Heart India

: 2019  |  Volume : 7  |  Issue : 4  |  Page : 137--144

Radial anomalies in North Indian patients undergoing TRAns-radial catheterization: A prospective observational study (RAIN-TRAC study)

Dibbendhu Khanra1, Pradyot Tiwari2, SK Sinha3, Puneet Aggrawal3, Shishir Soni1,  
1 Department of Cardiology, All India Institution of Medical Sciences, Rishikesh, Uttarakhand, India
2 Department of Cardiology, Apex Heart Institute, Ahmedabad, Gujarat, India
3 Department of Cardiology, LPS Institution of Cardiology, Kanpur, Uttar Pradesh, India

Correspondence Address:
Dr. Dibbendhu Khanra
Department of Cardiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand


Background: Radial artery anomalies are relatively common and one of the major causes of transradial procedure failure. Aim: The study was aimed to assess the incidence of radial axis anomalies in patients undergoing transradial cardiac catheterization and their impacts on procedural failure. Materials and Methods: This was a prospective, single-center study, 1870 consecutive patients underwent transradial coronary catheterization. Radial artery anatomy was determined by injecting diluted contrast agent through radial sheath. Results: About 11.4% patients (213/1870) were noted to have abnormal radial artery anatomy which was associated with significantly higher procedural failure rate (odds ratio [OR] [95% confidence interval [CI] = 240.72 [57.98–999.43]) and radial artery spasm (OR [95%CI] = 7.12 [4.06–12.49]) than patients with normal radial artery anatomy. Among all the radial artery anomalies, high bifurcation was the most common anomaly, found in 128 (60%) patients. The high bifurcation was found most commonly at the mid-humerus level (53.12%). Extremely tortuous radial artery was found in 43 (20%) patients. Radial artery loop was found in 22 (10%) patients and was associated with the highest failure rate (54.5%). Other unclassified anomalies were found in 20 patients (10%). In bivariate analysis, the incidence of each of the radial artery anomalies was found to have significant correlation with older age, short stature, female sex, and hypertension. Conclusion: Radial artery anomalies are not uncommon and are related to significant procedural failure. Retrograde radial arteriography helps to identify patients with unfavorable radial artery anatomy, which can be performed with a minimum amount of contrast and should be considered part of a routine transradial procedure.

How to cite this article:
Khanra D, Tiwari P, Sinha S K, Aggrawal P, Soni S. Radial anomalies in North Indian patients undergoing TRAns-radial catheterization: A prospective observational study (RAIN-TRAC study).Heart India 2019;7:137-144

How to cite this URL:
Khanra D, Tiwari P, Sinha S K, Aggrawal P, Soni S. Radial anomalies in North Indian patients undergoing TRAns-radial catheterization: A prospective observational study (RAIN-TRAC study). Heart India [serial online] 2019 [cited 2020 Jan 23 ];7:137-144
Available from: http://www.heartindia.net/text.asp?2019/7/4/137/272662

Full Text


Transradial coronary intervention is associated with lesser incidence of vascular complications, shorter duration of hospital stay, lesser contrast-induced nephropathy, and lower costs, and thus gaining worldwide popularity over the transfemoral approach.[1],[2],[3],[4] Anatomical variations along with radial artery spasm and inability to puncture account for majority of technical failure in the transradial coronary procedures. These anatomical variations of radial artery are known to have geographical heterogeneity, and there are limited data from India. The study was aimed to assess the incidence of radial artery anomalies in patients undergoing transradial coronary catheterization in the North Indian population and to study the impact of these anomalies on procedural outcome.

 Materials and Methods


This was a prospective, nonrandomized, single-center study conducted in a tertiary care hospital of North India between January 2016 and July 2017. With hypothesized frequency of radial artery anomaly of 50%, precision of 5%, and confidence interval of 99.9%, the sample size was calculated to be 1082 [Supplementary Table 1].[INLINE:1]

Inclusion and exclusion criteria

In total, 1870 consecutive patients were enrolled who underwent transradial coronary angiography for (a) acute coronary syndrome, (b) diagnostic evaluation of typical and atypical chest pain, (c) to rule out coronary artery disease (CAD) in patients with valvular heart disease before surgical valve replacement, and (d) chronic stable angina not controlled by guideline-directed medical therapy. Coronary angiography was done with the intent to perform ad hoc or staged percutaneous coronary intervention (PCI) in appropriate cases. Patients with cardiogenic shock, decompensated heart failure, chronic renal failure, and abnormal Allen's test were excluded from the study. Informed consent was obtained from each patient prior to enrollment. The study protocol was approved by the local ethics committee and followed the Declaration of Helsinki.


The enrolled patients underwent clinical examination and investigations including electrocardiogram, cardiac enzymes, echocardiogram, and coronary angiogram as a part of their diagnostic procedure. Prior to enrollment, Allen's test was performed on all patients and patients with an abnormal Allen's test were excluded. In case of failure of right radial access, ipsilateral ulnar or contralateral radial access was undertaken based on the operator's discretion. Coronary interventions were undertaken in either PHILIPS Allura Xper FD20/10 or Siemens flat panel Artis Zee cathnlab. CAD was defined by detection of plaque or luminal stenosis in at least one coronary artery. Obstructive lesion was defined as more than 70% luminal narrowing, nonobstructive as <50% luminal narrowing, and intermediate as 50%–70% luminal narrowing.

Radial artery cannulation

Radial artery was punctured by a 21-G needle and a 0.021” guide wire (Avanti transradial kit; Cordis Corp, USA) was inserted. A 5F sheath was used for diagnostic cases and 6F sheath for intervention. After sheath insertion, cocktail containing 5000 IU unfractioned heparin, 200 mcg nitroglycerin, and 2.5 mg diltiazem was injected. Angiography was performed by 5F TIG catheter (Terumo Radifocus Optitorque, Japan). The radial sheath was removed just after the procedure and compression was performed for 2 h with a radial compression device (TR band; Terumo, Inc.) using the “patent hemostasis” protocol. The TR band was inflated with around 15 ml of air. The patency of the radial artery was checked every 15–20 min by palpation and color of palm and was removed after 2 h of sheath removal. A light pressure bandage was applied which was removed the following day.

Retrograde radial arteriography

Retrograde radial arteriography was performed following administration of cocktail to define radial artery anatomy from mid-radius to radiobrachial anastomosis. About 3 ml of contrast mixed with 7 ml of blood (to dilute the contrast and minimize discomfort from contrast injection) was injected through the sidearm of the sheath, and radiographic acquisition at the elbow was taken in anteroposterior projection. If a high-bifurcating radial origin was identified, a further arteriogram was obtained higher up to identify the point of anastomosis to the brachial artery. Further, retrograde angiography was only undertaken if there was any hindrance to catheter progression.

Classifications and definitions

Radial artery anomalies were classified using a modification of McCormack's, Uglietta's, and Niedenfuhr's definitions as proposed by Lo et al.[5],[6],[7],[8]

High radial artery bifurcation

The site of anomalous origin was determined with reference to the intercondylar line of the humerus, which is a fixed-line representing the proximal border of the antecubital fossa. Bifurcation of the brachial artery proximal to this line is considered a high bifurcation. A high-bifurcating origin was further subclassified into lower third of humerus, middle third of humerus, upper third of humerus, or axillary according to the site of anastomosis with the main vessel. High-bifurcating radial artery caliber was also categorized as <2.0 mm, 2.0–2.5 mm, 2.5–3.0 mm, and >3.0 mm by visual comparison with the arterial sheath.

Radial loop

A radial artery loop was defined, as the presence of a full 360° loop of the radial artery distal to the bifurcation of the brachial artery.

Extreme radial tortuosity

Extreme radial tortuosity was defined as the presence of a bend of more than 90° in the contour of the vessel.

Other anomalies

Anatomical variations that did not fit into these specified categories were grouped together and categorized as “other” anomalies.

Procedural failure

Procedural failure was defined as the inability to complete the planned procedure via the initially selected radial access route.

Vascular complications

Minor vascular complications were defined as hematoma <5 cm, vessel dissection without ensuing ischemia, pseudoaneurysm, and localized infection. Major vascular complications were defined as hematoma >5 cm, any access site complications that required surgical or radiological intervention, >3 g/dl hemoglobin drop due to access site bleeding, bleeding requiring transfusion, limb ischemia, and/or compartment syndrome.

Statistical evaluation

Statistical analyses were performed using the SPSS 17.0 (SPSS Inc., Chicago, Illinois, USA). Continuous variables were expressed as mean ± standard deviation, whereas categorical variables were given as numbers (percentages). Comparisons between the groups were done by Mann–Whitney U-test for continuous variables and by Chi-square or Fisher's test for categorical variables. P < 0.05 was considered statistically significant.


A total of 2320 consecutive patients undergoing transradial catheterization were screened for the study and 1870 patients were included in the final analysis after excluding 450 patients for various reasons including positive Allen's test, impalpable radial arteries, and inability to give consents.

Baseline characteristics

Baseline characteristics of the participants are presented in [Table 1]. Angiography showed CAD in 1791 patients (95.8%), while the remainder had normal coronary arteries (n = 79; 4.2%). Obstructive, intermediate, and nonobstructive CADs were noted in 1385 (74.1%), 307 (16.4%), and 99 (5.3%) patients, respectively.{Table 1}

Procedural characteristics

Procedural details are presented in [Table 1]. Most of the procedures were done via a 6F sheath (n = 1099; 58.8%). The mean fluoroscopy time was 18.4 ± 10.2 min for ad hoc PCI, 16.6 ± 9.8 min for an elective PCI, and 6.1 ± 4.4 min for diagnostic angiography. Right radial artery puncture was attempted in all 1870 patients. It was successful in 1837 patients and 33 patients had failed right radial puncture. These patients were all successfully crossed over to left radial artery. Retrograde radial angiography was performed in all these patients.

Radial arterial anomaly

Normal radial artery anatomy was found in 1657 patients (88.6%), with rest of the patients (11.4%) having an anomalous radial artery anatomy [Figure 1]a. High bifurcation was the most common anomaly found in 128 (6.84%) patients. Radial loop was found in 22 (1.17%) patients and extremely tortuous radial artery in 43 (2.29%) patients. Other unclassified anomalies were found in 20 patients (1.06%) [Figure 1]b.{Figure 1}

Procedural failure

Patients with normal radial axis had a low procedural failure rate of 0.12% (2/1657), while patients with radial artery anomalies had a higher procedural failure rate of 22.5% (48/213) necessitating switch to contralateral radial/ipsilateral ulnar/femoral approach [Figure 2]a. This difference was found to be statistically significant (P < 0.0001). Radial artery loop was the most common anomaly to be associated with procedural failure in our study [Figure 2]b.{Figure 2}

Incidence of radial artery anomalies and correlations with baseline parameters

Bivariate analysis of the baseline characteristic and incidence of radial artery anomalies are depicted in [Table 2]. Incidences of radial artery anomalies were significantly higher in aged patients, female sex, short stature, and hypertension. However, no correlation was found between other baseline variables (such as diabetes mellitus, smoking, and dyslipidemia) and the incidence of radial artery anomalies [Supplementary Table 2].{Table 2}[INLINE:2]

Description of individual radial artery anomalies

High bifurcation of radial artery

High bifurcation was the most common type of radial anomaly found in our study (128, 6.84%). 17.9% of such patients had procedural failure. 45.3% of patients with high radial artery bifurcations had hypoplastic radial arteries with diameter of 2–2.5 mm [Supplementary Table 3]. The high bifurcation was found most commonly at the mid-humerus level (53.12%) [Supplementary Table 4].[INLINE:3][INLINE:4]

Radial artery loop

Radial artery loop was found in 22 (1.17%) patients and was associated with the highest failure rate (54.5%). Most of these loops were located in the forearm below brachial artery bifurcation. Accessory radial artery was seen arising from the apex of the loop in three patients. Radial artery loop was associated with significantly prolonged fluoroscopy time (P = 0.027) and were significantly higher among aged (P = 0.0014) and female (P = 0.0019) patients.

Extreme radial tortuosity

Extreme radial tortuosity was found in 43 (2.29%) patients and associated with a failure rate of 23.2%. It was also associated with a significantly higher fluoroscopy time (P = 0.0063). Extreme radial tortuosity were found to be significantly higher among aged (P < 0.0001) female (P = 0.0009) patients with short stature (P < 0.0001) and hypertension (P = 0.04).

Other anomalies

Unclassified anomalies were found in 20 (1.06%) patients. Eleven of these patients had subclavian artery tortuosity, eight had innominate artery tortuosity, and one had arteria lusoria. Procedure failure occurred in the patient with arteria lusoria and two of the patients with extreme subclavian artery tortuosity.

Vascular complications

Vascular complications were depicted in [Table 3]. Radial artery spasm was found to be significantly (P < 0.0001) higher in patients with anomalous radial artery anatomy (11.2%) than the patients with normal radial artery anatomy.{Table 3}


Incidence of radial artery anomalies

The incidence of radial artery anomalies found in our study was 11.4%. This finding is similar to the findings of Yokoyama et al. (9.6%), Karlsson and Niechajev (11%), Burzotta et al. (12.6%), and Uglietta and Kadir (9%).[6],[9],[10],[11] Surprisingly, in the study by Yoo et al. the incidence of radial artery anomalies was only 3.2%.[12] The reason for such discrepancy might be of racial nature. Autopsy studies also reported incidence of radial artery anomalies to range between 4% and 18.5%.[7],[13],[14] When two-dimensional ultrasonography and color Doppler were used this figure was 9.6%,[9] whereas arteriography studies reported between 7.4% and 22.8%.[6],[12],[15]

Procedural failures

The radial artery anomalies account for a higher procedural failure rate of transradial coronary catheterization which range from 1% to 5%.[16],[17],[18] In our study, procedural failure rate was 2.67% (50/1870). However, progressive technical advances and miniaturization of hardwares and increasing experiences of the operators have been responsible for improving success rates of transradial procedures.

Individual radial artery anomalies

High radial bifurcation [Figure 3]a{Figure 3}

In our study, the most frequent radial artery anomaly was found to be high radial bifurcation, and it constituted 60% of all cases of anomalous radial artery with an overall incidence of 6.8% (128/1870). This abnormal high origin is regarded as the most common radial anomaly in other reports also.[8],[15] The incidence of high radial bifurcation in 1191 Korean patients was 2.4%, while in 3000 Chinese patients, it was 7.7% in accordance with our study.[12],[19] Hassan et al. reported a similar rate of 6.2% as well.[20] However, in the study of Valsecchi et al., the incidence of high radial artery bifurcation was 8.3%.[15] In autopsy studies, the incidence reached up to 14%.[7],[14] High bifurcation was associated with hypoplastic radial arteries, with 92.2% of radial arteries found to be <3 mm in diameter in our study. This was similar to the results by Hassan et al. and Lo et al.[8],[20] The most common site for high bifurcation was found at mid humerus level in accordance with other studies.[8],[20]

Procedural failure rate in patients with high radial artery bifurcation was found to be 17.9% in our study. This was lower than the 30% procedural failure rate found by Hassan et al., but higher than the 4.6% failure rate found by Lo et al.[8],[20] Most successful cases of high bifurcation with hypoplastic radial artery were managed by use of smaller 5F equipment, use of hydrophilic guide wire and 0.0014” angioplasty wire (if needed) with or without repeated dosages of spasmolytic cocktail. In resistant cases, use of balloon-assisted tracking as described by Patel et al.[21] was helpful.

Extreme radial tortuosity [Figure 3]b

Extreme radial tortuosity was found to be the second most common anomaly with an incidence of 2.29% in our study in accordance with the incidences found in other studies which range from 2.0% to 5.2%.[8],[9],[12],[15],[20] The incidence of extreme radial tortuosity was significantly more with increasing age as seen in other studies also.[8] The origin of extreme tortuosity is thought to be vascular hypertrophy with age. Alternatively, they may represent redundant arterial tissue that allows movement of the forearm without compromising vascular integrity from stretching as the forearm moves.[21] Female preponderance was similarly reported by Lo et al.[8] Female preponderance might reflect the effect of progesterone on vascular wall which promotes smooth muscle cell growth.

Extreme radial artery tortuosity was also associated with a procedural failure of 23.2% which was similar to the study by Lo et al.[8] Extreme radial tortuosity was successfully handled in majority of patients by use of 0.014” wire, buddy wire, and the use of balloon-assisted tracking techniques.[21],[22],[23]

Radial loop [Figure 3]c

Radial loop was found in 1.17% of the study population. Lo et al. found an incidence of radial loop of 2.3% in their study.[8] Radial loop was the anomaly which was associated with the highest procedural failure rate reaching up to 54.5%. In our study, accessory radial artery was seen to arise from the radial artery loop only in two patients in contrast to Lo et al. who found this as a universal finding.[8]

Earlier, radial artery loop was considered as a potential contraindication to cardiac catheterization through radial route, but now it is being successfully handled in majority of patients by use of 0.014” wire, buddy wire, and the use of balloon-assisted tracking techniques.[21][22][23]

Other anomalies

Procedure failure occurred in the patient with arteria lusoria [Figure 3]d and two patients with extreme subclavian artery tortuosity [Figure 3]e. The incidence in the literature varies from 0.2% to 1.7%.[21]

Vascular complications

The incidence of radial artery spasm was significantly more in the anomalous radial anatomy group than their normal counterparts. This was similar to the observations by Biljana et al.[24] The incidence of major and minor vascular complications was not dissimilar between the two groups.


Our study is limited to North Indian populations only and restricted to single-center experience. Moreover, females were underrepresented in our study group of patients. Radial artery anomalies are relatively common and one of the major causes of transradial procedure failure even in the hands of experienced operators. Retrograde radial arteriography helps to delineate underlying anomalies and identify patients with unfavorable anatomy, thereby informing the operator to plan a strategy to overcome the anomaly or change access route with the potential to save time and avoid potential procedural failure. This can be performed with a minimum amount of contrast and should be considered part of a routine transradial procedure.


The authors are grateful to Dr. Indranill Basu Ray MD, DNB (Card), FACP, FACC. Cardiologist and Interventional Electrophysiologist at St. Francis Hospital, 5959 Park Ave, Memphis, TN 38119, USA, for thoroughly revising the manuscript for grammar check and English language editing.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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