KJIM The Korean Journal of Internal MedicineKorean J Intern Med 1226-3303 2005-6648 The Korean Association of Internal Medicine 10.3904/kjim.2020.685 kjim-2020-685 Original Article Cardiology Reference diameter and characteristics of the distal radial artery based on ultrasonographic assessment LeeJun-Won 1 * SonJung-Woo 1 * GoTae-Hwa 2 KangDae Ryong 3 LeeSang Jun 1 KimSe Eun 1 ChoDong-Hyuk 1 ParkYoung Jun 1 YounYoung Jin 1 AhnMin-Soo 1 AhnSung Gyun 1 KimJang-Young 1 YooByung-Su 1 YoonJunghan 1 http://orcid.org/0000-0002-1186-0917 LeeSeung-Hwan 1 Division of Cardiology, Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea Department of Biostatistics, Yonsei University Wonju College of Medicine, Wonju, Korea Department of Precision Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea Correspondence to Seung-Hwan Lee, M.D. Division of Cardiology, Department of Internal Medicine, Yonsei University Wonju College of Medicine, 20 Ilsan-ro, Wonju 26426, Korea Tel: +82-33-741-0920, Fax: +82-33-741-1219, E-mail: carshlee@yonsei.ac.kr

These authors contributed equally to this work.

 1 2022 29 12 2021 37 1 109 118 24 12 2020 22 09 2021 21 10 2021 Copyright © 2022 The Korean Association of Internal Medicine 2022 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Background/Aims

While distal radial artery (DRA) access is increasingly being used for diagnostic coronary angiography, limited information is available regarding DRA size. We aimed to determine the DRA reference diameters of Korean patients and identify the predictors of DRA diameter < 2.3 mm.

 Methods

The outer bilateral DRA diameters were assessed using a linear ultrasound probe in 1,162 consecutive patients who underwent transthoracic echocardiography. The DRA diameter was measured by the perpendicular angle in the dorsum of the hand, and the average values were compared by sex. DRA diameter < 2.3 mm was defined as unsuitable for routine diagnostic coronary angiography using a 5 Fr introducer sheath.

 Results

The mean DRA diameters were 2.31 ± 0.43 mm (right) and 2.35 ± 0.45 mm (left). The DRA was smaller in women than men (right: 2.15 ± 0.38 mm vs. 2.43 ± 0.44 mm, p < 0.001; left: 2.18 ± 0.39 mm vs. 2.47 ± 0.45 mm, p < 0.001). The DRA diameter was approximately 20% smaller than the radial artery diameter. A total of 630 (54.2%) and 574 (49.4%) patients had DRA diameter < 2.3 mm in the right and left hands, respectively. Female sex, low body mass index (BMI), and low body surface area (BSA) were significant predictors of DRA diameter < 2.3 mm.

 Conclusions

We provided reference DRA diameters for Korean patients. Approximately 50% of the studied patients had DRA diameter < 2.3 mm. Female sex, low BMI, and low BSA remained significant predictors of DRA diameter < 2.3 mm.

 Radial artery Ultrasonography Body mass index Body surface area Graphical abstract

INTRODUCTION

Radial access is recommended as the standard approach for coronary angiography (CAG) and percutaneous coronary intervention (PCI) based on the evidence that it is associated with reduced mortality and bleeding events compared to femoral access [1-3]. The use of distal radial access has recently increased owing to the publication of several studies that reported easy hemostasis, decreased bleeding, and low arterial occlusion rates with its use [4-6]. However, the distal radial artery (DRA) diameter is smaller than the radial artery (RA) diameter, which may limit its widespread use [5]. There is a lack of information regarding DRA diameter, which may complicate the identification of suitable patients in whom distal radial access may be adopted. This study aimed to determine the DRA reference diameter using ultrasonography in Korean patients. We also evaluated the clinical factors predictive of a DRA diameter < 2.3 mm.

 METHODS Study population

This was a retrospective observational study (DRAUS ClinicalTrials.gov identifier: NCT04303923). Between July 2017 and April 2018, 1,162 patients scheduled for transthoracic echocardiography were recruited in the echocardiography laboratory at a single center (Fig. 1). Cases with patients under 20 years of age, images of poor quality and difficult to interpret, and repeated measurements in the same patients were excluded. If a patient was scheduled for an invasive coronary procedure, that patient was moved to the catheterization laboratory after finishing the ultrasonographic evaluation in the echocardiography laboratory. Our local Institutional Review Board of Wonju Severance Christian Hospital approved the study protocol (CR318128) and waived the requirement for written informed consent due to the study’s retrospective nature.

 Study endpoints

The primary endpoint was the mean DRA diameter of both hands. The secondary endpoints were the mean diameter of both RA, arterial diameter indexed according to body surface area (BSA), DRA/RA ratio, and proportion of patients with a DRA diameter < 2.3 mm. The reference diameter of 2.3 mm was derived from the average value (2.27 mm) of seven available radial introducer sheaths (Table 1). A DRA diameter < 2.3 mm was defined as unsuitable for routine diagnostic coronary angiography using a 5 Fr introducer sheath. BSA was calculated using the Mosteller formula as follows [7]:

BSA(m2)=height(cm)×weight(kg)3,600(cm×kg/m4) Assessment of arterial diameter by ultrasonography

The patients were asked to relax on a bed in a quiet room. The anatomical landmark for the DRA measurement was the dorsum of the hand in which the DRA was superficially located (Fig. 2). The RA diameter was measured as a distance of 2 to 3 cm above the wrist crease. The DRA and the cephalic vein were discriminated using color Doppler and vessel compression methods with an ultrasonographic probe. The round shape of the artery in the short-axis plane was determined by tilting of the probe. The outer diameters of the DRA and RA were assessed at a perpendicular angle, and the average values were recorded. The vessel diameters were measured twice by experienced sonographers and confirmed by a dedicated investigator using an 11L-D linear array ultrasound probe transducer (4.5 to 12.0 MHz bandwidth) with a Vivid E95 (GE Health Care, Milwaukee, WI, USA) or an L12-3 broadband linear array ultrasound probe transducer (3.0 to 12.0 MHz bandwidth) with a Philips EPIQ 7 (Philips Medical Systems, Andover, MA, USA). The intra-class correlation coefficients of intra- and interobserver variabilities in the arterial diameter measurements were 0.97 and 0.98.

 Statistical analysis

Continuous variables were expressed as mean ± standard deviation and compared using the two-sample t test. Categorical variables were expressed as counts and percentages, and the statistical analyses were performed using the chi-square test. Simple and multiple logistic regression analyses were used to predict a DRA diameter < 2.3 mm. Model 1 was adjusted for body mass index (BMI) and other significant variables in a simple logistic regression analysis. Model 2 was adjusted for the same variables; however, BMI was replaced with BSA. Statistical significance was set at p < 0.05. The statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC, USA) and MedCalc for Windows version 19.4.1 (MedCalc Software, Ostend, Belgium).

 RESULTS Baseline characteristics

Table 2 summarizes the baseline characteristics of the enrolled patients. The mean age was 65.1 ± 13.0 years, and 671 (57.7%) were male. The female patients were older and had a similar BMI but lower BSA than the male patients. The medical histories of hypertension, diabetes mellitus, dyslipidemia, chronic kidney disease, coronary artery occlusive disease (CAOD), old cerebrovascular accident, peripheral arterial occlusive disease, and atrial fibrillation were similar between the two groups. There were no statistical differences in the history of CAG, PCI, or the use of radial access.

 DRA and RA diameters and characteristics

The mean DRA diameters were 2.31 ± 0.43 mm (total patients), 2.43 ± 0.44 mm (men), and 2.15 ± 0.38 mm (women) in the right hand and 2.35 ± 0.45 mm (total patients), 2.47 ± 0.45 mm (men), and 2.18 ± 0.39 mm (women) in the left hand (Table 3). The DRA and RA sizes were significantly smaller in women (Fig. 3). However, the DRA and RA diameters indexed by BSA were similar in men and women. The DRA/RA ratios were 0.81 ± 0.12 and 0.83 ± 0.12 in the right and left hands, respectively.

The proportion of patients with a DRA diameter < 2.3 mm in the right and left hands was 54.2% and 49.4%, respectively. The proportion of women with a DRA diameter < 2.3 mm was greater than that of men (67.8% vs. 44.3%, p < 0.001 in the right hand; 66% vs. 37.3%, p < 0.001 in the left hand). Fig. 4 shows the cumulative frequency of the DRA and RA diameters for men and women.

 Clinical predictors of a DRA diameter < 2.3 mm

In the simple logistic regression analysis, female sex, BMI, BSA, CAOD, and history of PCI were the common predictors of a DRA diameter < 2.3 mm (Table 4). In the multiple logistic regression analysis, female sex (odds ratio [OR], 2.740; 95% confidence interval [CI], 2.135 to 3.516) and BMI (OR, 0.931; 95% CI, 0.899 to 0.964) were significant predictors of a right DRA < 2.3 mm in Model 1. Age (OR, 0.987; 95% CI, 0.976 to 0.997), female sex (OR, 1.851; 95% CI, 1.387 to 2.471), and BSA (OR, 0.148; 95% CI, 0.066 to 0.334) were significant predictors of a right DRA diameter < 2.3 mm in Model 2. The predictors of a left DRA diameter < 2.3 mm were similar.

 DISCUSSION

The main aim of this study was to determine the DRA reference diameter in Korean patients. The mean DRA diameters were 2.31 ± 0.43 mm (right) and 2.35 ± 0.45 mm (left). Women had a smaller DRA than men (2.15 ± 0.38 mm vs. 2.43 ± 0.44 mm in the right hand; 2.18 ± 0.39 mm vs. 2.47 ± 0.45 mm in the left hand). The other major findings were as follows: (1) DRA diameter was approximately 20% smaller than RA diameter; (2) female patients had a smaller DRA diameter than male patients; (3) approximately 50% of patients had a small DRA (< 2.3 mm); and (4) female sex, low BMI, and low BSA were predictors of a DRA diameter < 2.3 mm.

Several studies have reported on DRA diameter (Table 5). Mizuguchi et al. [8] evaluated the DRA at two available puncture points (within and outside the anatomical snuffbox [on the dorsum of the hand]) using ultrasonography in 228 patients. The measured DRA diameter was similar to that observed in the present study. The DRA increased in size the day after the procedure and then returned to the baseline measurement after 1 month. The DRA diameter in the anatomical snuffbox was greater in a Japanese study than that observed in our study [9]. Based on the quantitative coronary angiography data obtained by Kim et al. [6], the DRA size after the injection of spasmolytics (nitroglycerin and verapamil) was similar to that reported by Norimatsu et al. [9] and was greater than that noted in our study. The smallest DRA diameter was reported by Naito et al. [10] (2.04 ± 0.60 mm in men and 1.96 ± 0.44 mm in women). The angiographic evaluation of 52 patients from Italy revealed a mean DRA diameter of 2.22 ± 0.14 mm after the administration of a vasodilatory cocktail containing 2.5 mg of verapamil, 1 mL of lidocaine hydrochloride, and 1 mL of bicarbonate [11]. The inconsistent values may be attributed to disparate definitions of vessel diameter and different points of measurement among investigators. Naito et al. [10] measured the vessel diameter of the tunica media, while we measured the outer surface of the vessels because the ultrasonographic resolution was not optimal to clearly define the inner wall of the DRA. The anatomical landmarks for the measurement of vessel diameter may also differ among investigators. To the best of our knowledge, our study included the largest number of patients to evaluate the DRA diameter. Furthermore, this study provides information on the DRA and RA diameters.

There is no consensus regarding the ideal method for assessing DRA diameter. The arterial diameter may be affected by emotional status, room temperature, vasospasm during skin preparation with cold antiseptic agents (povidone-iodine, betadine, and chlorhexidine gluconate), the use of spasmolytics before measurement, ultrasonographer’s technical skills, and discordance between ultrasonography and angiography measurement methods. Accordingly, a systematic protocol for assessing DRA diameter from the time of adopting the initial approach during follow-up, especially using ultrasonography, would aid in popularizing this novel approach based on the anatomic and physiological rationale [12,13]. Of note, the diameter of the actual punctured site of the DRA may be equal to or greater than the measured value because the needle usually punctures the vessel wall in an area proximal to the measured area [8].

In this study, the DRA diameter was apparently associated with a low BMI and a low BSA. BMI was significantly correlated with DRA diameter (r = 0.66, p < 0.0001) in a Japanese study of 142 patients [9]. However, another Japanese study of 120 patients did not report an association between vessel diameter and clinical variables, including BMI, in multivariate analysis [10]. In our study, a low BMI was a significant predictor of a DRA diameter < 2.3 mm in both hands. Moreover, female sex and a low BSA were strong predictors of a DRA diameter < 2.3 mm. The association between sex and RA diameter was reported in several studies. In a large-scale study evaluating RA diameter that included 1706 patients from Indonesia, India, and Macedonia, female sex was associated with a small RA (diameter < 2.8 mm) (OR, 1.72; 95% CI, 1.40 to 2.12; p < 0.001); however, a BMI < 25 kg/m2 was not a predictor for a small RA (OR, 1.0; 95% CI, 0.82 to 1.22; p = 0.93) [14]. A study conducted of a population in the United States (n = 175) reported that female sex was the only predictor of a small RA diameter [15]. Data showing an association between a low BSA with a small DRA are not available except in the current study. However, there were no sex-based differences in the indexed DRA diameter by BSA. It is worth remembering the guideline for echocardiography, which states that the cardiac volume, dimension, and valve area should be indexed with BSA for comparison with individuals with different body sizes [16-18]. From this viewpoint, a smaller DRA may be present in women with a small body size, indicating a low BSA.

A small DRA diameter is a natural limitation that should be overcome for routine CAG and PCI. An international consensus paper on preventing radial artery occlusion (RAO) after transradial angiography and interventions reported that RAO was significantly associated with an RA/sheath ratio < 1 as well as female sex, a low BMI, age, and ethnicity [19]. Miniaturized devices with a hydrophilic coating, such as the sheathless guiding catheter (Asahi Intecc, Nagoya, Japan) and the Glidesheath slender sheath (Terumo, Tokyo, Japan), may increase the possibility of using the distal radial access in patients with a small DRA and reduce the risk of DRA occlusion. A randomized study comparing distal radial access and radial access is warranted to delineate the clinical benefits and disadvantages of this alternative route.

This study has several limitations. First, the arterial diameters might have been underestimated because vasodilators were not intended to be used before measurements were taken in the echocardiography laboratory. Second, the measured DRA diameters do not reflect normative values in the general population. However, patient-level data may be valuable for individuals scheduled to undergo invasive coronary procedures. Third, there was a discrepancy between the actual puncture site and the point of measurement. A standardized protocol for assessing the DRA diameter is warranted. Fourth, technical difficulties in identifying the true inner lumen may lead to vessel size overestimations and an increased risk of arterial occlusion.

In conclusion, here we provided the DRA reference diameters of Korean patients. Approximately 50% of patients had a DRA diameter < 2.3 mm. Female sex, a low BMI, and a low BSA remained significant predictors of a DRA diameter < 2.3 mm. Ultrasonographic evaluations with clinical assessments may guide the use of distal radial access.

 KEY MESSAGE

1. This study provides the distal radial artery (DRA) reference diameters of Korean patients. The mean DRA diameters were 2.31 ± 0.43 mm (total patients), 2.43 ± 0.44 mm (men), and 2.15 ± 0.38 mm (women) in the right hand and 2.35 ± 0.45 mm (total patients), 2.47 ± 0.45 mm (men), and 2.18 ± 0.39 mm (women) in the left hand.

2. The DRA diameter was approximately 20% smaller than the radial artery diameter. Approximately 50% of patients had a DRA diameter < 2.3 mm.

3. Female sex, a low body mass index, and a low body surface area were strong predictors of a DRA diameter < 2.3 mm.

No potential conflict of interest relevant to this article was reported.

We thank Ji Eun Sim for allowing us to take representative images for assessment of the distal radial artery diameter using ultrasonography. This study was funded by a grant from Yonsei University Wonju College of Medicine (YUWCM-2020-38).

 REFERENCES ValgimigliM GagnorA CalabroP Radial versus femoral access in patients with acute coronary syndromes undergoing invasive management: a randomised multicentre trial Lancet 2015 385 2465 2476 IbanezB JamesS AgewallS 2017 ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: the task force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC) Eur Heart J 2018 39 119 177 NeumannFJ Sousa-UvaM AhlssonA 2018 ESC/EACTS guidelines on myocardial revascularization Eur Heart J 2019 40 87 165 KiemeneijF Left distal transradial access in the anatomical snuffbox for coronary angiography (ldTRA) and interventions (ldTRI) EuroIntervention 2017 13 851 857 LeeJW ParkSW SonJW AhnSG LeeSH Real-world experience of the left distal transradial approach for coronary angiography and percutaneous coronary intervention: a prospective observational study (LeDRA) EuroIntervention 2018 14 e995 e1003 KimY AhnY KimI Feasibility of coronary angiography and percutaneous coronary intervention via left snuffbox approach Korean Circ J 2018 48 1120 1130 MostellerRD Simplified calculation of body-surface area N Engl J Med 1987 317 1098 MizuguchiY IzumikawaT HashimotoS Efficacy and safety of the distal transradial approach in coronary angiography and percutaneous coronary intervention: a Japanese multicenter experience Cardiovasc Interv Ther 2020 35 162 167 NorimatsuK KusumotoT YoshimotoK Importance of measurement of the diameter of the distal radial artery in a distal radial approach from the anatomical snuffbox before coronary catheterization Heart Vessels 2019 34 1615 1620 NaitoT SawaokaT SasakiK Evaluation of the diameter of the distal radial artery at the anatomical snuff box using ultrasound in Japanese patients Cardiovasc Interv Ther 2019 34 312 316 ValsecchiO VassilevaA CeredaAF Early clinical experience with right and left distal transradial access in the anatomical snuffbox in 52 consecutive patients J Invasive Cardiol 2018 30 218 223 SguegliaGA Di GiorgioA GaspardoneA BabunashviliA Anatomic basis and physiological rationale of distal radial artery access for percutaneous coronary and endovascular procedures JACC Cardiovasc Interv 2018 11 2113 2119 HadjivassiliouA KiemeneijF NathanS KlassD Ultrasound-guided access to the distal radial artery at the anatomical snuffbox for catheter-based vascular interventions: a technical guide EuroIntervention 2021 16 1342 1348 DharmaS KedevS PatelT RaoSV BertrandOF GilchristIC Radial artery diameter does not correlate with body mass index: a duplex ultrasound analysis of 1706 patients undergoing trans-radial catheterization at three experienced radial centers Int J Cardiol 2017 228 169 172 LeeL KernJ BairJ RosenbergJ LeeM NathanS Clinical determinants of radial artery caliber assessed at the time of transradial cardiac catheterization using routine prospective radiobrachial angiography Cardiovasc Revasc Med 2018 19 939 943 LangRM BadanoLP Mor-AviV Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging J Am Soc Echocardiogr 2015 28 1 39 NishimuraRA OttoCM BonowRO 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association task force on practice guidelines J Am Coll Cardiol 2014 63 e57 e185 BaumgartnerH FalkV BaxJJ 2017 ESC/EACTS guidelines for the management of valvular heart disease Eur Heart J 2017 38 2739 2791 BernatI AminianA PancholyS Best practices for the prevention of radial artery occlusion after transradial diagnostic angiography and intervention: an international consensus paper JACC Cardiovasc Interv 2019 12 2235 2246 Figures and Tables

Study flowchart.

Assessment of the distal radial artery diameter using ultrasonography. (A) Hand position for the assessment of the distal radial artery. (B) Ultrasonographic image showing the short-axis plane of the distal radial artery between first and second metacarpal bone. (C) Schematic illustration showing the relationship between the distal radial artery and extensor pollicis longus tendon.

Differences in the distal radial and radial artery diameters by sex.

Cumulative frequencies of the distal radial artery (DRA) and radial artery (RA) diameters (A) in the right and (B) left hands of men versus women.

Outer diameter of radial introducer sheaths

Product name Company Outer diameter (mm)
4 Fr 5 Fr 6 Fr 7 Fr
Glidesheath Slender® Terumo Corporation - 2.13 2.46 2.79
Prelude IDeal™ Merit Medical Systems, Inc. 1.78 2.13 2.44 2.77
RAIN Sheath™ Cordis, a Cardinal Health company 1.79 2.14 2.46 2.82
Radifocus® Introducer II Terumo Corporation 1.96 2.29 2.62 2.95
PreludeEASE™ Merit Medical Systems, Inc. 2.07 2.38 2.66
AVANTI®+ Cordis, a Cardinal Health company 2.06 2.41 2.72 3.07
Flexor® Check-Flo® Cook Medical 2.06 2.41 2.73 3.08
Average 1.95 2.27 2.58 2.91

Baseline patient characteristics

Characteristic Total patients (n = 1,162) Men (n = 671) Women (n = 491) p value
Age, yr 65.1 ± 13.0 63.6 ± 12.9 67.1 ± 12.9 < 0.001
Height, cm 160.7 ± 9.5 166.5 ± 6.7 152.8 ± 6.5 < 0.001
Weight, kg 65.0 ± 12.4 69.7 ± 11.5 58.6 ± 10.6 < 0.001
BMI, kg/m2 25.1 ± 3.6 25.1 ± 3.4 25.0 ± 3.9 0.858
BSA, m2 1.70 ± 0.20 1.79 ± 0.17 1.57 ± 0.16 < 0.001
Medical history
  Hypertension 690 (59.4) 400 (59.6) 290 (59.1) 0.851
Diabetes mellitus 332 (28.6) 189 (28.2) 143 (29.1) 0.721
Dyslipidemia 606 (52.2) 345 (51.4) 261 (53.2) 0.557
Chronic kidney disease 114 (9.8) 67 (10) 47 (9.6) 0.815
CAOD 207 (17.8) 129 (19.2) 78 (15.9) 0.142
MI 83 (7.1) 59 (8.8) 24 (4.9) 0.011
CABG 8 (0.7) 7 (1.0) 1 (0.2) 0.087
CVA 96 (8.3) 60 (8.9) 36 (7.3) 0.325
PAOD 42 (3.6) 30 (4.5) 12 (2.4) 0.067
Atrial fibrillation 139 (12) 90 (13.4) 49 (10) 0.075
Current smoking 230 (19.8) 210 (31.3) 20 (4.1) < 0.001
Systolic BP, mmHg 134.9 ± 19.6 135.2 ± 19.9 134.5 ± 19.2 0.535
Diastolic BP, mmHg 78.5 ± 12.4 79.1 ± 12.6 77.7 ± 12.2 0.067
Heart rate, bpm 73.1 ± 14.3 72.7 ± 14.3 73.7 ± 14.3 0.206
History of CAG 295 (25.4) 176 (26.2) 119 (24.2) 0.441
History of PCI 168 (14.5) 104 (15.5) 64 (13) 0.238
History of radial access 288 (24.8) 172 (25.6) 116 (23.6) 0.434
Left radial artery 233 (75.4) 140 (76.9) 93 (73.2) 0.458
Right radial artery 94 (30.4) 56 (30.8) 38 (29.9) 0.873

Values are presented as mean ± standard deviation or number (%).

BMI, body mass index; BSA, body surface area; CAOD, coronary artery occlusive disease; MI, myocardial infarction; CABG, coronary artery bypass graft; CVA, cerebrovascular accident; PAOD, peripheral arterial occlusive disease; BP, blood pressure; CAG, coronary angiography; PCI, percutaneous coronary intervention.

Diameters and characteristics of the distal radial and radial arteries

Characteristic Total patients (n = 1,162) Men (n = 671) Women (n = 491) p value
Vessel diameter, mm
  Distal radial
 Right 2.31 ± 0.43 2.43 ± 0.44 2.15 ± 0.38 < 0.001
 Left 2.35 ± 0.45 2.47 ± 0.45 2.18 ± 0.39 < 0.001
Radial
 Right 2.90 ± 0.52 3.07 ± 0.47 2.66 ± 0.49 < 0.001
 Left 2.86 ± 0.54 3.04 ± 0.51 2.63 ± 0.49 < 0.001
Δ Diameter (radial – distal radial)
 Right 0.59 ± 0.38 0.64 ± 0.39 0.51 ± 0.36 < 0.001
 Left 0.52 ± 0.38 0.57 ± 0.39 0.45 ± 0.35 < 0.001
Diameter index, mm/BSA
Distal radial
 Right 1.37 ± 0.26 1.36 ± 0.26 1.38 ± 0.27 0.218
 Left 1.39 ± 0.27 1.39 ± 0.27 1.40 ± 0.28 0.351
Radial
 Right 1.72 ± 0.32 1.73 ± 0.30 1.71 ± 0.35 0.368
 Left 1.70 ± 0.32 1.71 ± 0.31 1.69 ± 0.34 0.291
Ratio of arterial size
Distal radial/radial
 Right 0.81 ± 0.12 0.80 ± 0.12 0.82 ± 0.12 0.001
 Left 0.83 ± 0.12 0.82 ± 0.12 0.84 ± 0.12 0.004
Distal radial artery < 2.3 mm
 Right 630 (54.2) 297 (44.3) 333 (67.8) < 0.001
 Left 574 (49.4) 250 (37.3) 324 (66) < 0.001
 Both 476 (41) 193 (28.8) 283 (57.6) < 0.001

Values are presented as mean ± standard deviation or number (%).

BSA, body surface area.

Predictors of a distal radial artery < 2.3 mm

Variable Univariate
 Multivariate
Model 1
 Model 2
OR 95% CI p value OR 95% CI p value OR 95% CI p value
Right distal radial artery
  Age 1.001 0.992–1.010 0.862 0.993 0.984–1.003 0.164 0.987 0.976–0.997 0.013
Female sex 2.654 2.081–3.384 < 0.001 2.740 2.135–3.516 < 0.001 1.851 1.387–2.471 < 0.001
Height 0.956 0.944–0.968 < 0.001
Weight 0.965 0.956–0.975 < 0.001
BMI 0.940 0.910–0.971 < 0.001 0.931 0.899–0.964 < 0.001
BSA 0.099 0.053–0.184 < 0.001 0.148 0.066–0.334 < 0.001
Hypertension 0.852 0.673–1.079 0.184
DM 0.950 0.736–1.227 0.696
Dyslipidemia 0.805 0.639–1.015 0.067
CKD 1.278 0.863–1.894 0.221
CAOD 0.666 0.492–0.900 0.008 0.785 0.405–1.521 0.473 0.758 0.391–1.469 0.412
MI 0.812 0.520–1.269 0.361
CVA 1.145 0.751–1.747 0.528
PAOD 1.721 0.896–3.304 0.103
Atrial fibrillation 0.988 0.693–1.410 0.948
History of PCI 0.656 0.472–0.911 0.012 0.865 0.422–1.774 0.693 0.899 0.438–1.845 0.772
History of right radial access 0.617 0.378–1.007 0.053
Left distal radial artery
Age 0.995 0.986–1.004 0.273 0.986 0.976–0.996 0.007 0.983 0.971–0.993 0.001
Female sex 3.267 2.561–4.168 < 0.001 3.513 2.730–4.521 < 0.001 2.671 1.992–3.583 < 0.001
Height 0.957 0.945–0.969 < 0.001
Weight 0.969 0.959–0.979 < 0.001
BMI 0.953 0.923–0.984 0.003 0.945 0.912–0.980 0.002
BSA 0.117 0.063–0.216 < 0.001 0.267 0.116–0.613 0.002
Hypertension 0.775 0.613–0.980 0.033 0.924 0.712–1.200 0.555 0.921 0.710–1.195 0.536
DM 0.889 0.689–1.146 0.363
Dyslipidemia 0.755 0.599–0.951 0.017 0.805 0.623–1.040 0.097 0.790 0.612–1.020 0.070
CKD 1.298 0.880–1.915 0.188
CAOD 0.680 0.502–0.922 0.013 0.892 0.452–1.757 0.740 0.879 0.446–1.732 0.710
MI 0.770 0.491–1.208 0.256
CVA 1.289 0.847–1.962 0.235
PAOD 1.250 0.673–2.321 0.480
Atrial fibrillation 0.917 0.643–1.307 0.630
History of PCI 0.675 0.484–0.940 0.020 0.888 0.427–1.847 0.750 0.909 0.437–1.890 0.798
History of left radial access 1.170 0.692–1.979 0.557

Model 1: clinical risk factors and BMI; Model 2: clinical risk factors and BSA.

OR, odds ratio; CI, confidence interval; BMI, body mass index; BSA, body surface area; DM, diabetes mellitus; CKD, chronic kidney disease; CAOD, coronary artery occlusive disease; MI, myocardial infarction; CVA, cerebrovascular accident; PAOD, peripheral arterial occlusive disease; PCI, percutaneous coronary intervention.

Comparison of distal radial artery diameters among studies

Study Country Method Location No. of patients
 Diameter of distal radial artery, mm
Total Men Women Total Men Women
Present study (DRAUS) Korea Ultrasonography Outside ASB 1,162 671 491 R: 2.32 ± 0.44 R: 2.43 ± 0.44 R: 2.16 ± 0.38
L: 2.35 ± 0.45 L: 2.47 ± 0.45 L: 2.18 ± 0.39
Mizuguchi et al. [8] Japan Ultrasonography Within ASB and outside ASB 228 162 66 Within ASB: 2.4 ± 0.5 - -
Outside ASB: 2.3 ± 0.5
Norimatsu et al. [9] Japan Ultrasonography Within ASB 142 96 46 2.6 ± 0.5 2.6 ± 0.5 2.5 ± 0.5
Naito et al. [10] Japan Ultrasonography Within ASB 120 105 15 - 2.04 ± 0.43 1.96 ± 0.44
Lee et al. (LeDRA) [5] Korea Ultrasonography Outside ASB 151 103 48 R: 2.36 ± 0.49 R: 2.44 ± 0.47 R: 2.17 ± 0.47
L: 2.41 ± 0.50 L: 2.51 ± 0.47 L: 2.22 ± 0.52
Kim et al. [6] Korea Angiography Within ASB 101 69 32 - 2.65 ± 0.46 2.40 ± 0.53
Valsecchi et al. [11] Italy Angiography Within ASB 52 43 9 2.22 ± 0.14 - -

ASB, anatomical snuffbox; R, right; L, left.