Cath Lab Digest - September 2007 - (Page 28)

28 PATIENT ACCESS SEPTEMBER 2007 Essential Technical Components of the Transradial Approach Ronald Caputo, MD, Associate Director Cardiac Cath Lab St. Joseph’s Hospital, Syracuse, New York Figure 1. 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. 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. Figure 2. C ardiac 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 transradial 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. 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

Table of Contents Feed for the Digital Edition of Cath Lab Digest - September 2007

St. Dominic Hospital The Genous Bio-engineered R Stent Percutaneous Treatment of Peripheral Arterial Chronic Total Occlusions: Device Options and Clinical Outcomes Contents Clinical Editor’s Corner Percutaneous Revascularization of Peripheral Chronic Total Occlusion — Which Patients, Why, and How? Myocardial Infarction and Syncope: A Manifestation of the “Raynaud-Prinzmetal Syndrome”? Essential Technical Components of the Transradial Approach If You Build It, Will They Come? Evidence-Based Medicine with Drug-Eluting Stents Back to School: The Value of Education in Cardiovascular Services The ACVP Standards and Competencies: Are You Using Them Effectively? What Do You Think? My Experience with Fibromuscular Dysplasia and Stroke A Brief Review of Fibromuscular Dysplasia Letter to the Editor A Look at On-the-Job Training: Perceptions, Reality and Our Profession Doing the Wave: Inventory Management with RFID The Ten-Minute Interview with… Paul Pinsker, RCIS CLD’s Annual Salary Survey Harrisburg Area Community College Volunteer Survey CEU Education Center SICP* Section Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab Clinical & Industry News

Cath Lab Digest - September 2007

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