Arterial Anomalies of the Upper Limb and Their Influence on Transradial Coronary Procedures

Abstract: Objectives. During transradial coronary procedures, arterial anomalies of the upper limb can lead to transradial navigation difficulties. We aimed to evaluate the incidence and impact of these anomalies on transradial procedures. Methods. In consecutive patients undergoing transradial coronary procedures, antegrade upper-limb arterial angiography was done at the end of the procedure with the catheter tip in the subclavian artery. Radial artery angiography from the sheath was done only if the guidewire or catheter could not be navigated. Patient characteristics, upper-limb arterial anatomy, and transradial outcomes were assessed. Results. Among 1195 patients, upper-limb arterial anomalies were noted in 117 patients (9.7%). High origin of the radial artery was the most common anomaly (8.1%) followed by radial artery loop (0.9%). Transradial navigation difficulties and failures were significantly more frequent in patients with these anomalies vs those without anomalies (42.7% vs 2.0% [P<.001] and 9.4% vs 0.9%, [P<.001], respectively). There was a greater need for radial road mapping and navigation assistance techniques, including balloon/pigtail assisted tracking. Passage for radial artery loop was associated with maximum navigation difficulties and higher transradial failure rate (63.6%). Fluoroscopy time, radiation dose, and transradial complications, including forearm hematoma and radial artery occlusions, were also significantly higher in patients with upper-limb arterial anomalies. Conclusion. Different upper-limb arterial anomalies are associated with different degrees of impact on transradial outcomes; these patients require an individualized approach for transradial navigation.  

J INVASIVE CARDIOL 2021;33(3):E165-E171. Epub 2021 February 4. 

Key words: radial artery anomalies, transradial angiography, transradial angioplasty, transradial approach, transradial navigation 

The transradial approach (TRA) for coronary procedures is well established and is associated with fewer vascular complications than transfemoral approach (TFA).^1-4 TRA has been recommended as the standard approach, unless there are overriding procedural considerations.⁵ Arterial anomalies of the upper limb are one of the important factors responsible for TRA failure requiring conversion to TFA.^6-11 Knowledge about the various types of anomalies and their prevalence can be helpful in planning different navigation techniques to overcome this hurdle. Only limited data are available regarding the prevalence and types of anomalies, as well as techniques to overcome the difficulties posed by them. Reported prevalence of anomalies ranges from 4.0%-18.5% in autopsy studies,^12,13 9.6% in vascular Doppler studies,^14,15 and 8.8%-22.8% in angiographic studies.^6-11,16-21 To date, there is no angiographic study on an Indian population to evaluate the types and prevalence of upper-limb arterial anomalies and techniques to overcome the difficulties posed by them. We therefore conducted this prospective study to evaluate the prevalence and types of upper-limb artery anomalies and their influence on the TRA procedure in an Indian population.

Methods

Between January 2018 and December 2018, consecutive patients undergoing TRA diagnostic coronary angiography or angioplasty were prospectively included. Patients with failed right radial artery puncture or hemodynamic instability were excluded. Patients with previous coronary artery bypass graft surgery were also excluded. All procedures were performed by experienced, high-volume radial operators. Subjects provided informed consent and the study conformed to institutional guidelines and those of the American Physiological Society.

Radial artery access. The access site was anesthetized with lidocaine and right radial arterial access was taken using a 5 Fr or 6 Fr Radifocus Introducer II radial sheath (Terumo). To reduce vasospasm and forearm discomfort, a preprepared mixture containing 100µg of nitroglycerin, 5 mg of diltiazem, and 21.3 mg of lidocaine was administered through the radial sheath. Unfractionated heparin was administered in all patients (50 U/kg for diagnostic angiography, 100 U/kg for percutaneous coronary intervention [PCI] if glycoprotein IIb/IIIa inhibitor was not used, and 70 U/kg if glycoprotein IIb/IIIa inhibitor was used). Glycoprotein IIb/IIIa inhibitors were administered at the discretion of the operating physician. Immediately after the procedure, the radial artery sheath was removed and hemostasis was achieved with the application of a TR Band hemostasis device (Terumo) using patent hemostasis technique.²² 

Angiography of upper-limb vessels. Angiography of the upper-limb arterial tree was performed at the end of procedure in all cases. About 5 mL of contrast diluted with saline in 1:1 proportion was used for upper-limb arterial angiography. Contrast injection was performed through the catheter used for coronary angiography or guiding catheter used for intervention. The tip of the catheter was placed in the subclavian artery during the injection and was gradually pulled back with continuous gentle injection of contrast material until catheter removal from the radial sheath (Video 1). Additional retrograde injection from the sheath was done if distal arteries were not visualized with the initial injection. Radiographic acquisition was done with C-arm in anteroposterior projection with forearm in supine posture. Images were acquired from the origin of the subclavian artery to the distal radial and ulnar arteries. All angiograms were evaluated by 2 independent, experienced investigators who were blinded to the data.

Upper-limb arterial anomalies. Upper-limb arterial anatomy and anomalies were noted and classified using a modification of previous definitions by McCormack, Uglietta, and Rodriguez-Niedenfuhr.^12,13,21 High origin of the radial artery was defined as radial artery arising from either the axillary artery or brachial artery above the level of the intercondylar line of humerus, which corresponds to the proximal margin of the antecubital fossa. Arterial loop was defined as the presence of complete 360° angulation, forming a loop of the artery. Extreme radial artery bend was defined as the presence of a bend >90° in the contour of the radial artery. Overdeveloped recurrent radial artery (accessory radial artery) was defined as a branch of the radial artery that assumes a straight path into the upper arm with and without connection to the brachial or axillary artery. Minor tortuosity was defined as a bend <90° and was not taken as an anomaly. All angiograms were also reviewed for radial artery dissection and/or perforation, if any. 

Navigation of the upper-limb artery anomalies. Initially, a transradial diagnostic catheter was inserted in all patients over a regular 0.035˝ wire. If any difficulty was encountered in transradial navigation, soft J-tip hydrophilic guidewire-assisted navigation under fluoroscopy was tried. In cases of hydrophilic guidewire-assisted navigation failure, radial artery road mapping was done by injecting the contrast material through the side port of the radial sheath to look for any abnormality. Then, navigation of a soft, hydrophilic guidewire/catheter was tried under angiographic assistance done through the side port of the radial sheath. If a soft, hydrophilic guidewire could not be navigated, then a coronary angioplasty wire was attempted under angiographic assistance. In all patients with successful transradial navigation of either 0.035˝ guidewire or coronary angioplasty wire, the coronary diagnostic catheter was gently attempted to navigate over the initial wire. In cases of failure, balloon-assisted tracking (BAT) technique was used for transradial navigation.²³ In cases in which 5 Fr diagnostic catheter could be navigated, but 6 Fr guide catheter could not be navigated, either pigtail-assisted tracking (PAT) technique²⁴ or BAT technique for guide-catheter navigation was tried. If all of these measures failed, route was changed to left TRA or TFA.

Transradial outcome measures. Data on demographics, clinical characteristics, procedural characteristics, and transradial outcomes were recorded for each patient. TRA success was defined as completion of the intended procedure through the initially selected radial access route. Difficulty in transradial navigation was defined based on the opinion of the operator regarding the resistance felt while advancing the guidewire/catheter. All patients were observed for transradial complications. Minor vascular complications were defined as hematoma, vessel dissection without ensuing ischemia, pseudoaneurysm, and localized infection. Major vascular complications were defined as hematoma >5 cm, drop in hemoglobin due to access-site bleeding requiring transfusion, limb ischemia and/or compartment syndrome, and any other access-site complications that required surgical or radiological intervention. Clinical radial artery patency was assessed by radial pulse examination on the next day of procedure. Fluoroscopy time and radiation dose were also noted. TRA outcome variables were compared between patients with normal upper-limb arterial anatomy vs those with arterial anomalies. Effect of individual upper-limb arterial anomaly on different TRA outcome measures was also evaluated.

Statistical analysis. Continuous variables are presented as mean ± standard deviation and categorical variables as number and percentage. The Chi-square test was used for comparisons among categorical variables. The between-group comparisons of the continuous variables were carried out using independent Student t-test. A 2-tailed P-value of <.05 was considered a statistically significant result. All statistical analyses were performed using SPSS software, version 20.0 (SPSS).

Results

Study population characteristics. A total of 1195 patients were included in the study (Table 1). Nearly one-half of the cases (47.9%) were diagnostic angiograms and the rest (52.1%) were PCIs. The majority of our patients (54.3%) presented with an acute coronary syndrome. The mean age of the study patients was 56 years, and males constituted 74.4% of cases. The mean body mass index (BMI) in the population was 23 kg/m². One-third of the study population had diabetes mellitus (DM) and more than one-half of the patients were hypertensive. Dyslipidemia was present in 21.7% and 15.5% were smokers. 

Upper-limb arterial anomalies and their transradial outcomes. Upper-limb arterial anomalies were present in 117 patients (9.8%) (Table 2). High origin of the radial artery was the most common anomaly (82.5%) followed by radial artery loop (9.4%). About one-fourth of arterial anomalies were detected before the coronary angiography during radial road mapping done to overcome significant transradial navigation difficulties. In the remaining patients, anomalies were detected during postprocedural per-protocol upper-limb arteriography. Transradial outcomes stratified by the upper-limb anomaly types are shown in Table 3. Tortuosity was not considered to be an anomaly in this study. However, upper-limb arterial tortuosity was present in 197 patients (16.5%). In some patients, multiple upper-limb arteries were tortuous. 

High origin of the radial artery. High origin of the radial artery was the most common anomaly and was present in 97 patients (8.1%); it constituted 82.9% of total anomalies. The radial artery originated from the axillary artery, upper one-third of the brachial artery, middle one-third of the brachial artery, and lower one-third of the brachial artery in 26.8%, 45.4%, 21.6%, and 6.2%, respectively (Figure 1). Most of these high originating radial arteries were of relatively small caliber and were tortuous. Interestingly, 1 patient had associate radiobrachial anastomotic sling at the cubital fossa level (Figure 2). In this patient, both high originating radial artery as well as the anastomotic sling were tortuous and were of relatively small caliber. This anomaly was recognized only after completion of diagnostic coronary angiogram during per-protocol upper-limb arterial angiogram (Video 2).

Although high origin of the radial artery was the most common upper-limb artery anomaly, they posed the least difficulty during transradial navigation, with failure to navigate in only 4.1% of patients. Two patients who had angulation at the radiobrachial joining point required PAT for successful guide-catheter navigation. In most of the patients (89.7%), this anomaly was recognized only post procedure during per-protocol upper-limb arteriogram. Transradial complications were uncommon (forearm hematoma in 5.1%, radial artery dissection in 3.1%, and radial artery occlusion in 4.1% patients). 

Radial artery loop. Radial artery loop was the second-most common anomaly; it was present in 11 patients (0.9%) and constituted 9.4% of upper-limb arterial anomalies (Figure 3A and Video 3). All patients with radial artery loop have associated recurrent radial artery originating from the apex of the loop and then running superiorly in a straight direction. Interestingly, in 1 patient, associated overdeveloped recurrent radial artery was communicating with the axillary artery (Video 4). 

Radial artery loops were the most difficult to navigate and were associated with highest transradial navigation failure (63.6%). All of them had difficulty during transradial navigation and required delineation by radial artery road mapping before coronary angiography. During loop navigation, contrast guidance through the side port of the radial sheath was done in all patients.  Complex navigation techniques like coronary angioplasty wire assistance (Video 5), BAT technique (Video 6), and PAT technique (Video 7) were frequently required. This anomaly was associated with the highest rate of transradial complications (forearm hematoma in 36.4%, radial artery dissection in 18.2%, and radial artery occlusion in 18.2% patients).

Extreme radial artery bends. Extreme radial artery bend was present in 5 patients (0.4%), with anomaly incidence of 4.3%. (Figure 3B). All of these patients posed difficulty during transradial navigation and the bends were crossed under contrast guidance through the side port of radial sheath. However, transradial navigation was successful in all of these patients. Postprocedural forearm hematoma in 1 patient was the only transradial complication.  

Brachial artery loop. Brachial artery loop was present in 2 patients (0.2%), with anomaly incidence of 1.7% (Figure 3C). Brachial loop posed difficulty in both patients during transradial navigation; both were crossed using soft, hydrophilic wire under contrast guidance. Transradial navigation was successful in both patients without any transradial complications. 

Isolated overdeveloped recurrent radial artery. Interestingly, isolated overdeveloped recurrent radial artery independent of radial artery loop was present in 2 patients (0.2%), with anomaly incidence of 1.7% (Figure 4 and Video 8). In both of these patients, guidewire was used to enter preferentially into the overdeveloped recurrent radial branch rather than toward the brachial artery. This led to difficulty in the procedure, which was managed with contrast-guided soft hydrophilic guidewire navigation into the brachial artery. Subsequent transradial navigation was easy and successful in both the patients. No transradial complication was noted.

Comparison of transradial outcomes in patients with vs without upper-limb arterial anomalies (Table 4). Difficulty in transradial navigation was significantly greater in those with upper-limb arterial anomalies vs those without anomalies (42.7% vs 2.0%, respectively; P<.001). Difficulty in transradial navigation in patients without any anomaly was mainly due to upper-limb arterial tortuosity and radial artery spasm. Transradial complications occurred significantly more frequently in patients who had upper-limb arterial anomalies. Forearm hematoma and radial artery occlusion were the most common complications and were observed in 52 patients (4.3%) and 40 patients (3.3%), respectively. Both complications occurred more frequently in patients with upper-limb arterial anomalies than without anomaly (8.5% vs 3.9%, respectively [P=.02] and 5.1% vs 3.1%, respectively [P=.01]). None of our patients required vascular surgery or blood transfusion. Fluoroscopy time (12.3 ± 7.2 minutes vs 8.9 ± 7.1 minutes; P≤.001) and radiation dose (1.5 ± 1.0 Gy vs 1.2 ± 1.0 Gy; P≤.001) were significantly higher in those with upper-limb arterial anomalies.

Discussion

This study shows that upper-limb arterial anomalies are encountered commonly during transradial procedures and are associated with a significantly higher rate of transradial navigation difficulties, transradial failures, and local vascular complications. High origin of the radial artery is the most common anomaly, but it does not pose much navigation difficulty. Radial artery loop is an uncommon anomaly, but is associated with maximum navigation difficulties and highest rate of transradial failure. 

The angiographic incidence of upper-limb arterial anomalies in our study was 9.8% while previous studies reported rates from 8.8%-22.8%.^6-11,16-21 This wide variation is mainly due to non-uniformity in the definition used to describe these anomalies. Our results are in agreement with the prior studies that excluded tortuosity as an anomaly,^19,20 but are much lower than those reported in studies that included tortuosity as an anomaly.^6,9,11 In our study, tortuosity was not taken as an anomaly, since it is likely to be acquired in many cases (particularly in the elderly population). Lo et al reported a higher prevalence of upper-limb arterial anomalies among elderly and/or female patients.⁶ Ostojic et al also reported tortuosity as the only anomaly with gender-related predisposition.²⁰ Therefore, angiographic incidence of different upper-limb arterial anomalies as reported in our study represents the true picture of these anomalies. 

In the present study, high origin of the radial artery was the most common anomaly, with angiographic incidence of 8.1% (anomaly incidence of 82.9%). Radial artery loop was the second-most common anomaly, while the other anomalies were occasionally present. Our results are in accordance of all the previous studies reporting high origin of the radial artery as the most common anomaly, with angiographic incidence ranging from 4.9%-8.3%.^6-9,18,19

In the present study, transradial failure was significantly more frequent in patients with upper-limb arterial anomalies, as was reported in all previous studies.^6-10,15,16 Transradial failure rates in patients with radial anomalies in our study was 9.4% while the previous studies reported it in 7%-39% patients.^6-10,15,16 This relatively lower transradial failure rate in our study may be due to the frequent use of various transradial navigation assistance techniques, including BAT and PAT. Transradial failures in patients without anomalies were due to radial artery spasm and tortuosity, which is in accord with previous studies.

High origin of the radial artery posed the least difficulty during transradial navigation (failure in only 4.1% of patients). Complex navigation assistance techniques were only rarely required. Our results are in accord with most of the previously published studies,^6,10,25 but contradict a study by Hassan et al¹¹ in which high origin of the radial artery was associated with transradial failure in 36.4%. The authors attributed it to the tortuosity and narrow arterial caliber.  

Radial artery loops were the most difficult to navigate and were associated with the highest transradial navigation failure, as reported in the previous studies.^6,9,16 Even after negotiation of the loop by a soft hydrophilic guidewire or coronary angioplasty wire, the catheter may not be navigated through the loop in many of these patients. Many times, this may lead to forearm pain, radial artery spasm, and dissection/perforation of the radial artery, leading to forearm complications. Overdeveloped recurrent radial artery was another anomaly that was associated with difficulty in transradial navigation. In this anomaly, the guidewire has a tendency to selectively enter into this branch (because of its straight direction) with navigation difficulty at mid arm level, requiring radial road mapping and navigation assistance. We recommend the use of fluoroscopy during transradial navigation while advancing the guidewire or catheter. In the event of any difficulty or if the guidewire passes in some abnormal direction, one should perform radial road mapping to elucidate the path and then gently manipulate the guidewire/catheter accordingly. Overzealous manipulation may cause dissection/perforation, leading to vascular complications and transradial failure. Knowledge of these anomalies and their careful systematic navigation may improve the transradial success rate and reduce local vascular complications.

This is the first study documenting 3 upper-limb anomalies, ie, high origin of the radial artery with a radiobrachial anastomotic sling, isolated overdeveloped recurrent radial artery, and radial artery loop with overdeveloped recurrent radial artery communicating with axillary artery. The results may be due to the systemic nature of the study or may be a chance finding. Subsequent large studies will settle this issue.

Study limitations. Firstly, this was a hospital-based angiographic study; hence, it does not directly provide the prevalence of upper-limb anomalies in the general population. Second, only upper-limb arterial anomalies were evaluated. Subclavian artery anomalies, including arteria lusoria, were not evaluated. Third, since the definition of various anomalies is not uniform, there is a possibility of interobserver variability. For example, overdeveloped recurrent radial artery communicating with axillary artery may be interpreted as double brachial artery. Fourth, successful radial access was required to be included in the study. Last, radial artery patency assessment by radial pulse examination rather than by reverse Barbeau test might have underestimated the radial artery occlusion rate. 

Conclusion

Arterial anomalies of the upper limb are associated with significantly higher rate of transradial navigation difficulties, transradial failures, and local vascular complications. Different anomalies are associated with different degrees of impact on transradial outcomes and require an individualized approach for their transradial navigation. High origin of the radial artery is the most common anomaly, but it does not result in many navigation difficulties. Radial artery loop is an uncommon anomaly, but is associated with maximum navigation difficulties and the highest transradial failure rate. Knowledge of the anatomy and different navigation assistance techniques to manage these anomalies is likely to improve the success rate in this group of patients.

View supplemental video here

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From the Department of Cardiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

The authors report that patient consent was provided for publication of the images used herein.

Manuscript accepted July 24, 2020.

Address for correspondence: Prof Naveen Garg, Department of Cardiology, Sanjay Gandhi PGIMS, Raibareli Road, Lucknow, India. Emails: navgarg@gmail.com and navgarg@sgpgi.ac.in