58

DepartmYor

AddresRadGusfisch

A Technical Guide Describing the Use ofTransradial Access Technique for EndovascularInterventions

Aaron M. Fischman, MD, Nathaniel C. Swinburne, MD, and Rahul S. Patel, MD

1089-2516/15http://dx.doi.o

ent of Radiolk, NY.s reprint requiology, Icahntave L. Levyman@mount

Transradial arterial access (TRA) has been employed for transcatheter coronaryprocedures for more than 25 years, with numerous studies demonstrating improvedpatient safety as compared with transfemoral arterial access. However, TRA remainsunderused by the interventional radiology and vascular surgery communities. Advan-tages of TRA over transfemoral arterial access include easier accomplishment ofpostprocedure hemostasis, decreased risk of hemorrhagic complications, shorter patientrecovery leading to immediate ambulation and decreased procedure-related costs, andincreased patient satisfaction. In particular, TRA may be advantageous in the populationof patients with obesity. The primary patient selection factor to consider beforeattempting TRA is whether the patient has adequate collateral perfusion to the hand;this is assessed using the Barbeau test. Limitations of TRA may include operatorunfamiliarity or learning curve and unavailability of adequate length catheters. The mostcommon complication, although still rare, is localized access site hematoma, which isoften asymptomatic. Radial artery occlusion is rare and rarely symptomatic owing tocollateral perfusion to the hand. Theoretical increased risk of cerebral embolism duringTRA may be minimized by preferentially accessing the left wrist during below-diaphragmprocedures, which limits transcatheter manipulation of the aortic arch. Transulnar arteryaccess is under investigation for use in patients who cannot undergo TRA. Providingpatients the option of TRA can lead to improved outcomes, potentially increasing safetyand patient satisfaction while decreasing procedure costs.Tech Vasc Interventional Rad 18:58-65 C 2015 Elsevier Inc. All rights reserved.

KEYWORDS transradial, endovascular, radial artery

BackgroundUse of the radial artery as the primary access vessel into thearterial system for transcatheter diagnosis and interventionis not a new concept. The first series describing diagnosticangiography of the coronary circulation using transradialarterial access (TRA) was published in 1989 by LucienCampeau at the Montreal Heart Institute.1 Campeausuggested percutaneous radial access as a safer alternativeto percutaneous and “cutdown” brachial or axillary access.

/$ - see front matter & 2015 Elsevier Inc. All rights reservrg/10.1053/j.tvir.2015.04.002

ogy, Icahn School of Medicine at Mount Sinai, New

ests to Aaron M. Fischman, MD, Department ofSchool of Medicine at Mount Sinai, Box 1234, OnePlace, New York, NY 10029. E-mail: aaron.

sinai.org

His series of 100 patients demonstrated an 88% technicalsuccess rate and a 6% asymptomatic radial artery occlusionrate, which was a significant improvement over brachial oraxillary upper arm access.1 Shortly thereafter, in 1992,Kiemeneij performed the first successful transradial coro-nary angioplasty procedure and then, in 1993, the TRcoronary stent placement via the radial artery.2 Since then,the use of this technique has grown significantlyworldwide.Despite this growth, TRA is estimated to account for

only 10% of percutaneous coronary interventions (PCIs)worldwide.3 There are some areas in Canada and Europethat perform approximately 95% of PCIs via the TRapproach.3 In the United States, TRA is estimated to havegrown from 1.2% of all PCI procedures in 2007 toslightly more than 16% in 2012.4 Its usage is largelyabsent within the interventional radiology and vascular

ed.

Transradial access technique 59

surgery communities, however. The brachial artery con-tinues to be the most common upper extremity arteryused for noncoronary interventions. Reasons for under-use of TRA outside the cardiac catheterization laboratorymay include a lack of appropriate training, equipmentlimitations such as inappropriate catheter length andshape, and the initial learning curve.This review describes the technique of TRA for non-

coronary interventions, including below-diaphragm inter-ventions such as hepatic embolization, and the issuessurrounding its usage.

Advantages of the TransradialApproachThere are several obvious advantages of TRA over trans-femoral arterial access (TFA). First, the radial artery ismore superficial than the femoral artery, and there are nosurrounding critical structures that are susceptible toinjury. In addition, inadvertent injury to the artery itself,such as dissection or thrombosis, is significantly lessdetrimental to the patient because of the dual bloodsupply to the hand.1 The radial artery is also readilycompressible, which decreases the incidence of postproce-dural bleeding complications during PCI and, in somestudies, decreased cardiac mortality.6-8 Hemostasis can beachieved without the introduction of a foreign body, suchas a vascular closure device, which is a common practice inmany interventional suites that use TFA.Patient comfort issues are also of paramount impor-

tance, especially in the current climate in which patientschoose among many treatment options. Following TRA,patients are able to ambulate immediately, sit up in bed,and are discharged home faster. In a randomized trial,Cooper et al demonstrated a strong patient preference,improved quality-of-life metrics, and decreased hospitalcosts for TRA over TFA during cardiac catheterization.9

The specific advantages of immediate ambulation anddecreased incidence of back pain are of particular impor-tance during hepatic embolization, which is performed in apatient population that frequently experiences nausea andvomiting.

Patient SelectionAs is the case with every procedure, patient selection isparamount. Although not every patient is ideally suited forTRA, many operators believe that approximately 90% ofpatients can undergo TRA for PCI using a “radial first”approach. It remains to be seen whether this highpercentage translates to the noncoronary space. It hasbecome clear that TRA is associated with a steeper learningcurve as compared with TFA. When initially learning thistechnique, higher rates of femoral crossover are seen,particularly in patients with smaller-caliber radial arteries,anatomical variants, and aortic disease and tortuosity.3

In our practice, TRA is preferred in patients with obesitybecause of the associated difficulty in locating the commonfemoral artery, as well as the difficulty in detecting andcontrolling postprocedural hemorrhage. In 2007, theTransradial Approach in Overweight Patients (TROP)registry demonstrated that TRA significantly reducedvascular complications in patients with obesity.10 A retro-spective review in 2012 examining access site complica-tions in patients with extreme obesity (body mass indexZ40) found a significantly decreased rate of majorbleeding and access site injuries following TRA as com-pared with TFA.11

For similar reasons, TRA may be advantageous forpatients who are deemed high risk for bleeding complica-tions, such as those with thrombocytopenia, coagulationdisorders, or liver dysfunction, those receiving anticoagu-lation, and patients of advanced age.3 Elderly patientsoften benefit from the TR approach; however, anatomicalissues such as vascular tortuosity and atherosclerosis maymake these cases technically more challenging. Female sexhas also been shown to be a risk factor for increasedbleeding during PCI. In 2007, Pristipino et al demon-strated a significantly decreased risk of major and minorbleeding in women with TRA as compared with TFA.12 Itshould be noted, however, that women tend to havesmaller radial arteries than men (average diameter 2.43� 0.38 mm in women vs 2.69 � 0.40 mm in men13),which can present a technical challenge for TRA.All patients being considered for TR catheterization

should first be evaluated for adequate collateral perfusionto the hand via a modified Allen's test with a pulseoximeter, also known as the Barbeau test.5 A pulseoximeter is placed on the patient's thumb, the radial pulseis identified, and the waveform is analyzed. The radialartery is then compressed, and the pulse oximeter wave-form is again analyzed for up to 2 minutes and graded.Ulnopalmar patency includes the following 4 types: (A) nodamping of the pulse tracing immediately after compres-sion, (B) damping of pulse tracing, (C) loss of pulse tracingfollowed by recovery within 2 minutes, and (D) loss ofpulse tracing without recovery within 2 minutes (Fig. 1).5

Barbeau et al demonstrated that this technique is moresensitive than Allen's test in determining suitable candi-dates for TRA by direct comparison in 1010 patients.5 Itwas also shown that only 1.5% of patients were notsuitable for TRA (Barbeau type D).It is important to note that the Barbeau D waveform is

the only true contraindication to TRA, as Barbeau types A-C confirm patency of the ulnopalmar arch. Other relativecontraindications for TRA include small radial artery(o2 mm) and patients with a dialysis fistula or thosenearing dialysis who may depend on the radial artery foraccess.Another minor drawback related to TRA is that intra-

procedural cone beam computerized tomography (CT)may be technically more challenging to obtain as com-pared with TFA. However, cone beam CT acquisitionduring TRA is possible (Fig. 2), and new imaging protocolsare in development to facilitate this technique.

Figure 1 The Barbeau test. (Reprinted with permission fromBertrand et al.5)

Figure 3 Arm positioned at an acute angle to the table for easiervessel access with ultrasound. Note the towel roll used to supportthe wrist. (Color version of figure is available online.)

A.M. Fischman, N.C. Swinburne, and R.S. Patel60

Below-Diaphragm InterventionsUsing Transradial Approach

Setup and Access

For interventional procedures below the diaphragm, suchas hepatic embolization, left radial artery access is pre-ferred over right-sided access for several reasons. There is aslightly shorter distance to the target vessel from the leftwrist, which can be crucial given the current limitations ofcatheter lengths (discussed subsequently in detail). In

Figure 2 (A) Axial and (B) coronal cone beam CT images ohypervascular lesion (arrows) in the right hepatic lobe. (Co

addition, the guiding catheter or sheath is not positionedacross the great vessels during the procedure, theoreticallylimiting the risk of cerebral emboli or thrombus formation.The patient's arm can be positioned in several ways. One

option is to position the arm at 75º-90º, almost perpen-dicular to the table (Fig. 3). This allows for easier access tothe vessel but makes catheter exchanges somewhat awk-ward and cumbersome. We prefer to position the arm atthe patient's side in a similar position to that of thepatient's groin. This allows for catheters or wires to bepositioned over the patient's draped body similar to TFA(Figs. 4A and B). Arm positioning boards can also be used,and there are several such options available in the markettoday. The wrist should be slightly hyperextended, and atowel roll is used to support the wrist (Fig. 3). Pronepositioning has also been described, allowing the left radialartery to be accessed and positioned in a similar fashionto those of the right common femoral artery.14 This

btained during a transradial procedure demonstrate alor version of figure is available online.)

Transradial access technique 61

technique can be used in patients with chronic back painwho are unable to lie supine.The pulse oximeter is always placed on the thumb or

forefinger of the wrist being accessed. The PRE-DILATEprotocol, which entails topical application of 30 mg ofnitroglycerin ointment and 40 mg of lidocaine cream tothe radial artery access site 30 minutes before catheter-ization, significantly increases radial artery cross-sectionalarea, with the lidocaine also serving as a local anesthetic.15

Our laboratory uses EMLA cream (lidocaine 2.5% andprilocaine 2.5%) in place of pure lidocaine cream.In our laboratory, radial artery access is obtained using

ultrasound guidance and the Seldinger technique with a21-gauge echogenic-tip needle (Fig. 4C). Other laborato-ries use the “angiocath technique.” A small intra venouscatheter is advanced through both walls of the radial arteryunder direct palpation and slowly pulled back until bloodflow is seen. A 0.018-in wire is advanced into the radialartery (Fig. 4D). If there is any resistance, the wire is pulledback and readjusted. If the wire cannot be advanced,fluoroscopy and direct visualization with contrast isperformed.A specialized radial access sheath with a hydrophilic

coating is then used. The dilators on these sheaths aretapered to 0.018 in to allow for immediate sheath

Figure 4 (A) Arm positioned more parallel to the procedure tabmore comfortable wire and catheter exchange; standard femoradial artery with a 21-G micropuncture needle. (D) A 0.018finger pressure over the access site as the sheath is advanced o

placement without an incision or wire exchange. The mostcommon hydrophilic sheath used in our laboratory is the10-cm length Glidesheath (Terumo Interventional Sys-tems, Somerset, NJ) (Fig. 5A). Other commonly usedhydrophilic radial sheaths include PreludeEASE (MeritMedical Systems, Inc, South Jordan, UT) and Flexor RadialIntroducer (Cook Medical, Inc, Bloomington, IN). Rathoreet al16 showed that the use of hydrophilic sheathsdecreases the incidence of radial artery spasm and painduring TRA. Most of the diagnostic and interventionalprocedures can be performed with 5- to 6-F sheaths;however, safe radial access can be performed with sheathsranging in size from 4-7 F. The Glidesheath Slender(Terumo Interventional Systems) is a radial sheath with avery thin wall, providing a 6-F lumen while maintaining anouter diameter matching that of a 5-F sheath (Fig. 5B). In aprospective feasibility study enrolling 114 patients, Ami-nian et al17 demonstrated greater than 99% technicalsuccess using the Glidesheath Slender with no majorsheath kinking and a radial artery occlusion rate less than1% at 30-day follow-up. Table 1 lists several radial arteryaccess sheaths presently in the market.After sheath placement, a medication “cocktail” is

administered intra-arterially directly though the accesssheath. Nitrates, calcium channel blockers, and heparin

le. (B) The arm in parallel position to the table allows forral drapes are used. (C) Ultrasound-guided access to the-in wire is used to cannulate the radial artery; note thever the wire. (Color version of figure is available online.)

Figure 5 (A) Glidesheath hydrophilic radial artery access sheath.Cross-sectional schematic comparing luminal and (B) externaldimensions of the Glidesheath and Glidesheath Slender accesssheaths (Terumo Interventional Systems, Somerset, NJ). (Colorversion of figure is available online.)

A.M. Fischman, N.C. Swinburne, and R.S. Patel62

are typically used to prevent arterial spasm and reducevascular tone. Although there are numerous recommen-dations, there is no consensus on the ideal mixture. Ourlaboratory uses 3000 IU of heparin, 200 mg of nitro-glycerin, and 2.5 mg of verapamil. It is important to notethat verapamil causes a significant burning sensation uponinjection, so continual hemodilution and slow injection isrecommended (Fig. 6).

Figure 6 A medication cocktail is injected intra-arterially imme-diately after sheath placement. Nitrates, heparin, and calciumchannel blockers are used. Note the use of hemodilution withblood during injection to decrease the pain associated withcalcium channel blockers. (Color version of figure is availableonline.)

Catheter SelectionIn most cases, a 110-cm Jacky Radial or Sarah RadialOptitorque catheter (Fig. 7) (Terumo) and a standard0.035-in access wire are used to navigate the subclavianregion and engage the descending aorta. The catheter isthen “hubbed” in the sheath, and small aliquots of contrastare used as the catheter is pulled back to engage thesuperior mesenteric artery and celiac artery. Other cathe-ters that may be used for subdiaphragmatic interventioninclude the Merit Ultimate catheters (Merit Medical Sys-tems, Inc, South Jordan, UT). In addition to the uniqueshape of these catheters, the 110-cm length makes themvery useful in taller patients where 100 cm is not adequate.One of the major limitations of TRA for hepatic

embolization is the limited availability of unique shapesand lengths for engaging the mesenteric vessels. Efforts arecurrently underway to design new catheters for thispurpose. For hepatic embolization procedures, standard-length microcatheters (130 and 150 cm) are then used toselect the appropriate hepatic artery for treatment pur-poses. In general, 150-cm length microcatheters arerecommended when using diagnostic catheters that arelonger than 100 cm, particularly if Tuohy-Borst adaptersare being used.

Figure 7 (A) Jacky Optitorque catheter (Terumo InterventionalSystems) and (B) the Sarah radial Optitorque catheter (TerumoInterventional Systems). (Color version of figure is availableonline.)

Table 2 Radial Compression Devices Approved in theUnited States

Device Name Company

VasoStat Forge Medical (Philadelphia, PA)HemoBand Hemoband Corporation (Portland, OR)RADstat, Finale Merit Medical Systems, IncRadiStop St Jude Medical, IncTR Band Terumo Interventional SystemsVasc Band Vascular Solutions, Inc

Table 1 Radial Access Sheaths Approved in theUnited States

Device Name Company

Flexor Radial Introducer Cook Medical, IncRadialSource, Avanti Cordis (Bridgewater Township,

NJ)PreludeEASE Merit Medical Systems, IncAdelante Radial Oscor, Inc (Palm Harbor, FL)Engage TR St Jude Medical, Inc (St Paul,

MN)Glidesheath, GlidesheathSlender

Terumo Interventional Systems

VSI Radial Vascular Solutions, Inc(Minneapolis, MN)

Transradial access technique 63

In our practice, TRA is most commonly used in trans-arterial chemoembolization (TACE) and transarterialradioembolization (TARE) in both the macroaggregatedalbumin mapping procedures and delivery of yttrium-90.In 2003, TACE using TRA was first described in Japan.18

Shiozawa et al retrospectively compared 150 TACEpatients who underwent TFA and 177 patients whounderwent TRA. Of the 70 patients who received bothapproaches, 92.9% preferred TRA. Although unpublished,our data using the TRA approach currently suggest thesame trend.Uterine fibroid embolization may also be safely per-

formed using TRA. In a retrospective study examiningtransradial uterine fibroid embolization in 29 patients,100% technical success was achieved using a 4-F 120-cmGlidecath (Terumo), with additional use of a microcatheterrequired in 12 cases for cannulation of the horizontalsegment of the uterine arteries. No major or minorcomplications were experienced, and there were no casesof radial artery occlusion at 1-month follow-up.19

Imaging evaluation and intervention planning nowinclude a complete vascular evaluation with CT angiog-raphy or magnetic resonance angiography of the hepaticvasculature. The angle of the access artery (celiac orsuperior mesenteric) to the aorta as well as the vasculartortuosity (iliac or aortic arch) is taken into account whenplanning TRA or TFA. Difficult access cases can be triagedto a single technique based on the perceived difficulty ofvascular access. For complex mesenteric, renal, and iliacinterventions, 5- and 6-F guide catheters are used forballoon angioplasty, intravascular ultrasound, and stentplacement. The Launcher coronary guide catheter (Med-tronic, Inc, Minneapolis, MN) and the Runway guidingcatheter (Boston Scientific Corporation, Natick, MA) aremost commonly used. These are available in differentcatheter tip shapes and multiple lengths, including 100,110, 118, and 125 cm.

Figure 8 (A) The TR Band (Terumo Interventional Systems) and(B) the “patent” hemostasis technique. (Color version of figure isavailable online.)

Radial Artery HemostasisNonocclusive “patent” hemostasis is a key technique inminimizing risk of postprocedural radial artery

thrombosis. The prevention of radial artery occlusion-patent hemostasis evaluation trial (PROPHET) study in2008 demonstrated that this technique is superior toocclusive pressure in maintaining radial artery patency.20

Nonocclusive hemostasis is typically performed using awrist band device. There are several such devices in themarket today, which are listed in Table 2. The mostcommon device used in our laboratory is the TR Band(Terumo Interventional Systems) (Fig. 8). A distal radialartery pulse should be palpable during the hemostasisperiod, which ranges from 30-120 minutes, depending onthe complexity of the procedure performed. After a typicalTACE or TARE procedure using a 5-F access sheath, theband is slowly deflated in 15 minutes after 75-90 minutesof patent hemostasis. If bleeding or “oozing” is seen fromthe puncture site during the removal process, the band isreinflated for 20 minutes, and the process is repeated.Once the band is successfully removed, the patient isobserved for 30 minutes before discharge.

A.M. Fischman, N.C. Swinburne, and R.S. Patel64

ComplicationsThe most common, albeit rare, complication seen in ourpractice is a localized minor hematoma (grade 1) with mildpain at the access site. This is often self-limited and can betreated with nonsteroidal anti-inflammatory drugs if nec-essary. Despite proper patent hemostasis technique, radialartery thrombosis will occur in a minority of cases, whichare almost always asymptomatic.21 Factors associated witha decreased rate of radial artery occlusion includeincreased heparin dose, smaller sheath size, and use of ahydrophilic sheath.20 Other rare complications includeradial artery pseudoaneurysm, perforation, radial arteritis,severe spasm, and dissection. Digital ischemia is exceed-ingly rare and has been described in the literature inpatients who do not have a patent ulnopalmar arch.22

One concern when performing TRA instead of TFA isthe theoretical risk of cerebral embolization related to archmanipulation. In addition, catheter placement from the leftradial artery will lie across the left vertebral artery duringsubdiaphragmatic interventions. Several studies have con-cluded that silent brain infarcts occur at rates as high as15%-22% after cardiac catheterization using TFA.23-25

Hamon et al26 performed diffusion-weighted magneticresonance imaging on 41 consecutive patients after right-sided TRA and identified 2 procedure-related ischemiclesions (4.9%), both of which were asymptomatic. Thisstudy concluded that TRA has a lower incidence ofcerebral embolization compared with TFA when interven-ing on the coronary circulation based on previous studiespublished in the interventional cardiology literature.Anecdotally, the incidence of cerebral embolization whenusing the left radial approach for interventions below thediaphragm is exceedingly low and theoretical at this point,with no published literature on this to date. In our single-center experience of more than 1300 TRA interventions,there were no complications related to cerebral infarction(manuscript in preparation).

Patient Preference and Cost-EffectivenessAs more interventions move from the hospital setting tooutpatient offices, improved patient comfort and fasterdischarge times are increasingly important. This is cur-rently the trend in busy interventional oncology practicesacross the United States, Canada, and Europe. In ourpractice, TARE is performed solely on an outpatient basis,and TACE is performed with a 23-hour observationadmission and trending toward a completely outpatientprocedure. Procedure cost is also an extremely importantissue as we move toward the next phase of health carereform. Many studies have demonstrated decreased costsassociated with TRA as compared with TFA.8,27,28 Inperipheral interventions, TR direct procedure costs willgenerally be lower because of decreased use of closuredevices. Additionally, indirect costs will be lower becauseof decreased readmission for bleeding complications.

Further research is being performed in this area toinvestigate this concept.In our practice, patient preference overwhelmingly

favors TRA over TFA for hepatic embolization procedures,mainly owing to earlier ambulation and discharge times.We must pay attention to patient satisfaction as we buildcomprehensive interventional oncology practices. Webelieve TRA should be learned by busy operators so thatwe can offer this technique to our patients.

Future DirectionsInability to successfully access the radial artery does notpreclude a patient from distal arm access. Many operatorshave used the ulnar artery as an alternative to the radialartery, especially if radial artery spasm or severe tortuosityis encountered or if the ulnar artery is dominant. DeAndrade et al29 described their experience with transulnaraccess in a prospective registry of 410 patients, with a lowaccess site complication rate of 3.9%.Other potential applications for TRA in the future

include renal artery denervation and carotid, iliac, andinfrainguinal interventions. Several studies have alreadydescribed some of these techniques.30-32 Cerebral angiog-raphy from the radial artery has been performed anddescribed for more than a decade,33,34 including a largeseries of more than 1000 patients in Korea in 2010.35 Morerecently, complex cerebral interventions, including aneur-ysm coiling, have been performed using TRA.36 Wide-spread adoption in the United States is currently limited byavailability of equipment required to successfully performthese cases.

ConclusionTransradial intervention has broad applications for inter-ventional radiology. In particular, hepatic embolizationprocedures are well suited for this approach. Learning andimplementing transradial access technique enables oper-ators to offer comprehensive, cost-efficient, and safe care totheir patients.

References1. Campeau L: Percutaneous radial artery approach for coronary

angiography. Cathet Cardiovasc Diagn 16:3-7, 19892. Kiemeneij F, Laarman GJ: Percutaneous transradial artery approach

for coronary stent implantation. Cathet Cardiovasc Diagn30:173-178, 1993

3. Frangos C, Nobel S: How to transform you into a radialist: Literaturereview. Cardiovasc Med 14:277-282, 2011

4. Feldman D, Swaminathan R, Kaltenbach L, et al: Adoption of radialaccess and comparison of outcomes to femoral access in percuta-neous coronary intervention. Circulation 127:2295-2306, 2013

5. Bertrand OF, Belisle P, Joyal D, et al: Comparison of transradial andfemoral approaches for percutaneous coronary interventions: Asystematic review and hierarchical Bayesian meta-analysis. Am HeartJ 163:632-648, 2012

6. Romagnoli E, Biondi-Zoccai G, Sciahbasi A, et al: Radial versusfemoral randomized investigation in STsegment elevation acutecoronary syndrome: The RIFLE-STEACS (Radial Versus Femoral

Transradial access technique 65

Randomized Investigation in ST-Elevation Acute Coronary Syn-drome) study. J Am Coll Cardiol 60:2481-2489, 2012

7. Mehta SR, Jolly SS, Cairns J, et al: Effects of radial versus femoralartery access in patients with acute coronary syndromes with orwithout ST-segment elevation. J Am Coll Cardiol 60:2490-2499,2012

8. Cooper CJ, El-Shiekh RA, Cohen DJ, et al: Effect of transradial accesson quality of life and cost of cardiac catheterization: A randomizedcomparison. Am Heart J 138:7, 1999

9. Benamer H, Louvard Y, Sanmartin M, et al: A multicentre compar-ison of transradial and transfemoral approaches for coronaryangiography and PTCA in obese patients: The TROP registry.EuroIntervention 3:327-332, 2007

10. Pristipino C, Pelliccia F, Granatelli A, et al: Comparison of access-related bleeding complications in women versus men undergoingpercutaneous coronary catheterization using the radial versusfemoral artery. Am J Cardiol 99:16-21, 2007

11. Hibbert B, Simard T, Wilson K, et al: Transradial versus transfemoralartery approach for coronary angiography and percutaneous coro-nary intervention in the extremely obese. JACC Cardiovasc Interv5:819-826, 2012

12. Barbeau GR, Arsenault F, Dugas L, et al: Evaluation of theulnopalmar arterial arches with pulse oximetry and plethysmogra-phy: Comparison with the Allen's test in 1010 patients. Am Heart J147:489-493, 2004

13. Yoo BS, Yoon J, Ko JY, et al: Anatomical consideration of the radialartery for transradial coronary procedures: Arterial diameter, branch-ing anomaly and vessel tortuosity. Int J Cardiol 101:421-427, 2005

14. Kwon SW, Cha JJ, Rhee JH: Prone position coronary angiographydue to intractable back pain: Another merit of transradial approachcompared to transfemoral approach. J Invasive Cardiol 24:605-607,2012

15. Beyer A, Ng R, Singh A, et al: Topical nitroglycerin and lidocaine todilate the radial artery prior to transradial cardiac catheterization: Arandomized, placebo-controlled, double-blind clinical trial: ThePRE-DILATE Study. Int J Cardiol 168:2575-2578, 2013

16. Rathore S, Stables RH, Pauriah M, et al: Impact of length andhydrophilic coating of the introducer sheath on radial artery spasmduring transradial coronary intervention: A randomized study. JACCCardiovasc Interv 3:475-483, 2010

17. Aminian A, Dolatabadi D, Lefebvre P, et al: Initial experience withthe Glidesheath Slender for transradial coronary angiography andintervention: A feasibility study with prospective radial ultrasoundfollow-up. Catheter Cardiovasc Interv 84:436-442, 2014

18. Shiozawa S, Tsuchiya A, Endo S, et al: Transradial approach fortranscatheter arterial chemoembolization in patients with hepatocel-lular carcinoma: Comparison with conventional transfemoralapproach. J Clin Gastroenterol 37:412-417, 2003

19. Resnick N, Kim E, Patel R, et al: Uterine artery embolization using atransradial approach: Initial experience and technique. J Vasc IntervRadiol 25:443-447, 2014

20. Pancholy S, Coppola J, Patel T, et al: Prevention of radial arteryocclusion-patent hemostasis evaluation trial (PROPHET study): A

randomized comparison of traditional versus patency documentedhemostasis after transradial catheterization. Cathet Cardiovasc Interv72:335-340, 2008

21. Pancholy SB, Patel TM: Effect of duration of hemostatic compressionon radial artery occlusion after transradial access. Cathet CardiovascInterv 79:78-81, 2012

22. de Bucourt M, Teichgraber U: Digital ischemia and consecutiveamputation after emergency transradial cardiac catheter examina-tion. Cardiovasc Interv Radiol 35:1242-1244, 2012

23. Omran H, Schmidt H, Hackenbroch M, et al: Silent and apparentcerebral embolism after retrograde catheterisation of the aortic valvein valvular stenosis: A prospective, randomised study. Lancet361:12411246, 2003

24. Büsing KA, Schulte-Sasse C, Flüchter S, et al: Cerebral infarction:Incidence and risk factors after diagnostic and interventional cardiaccatheterization—Prospective evaluation at diffusion-weighted MRimaging. Radiology 235:177-183, 2005

25. Lund C, Nes RB, Ugelstad TP, et al: Cerebral emboli during left heartcatheterization may cause acute brain injury. Eur Heart J.26:1269-1275, 2005

26. Hamon M, Gomes S, Clergeau MR, et al: Risk of acute brain injuryrelated to cerebral microembolism during cardiac catheterizationperformed by right upper limb arterial access. Stroke 38:2176-2179,2007

27. Corvoisier PL, Gellen B, Lesault PF, et al: Ambulatory transradialpercutaneous coronary intervention: A safe, effective and cost-savingstrategy. Catheter Cardiovasc Interv 81:15-23, 2013

28. Mitchell MD, Hong JA, Lee BY, et al: Systematic review and cost-benefit analysis of radial artery access for coronary angiography andintervention. Circ Cardiovasc Qual Outcomes 5:454-462, 2012

29. de Andrade PB, Tebet MA, Nogueira EF, et al: Transulnar approachas an alternative access site for coronary invasive procedures aftertransradial approach failure. Am Heart J 164:462-467, 2012

30. Mendiz OA, Sampaolesi AH, Londero HF, et al: Initial experiencewith transradial access for carotid artery stenting. Vasc EndovascSurg 45:499-503, 2011

31. Cortese B, Peretti E, Troisi N, et al: Transradial percutaneous iliacintervention, a feasible alternative to the transfemoral route. Car-diovasc Revasc Med 13:331-334, 2012

32. Trani C, Tommasino A, Burzotta F: Pushing the limits forward:Transradial superficial femoral artery stenting. Cathet CardiovascInterv 76:1065-1071, 2010

33. Levy EI, Boulos AS, Fessler RD, et al: Transradial cerebral angiog-raphy: An alternative route. Neurosurgery 51:335-340

34. Nohara AM, Kallmes DF: Transradial cerebral angiography: Techni-que and outcomes. Am J Neuroradiol. 24:1247-1250, 2003

35. Jo KW, Park SM, Kim SD, et al: Is transradial cerebral angiographyfeasible and safe? A single-center's experience. J Korean NeurosurgSoc 47:332-337, 2010

36. Lawson MF, Velat GJ, Fargen KM, et al: Direct radial artery accesswith the 070 neuron guide catheter for aneurysm coiling: A novelapplication of the neuron catheter for cerebral interventions. Neuro-surgery 71:E329-E334, 2012 suppl 2 operative, [discussion E334]