Analysis of Right Radial Artery for Transradial Catheterization by Quantitative Angiography (FULL TITLE BELOW)

ABSTRACT: Objectives. To determine the optimal radial puncture point, we analyzed the anatomy and luminal diameter of the right radial artery (RA) by quantitative angiography. Background. Difficulty of radial puncture has impeded the establishment of the transradial approach as the standard procedure for cardiac catheterization. Methods. Antegrade angiography was performed from the right brachial artery in 135 patients who underwent coronary angiography. Presence and location of a bifurcation in the area of the RA puncture were analyzed. Furthermore, inner luminal diameter of the RA was quantitatively measured. We used the line between the styloid process and the ulnar styloid process (R-U line) as an anatomical reference point. Results. Radial arterial bifurcation with a superficial palmar branch was angiographically observed in 66 patients (48.9%). The inner luminal diameter was significantly larger at the proximal point to the point of bifurcation. The bifurcation level was located at a median of -3.33 mm (interquartile range: -5.60 to 4.69 mm) below the R-U line. Radial puncture at 10 mm proximal to the R-U line could avoid bifurcation in 91.9% of all cases. Mean radial, ulnar and brachial arterial inner diameters were 2.94 ± 0.52 mm, 2.51 ± 0.49 mm and 4.53 ± 0.62 mm. The RA size within 10–60 mm above the R-U line was nearly invariable throughout the range. Conclusion. The radial puncture level should be proximal to the radial bifurcation because of its lumen size. The ideal puncture point was found to be at least 10 mm proximal to the R-U line.

J INVASIVE CARDIOL 2010;22:372–376

Key words: transradial intervention; radial puncture; radial arterial bifurcation

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Since coronary angiography via the radial arterial approach was reported by Campeau in 1989 for the first time,¹ it has come to be recognized as a useful technique in coronary intervention.² Nowadays, transradial intervention (TRI) is used not only for coronary artery catheterization, but also for renal and carotid artery catheterization.^3–5 TRI has several advantages such as a lower rate of bleeding complications at the puncture site and short hospital stays.6–12 Nonetheless, the transfemoral approach is currently the standard procedure for coronary intervention because of the larger vascular diameter, easy puncture and facile catheter technique, among other reasons. Difficulty of radial puncture is a major reason why many operators tend to avoid the transradial approach. However, few analyses on radial arterial anatomy have been conducted with the aim of making the radial puncture technique easier. In this study, we performed quantitative angiography via the brachial artery to analyze the radial arterial diameter and bifurcation in detail. We describe the optimal radial puncture point that would produce a higher success and lower complication rates.

Materials and Methods

Study population. We prospectively studied 135 consecutive patients who underwent transbrachial coronary angiography for the first time from May 2007 to December 2007 at the Tokai University School of Medicine. Exclusion criteria were as follows: no indication for coronary catheterization, contraindication to the brachial approach such as brachial artery occlusion or brachial joint contracture, prior catheterization from the ipsilateral radial artery (RA), serum creatinine level > 1.5 mg/ml, contrast medium allergy and emergency cases. All patients gave written informed consent. Antegrade arteriography of the upper limb. Under local anesthesia, a sheath was inserted into the right brachial artery. A 5 Fr sheath was utilized in all patients. Antegrade arteriography of the upper limb arteries was performed after coronary angiography or intervention. Isosorbide dinitrate was administrated systemically as a vasodilator during coronary angiography. Eight ml of contrast medium was mixed with 2 ml of normal saline and then injected from the side arm of the inserted sheath into the right brachial artery. Arteriography was performed without upper limb pain using the 80% diluted contrast medium. Angiography was performed on the entire radial, ulnar and brachial arteries and the palmar artery using an anteroposterior projection. Quantitative angiographic analysis. Quantitative angiographic analysis was performed with an automated edge detection system (QCA-CMS version 6.0, Medis, Medical Imaging Systems, Leiden, the Netherlands). The outer luminal diameter of the inserted sheath was used as the calibration reference for quantitative angiographic analysis. The outer luminal diameter of the 5 Fr sheath (Terumo, Tokyo, Japan) used in this study was 2.20 mm. The inner luminal diameter of the upper limb arteries or the distance from the anatomical reference line was measured quantitatively with this system. Quantitative analysis of radial arterial bifurcation. An anatomical reference was necessary to perform quantitative angiographic analysis of the upper-limb arteries. We connected the most proximal part of the top of the radial styloid process and the top of the ulnar styloid process with a straight line, and named it the “R-U line” (Figure 1). The R-U line was defined as an anatomical reference line to analyze the angiogram of the upper-limb arteries for all the measurements in this study. In this study, the reference point of the R-U line was set at 0 mm, the proximal side from the R-U line was defined as plus, and the distal side from the R-U line was defined as minus. Figure 1 shows angiographic images of the RA bifurcation. The optimal radial puncture point was from the following three approaches by quantitative angiographic analysis. 1. Distribution of radial arterial bifurcation. The RA has a bifurcation around the radial puncture site joining the superficial palmar branch. To identify this radial bifurcation level, the distance from the R-U line to the proximal edge of this bifurcation was measured. 2. Comparison of inner luminal diameter of the RA proximal and distal to the bifurcation. To compare the lumen diameter at points proximal and distal to the bifurcation, the inner lumen diameter of RA was measured at 1 mm proximal and 1 mm distal to the bifurcation. 3. Variation of radial artery size around the radial puncture site. To study the variation of radial artery size around the radial puncture site, measurements were made of the inner luminal diameter of the RA at 5 mm intervals from the R-U line toward the proximal direction for up to 60 mm by quantitative angiographic analysis. Data analysis. The results were summarized as mean values ± standard deviation. Statistical analysis was performed using SAS version 9.1.3 (SAS Institute, Inc. Cary, North Carolina). χ2 and Fisher’s exact tests were used for comparison of categorical variables, as appropriate. Comparison of continuous variables was performed by means of the Student’s t-test or the Wilcoxon rank-sum test, as appropriate. A p-value Results Patient and procedural characteristics. A total of 135 consecutive patients (90 males and 45 females) were included in this study. Baseline demographic and clinical characteristics are summarized in Table 1. The mean age of the patients was 65.7 ± 10.9 years. Quantitative Analysis of Radial Artery Bifurcation 1. Distribution of RA bifurcation. The RA bifurcation to the superficial palmar branch was angiographically detected in 66 patients (48.9 %). As shown in Figure 2, the bifurcation level was located at a median of -3.33 mm (interquartile range [IR]: - 5.60 to 4.69 mm) below the R-U line. This graph showed a normal distribution within a range of -14 to 6 mm, excluding 14 cases of “high take-off bifurcation” anomalies. To study the relationship of the puncture site and the level of radial bifurcation in radial puncture, a cumulative frequency curve of RA bifurcation was drawn for all 135 patients (Figure 3). This graph indicates that the puncture point at 10 mm above the R-U line is proximal to the bifurcation, with a probability of 91%. 2. Comparison of inner luminal diameter of the RA proximal and distal to the bifurcation. The difference of the inner luminal diameter between the proximal and distal points to the bifurcation was analyzed quantitatively. This analysis was performed in the 66 patients who had an angiographically detectable RA bifurcation. Figure 4 shows that the inner luminal diameter of the RA at 1 mm proximal to the bifurcation is 3.20 ± 0.51 mm, and at 1 mm distal to the bifurcation the inner luminal diameter of the RA is 2.81 ± 0.58 mm (p 3. Variation of RA size around the radial puncture site. The inner luminal diameter of the RA was measured in 131 patients (97.0%) at 5 mm intervals from the R-U line toward the proximal direction by quantitative angiographic analysis to study the transition of the RA size around the radial puncture site. As shown in Figure 5, the RA diameter increased slightly within a range of 0–10 mm from the R-U line, probably due to the existence of an RA bifurcation around this area. Its diameter within 10–60 mm above the R-U line was nearly invariable throughout the range. The mean value of the radial, ulnar and brachial artery inner diameters was 2.94 ± 0.52 mm, 2.51 ± 0.49 mm and 4.53 ± 0.62 mm, respectively, in all patients regardless of gender (Figure 6). Figure 6 shows that the inner luminal diameter of the RA is significantly larger in males than in females. The cumulative frequency curve of the inner luminal diameter of the RA at 10 mm proximal to the R-U line is presented by gender in Figure 7.

Discussion

The RA has a bifurcation to the superficial palmar branch around the radial puncture site.^13,14 Puncture distal to the RA bifurcation may be a potential cause of occlusive complications due to a smaller lumen diameter or bleeding complications due to penetration of both RA branches. The small luminal diameter of the RA was reported to influence the success rate of radial puncture or the radial occlusion rate.^15–17 Despite the clinical importance, the RA bifurcation has been discussed very little.^18–21 In this study, we analyzed the anatomy of the upper-limb arteries, particularly bifurcations and luminal diameter of the RA, to determine a safe and optimal radial puncture point by quantitative angiographic analysis. There have been no reports where quantitative angiographic analysis was used to evaluate upper-limb arteries, although some analyses by ultrasonography or intravascular ultrasound have been reported.^16,17,22,23 RA bifurcation was observed in 49% of the cases. As shown in Figure 2, the RA bifurcation had a bimodal distribution which consisted of a large group distributed normally around the R-U line (52 of 66 patients, 78.9 %; Distal Group), and a small group distributed at least 10 mm proximal to the R-U line (14 of 66 patients, 21.2 %; Proximal Group). Considering all the cases, the location of the RA bifurcation was not normally distributed. However, it showed clear, normal distribution only in the Distal Group, suggesting that the Distal Group might represent the normal anatomy. Conversely, the proximal group with “high take-off” bifurcations deviated from this distribution and might represent a kind of RA anomaly. Several studies have reported the high take-off at the RA itself.^24–28 However, the high take-off of the radial bifurcation around the puncture site has not been studied in terms of transradial catheterization. The data show that a radial puncture at a point 10 mm proximal to the R-U line should avoid the RA bifurcation in 91.1% of all cases (Figure 3). Based on these results, the optimal radial puncture point is the area with a good pulsation at ≥ 10 mm proximal to the R-U line, which coincided with the radial puncture site proposed by Kiemeneij when he started TRI (personal communication). We produced a graph (Figure 7) similar to the cumulative graph of the RA diameter reported by Saito et al who performed an ultrasound analysis.²² Our angiographic data were very similar to Saito’s; the RA diameter at 10 mm above the R-U line exceeded the outer diameter of the current 6 Fr sheath size in 84% of all patients. Furthermore, the angiographic data showed an average RA diameter of 29.4 ± 0.55 mm in all patients, 3.08 ± 0.52 mm in all males, and 2.67 ± 0.52 mm in all females. This was consistent with prior reports.^{22,23,29–31}Study limitations. A limitation was that patients with chronic kidney disease (CKD) were excluded from this study. Patients with CKD may have a different RA diameter distribution compared to those without CKD. This might influence the results of the analysis. We speculated that a distal puncture to the RA bifurcation is not safe because of the smaller diameter and the risk of puncturing both RAs. In femoral arterial puncture, many reports showed that the optimal, safest radial puncture point is to avoid the femoral bifurcation.^32–38 However, this presumption was not based on the clinical results in RAs. Prospective studies may be necessary to prove the safety of this recommended puncture point.

Conclusion

We propose that the optimal puncture point of the RA should be at least 10 mm proximal to the R-U line based on analysis of RA bifurcations.

References

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From the Division of Cardiology, Tokai University School of Medicine, Isehara, Japan. The authors report no conflicts of interest regarding the content herein. Manuscript submitted March 9, 2010, provisional acceptance given April 8, 2010, final version accepted May 18, 2010. Address for correspondence: Yuji Ikari, MD, PhD, Professor of Medicine, Department of Cardiology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, 259-1193, Japan. E-mail: ikari@is.icc.u-tokai.ac.jp