Author + information
- †Interventional Cardiology, Quebec Heart-Lung Institute, Quebec City, Quebec, Canada
- ‡Medical Malpractice Department, Cipriani & Werner PC, Scranton, Pennsylvania
- §Penn State Heart and Vascular Institute, M.S. Hershey Medical Center, Hershey, Pennsylvania
- ↵∗Reprint requests and correspondence:
Dr. Olivier F. Bertrand, Interventional Cardiology, Quebec Heart-Lung Institute, 2725, Chemin Ste Foy, Quebec City QC G1V 4G5, Canada.
Transradial access (TRA) is becoming widely adopted by interventional cardiologists around the world as the preferred access site for coronary diagnostic angiography and interventions. Although it was initially described >20 years ago, TRA adoption remained stagnant for a long time despite zealous grassroots promotion by a small group of aficionados, as it was generally ignored by a large majority of interventional cardiologists. Recently, several factors have spawned growing popularity of TRA, including better recognition of the detrimental impact of periprocedural bleeding, the reduction of costs associated with the neutralization of vascular complications and early hospital discharge, and the overwhelming preference of patients.
Modern medicine has moved from its traditional practice as an art on the basis of unique interaction between practitioner and patient to a practice guided by evidence-based medicine supported by the results of clinical trials and observational studies. Because of a lack of support from large industry funding, it took a long time to perform randomized clinical trials to establish the benefits and safety of TRA compared with the standard transfemoral approach. There is now good evidence that shows substantial and drastic reductions of vascular access complications and bleeding with TRA after diagnostic angiography and interventions in all clinical scenarios (1). More recent studies have even shown reductions in early mortality with TRA for patients undergoing primary percutaneous coronary intervention, although the extent and exact mechanisms of such benefit remain debatable (2).
If the benefits of TRA and patients' preference for it become widely acknowledged, efforts should be directed so that the radial artery (or the ulnar artery in some cases) becomes the default access site, with the femoral artery reserved for bail-out access. Yet it must be recognized that TRA is not always technically feasible, so that even in experienced hands, primary failure or crossovers to the femoral approach may still occur (3). For that reason, optimal access-site management in general and judicious selection of antithrombotic regimens in particular for the femoral approach remain paramount.
The types of patients to whom TRA should be eventually denied remain a hot topic, and the issue of using or not the Allen test (AT) before undertaking TRA is probably one of the most important. The main controversy with the use of the subjective AT, or the more objective method of oximetry-plethysmography, is to evaluate whether those tests can reliably predict significant ischemic risk for the hand, presumably due to periprocedural radial artery occlusion (RAO).
Although acute RAO has been described since the initial description of TRA, its clinical relevance remains controversial. In a recent international survey among radial operators, the incidence of RAO at hospital discharge was not assessed in 50% of cases (4). Although RAO has been documented in up to 30% of patients after transradial catheterization, it is a common clinical observation that RAO remains asymptomatic in the large majority of patients. In contrast, it should be recalled that acute limb ischemia has been reported in up to 2% of patients after periprocedural femoral artery occlusion (5). Reports of leg amputation after transfemoral catheterization exist, and death can occur, directly resulting from femoral artery injuries or retroperitoneal bleeding. To date, no hand or finger amputation has been reported after TRA for diagnostic angiography or intervention, even though TRA has been used worldwide for >20 years (6). It is obvious that the generous and redundant vascularization of the hand by the radial, ulnar, and interosseous arteries provides protection against distal ischemia in case of RAO after catheterization (Fig. 1). This does not guarantee that distal finger ischemia or gangrene cannot occur after radial artery manipulation. However, in most cases of distal ischemia reported in the published data, AT results were considered normal before the procedure, and angiographic findings revealed distal embolization in addition to RAO (7).
In the RADAR (Should Intervention Through Radial Approach be Denied to Patients With Negative Allen's Test Results?) study, reported in this issue of the Journal, Valgimigli et al. (8) studied the relationship between functional assessment of dual-artery circulation to the hand (using the AT and plethysmography-oximetry) and measures of distal ischemia (lactate), collateralization between the radial and ulnar arteries (ulnar frame count), and strength and discomfort of the hand after TRA. Although their catheterization laboratory is a radial-first laboratory, and they intended to study all comers, only 203 of the 942 screened patients (22%) were ultimately recruited and completed the study. AT results were categorized as normal in 40%, intermediate in 30%, and abnormal in 30% of the patients. This means that in a typical patient group referred for elective catheterization, 60% of patients had mean time to recolor the skin of ≥6 s after releasing ulnar artery compression and maintaining occlusion of the radial artery. Conversely, the D pattern after plethysmography-oximetry, thought to indicate poor collateralization between the vascular palmar arches, was found in 40% of the patients, but only in those with abnormal AT results. This indicates that in patients referred for coronary angiography, compression of the radial artery while keeping the ulnar artery patent will lead to very variable results in terms of timing to the subjective assessment of skin coloration or the more objective reading of oximetry-plethysmography curves. Furthermore, there was a weak correlation between the 2 tests. The investigators also noted large variability over time in the oximetry-plethysmography curves.
What is the impact of these pre-tests on ischemia, angiography, and the function of the hand during and after transradial catheterization? First, the investigators nicely demonstrate that the capillary lactate measured at the thumb level (the primary end point) immediately after the procedure and up to 1 year later remained independent of the results of the AT or oximetry-plethysmography. Second, it is remarkable that the lactate levels in patients with abnormal AT results were virtually identical to those in a previously published Canadian study in which operators occluded the radial artery for 30 min with a clamp. Importantly, it must be noted that the levels of lactate during or after these occlusive tests of the radial artery remained in normal range (9). Furthermore, it is worth observing that higher lactate levels were measured during the hemostasis period than during the period when the sheaths were in place. On the basis of this study, it is reassuring, although not surprising, that transradial catheterization does not induce an elevation in lactate levels, even in patients with persistent RAO.
For the first time, Valgimigli et al. (8) have studied ulnar frame count on the basis of the technique developed by the Thrombolysis In Myocardial Infarction group (the lower the frame count, the better). Although it must be acknowledged that the ulnar frame count may vary according to proximal as well as distal vasculature changes, the investigators did observe a number of meaningful changes. Before the procedure (after radial sheath insertion), ulnar frame counts were significantly higher, in accordance with AT results. Yet the range of values in patients with abnormal AT results was wider than in those with normal and intermediate AT results. At the completion of the study (about 1 h later), ulnar frame counts decreased in all patients, albeit with significant reductions only in patients with abnormal AT results. This may indirectly suggest that proximal or distal collateral vessels were recruited, especially in patients with abnormal AT results, because ulnar frame count is performed when RAO is produced by the radial sheath.
Most important, the investigators also performed functional testing of the hand. Using a handgrip strength test, they did not find any difference according to AT results, and strength remained stable or slightly increased in all groups over time. Finally, on the basis of visual analogue scale ratings, discomfort in the hand was moderately increased during the transradial catheterization and hemostasis phase, but it almost disappeared after 24 h, with no residual discomfort up to 1 year later. Again, no relationship with AT or oximetry-plethysmography results was noted.
From this carefully performed mechanistic study, one can conclude that the AT and oximetry-plethysmography are not reliable tests to predict distal ischemia, loss of strength, or discomfort after transradial catheterization. In the context of the privileged relationship between the cardiologist and the patient, or from a legal point of view, it is more important to discuss the relative benefits and risks of radial access compared with femoral access for diagnostic angiography and intervention. Ultimately, the selection of femoral versus radial access site should take into account the potentially life-threatening femoral complications compared with the less severe radial complications. Moreover, on the basis of current evidence-based medicine, concerted efforts between physicians and staff members should be combined to reduce the risks of periprocedural RAO, not from the fear of distal complications but because chronic RAO hampers future use of the radial artery as a repeat access site (10).
On the basis of the results of RADAR, we believe that the denial of radial access for diagnostic angiography or interventions solely on the basis of an abnormal AT or oximetry-plethysmography curve is not warranted, because these tests are not scientifically predictive of pathologic rises in lactate levels, weakness in the hand, or persistent discomfort during or after transradial catheterization. The time has come to remove the AT from pre-procedural triage for transradial catheterization. We need to refocus our attention on the use of oximetry-plethysmography and other techniques to guide “patent hemostasis” once the transradial procedure is completed to minimize RAO (11,12).
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
- Bertrand O.F.,
- Patel T.
- Abdelaal E.,
- Brousseau-Provencher C.,
- Montminy S.,
- et al.
- Bertrand O.F.,
- Rao S.V.,
- Pancholy S.,
- et al.
- Valgimigli M.,
- Campo G.,
- Penzo C.,
- et al.
- Van Hall G.,
- Jensen-Urstad M.,
- Rosdahl H.,
- Holmberg H.C.,
- Saltin B.,
- Calbet J.A.
- Pancholy S.,
- Coppola J.,
- Patel T.,
- Roke-Thomas M.