Cardiac catheterization through the transradial approach is commonly utilized outside the United States, enjoying significant popularity in Japan, Europe and Canada. While only 7–8% of cardiac catheterization laboratories in the U.S. currently perform significant numbers of transradial catheterizations, this approach is gaining popularity. Compelling reasons to consider transradial catheterization include the virtual elimination of bleeding complications, more efficient patient throughput, patient preference and possible economic advantages.

One barrier to the acceptance of transradial catheterization in the U.S. is the dearth of formal training within fellowship programs. Many invasive cardiologists are faced with the challenge of learning a new technique in the setting of a busy clinical practice. This was a challenge we faced 10 years ago when we decided to begin a trans-radial program at our center. In order to provide insight for those currently considering initiation of a transradial program, I have used our experience to distill the essential technical components of the procedure.
There are four main components:

1) Patient preparation;

2) Arterial access;

3) Navigation of the catheter to the aortic root and proper catheter positioning;

4) Post procedure care.

Patient Preparation
Patient preparation is relatively straightforward. An essential component of patient positioning is an armboard extending (usually) from the right side of the catheterization table, and preferably hinged to allow lateral motion toward and away from the table. The patient is placed on the catheterization table in the usual fashion with the right arm extended on the armboard, palm upward. It is important to extend the wrist by placing a roll of gauze, a rolled-up washcloth, etc. underneath the wrist (Figure 1). The hand can be taped down loosely in order to ensure stability. Sterile drapes can now be applied. It is important to place the center of the circular portion of the drape proximal to (above) the skin creases of the wrist in order to avoid the flexor retinaculum which lies across the distal wrist.

Figure 1.

Special considerations for programs new to the transradial technique should include appropriate sedation/analgesia and concurrent preparation of the femoral site. Sedation and analgesia are especially important for an operator initiating a transradial program as often multiple attempts at arterial access are required. Preparation of the groin is an excellent failsafe strategy for a new operator and often will prevent over-extensive attempts at failed radial access and prolonged procedure times. There is less resistance to switch to the femoral approach if the groin has been prepped.

Arterial Access
Arterial access is the first technical challenge. The operator should take time to identify the exact location of the radial pulse. I find that, occasionally, the artery is more lateral or superficial than initially suspected. The location for arterial puncture should be proximal to the skin creases in the wrist and the styloid process of the radius in order to avoid the flexor retinaculum. Following the administration of subcutaneous local anesthetic, a small superficial scalpel “nick” (~2 mm) can be made to ease passage of the sheath through the skin. Several types of needles can then be used to gain access to the artery. Regardless of the type and size of access needle, a single wall puncture (rather than the Seldinger technique) is advised. Needle sizes range from 18 to 24 gauge. The length of the needle should be less than 2”, in my opinion, for easier manipulation. Some specialized access needles incorporate a small guidewire within the system and/or a small over-sheath (similar to a typical IV) (Arrow International, Reading PA; Surflo, Terumo Co., Tokyo, Japan). I use a bare 18-gauge needle in order to accurately assess the strength and pulsatile quality of “bleed-back.” This ensures that the end of the needle is in the center of the arterial lumen prior to wire advancement.

Once arterial access has been achieved, a small guidewire of appropriate size (usually no larger than 0.021”) is advanced through the needle into the arterial lumen. At this point, special care must be taken to appreciate tactile feedback on the wire. There should be no palpable resistance to wire advancement. Early resistance as the wire exits the needle indicates the wire is not in the center of the lumen and further advancement could result in entry into a tissue plane rather than the lumen. In the case of resistance, the wire should be withdrawn and the needle re-positioned prior to further advancement. If resistance is encountered further upstream, this often indicates passage of the wire into a bend or sidebranch in the artery. Severe spasm may also be encountered at this point. The wire can be removed and a gentle curved shape can be made on the distal end which may then allow for successful passage beyond a sidebranch. Medications to relieve spasm (nitroglycerine, verapamil, diltiazem, papavarine, etc.) can be administered through the needle or following partial introduction of the sheath.

With the wire in position, the needle is removed and a sheath is advanced into the artery. Features to consider when selecting an arterial sheath are length, tapering at the tip, a very smooth transition between the dilator and the sheath, and the presence of a hydrophilic coating. A highly tapered tip and hydrophilic coating allow for easier passage of the sheath through the skin and into the artery. This is important due to the small caliber of the wire used for arterial access. I have recently started using the Glidesheath (Terumo Co., Tokyo Japan), which provides all of these features. Although I use a short (10cm) length sheath, some operators feel that a longer sheath (21–25 cm) extending to the brachial artery helps facilitate catheter manipulation. If there is any resistance, sheath advancement must be immediately stopped. An arteriogram with half strength contrast is often helpful at this point in order to define the cause of obstruction. If the sheath is not in the lumen, the transradial approach must be abandoned. Otherwise, tortuousity and spasm can usually be overcome with the selection of a torquable/hydrophilic wire or anti-spasm medications.

With the sheath in place, consideration regarding medications must be given. I routinely administer 0.2 µg of nitroglycerin through the side arm of the sheath in order to prevent proximal arterial spasm. Many operators also administer a calcium channel blocker such as diltiazem 500µg or verapamil 250–500µg. Heparin is also an important medication. As post-procedure patency of the radial artery correlates with level of anticoagulation, I routinely administer 5000u for diagnostic cases. I always administer the heparin within the central circulation though the catheter (aortic root) as it is an acidic medication and patients frequently complain of a burning pain when it is administered through the sheath.

It is also important to consider analgesics and anxiolytics. In our lab, midazolam and sublimaze are routinely administered unless there is a contraindication. This makes the procedure more comfortable for the patient — and therefore often makes it a more comfortable case for the physician!

Navigation of the Catheter to the Aortic Root and Proper Catheter Positioning
Once the arterial sheath is in place, catheters are advanced into the aortic root.
Advancement of the catheter over an 0.035-0.038” guidewire is encouraged in order to facilitate crossing of the inominate artery and its branches. Tortuous, calcified subclavian/inominate arteries are sometimes encountered, especially in elderly and hypertensive patients. Use of a shapeable and steerable wire along with a deep breath hold by the patient can help catheter navigation. I usually use a 0.035” flexible J tip wire with a moveable core (Emerald, Cordis Corporation, Miami, FL) which allows adjustment of the stiffness at the end of the wire. The choice of optimal catheters from the right radial approach is important. Compared to angiography from the femoral approach, right Judkins and pigtail catheters can be sufficient, but the left Judkins is often suboptimal. An AL-2 or Castillo-2 (Cordis) catheter is often a good choice for angiography of the left coronaries. There are also specialty catheters which allow for angiography of both left and right coronaries, such as Kimny (Boston Scientific, Maple Grove, MN) or Sones. A multi-purpose or Sones catheter can also be used for ventriculography. As an aside, I would recommend performing all catheter exchanges over a wire. This maintains access to the central vasculature in the event of spasm and likely reduces the potential for vascular injury (dissection, embolization, etc.).
There are some unique features to performing coronary interventions from the radial approach. Due to the differences in working space, I will often have a Mayo stand or similar small table covered with a sterile drape and placed between the armboard and the table. While not necessary, the working space makes it preferable to use short wires and rapid exchange platforms. In regard to guiding catheters, I use only 6 French sizes and have found that AL0.75 and Hockey Stick guiding catheters provide excellent support for the vast majority of right coronary interventions. Note that different Hockey Stick shapes are provided which often differ by manufacturer. Interestingly, guiding catheter support from the right upper extremity approach is generally superior to that found by the femoral approach. For left coronary interventions, the size of the aortic root and the take-off of the left main coronary determine the appropriate shape guiding catheter. Common considerations include EBU-3.5, EBU4.0, XB-3.5, XB-4.0, KIMNY, AL-1.5, and AL-2 shapes.

Figure 2.

Post Procedure Care
Following the procedure, the sheath is removed and pressure is applied over the radial artery for total of 1 to 1.5 hours. Pressure should be occlusive for the first 10–15 minutes and gradually released over the remaining duration. Different methods are utilized for the continuous application of pressure. A firmly-rolled gauze “bullet” can be applied under a HemoBand (HemoBand Corp., Portland, OR), or specially-designed devices can also be utilized. The newest is the TRI band (Terumo), which consists of clear polymer bracelet with an inflatable bladder positioned over the puncture site (Figure 2). This device is comfortable for the patient and has the advantage of allowing continuous observation of the puncture site. Once the pressure device is removed, we apply a folded 4x4 gauze over the site and secure it with elastic tape. The patient removes this dressing the following day and applies a BandAid. Instructions are given to avoid lifting anything heavier than 5 lbs. for 3–4 days.

The transradial approach to cardiac catheterization has achieved significant popularity in many countries outside of the United States and has been a significant benefit to the patients served by our cardiac catheterization laboratory. With increasing physician and patient awareness and the potential for increased availability for industry-sponsored educational and training opportunities (Terumo, Cordis, and Boston Scientific all offer programs), the popularity of this technique within the U.S. may see similar growth.

Dr. Caputo can be contacted at caputo331@msn.com