Transradial Approach for Cardiac Catheterization in Patients With Negative Allen`s Test
Abstract: Aims. To assess the efficacy and safety of transradial approach regardless of the Allen’s test results for coronary angiography and angioplasty. Methods and Results. Prospective data collection of 1035 consecutive patients who underwent coronary angiography with or without ad hoc angioplasty through the radial approach was conducted. Baseline demographic and procedural data were recorded. Allen’s test was evaluated in all subjects before the procedure and catheterization was performed from the radial approach irrespective of the results. Radial artery patency was evaluated at discharge clinically, or by Doppler examination if pulse was not palpable. A total of 256 patients (24.7%) were found to have a negative Allen’s test and 779 patients (75.3%) had a positive test. The baseline and procedural characteristics were similar in both groups. No significant differences in complications were reported. Radial artery thrombosis was observed in 6.2% of the negative Allen’s test group and 4.8% of the positive Allen’s test group (P=.85), but this was clinically silent even in the negative Allen’s test group. Conclusion. Transradial approach for coronary angiography and ad hoc angioplasty can be performed with similar efficacy and safety regardless of the Allen’s test results before the procedure.
J INVASIVE CARDIOL 2015;27(9):416-420. Epub 2015 June 15
Key words: angioplasty, interventional cardiology, access-site management
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Coronary artery disease (CAD) is a major risk factor for cardiovascular mortality. Coronary angiography is considered a cornerstone in the diagnosis of CAD, and its standard treatment is coronary angioplasty.1-3 Currently, most coronary angiography and angioplasty procedures are performed via the femoral artery using the Seldinger technique. The transradial approach to cardiac catheterization is an alternate approach with many advantages over the transfemoral approach. Thus, it is increasingly being used for both diagnostic coronary angiography and percutaneous coronary intervention (PCI). Reduced vascular access-site complications4-6 and major bleeding events are associated with this technique when compared with the femoral approach.7 Furthermore, it allows for briefer ambulation time or even same-day hospital discharge,8,9 thus resulting in decreased medical expenses.10,11 There might be a survival benefit in patients with ST-elevation myocardial infarction (STEMI).12 The major complication of transradial catheterization is radial artery occlusion, which can be permanent and is reported at 1%-10% in different studies.13 Ulnar artery patency tested by Allen’s test is a relatively easy way to document double-artery perfusion of the hand, excluding the risk of hand ischemia in case of radial artery occlusion. However, in many high-volume radial centers, the Allen’s test is no longer used and its usefulness is questioned. This study aims to compare the efficacy and safety of the transradial approach in coronary angiography and coronary angioplasty in a single center in subjects with negative versus positive Allen’s test.
Methods
This study is a prospective cohort study. All consecutive patients who underwent coronary angiography and/or coronary angioplasty at the Second Cardiology Department of the Red Cross Hospital of Athens (Athens, Greece) between March 2011 and January 2014 via transradial approach were recruited, irrespective of the indication. Transradial approach is the main approach at our facility, and it was used in 55% of patients who underwent catheterization during the study period. Femoral (43%), ulnar (1%), and brachial (1%) approaches were also used.
All patients were tested by five independent colleagues who performed Allen’s test before the procedure, with the results remaining unknown to the operators in order to reduce bias. Allen’s test is well established in the literature. In short, the hand is perfused by both the radial and ulnar arteries. The radial artery is not an end artery like the femoral or brachial arteries. In the event of radial artery block, albeit quite uncommon, the hand continues to get blood supply via the ulnar artery. The patient is instructed to clench their fist. The examiner then compresses the radial and ulnar arteries simultaneously, and the patient is asked to relax the hand. The ulnar artery is then released and the time needed for maximal palmar blush to return is recorded. Return of the palmar blush within 5-10 seconds is typically considered normal (positive modified Allen test) and indicates adequate collateral circulation. In our study, we did not use a pulse oximeter. After 6 Fr radial sheath insertion, 5000 IU unfractionated heparin and 5 mg verapamil were introduced through the sheath in order to minimize spasm and radial artery thrombosis. No further anticoagulation was administered in patients undergoing coronary angiography only. If ad hoc coronary angioplasty was decided by the treating physician, more unfractionated heparin (in order to reach 100 IU/kg of patient weight) or bivalirudin (0.75 mg/kg bolus and 1.75 mg/kg/hour infusion) was given until the end of the procedure. Platelet glycoprotein IIb/IIIa receptor inhibitors were used only as a bail-out strategy. The patients underwent coronary angiography and/or angioplasty according to the current standard guidelines and all sheaths were withdrawn in the lab at the end of the procedure. The sheaths were removed immediately after the procedure. Hemostasis was performed using various radial artery closing devices for 4-6 hours and patent hemostasis was attempted in all patients.
Radial artery patency was clinically tested at discharge; if radial pulse was not palpable, a Doppler examination was performed in order to confirm the occlusion. In-hospital events were recorded. A total of 94% of the transradial procedures were performed via the right radial artery with 6 Fr sheaths. Procedure success in coronary angiography was defined as the ability to selectively engage and adequately visualize all of the coronary trees. Procedure success in coronary angioplasty was defined as the ability to perform angioplasty with residual stenosis <30%. Serious complications included hemodynamic destabilization, arrhythmias, neurologic complications, perforations, and bleeding that required blood transfusion.
Statistical analysis. Demographics and clinical characteristics were expressed as mean ± standard deviation or median (25th-75th quartile) for continuous variables depending on the Shapiro-Wilk test for normal distribution. Comparative analysis of categorical variables was performed using a Chi-square test or Fisher’s exact test. Continuous variables were analyzed using independent t-tests for normal distribution; otherwise, the Mann-Whitney U-test was employed. All P-values are two-tailed, and P<.05 indicates statistical significance. All statistical analysis in this study was performed using IBM SPSS software version 20.0 (SPSS, Inc).
Results
There were 1879 cardiac catheterizations performed in 1776 patients during the examined period. Out of these, 1035 (55%) procedures were performed via radial approach. A total of 588 procedures (56.8%) were coronary angiography only, while 447 (43.2%) underwent coronary angiography plus ad hoc angioplasty.
Allen’s test was negative in 256 cases (25%) and positive in 779 cases (75%). The baseline characteristics of the patients are shown in Table 1. All demographic data were comparable between groups except for a trend for higher ratio of subjects with a history of prior PCI in the positive Allen’s test group (16.4% vs 21.7%; P=.05).
The indications for coronary angiography and ad hoc angioplasty are shown in Table 2. No statistically significant differences were observed between groups. The details of the procedure results are shown in Tables 3 and 4.
The fluoroscopic time, radiation dose, and amount of contrast media used were comparable in both groups. The number of lesions that required angioplasty was not significantly different between groups (1.15 vs 1.10; P=.20). The procedural success rate was also similar (90.5% vs 89.1%; P=.65). Sixteen patients (3.6%) had to switch to the transfemoral approach.
Two cases (0.4%) treated via transfemoral approach failed due to tortuosity of the iliac artery and aorta and the patients had to switch to the transradial approach (these cases were included in our study). Radial artery thrombosis was observed in 6.2% of the negative Allen’s test group and 4.8% of the positive Allen’s test group (P=.85), but was clinically silent in both groups. The complications after angioplasty for both groups are shown in Table 5.
Discussion
This is a prospective observational study comparing the safety and efficacy of the transradial approach among patients with different Allen’s test results. The results presented reflect the outcomes of the transradial approach in a cardiac catheterization laboratory since March 2011, with similar baseline characteristics in both groups. No statistically significant differences were observed for all outcomes. Radial artery thrombosis was observed in 6.2% of the negative Allen’s test group and 4.8% of the positive Allen’s test group (P=.85), but was clinically silent and not reported as a serious complication.
Transradial access appears to be safer compared with femoral puncture in acute coronary syndrome patients due to its superficial course and the absence of nerves or veins of significant size near the usual puncture site. Anatomically, the radial and ulnar arteries are connected at the wrist of most patients by the deep and superficial palmar arches, with interosseous collaterals providing additional communications. This provides the hand with arterial supply from both radial and ulnar arteries, thus adding an extra level of safety to the arterial puncture in case of thrombotic or traumatic arterial occlusion. It has been shown that in critically ill patients with prolonged cannulation of the radial artery, ischemic damage occurrence is minimal despite frequent arterial occlusion.14 This safety is provided by the increase in flow in the ulnar collateral circulation in cases where the radial artery becomes occluded.
An abnormal Allen’s test is observed in 6.4%-27.0% of patients undergoing coronary angiography.15,16 Although the visual assessment of the Allen’s test may be pathologic, it has a limited specificity because of delayed recruitment of collateral flow, as is shown by Doppler ultrasound, plethysmography, and pulse oximetry, which reveal a sufficient supply by the ulnar artery in most patients.15,17 An alternate method was developed by Barbeau, who used plethysmography and pulse oximetry in order to improve the sensitivity of the modified Allen’s test. The examiner places a pulse oximeter on the ipsilateral thumb and the morphology of the plethysmography tracing is noted. Then, the radial artery is occluded and any change in the tracing is noted. The test is considered positive (positive oximetry) when the pulse oximeter gives a constant reading and negative (negative oximetry) when it cannot find a reading. Four types or response exist. Types A and B are characterized by uninterrupted arterial filling during radial occlusion. Type C is characterized by the delayed appearance of a pulsatile tracing. This is probably the result of the recruitment of collaterals, and patients in this category are those who might have been excluded from radial catheterization based on a traditional Allen’s test. Finally, in type-D response, no pulsatile collateral flow is noted. Approximately 1.5% of patients belong to this type and are excluded from transradial catheterization. The authors report no incidence of hand ischemia in over 7000 patients undergoing transradial procedures with the Barbeau test, but an elevated thumb capillary lactate level was reported.18 Compared to the typical Allen’s test that we used in our study, which applies to a non-type A case in the Barbeau classification, the Barbeau method improved the sensitivity with the use of oximetry and plethysmography.
Radial artery occlusion is a relatively rare complication of transradial catheterization, occurring in 1%-10% of subjects,19,20 and can lead to permanent occlusion of the radial artery. Only a few cases of severe hand ischemia after radial occlusion have been reported.21,22 In the RIVAL study, the largest randomized trial of radial vs femoral access, symptomatic radial occlusion requiring medical attention occurred in only 0.2% of patients.5 Current practice in many centers is to avoid using the transradial approach in the presence of an abnormal Allen’s test unless the risk of the transfemoral approach is exceedingly increased (eg, severe peripheral vascular disease, morbid obesity, large abdominal aortic aneurysm, Leriche syndrome). No consensus exists as to the optimal cutoff time for a positive Allen’s test and both false-positive and false-negative results are common.23,24 The risk of transient or permanent radial artery occlusion with a normal Allen’s test is 5.3% and 2.8%, respectively,25 which is close to our findings.
Radial occlusion must be prevented regardless of the Allen’s test results. The following factors have been identified as independent predictors in the majority of studies: the diameter of the sheath and its relation to the size of the radial artery,26,27 the post-procedural compression time and the presence of anterograde flow in the artery during hemostasis,28,29 and the use of anticoagulation. In our opinion, those factors are far more important than a negative Allen’s test. Our findings showed no differences in complications between groups and thus the prevention of artery occlusion seems to be independent of the Allen’s test results.
Study limitations. Our study had a few limitations. First, it was not a randomized study, and thus there might be bias in terms of patient selection and outcome measurement. Second, the number of patients in the two groups was disproportionate. As such, there were only 256 patients in the negative Allen’s test group. The results apply to non-type A cases, using Barbeau’s classification scheme. The observed differences in radial thrombosis (6.2% vs 4.8%) would potentially reach statistical significance in a larger group of patients. However, its strength lies in including all comers who presented to our catheterization laboratory. The results represent pragmatic outcomes of the transradial approach during a catheterization procedure in a moderate-size catheterization laboratory. Our results have important clinical applications, as they are encouraging for the use of the transradial approach as the first choice instead of the traditional transfemoral approach. They serve to add information to the knowledge gap of the current evidence derived mainly from high-volume, highly experienced centers concerning a negative Allen’s test. The transradial approach is safe, effective, and promising.
Conclusion
The transradial approach for coronary angiography and ad hoc angioplasty can be performed with similar efficacy, fewer local complications, briefer ambulation, and greater patient satisfaction compared with the standard transfemoral approach regardless of the preprocedural Allen’s test results. Further large observational and randomized studies are needed to evaluate all methods of documentation of the double artery perfusion of the hand.
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From the 12nd Cardiology Department of Hellenic Red Cross Hospital, Athens, Greece; 21st Cardiology Department of Hellenic Red Cross Hospital, Athens, Greece; and 3Department of Endocrinology, Diabetes and Metabolism, Evangelismos Hospital, Athens, Greece.
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 September 30, 2014, provisional acceptance given November 14, 2014, final version accepted February 2, 2015.
Address for correspondence: Christos Maniotis, MD, PhD, 2nd Cardiology Department of Hellenic Red Cross Hospital, Athens, Greece. Email: chrmn21@gmail.com
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