Incidence and Predictors of Radial Artery Occlusion After Transradial Coronary Angioplasty: Doppler-Guided Follow-up Study

Abstract: Objectives. To evaluate the incidence and predictors of radial artery occlusion (RAO) after transradial coronary angioplasty (TRA). Background. RAO can occur after TRA but has not been well studied by serial vascular Doppler examination. Methods. A total of 198 patients undergoing TRA were included. Radial pulse and Doppler examination of the radial artery were performed 1 day before, 1 day after, and 3 months after the procedure. RAO was defined as an absence of antegrade flow on Doppler studies. Logistic regression analysis was done to evaluate the predictors of RAO. Results. The mean radial arterial diameter was 2.8 ± 0.4 mm. On the day after TRA, radial artery Doppler examination revealed RAO in 30 patients (15.2%). Radial pulse was still palpable in 30.0% of these patients. All of them were asymptomatic. At 3-month follow-up, no new RAO was noted. Interestingly, the radial artery had spontaneously recanalized in 8 patients (26.7%) with RAO. Patients with persistent RAO remained asymptomatic. On univariate analysis, female sex, diabetes, lower body mass index, radial artery diameter ≤2.5 mm, lower peak systolic velocity, and radial artery to sheath ratio <1 were predictors of RAO. Interestingly, procedural characteristics and duration of the procedure were not identified as predictors of RAO. On multivariate analysis, radial artery diameter ≤2.5 mm and preprocedural peak systolic velocity emerged as independent predictors for RAO. Conclusion. Asymptomatic RAO occurs in about 15% of patients after TRA. Spontaneous recanalization occurs in about one-fourth of these patients. Preprocedure radial artery inner diameter ≤2.5 mm and peak systolic velocity are the independent predictors of RAO. 

J INVASIVE CARDIOL 2015;27(2):106-112

Key words: radial artery occlusion, transradial access

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Transradial access for coronary angiography and angioplasty has gained increasing popularity because of its advantages over the femoral approach. Transradial access is associated with fewer vascular access complications^1,2 and has been shown to reduce major bleeding when compared with the femoral approach. In the multicenter RIVAL trial, transradial coronary angioplasty (TRA) was shown to have mortality benefit over transfemoral coronary angioplasty in acute coronary syndrome patients.³ 

Radial artery occlusion (RAO) and increased radiation exposure^4,5 remain the primary concerns of transradial access. Radiation exposure mainly depends on operator training and experience with transradial access. RAO can lead to permanent occlusion of the radial artery and is the “Achilles’ heel” of the transradial technique.⁶ RAO is usually clinically silent because of the dual blood supply to the hand, and for this reason it is often overlooked. However, the complication is not always benign, as hand ischemia resulting from RAO has been reported.^7-9 Furthermore, once the artery is occluded, it cannot be used as an access site for future catheterization or as an arterial conduit for bypass surgery. 

In the published data, RAO rates are surprisingly variable, ranging from 5% to 38%.^10-14 The large variance might be related to the fact that radial artery patency after catheterization was assessed by clinical forearm inspection and pulse palpation rather than by vascular ultrasound in the vast majority of studies. Secondly, most of these studies, including two large currently available studies,^15,16 comprised a mixed patient population of TRA as well as diagnostic transradial coronary angiography. Until now, no study has examined RAO exclusively in patients undergoing transradial coronary angioplasty. In a study by Uhlemann et al,¹⁵ out of a total 455 patients studied, only 66 patients underwent transradial coronary angioplasty. Radial artery size was not measured before radial artery cannulation. Additionally, RAO rate in the 6 Fr arm was high (30.5%). In a study by Chugh et al,¹⁶ out of a total 2344 patients studied, follow-up data were available in only the last 613 patients (a mixed population who underwent angiography/angioplasty). RAO rate was low; only 1 patient had RAO at 4-week follow-up. Considering the limited data on RAO after transradial coronary angioplasty, this study was undertaken to evaluate the true incidence, predictors, and outcome of RAO after transradial coronary angioplasty using serial high-resolution vascular Doppler ultrasound. 

Methods 

Between January 2012 and June 2012, patients who were taken up for PCI or ad hoc PCI at our tertiary-care referral center were prospectively recruited in the study. Only patients who underwent successful transradial coronary angioplasty (TRA) and completed the 3-month follow-up were included. Patients with hemodynamic instability, those undergoing primary PCI, and those with negative Allen’s test were excluded from the study. Patients with access-site crossover to transfemoral approach and those not proceeding to PCI (mild/no coronary artery disease and patients advised for coronary artery bypass surgery) were excluded. Patients who were lost to follow-up were also excluded. All patients gave written informed consent and the authors conformed to institutional guidelines and those of the American Physiological Society. 

Data on demographics, medical history, and procedural characteristics were recorded for every patient. Routine hemogram, renal function test, and blood sugar levels were measured in all patients. Left ventricular ejection fraction (LVEF) was measured by echocardiography in all patients. Other investigations were performed when required. 

Clinical radial artery patency was assessed by radial pulse examination. Allen’s test was done in all patients. Radial artery Doppler, including 2-dimensional and color Doppler of the right radial artery, was performed using a 10 MHz linear transducer (VIVID 7; GE Healthcare). Peak systolic velocity was also noted. Ultrasound examinations of the radial artery were performed 1 day before, 1 day after, and 3 months after the procedure. Measurement of the right radial artery diameter was made at a point about 1 cm proximal to the styloid process, where the puncture of the radial artery was usually made. Internal lumen diameter of the radial artery as measured from “inner wall to inner wall” was taken as the radial artery diameter. A mean of three readings was taken for the diameter of the radial artery. Radial artery occlusion was defined as the absence of antegrade flow on Doppler studies. Pulse Doppler interrogation of waveform was also performed to rule out collateral flow suggesting upstream occlusion. Biphasic or triphasic signals were taken as normal flow, while monophasic signal was considered as collateral flow from an upstream block in the artery.

A 6 Fr radial sheath was used in all patients. Hydrophilic introducers were not reused in any patient. At least 5000 units of heparin were given to all patients. Hemostasis was achieved in all patients in the catheterization laboratory with a radial compression device (TR band; Terumo, Inc) using the “patent hemostasis” protocol.¹² After procedure completion, the TR band was placed at the distal forearm with placement of a small green box indicator present on the TR band proximal to the radial artery puncture site. A plethysmographic probe was attached to the index finger. Then, the sheath was pulled out by about 4 to 5 cm and the compression balloon was initially inflated with 18 mL of air to apply direct pressure at the access site; the sheath was then removed. This resulted in a total occlusion of antegrade flow across the radial artery. Plethysmographic signals obtained from the index finger at this stage indicated flow from the ulnar artery through the palmar arch. The ipsilateral ulnar artery was then compressed to block this palmar arch flow. This lead to a loss of plethysmographic signals from the index finger. Then, the pressure in the compression balloon of the TR band was gradually reduced by decreasing the amount of air in steps of 1 mL until the return of pulsatile plethysmographic signals (confirming radial artery patency) or occurrence of bleeding. If bleeding occurred during this process, pressure in the compression balloon was again slightly increased by injecting about 1 mL of air to ultimately achieve radial artery compression with “patent hemostasis.” Presence of pulsatile plethysmographic signals from the index finger while manually compressing the ipsilateral ulnar artery indicates patent radial artery hemostasis. The patency of the radial artery was checked at least once every 15 minutes. The TR wrist band was removed after 4 hours of sheath removal. A light pressure bandage was applied. Patent radial artery hemostasis was again confirmed by noting the presence of pulsatile plethysmographic signals from the index finger, while manual total compression of ipsilateral ulnar artery. Light pressure bandage was removed after about 8 hours. All patients were encouraged to squeeze and release the hand and to keep the arm in an elevated position during the entire compression period. 

Procedural details like angiographic severity of coronary artery disease, number of vessels stented, and total number of stents used in each patient were noted. The complexity of lesions demanding prolonged radial cannulation time or use of multiple hardware (eg, bifurcation lesions, chronic total occlusions, aorto-ostial lesions, lesions involving LAD, or LCX ostia) was noted. Total fluoroscopy time and radiation dose were also noted for each patient.

Statistical analysis. All data were prospectively collected and entered. Dichotomous variables are reported as numbers and proportions. Continuous variables are presented as mean ± standard deviation. Cut-off value for small radial artery was determined by ROC curve analysis. Potential risk factors for small radial artery size and postprocedural RAO were investigated first by univariate logistic regression analysis. A multivariate logistic regression model with all significant variables was established to estimate odds ratios (ORs) and inclusive 95% confidence bounds. All tests were performed as 2-sided at significance level of P<.05. Statistical analyses were performed with SPSS version 16.0 (SPSS, Inc). 

Results

Baseline characteristics. A total of 531 consecutive patients undergoing PCI or ad hoc PCI were prospectively screened for inclusion in the study and 198 patients were included in the final analysis (Figure 1). Baseline characteristics of the subjects are presented in Table 1. The mean age of subjects was 58.0 ± 10.2 years, the majority (80.8%) were male, mean body mass index (BMI) was 25.2 ± 2.5 kg/m², and mean body surface area (BSA) was 1.7 ± 0.1 m². About one-third of patients were diabetic and about one-half were hypertensive. About one-half of our patients had stable angina, while the rest had acute coronary syndrome. About one-half of our patients had single-vessel disease. The majority (86.9%) had relatively preserved ejection fraction (LVEF >40%). All patients received aspirin, clopidogrel/prasugrel, and a statin. The majority of our patients received beta-blocker and angiotensin-converting enzyme inhibitor/ angiotensin-receptor blocker. 

Procedural characteristics. Procedural characteristics are presented in Table 2. A 6 Fr radial sheath size was used in all patients. The majority of patients underwent single-vessel angioplasty. Complex PCI was done in about one-fourth of the patients. About one-third of the patients had prior radial artery cannulation. Glycoprotein inhibitors were used in about one-half of the patients. Mean fluoroscopy time was 16.2 ± 8.1 minutes. Mean radiation dose was 134.2 ± 63.8 Gy x cm². 

Radial artery size. The mean radial arterial diameter for our study population was 2.8 ± 0.4 mm (Table 1 and Table 3). The diameters ranged from 1.6 mm to 3.7 mm. Radial artery diameter was less than the sheath diameter (radial artery diameter to sheath ratio <1) in 14 patients. The mean radial artery diameter for males was larger (2.8 ± 0.4 mm) compared with females (2.4 ± 0.4 mm; P<.001).

The cut-off value for small radial artery was 2.5 mm with high sensitivity and specificity, as determined by ROC curve analysis. Factors predicting small diameter of the radial artery (radial artery size ≤2.5 mm) were analyzed using regression analysis (Table 4). On univariate regression analysis, female gender, lower BMI, and diabetes mellitus were found to be significant predictors of smaller radial artery while no correlation was found for age, height, weight, and body surface area (BSA). Female subjects were 3.8 times more likely to have smaller radial artery diameters (OR, 3.8; CI, 1.8-7.8; P<.001), and subjects with a lower BMI were likely to have smaller diameters (OR, 0.8; CI, 0.7-1.0; P=.04). Diabetics were 3.4 times more likely to have radial artery size ≤2.5 mm (OR, 3.4; CI, 1.8-6.5; P<.001). On multivariate analysis, female gender, diabetes mellitus, and lower BMI emerged as independent predictors of smaller radial artery size (Table 5).

Radial artery occlusion. On the day after TRA, radial artery Doppler examination revealed RAO in 30 patients (15.2%) (Table 3). In 12 of these 30 patients (40.0%) with Doppler evidence of RAO, the radial artery pulse was still palpable. All patients with RAO were asymptomatic. Grade 1 forearm hematoma was noted in 4 patients (2.0%). One patient developed a pseudoaneurysm of the radial artery. It was treated successfully with ultrasound-guided compression. There were no arteriovenous fistulas, and no moderate or severe access-site bleedings (according to Global Use of Strategies to Open Occluded Arteries definitions) requiring blood transfusion or surgical repair. At 3-month follow-up, no new RAO was noted. Interestingly, the radial artery had spontaneously recanalized in 8 patients (26.7%) with RAO. Patients with persistent RAO remained asymptomatic. 

Predictors of radial artery occlusion. The univariate analysis of predictors of postprocedural RAO is presented in Table 6. Female gender, lower BMI, diabetes mellitus, preprocedure radial artery diameter ≤2.5 mm, preprocedural peak systolic velocity, and radial artery to sheath ratio <1 were the significant predictors of postprocedural RAO. Interestingly, procedural characteristics and procedure duration were not identified as predictors of RAO. Prior radial artery cannulation and angiographic severity of coronary artery disease were also not predictors of RAO.

On multivariate logistic regression analysis (Table 7), preprocedure radial artery diameter ≤2.5 mm and lower peak systolic velocity emerged as independent predictors for postprocedural RAO. Female gender, diabetes, lower BMI, and radial artery to sheath ratio <1 did not prove to be independent predictors for postprocedural RAO.

Discussion

Results of our study showed that asymptomatic radial artery occlusion occurs in about 15% of patients after transradial coronary angioplasty. Spontaneous recanalization occurs in about one-fourth of these patients. Preprocedure radial artery inner diameter ≤2.5 mm and lower peak systolic velocity are the independent predictors of RAO. Patients with vascular-Doppler documented RAO can still have palpable radial pulse. Ours is the only study in which serial vascular Doppler examination of the radial artery was done exclusively in patients who underwent successful TRA, thus depicting the true incidence of RAO after TRA.

Compared with western populations, Asians have a smaller radial artery caliber. In a French study on adult patients with suspected coronary artery disease, radial artery diameter was reported to be 3.7 ± 0.8 mm.¹⁷ In our study, radial artery diameter was found to be 2.8 ± 0.4 mm (range, 1.6-3.7 mm). Our finding is in accordance with the previous studies done in Asian populations (2.6 ± 0.3 mm in Korea,¹⁸ 2.5 ± 0.4 mm in Japan,¹⁹ and 2.8 ± 0.5 mm in Taiwan²⁰). In a recent Indian study, right radial artery diameter was 1.9 ± 1.1 mm in males and 1.7 ± 0.3 mm in females.¹⁶ 

Our study showed that females, patients with lower BMI, and diabetics tend to have smaller radial artery size. Other studies also found that males tend to have significantly larger radial arteries.^21-23 As males are generally larger than females, it is not surprising that they have larger radial arteries. Similarly, persons with lower BMI also had smaller radial arteries, as reported previously by Velasco et al.²⁴ Diabetics were found to have smaller radial arteries. Patients with long-term diabetes mellitus have the propensity to develop arteriopathy and accelerated atherosclerosis. Ruengsakulrach et al²⁵ and Chowdhry et al²⁶ also demonstrated that factors predictive of intimal hyperplasia and atherosclerosis in radial arteries were age and diabetes. We hypothesize that female diabetic patients, especially with lower BMI, may be more difficult to cannulate with larger sheaths. This supports the observation of larger radial artery luminal diameter in non-diabetics and may have significance in the decision to harvest the radial artery for bypass grafting and using the radial artery for coronary interventions.  

The incidence of RAO in our study was relatively higher than previous studies. First, it may be because of Doppler-based diagnosis of RAO in our study. Patients with RAO can have palpable radial pulse even with occluded proximal segment of the radial artery because of collateral circulation from the palmar arch.^12,27 In studies using absent radial pulse as the only criteria for RAO, the rate of immediate RAO were reported in 2%-6% of patients.¹⁰ However, in some studies using Doppler, the rate of absence of antegrade flow ranged from 3% to 9%.^20,28 In a study by Huang et al,²² the rate of immediate occlusion was 4.7% by the radial pulse method and 10.7% by Doppler study.  A second possible reason for the relatively higher rate of RAO in our study could be the inclusion of  post-TRA patients only, and not including any patient with only diagnostic transradial coronary angiography. Previous studies have included mixed patient populations undergoing either diagnostic coronary angiography or TRA. Sheath size used in TRA is larger than that used in diagnostic transradial coronary angiography. Bigger sheath size used in all of our patients (post-TRA patients only) than previous studies including a mixed population of both coronary angiography and angioplasty could explain the relatively higher rate of RAO in our study. In fact, in the Leipzig registry,¹⁵ the RAO rate was very well correlated with the size of transradial sheath (13.7% vs 30.5% in 5 Fr vs 6 Fr sheath).    

Female gender, diabetes, lower BMI, preprocedure radial artery diameter ≤2.5 mm, lower preprocedure radial artery peak systolic velocity, and radial artery to sheath ratio ≤1 were found to be the univariate predictors of RAO. Females have relatively smaller average radial artery diameters, and are much more susceptible to vascular spasm and could be the reason for higher RAO in females. Deftereos et al²⁹ reported a significant univariate association between flow-mediated dilation of the radial artery and the occurrence of vascular spasm. In their study, female sex tended to be more prone to radial artery spasm.

In our study, a total of 14 patients had a radial artery diameter less than the radial sheath diameter used for TRA (6 Fr). Eight of these 14 patients developed RAO. Therefore, in our study, the occlusion rate was 57.1% in patients with radial artery to sheath ratio ≤1 as compared to 12% if the ratio was >1. This finding has importance, as Saito et al²⁸ demonstrated that a radial artery diameter/sheath-diameter ratio <1 is associated with a reduction in distal flow. A study by Nagai et al showed that the risk of diffuse late stenosis has correlated positively with the difference between the radial artery and the sheath size.¹⁹ However, in our study, radial artery to sheath ratio ≤1 was not an independent predictor for RAO on multivariate analysis, which may be due to the small sample size of our study.  

Lower preprocedure peak systolic velocity recorded on radial Doppler was an independent predictor of RAO. It is possible that lower peak systolic velocity represents higher resistance in the peripheral circulation because of arteriopathy. Radial arteries with arteriopathy in the microcirculation may be more prone to RAO. However, the importance of this finding needs to be explored further.  

The arterial remodeling that occurs after transradial catheterization has important clinical implications. Sakai et al³⁰ studied patients undergoing repeated transradial interventions in the same arm and found that the rate of radial access-site failure increases with successive procedures. This appears to be due to progressive narrowing of the artery with each procedure, rendering it more difficult to cannulate. On the basis of the above observation, we hypothesized that prior radial angiography or angioplasty done through the same radial artery used for the current procedure would result in a higher number of RAOs compared with procedures done in a radial artery being used for the first time. However, in our study, repeat radial artery cannulation was not an independent predictor for RAO, which may be due to the small number of patients in our study.  

In our study, a sizeable percentage of patients with RAO had complete recanalization at 3 months. All RAOs were asymptomatic, and no new RAO occurred once the patency of the radial artery was documented by vascular Doppler on the day after TRA. These factors indicate that RAO is a relatively harmless phenomenon. However, persistent RAO is of future medical relevance, because an occluded radial artery cannot be used for coronary bypass grafting, repeat coronary angiography/intervention, hemodynamic monitoring, or for shunt creation for hemodialysis. In addition, RAO renders the ipsilateral ulnar artery unusable as well, because instrumenting and cannulating the ulnar artery would put the patient’s hand at risk of ischemia.

Study limitations. It is a relatively small study. Further larger studies are required to confirm our findings. 

Conclusion

Asymptomatic RAO occurs in about 15% of patients after transradial coronary angioplasty. Spontaneous recanalization occurs in about one-fourth of these patients. Preprocedure radial artery inner diameter ≤2.5 mm and peak systolic velocity are the independent predictors of RAO.

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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.

Manuscript submitted December 2, 2013, provisional acceptance given January 9, 2014, final version accepted June 23, 2014.

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