Coronary Stenting : Practical Considerations, Equipment Selection, Tips and Caveats

Radial Access

Radial artery access has many advantages, though there are several possible limitations. The ultimate result of many of these limitations is the not infrequent difficulty in passing a wire and/or catheters into the aortic root. This challenge can result from a variety of circumstances including calcified radial arteries, small radial arteries, radial loops, subclavian tortuosity, heavy aortic and subclavian calcification, lack of dedicated radial equipment, and radial spasm.

Proper access to the radial artery is paramount. Anterior wall micro puncture is the most commonly used technique. With this technique, a low angle of puncture can be helpful in facilitating wire passage and sheath insertion. An additional access technique that is popular is a classic double-wall Seldinger technique using a dedicated “through and through” access system with a microcatheter over an access needle, similar in design to an angiocatheter. This technique allows for easier and more consistent passage of the wire. However, while uncommon (similar to femoral access), it can lead to hematoma formation in the radial artery due to posterior wall bleeding. Regardless of the technique used, it should be perfected and consistently applied to all cases in a repetitive manner.

The access location in the radial artery is important ( Fig. 14.1 ). Accessing the artery too distally, over the styloid process of the radius, can result in difficult wire passage given the introduction of some tortuosity in that segment of the artery. Additionally, punctures in this area can make it difficult to apply a radial artery compression band. Punctures of the radial artery that are too proximal can also lead to difficulties and complications. Proximal punctures tend to result in sheath passage through increased soft tissue and decrease the efficacy of radial artery compression bands, resulting in an increased rate of bleeding. Optimal access is obtained approximately 1 to 2 cm proximal to the styloid process. This allows for easy wire passage, smooth sheath insertion, and optimal effectiveness of the radial artery compression band.

Frequently, operators will encounter calcified radial arteries that can present access issues. For example, the artery may deflect the needle when access is attempted. Using the radius to pin the artery with the left index finger can allow for puncture into the true lumen. This technique is also useful in mobile radial arteries. Once a calcified artery is punctured, passage of a micro puncture 0.018–0.025-inch sheath wire can be difficult, as the wire is generally hydrophobic and not particularly flexible. An alternative can be the use of a 0.014-inch coronary guidewire. Typically, a workhouse wire will be able to navigate the calcification; however, under some circumstances, a polymer-jacketed wire is necessary. Operators should be careful to choose a wire with at least moderate support to facilitate sheath insertion and to avoid wire fracture. Once the sheath is inserted, the operator can either pass a small diagnostic catheter (4 or 5 Fr) over the wire (OTW) until a larger lumen is encountered, or balloon assisted tracking (BAT) can be used. Alternatively, after sheath insertion, the wire can be pulled out and a soft and steerable 0.035-inch (Wholey [Medtronic Inc., Minneapolis, MN], Versacore [Abbott, Abbott Park, IL], or Bentson [Cook Medical, Bloomington, IN]) can be used with a Judkins Right (JR) diagnostic catheter.

Small radial arteries can be challenging. The Slender Glidesheaths (Terumo Medical, Somerset, NJ) can be very useful when adequate diagnostic images are needed, without using a sheath with a large outer diameter (OD). Alternatively, using a smaller sheath, such as 4 Fr, can be helpful. A complex intervention can be staged; alternatively, simple interventions can be completed with a 5 Fr system. Fractional flow reserve (FFR) can be completed through most diagnostic catheters if a wire-based system is used. Aggressive use of antispasmodics and sedation can make a patient with a small radial artery more comfortable.

Radial loops present a unique challenge. They generally can be straightened; however, even passing a wire through a loop can be difficult. A steerable soft tip 0.035-inch wire (Wholley, Versacore, Bentson) can navigate a loop, though these wires are hydrophobic and may not be able to traverse a loop. Alternatively, a coronary 0.014-inch wire can be used. Once a coronary wire has been used, it is recommended to use BAT to pass diagnostic or guide catheters into the aorta. BAT is accomplished by placing a rapid exchange, semi compliant balloon halfway in and halfway out of the catheter on the wire. With the balloon inflated, the system is advanced OTW. This is analogous to the “torpedo technique” used with guide extensions (discussed later in this chapter). A 2-mm balloon can be used for 6 Fr catheters.

Subclavian tortuosity, like radial tortuosity, is challenging. Usually, the tortuosity can be navigated with either a steerable soft tip 0.035-inch wire (Wholley) or a standard angled glide wire. A multipurpose or JR diagnostic catheter will usually pass OTW into the aortic root. If the catheter will not pass, the operator can pass a small hydrophilic exchange catheter such as a CXI (Cook Medical) into the root and exchange for a stiff J-tip exchange length wire such as an Amplatz wire. In most cases, the tortuosity will straighten, and the operator can easily pass any catheter to the root. If this is not the case, there are commercially available hydrophilic diagnostic and guide catheters that will pass into the root. It is useful in these cases to use a universal catheter to minimize exchanges.

While the equipment dedicated for radial use is improving, many components still commonly used were designed for femoral use. An example of this is guide catheters. This is not an issue that can be resolved by the operator, but what can be understood is that sizing, particularly from the right radial, is generally smaller than from the femoral artery. For instance, a Judkins Left (JL) 3.5 as opposed to a JL 4 is usually a better fit from the radial, and for Contralateral Left Support (CLS; Boston Scientific, Marlborough, MA), Extra Back-Up (EBU; Medtronic Inc.) and Extra Back-Up (XB; Cordis Medical, Milpitas, CA) guides, a half size down for radial access is appropriate.

Radial spasm can make an ordinary case painful for the patient and the operator. Antispasmodics can be very helpful when given immediately after sheath insertion and between catheter exchanges. However, there is evidence that adequate moderate sedation is paramount. Using 4 Fr or 5 Fr catheters also improves patient comfort.

Ultimately, radial catheterization has a steep learning curve, but with practice and using the techniques described above, it can be safely completed. Transitioning to a radial-first approach will reduce access site bleeding and hospital time for your patients.

Femoral Access

While radial access has taken a foothold, most cases in the United States are still completed via femoral access. While typically devoid of many of the challenges of the radial approach, such as spasm and lack of dedicated equipment, there are many additional challenges that must be overcome. Femoral and iliac arteries can be prone to significant vascular disease, calcification, and tortuosity. Additionally, body habitus can greatly influence femoral artery access in a much more significant manner than radial access.

Accessing diseased and calcified femoral arteries must be done with care. A combination of palpation, fluoroscopy, and ultrasound can be used. With a strong femoral pulse, the operator can identify the anterior pelvis using fluoroscopy. The artery can then be accessed using a modified Seldinger technique. As opposed to using the wire provided with the sheath kit, the operator can utilize a steerable soft tip 0.035-inch wire (Wholley), with a bend that is commensurate with the size of patient’s femoral artery. This allows more wire purchase and the ability to navigate through disease proximal to the access site. Polymer-jacketed wires (such as a Glidewire) should not be passed through needles because the polymer coating can be stripped off. Once the wire is safely in the true lumen of the aorta, the sheath should be inserted; however, not infrequently, the sheath may not pass through the calcified artery. The operator can pass the sheath dilator and then the full sheath and dilator, or the dilator can be used to pass a stiff wire into the aorta, then pass a long or short sheath. If there is a weak or no pulse, then ultrasound in conjunction with fluoroscopy is useful. With ultrasound, there is evidence for a reduction in complications, as one can identify a less calcified segment and ensure an anterior wall puncture. It must be noted that regardless of the technique, fluoroscopy must be used to identify the anterior pubis. For optimal femoral access, the objective is to obtain a site of access which is overlying the pubis (see Fig. 14.1 ). This is critical in order to allow compression of the artery after sheath removal. A low puncture is not defined by the common femoral artery bifurcation, but by a puncture below the pubis. Additional common mistakes with access include a “through and through” technique which results in posterior wall bleeding and puncturing the artery with the local anesthetic needle, which also results in another non-controlled arterial puncture, even if it is small.

Iliac artery tortuosity is best navigated with a steerable soft tip 0.035-inch wire. A catheter can be used to exchange the wire for a stiff wire such as an Amplatz wire. Following this, a long sheath can be passed into the aorta. This minimizes friction and ensures that the operator does not need to repeatedly traverse the iliac artery or use an exchange length wire. When placing a long sheath, it is helpful to upsize by 1 Fr size. For example, if a 6 Fr system is desired, then pass a long 7 Fr sheath and use a 6 Fr catheter. This adds another layer of protection against friction and improves the ability to complete the procedure.

Overcoming large patient body habitus can be difficult. Use of a combination of palpation, fluoroscopy, and ultrasound is recommended. It is critical in the obese patient to access the common femoral artery over the anterior pubis. This allows the operator to have a host of hemostasis options including closure devices and manual pressure. Fluoroscopy is used to identify the pelvis, and ultrasound is then used to identify the femoral artery. Importantly, a femoral angiogram should be obtained immediately after access has been obtained, rather than performing it at the conclusion of the procedure. The rationale behind this is to expeditiously discover any acute problems that could contraindicate the use of anticoagulation or require urgent intervention (i.e., active bleeding at the access site) or possibly even require the operator to abort the PCI procedure (i.e., vascular perforation).

Ultimately, femoral artery access skills are essential even for radial operators. There will be cases where radial access is not possible. For example, if large systems, 8 Fr and above, are needed, then typically femoral access is preferred. In many CTO interventions, at least one femoral access is needed. Therefore, safe technique and proper understanding of the anatomy can improve outcomes and patient safety.