have a soft hydrophilic tip to easily track through tortuous foots vessels without damaging them. The body should also have reduced stiffness to track across the created loop, that’s why usually a 0.014″ guidewire is preferred.

6. Potential guidewire-related complications

The manipulation with a guidewire of smaller vessels such as the tibial and foot arteries can precipitate vasospasm. This can be quite common in young patients or in vessels with no calcification. It is very relevant to be able to recognize it and consequently avoid the confusion with atherosclerotic stenoses and perform angioplasty on those arteries, which can lead to dissection or even rupture (Figure 16). Several drugs can be administered intra-arterially to solve the issue. Agents commonly used for this purpose are nitroglycerin, verapamil, or papaverine. The dose to be injected should consider the blood pressure of the patient. The hemodynamic status of the patient should also be closely checked after the administration. They ideally should be given selectively through a diagnostic catheter to the target vessel. The guidewire can be gently withdrawn to a more proximal segment of the vessel, but without losing the ostium and consequently the access to the vessel.

Figure 16.

A—Initial angiogram showing an occlusion of the tibioperoneal trunk and a quite healthy posterior tibial artery. B—After having crossed the occlusion, a 0.018″ guidewire was advanced inside the posterior tibial artery causing diffuse spasm of the artery (string of beads appearance). C—Few minutes after having selectively administrated 200 μg of nitroglycerin, the posterior tibial artery is widely open again.

A perforation or an arteriovenous fistula that occurs while attempting to cross a chronic total occlusion is rarely of any clinical significance as it will almost constantly closes within few minutes when only a guidewire or a low-profile catheter has passed extraluminally [10] (Figures 17 and 18). Thus, one should be sure to be inside the vessel before inflating a balloon. Removing the devices to above the proximal cap of the chronic total occlusion and reattempting to cross the lesion from the top, may allow successful path and aid in solving the perforation or the arteriovenous fistula. When those complications do not auto-resolve, external compression guided by angiography or temporary vessel occlusion with a balloon can be attempted. Sometimes a covered stent may be needed. In very rare situations, coil embolization must be envisaged.

Figure 17.

A—Perforation of the lateral plantar artery; extraluminal contrast is easily noticed. B—Peroneal arteriovenous fistula. Adapted from [7].

Figure 18.

A—Occlusion of the popliteal artery, tibio-peroneal trunk, and proximal segment of peroneal artery. B—Perforation occurred while trying to cross the occlusion through the initial antegrade approach. C & D—Final result after a retrograde puncture of the peroneal artery and successful crossing of the occlusion.

An unintended wall dissection or perforation of an intact vessel distally after having crossed the target lesion can be quite challenging to solve and can threaten the success of the procedure or even worsen the ischemic condition of the patient. Therefore, the most relevant concerning this issue is to adopt correct guidewire choices and strategies to avoid it.

7. Future perspectives

X-ray fluoroscopy is still the gold standard imaging technique for the vast majority of endovascular procedures currently performed. Therefore, most of the endovascular devices, guidewires included, are designed to optimally perform under X-ray. However, its inherent ionizing radiation leads to safety concerns not only to the healthcare professionals, but also to the patients. As a result, recent advancements have been made toward magnetic resonance guided endovascular interventions [11]. Magnetic resonance imaging is a noninvasive, radiation-free imaging technique that can provide not only morphologic but also functional information (e.g., blood flow, tissue oxygenation, diffusion, or perfusion), which can potentially influence decisions during a procedure [11]. Yet, magnetic resonance guided interventions face a major challenge due to the presence of a large magnetic field, which limits the utilization of the currently available materials, including guidewires. Despite these challenges, significant progress has been recently made in the development of biocompatible, magnetic resonance safe, and visible interventional devices [11]. The guidewires presently used in the endovascular field have a long metallic core. In a magnetic resonance environment, it can create artifacts and can also induce thermal injury. As a result, new dedicated guidewires have been designed with the metallic core replaced by polymers reinforced by glass fibers or fiber composites. Those guidewires demonstrated to have improved stiffness and kink resistance [11]. Further research and development regarding magnetic resonance compatible devices and magnetic resonance imaging techniques will probably lead to a shift in the future standards of endovascular procedures.

8. Conclusions

Guidewires are the cornerstone of any endovascular revascularization. Therefore, a correct knowledge of the engineering aspects of wire technology can be the difference between failure and success as it allows an adequate guidewire choice in any situation and for each specific crossing technique. A vascular interventionist should subsequently master a relatively small number of guidewires to be able to fully translate in practice his theoretical knowledge on guidewire design.

Video materials

Video materials referenced in this chapter are available at: https://bit.ly/3jPF7aj.