Asian Cardiovasc Thorac Ann 2007;15:324-326
© 2007 Asia Publishing EXchange Ltd
Factors Influencing Radial Artery Size
Yee Jim Loh, MRCS,
Masakazu Nakao, MD,
Wei Ding Tan, MSc1,
Chong Hee Lim, FRCS,
Yong Seng Tan, FRCS,
Yeow Leng Chua, FRCS
Department of Cardiothoracic Surgery
1 Singapore Cardiac Data Bank, National Heart Center, Singapore
For reprint information contact: Yee Jim Loh, MRCS, Tel: 65 6436 7598, Fax: 65 6224 3632, Email: cardioryan{at}hotmail.com, National Heart Center, Mistri Wing, 17 Third Hospital Avenue, Singapore 168752.
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ABSTRACT
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Size matching of radial artery conduits to coronary arteries is important as it affects the long-term patency. However, factors affecting radial artery size have not been adequately investigated. We retrospectively reviewed 327 consecutive patients who had duplex ultrasonography of their radial arteries over a 2-year period. There were 225 men and 102 women. The mean radial artery size was 2.45 ± 0.54 mm. The factors found to positively affect the size of the radial artery were sex, hypertension, and hyperlipidemia. Diabetes mellitus and age were found to negatively affect radial artery size. Renal disease, race, and smoking did not significantly influence the size of the radial artery. However, as the R squared of this model was insignificant, further studies need to be undertaken to determine other factors that may influence radial artery size.
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INTRODUCTION
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It has been 32 years since the radial artery was first used by Carpentier and colleagues1 as an alternative conduit for coronary artery bypass grafting. Since then, there has been an increasing trend towards its usage, especially when data showing superior patency compared to saphenous vein grafts was published.2,3 The versatility of the radial artery extends beyond its use as a conduit; it is also increasingly being utilized as an alternative site of access for cardiac catheterization.4,5 There are various factors to be considered when deciding upon the suitability of the radial artery as a conduit. Rodriguez and colleagues6 reported that arteries < 2 mm and those with diffuse calcification or a negative Allen’s test should be abandoned. Size matching of conduits to the native coronary artery vessels is also important as it can affect the long-term patency.7 However, factors affecting the size of the radial artery have not been adequately investigated. Given the unique multiracial society of Singapore, we included race among the factors analyzed to determine which affected the size of the radial artery.
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PATIENTS AND METHODS
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We retrospectively reviewed 327 consecutive patients who had left radial and left ulnar artery duplex Doppler ultrasonography carried out in our vascular laboratory over a 2-year period. Scanning was performed with an Acuson 128 XP/10 computed sonography system (Acuson, Mountain View, CA, USA) and a Philips iu22 transducer (Philips Medical Systems, Bothell, WA, USA). A 2-D linear electronic probe L5 at 5.0 MHz and an L8-4 probe were used. The smallest internal diameter in each one-third segment of the radial and ulnar arteries was recorded after comparing the size at both the longitudinal and transverse sections. However, the average diameter of the radial artery (dependent or outcome variable) was used for analysis. Pre-existing risk factors for coronary artery disease at the time of ultrasonography were recorded: age, race, diabetes mellitus, hypertension, hyperlipidemia, smoking, and renal failure.
Tests of normality and graphical plots showed that the dependent variable followed a normal distribution, and Levene’s test for discrete factors showed that the assumptions of homogeneity of variance were met. One-way analysis of variance (ANOVA) was first performed to examine the association between the average diameter of the radial artery and each factor at the 5% significance level (within-factor effect). Then N-way ANOVA was used to examine the influence of those factors with possible association, after adjusting for the confounding effect. This determined the final combination of factors that had a significant influence on the average diameter of the radial artery (both between- and within-factor effect). As the data type of the dependent variable, the radial artery, is quantitative and continuous in nature, a generalized linear model was built with the average diameter of the radial artery as the outcome variable and using the combination of significant factors as predictors. The coefficients of the model were used to study the importance and contribution of each factor to the diameter of the radial artery, after adjusting for other factors.
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RESULTS
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The patient demographics are listed in Table 1
. The sex ratio was 2.2:1. The mean of the average radial artery sizes was 2.45 ± 0.54 mm, and the mean ulnar artery size was 2.3 ± 0.5 mm. The factors found to positively affect the size of the radial artery included sex, hypertension, and hyperlipidemia (Table 2). Diabetes mellitus and age were found to negatively affect the size. Race, renal failure, and smoking did not significantly influence the size of the radial artery (Table 2). The radial artery was significantly larger than the ulnar artery (p < 0.0001).
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DISCUSSION
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Our study shows that male patients with hypertension and hyperlipidemia tend to have significantly larger radial arteries. As males are generally larger than females, it is not surprising that they have larger radial arteries. Chronically elevated blood pressure can result in compensatory enlargement of the radial artery, similar to the effect of hypertensive heart disease. Khder and colleagues8 also found that hypertensive patients had larger luminal diameters of their radial arteries compared to normotensive controls; however, Mourad and colleagues9 did not find any significant difference. We are unable to account for the larger radial arteries seen in patients with hyperlipidemia. Our study found that as patients age and develop diabetes mellitus, the radial artery tends to decrease in size. Patients with long-term diabetes mellitus have the propensity to develop arteriopathy and accelerated atherosclerosis. Ruengsakulrach and colleagues10 and Chowdhury and colleagues11 also demonstrated that factors predictive of intimal hyperplasia and arteriosclerosis in radial arteries were age and diabetes. This supports our observations of a smaller arterial luminal diameter in elderly diabetics, and may have significance in the decision to harvest the radial artery. Coronary angiography performed through smaller radial arteries may also incur increased difficulty, and cannulation may take longer.
The limitations of our study are that we did not take into account the duration of diabetes mellitus, the type of diabetes, or the control of the diabetes. However, the duration of diabetes mellitus is notoriously inaccurate as the majority of patients are initially asymptomatic and diabetes is discovered incidentally. Also, the body surface area of patients was not recorded at routine duplex scans. Hence, we were unable to normalize the average radial artery diameter for comparison. The R-squared for our model was insignificant (Table 3). This implies that there are possibly other factors, in addition to those tested, that might account for the variation in the size of the radial artery.
From our model, we found that male sex, hypertension, and hyperlipidemia positively affected the size of the radial artery, while diabetes mellitus and age negatively affected the size. However, further studies need to be undertaken to determine other factors that may influence the average size of the radial artery.
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ACKNOWLEDGMENTS
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We would like to thank Ms. Caren Tan, Dr. Sriram Shankar, Dr. Kenny Sin, and Dr. Michael Caleb for their invaluable help and support.
Presented at the 58th Annual Meeting of The Japanese Association for Thoracic Surgery, Okayama City, Japan, October 5–7, 2005.
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REFERENCES
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- Carpentier A, Guermonprez JL, Deloche A, Frechette C, DuBost C. The aorta-to-coronary radial artery bypass graft. A technique avoiding pathological changes in grafts. Ann Thorac Surg 1973;16:111–21.[Medline]
- Tatoulis J, Buxton BF, Fuller JA. Patencies of 2127 arterial to coronary conduits over 15 years. Ann Thorac Surg 2004;77:93–101.[Abstract/Free Full Text]
- Desai ND, Cohen EA, Naylor CD, Fremes SE; Radial Artery Patency Study Investigators. A randomized comparison of radial-artery and saphenous-vein coronary bypass grafts. N Engl J Med 2004;351:2302–9.[Abstract/Free Full Text]
- Archbold RA, Robinson NM, Schilling RJ. Radial artery access for coronary angiography and percutaneous coronary intervention. BMJ 2004;329:443–6.[Free Full Text]
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- Rodriguez E, Ormont ML, Lambert EH, Needleman L, Halpern EJ, Diehl JT, et al. The role of preoperative radial artery ultrasound and digital plethysmography prior to coronary artery bypass grafting. Eur J Cardiothorac Surg 2001;19:135–9.[Abstract/Free Full Text]
- Shah PJ, Gordon I, Fuller J, Seevanayagam S, Rosalion A, Tatoulis J, et al. Factors affecting saphenous vein graft patency: clinical and angiographic study in 1402 symptomatic patients operated on between 1977 and 1999. J Thorac Cardiovasc Surg 2003;126:1972–7.[Abstract/Free Full Text]
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- Chowdhury UK, Airan B, Mishra PK, Kothari SS, Subramaniam GK, Ray R, et al. Histology and mophometry of radial artery conduits: basic study and clinical application. Ann Thorac Surg 2004;78:1614–21.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
