Beyond the Bend: A Literature Review and Case Report of Radial Artery Loop

ABSTRACT: Transradial cardiac catheterization is an exciting technique that has many advantages over the traditional femoral approach. Most importantly it is a safe option for PCI with potential same day discharge for uncomplicated cases. Despite its advantages, some challenges may be encountered with the transradial approach. After arterial access and spasm, vascular artery anomalies constitute a significant number of procedural failure. Radial artery anomalies are encountered in greater than 17% of cases performed in literature. In particular, radial loop is an important cause of transradial procedural failure. We present a literature review and a case from our institution and outline techniques in order to traverse the loop and make the transradial approach a success.

J Invasive Cardiol 2011;23(11):E271–E272

Key words: coronary intervention, IVUS, radial artery anomaly

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Transradial catheterization is becoming increasingly used for percutaneous coronary intervention (PCI) in the United States given its reduced risk of vascular complications when compared to femoral approach. There are many advantages to the transradial approach including early ambulation, reduced risk of bleeding, patient comfort, reduced hospitalization and costs, and potential for same day discharge for PCI. Despite these advantages, radial artery catheterization has not been fully embraced by interventionalists in the U.S. in comparison to their counterparts in Europe and Asia. Most often this has to do with a learning curve, increased time constraints (with inexperienced operators), increased radiation exposure and history of coronary artery bypass grafting with left internal mammary. In addition, a variety of anatomic variations have been described which can make radial access challenging. These include high bifurcation, tortuousity, hypoplasia, abnormal origin, stenosis and loop. Furthermore, radial artery anomalies are an important cause of transradial failure.

In the largest published report from China¹ which included 3000 patients that had a transradial coronary procedure, there were 610 vascular anomalies, 522 being radial. Radial anomalies included tortuous artery, hypoplasia, radioulnar loop, abnormal origin and stenosis. Radial loop accounted for 33/3000 (1.1%) cases requiring the operator to switch to the opposite arm in 3 cases, and use femoral approach in one. They suggested using a 4 French (Fr) catheter to cross the loop. Barbeau² published the second largest case series, 14/594 patients had vascular anomalies. 4/14 (0.6% of all cases) were secondary to radial loop and was successful in passing a wire and catheter in 3/4 patients. He suggests traversing the loop with either a guidewire or hydrophilic wire. If this failed, he used a 0.014-inch hydrophilic-coated coronary guidewire. Another group³ encountered vascular anomalies in 212/1533 patients. A radial loop was noted in 35 patients (2.2%), and was associated with high procedural failure in 13/35 (37%), which was the most common cause of failure secondary to anomalies. In that study, the authors suggest using a hydrophilic wire or guidewire to cross the loop.

Case Report

We describe a case of a 60-year-old female who was referred for cardiac catheterization after an abnormal dobutamine stress echcardiogram for 6 segments of inducible myocardial ischemia in anterior and lateral areas. Right radial artery access was obtained via the modified Seldinger technique and 6 Fr standard short hydrophilic sheath was placed. Initially, a standard 1.5 J 0.035″x180cm Rosen wire (Infiniti Medical, Inc.) was inserted; however, it was difficult to advance. An angiogram showed a radial loop.

The loop was successfully negotiated with a 0.035″x 150cm Glidewire (Terumo Medical Corp.). A 5 Fr JR4 catheter was passed over the wire and used to straighten the loop. Next, the Glidewire was exchanged for a Rosen wire. The JR4 catheter was removed and the short sheath was exchanged for a 35cm 6 Fr hydrophilic sheath. The procedure was successfully completed. The patient had no pain or complication noted either during or after the procedure. In addition, vascular complications and arterial spasm were successfully avoided.

Discussion

Transradial cardiac catheterization is an exciting technique that has many advantages over the traditional femoral approach. Most importantly it is a safe option for PCI with potential same day discharge for uncomplicated cases. Despite its advantages, some challenges may be encountered with the transradial approach. After arterial access and spasm, vascular artery anomalies constitute a significant number of procedural failure. Radial artery anomalies are encountered in greater than 17% of cases performed in literature. Of note, radial loop accounts for up to 16% of these anomalies. Furthermore, they account for high percentage of procedural failure. Other authors have suggested using hydrophilic wire to cross the loop, and then advancing catheters over this. In our institution, we use a standard Rosen wire which has a smaller J tip and can pass more easily than standard guidewires. In our case, we had difficulty traversing the radial loop with the Rosen wire. However, we were able to cross the loop. Initially, we used a hydrophilic wire (Glidewire, Terumo) to cross the loop and a 5Fr JR4 catheter to straighten it. However, in our experience exchanging the short sheath for a long hydrophilic sheath allows other bulkier catheters to cross easily. Therefore, we suggest that when a radial loop is encountered, a hydrophilic wire can be used to cross the loop. If the hydrophilic wire fails then a 0.014″ coronary wire can be used. A JR 4 catheter can be used to straighten the loop, however, if that is difficult then a hydrophilic catheter can be used. After successful negotiation, it is optimal to exchange the short sheath for a longer one, thus making interventions with bulkier catheters beyond the bend feasible, more safe, and successful. If these steps fail, transulnar approach can be used as a bailout. Currently, we are collecting data in our institution for a case series on transradial PCI.

Dr. Sarji can be contacted at rsarji@unmc.edu.

References

1. Nie B, Zhou Y, Li G, Shi D, Wang J. Clinical study of arterial anatomic variations for transradial coronary procedure in Chinese population. Chinese Med J 2009;122(18):2097-2102.
2. Barbeau G. Radial loop and extreme vessel tortuosity in the transradial approach:  Advantage of hydrophilic-coated guidewires and catheters. Cathet Cardiovasc Interv 2003;59(4):442–450.
3. Lo TS, Nolan J, Fountzopoulos E, et al. Radial artery anomaly and its influence on transradial procedural outcome. Heart 2009;95(5):410-415.
4. Yoo BS, Yoon J, Ko JY, et al. Anatomical consideration of the radial artery for transradial coronary procedures: arterial diameter, branching anomaly and vessel tortuosity. Int J Cardiol 2005 101(3):421–427.
5. Barman N, Chiu JH, Ellis SG. Transradial catheterization: the road less traveled.  J Invasive Cardiol 2004;16(11):639-640.
6. Agostoni P, Biondi-Zoccai GG, de Benedictis ML, et al. Radial versus femoral approach for percutaneous coronary diagnostic and interventional procedures; Systematic overview and meta-analysis of randomized trials. J Am Coll Cardiol 2004;21;44(2):349-356.

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Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. No conflicts of interest were reported regarding the content herein. Reprinted with permission from the Journal of Invasive Cardiology 2011;23(11): E271-E272.