| | Report on initial experience with transradial access for carotid artery stentingReceived 20 December 2006; accepted 13 February 2007. ObjectiveCarotid artery stenting is emerging as an attractive alternative to surgical endarterectomy for the treatment of carotid artery disease. This study reports our initial experience using the radial artery as access for carotid stenting. MethodsA retrospective study was performed in which 20 consecutive patients at high risk for carotid endarterectomy underwent carotid stenting with cerebral protection using radial artery access. All procedures were performed in the operating room from March 2006 to December 2006. Seven lesions were symptomatic, and 13 lesions were asymptomatic. Patients were evaluated for development of stroke or transient ischemic attacks, myocardial infarction, access site complications, procedural success, time to patient mobilization, and need for intravenous analgesia. ResultsProcedural success was achieved in 18 patients (90%). Intense radial artery vasospasm resulted in one failure, and the second failure occurred in a patient with a left-sided carotid lesion and type I arch. The 30-day incidence of stroke, transient ischemic attacks, myocardial infarction, and death was 0%. Radial artery occlusion only occurred in the one patient because of the development of intense vasospasm during the procedure. One patient had persistent local pain requiring intravenous medication for relief. All patients were mobilized ≤2 hours of intervention and were discharged on the first postoperative day. ConclusionsCarotid artery stenting with cerebral protection devices can be safely and effectively performed, with acceptable morbidity and high technical success, by using radial artery access. We recommend obtaining imaging of the aortic arch and supra-aortic trunks with computed tomography, as well as a duplex scan of radial artery, before attempting carotid artery stenting using radial artery access. Further study is needed before recommending that femoral access be replaced by radial access for carotid artery intervention. Stenting of the internal carotid artery has gained wide acceptance in the treatment of occlusive disease of the extracranial cerebral arteries.1 The results are constantly improving because of the introduction of new embolic protection devices and small caliber catheter and stenting systems. The conventional way to access the common carotid artery (CCA) during endovascular interventions is through the femoral artery; however, this approach is not always possible because of vessel pathology or aberrant anatomy in the iliofemoral arteries and the aortic arch. A transbrachial or a direct transcervical approach can be used as an alternative when femoral access is not possible. We have performed carotid artery stenting (CAS) in our hospital since 2001. We initially used the transcervical approach if femoral access was not possible. We decided to start using transradial access for CAS after several successful cerebral angiographies were performed by radial artery access. In this article, we report our early experience with transradial access and CAS. We also describe our technique and provide a review of the literature. Materials and methods  During the study period (March 2006 to December 2006), 46 patients were treated with carotid stents. This study is a retrospective review of 20 consecutive patients in whom CAS was performed by using transradial access. These 20 consecutive patients were treated by the first (L. P.) and senior authors (R. K.) in the institution. All patients underwent CAS because they were considered high risk for open carotid endarterectomy. The grade of carotid stenosis was determined by use of preoperative duplex ultrasonography, computed tomographic angiography (CTA), or magnetic resonance angiography (MRA), but the degree of stenosis was always verified by intraoperative angiography. All CAS procedures were performed in the operating room using a portable C-arm (OEC 9800 Plus, General Electric Medical Systems, Waukesha, Wis). All patients provided informed consent before any intervention. The major complications (≤30 days) evaluated were perioperative myocardial infarction, stroke, transient ischemic attacks (TIAs), and death. Also evaluated were technical success, peripheral nerve injury, access site hematoma, radial artery occlusion, pain, and early ambulation. Description of technique An Allen’s test is performed in every patient before transradial access. The test result is considered normal (negative Allen’s test) if the palm color returns to normal ≤10 seconds.2 The right arm of the patient is positioned on an arm holder, abducted at 45°. The wrist is hyperextended over a gel pad, and the arm is prepared and draped to the axilla. After access is gained, the arm can be left in an abducted position for left-handed operators or placed parallel to the body to facilitate catheter manipulations for right-handed operators. Local anesthesia is infiltrated along the distal radial pulse. The artery is punctured with a Check-Flo micropuncture radial artery access set (Cook, Indianapolis, Ind), and a 5F short sheath is introduced. Systemic unfractionated heparin is administered intravenously to achieve an activated clotting time of >350 seconds, and a spasmolytic “cocktail” of 200 μg of nitroglycerin and 2.5 mg of verapamil is given intra-arterially through the side arm of the sheath to prevent spasm secondary to vessel manipulation. It is necessary to use multiple views to optimize visualization of the carotid anatomy. We use variable projections and patient head positions to obtain the widest angle at the carotid origin. The right or left CCA is cannulated with an appropriately shaped diagnostic catheter and hydrophilic guidewire. We prefer to use the internal mammary artery (IMA), and Simmons 1 or Berenstein catheter configurations for cannulation of the right CCA. All selective catheters are Imager II from Boston Scientific, Natick, Mass. For cannulation of the left CCA in patients with bovine arch anatomy, we use the Berenstein or JB1 catheter (Imager II) configurations. For cannulation of the left CCA in patients with standard (normal) aortic arch anatomy, we prefer to use the Simmons 2 (Imager II) selective diagnostic catheter. The catheter is then advanced just proximal to the carotid bifurcation and an Amplatz Super Stiff (Boston Scientific) wire is positioned in the external carotid artery to provide support for the subsequent sheath exchange. In cases of angulated, tortuous aortic branch vessels, where access with the Super Stiff wire cannot be maintained, we use a telescope technique in which a hydrophilic 0.035-inch (260 cm) Glidewire (Terumo Medical Corporation, Tokyo, Japan) is used to advance a diagnostic angiography catheter into the distal CCA. The selected guiding sheath is then advanced over the catheter–wire combination just proximal to the carotid bulb. We use a 6F or 7F, 90-cm hydrophilic guide sheath; either a Terumo Destination carotid guiding sheath or a Shuttle SL Flexor with a Tuohy-Borst sidearm (Cook). The size of the guide sheath must accommodate the carotid stent platform (usually 5F or 6F) and allow for continuous flushing with heparinized saline and adequate contrast administration during the procedure. We have found that using matched French sizes for the guide sheath and the carotid stent limits our ability to perform adequate flushing and contrast injections; thus, we oversize the guide sheath by one French size in relation to the carotid stent system that is utilized. Roadmap angiography is performed to confirm that the degree of stenosis is ≥60%. The degree of angiographic carotid artery stenosis is calculated according to North American Symptomatic Carotid Artery Endarterectomy Trial (NASCET) criteria.3 The embolic protection device is deployed in the usual fashion, and after administration of 1 mg of intravenous atropine, predilatation of the carotid stenosis with a small diameter (3.0 or 3.5 mm) angioplasty balloon (Ultrasoft SV, Boston Scientific) is performed if necessary to facilitate positioning of the carotid stent. The carotid stent is deployed and postdilated with a 5.0-mm-diameter angioplasty balloon (Ultrasoft SV, Boston Scientific), if necessary. We prefer to use the Zilver Stent (Zilver 518, Cook) because of the very low profile (5F), but we have also used 6F systems such as the Carotid Wallstent Monorail (Boston Scientific) or Precise Stent (Cordis Corp, Miami, Fla). After completion angiography, the protection system and the sheath are removed without reversal of anticoagulation. The puncture site is compressed by hand for 5 minutes. We then use a 5-mL syringe, with both ends cut off that has been wrapped with gauze, to maintain pressure on the radial artery puncture site for 6 hours. The syringe is positioned longitudinally along the course of the distal radial artery and held in place with a noncircumferential elastic tape. The patient is moved to the postoperative care unit for 2 hours and then sent to the ward. The patient’s neurologic status is evaluated by the interventionalist at the completion of the procedure, at removal of the bandage, before discharge, and at 30-day follow-up. If a neurologic deficit is observed, then a neurologist is consulted to evaluate the patient. Patients are allowed to ambulate and eat without restrictions. They are kept for observation for one night in the hospital and discharged home on the first postoperative day. The radial pulse is palpated, and the adequacy of the hand’s blood supply is evaluated clinically when the dressing is removed, at the time of discharge, and at 30-day follow-up. Results The mean age of the treated patients (14 men, 6 women) was 72 years (range, 62 to 84 years). Seven patients were symptomatic (TIAs or stroke, or both; >60% stenosis). Thirteen patients were asymptomatic but had high-grade stenosis (>80%) on CTA, MRA, or conventional duplex ultrasonography. We did not exclude patients from transradial access (TRA) on the basis of preoperative imaging. The patients had the following comorbidities: 65% were smokers, 30% were diabetic, 70% were hypertensive, 45% had coronary artery disease, and 40% were hypercholesterolemic (see Table I). In 12 patients, the right carotid bifurcation had disease. Eight patients had left sided carotid stenosis, and four also had a bovine arch. Type I arch anatomy was present in 16 patients, and four had type II arch anatomy.4 | | |  | Characteristic | No. of patients (%) | |
|---|
| Symptomatic | 7 (35) | | | Asymptomatic | 13(65) | | | Smoking | 13(65) | | | Diabetes | 6(30) | | | Hypertension | 14(70) | | | Coronary artery disease | 9(45) | | | Hypercholesterolemia | 8(40) | | | Carotid artery disease | | | | Right | 12(60) | | | Left | 8(40) | | | Bovine arch | 4(20) | | | Type I arch | 16(80) | | | Type II arch | 4(20) | | | | |
We were able to successfully complete the CAS procedure using transradial access in 18 of 20 patients (90% technical success rate). The mean procedure time was 67 minutes (range, 45 to 90 minutes). In 15 patients, one diagnostic catheter was used, and two diagnostic catheters were used in three patients. The mean fluoroscopy time was 17 minutes (range, 11 to 29 min). Intense radial artery vasospasm developed in one patient that precluded passage of the guiding sheath. This patient was a 70-year-old man with diabetes who had a very calcified radial artery. After removal of the 7F sheath, we were unable to palpate a radial pulse proximal to the puncture site, but there was a Doppler signal in the palmar arch and no sign of hand ischemia. In the other patient, the left CCA could not cannulated. This patient had a type I arch, and despite three catheter exchanges, we were unable to cannulate the orifice of the left CCA and the procedure was aborted (Fig 1). No perioperative myocardial infarctions, strokes, TIAs, or deaths occurred (Table II). In the patient where radial artery spasm prevented completion of the procedure, the radial artery occluded postoperatively, but the patient remained asymptomatic. All other patients had clinically patent access arteries at the time of discharge and at the 30-day follow-up. No access site hematomas developed that required surgical evacuation. One patient had incapacitating pain requiring intravenous analgesia. All patients were ambulatory ≤2 hours of intervention. There were no instances of peripheral nerve injury or digital ischemia. All patients were discharged home on the first postoperative day. | | | | Outcome | No. of Patients (%) | |
|---|
| Stroke/transient ischemic attack | 0(0) | | | Acute myocardial infraction | 0(0) | | | Radial artery occlusion | 1(5) | | | Incapacitating pain | 1(5) | | | Surgical hematoma | 0(0) | | | Mobilization in 2 hours | 20(100) | | | | |
Discussion Systematic reviews of observational studies provide considerable data to support the performance of CAS.1 According to a publication by Burton and Lindsay,5 in which 2992 patients were evaluated in 26 studies from 2002 to 2004, CAS is associated with an adverse event rate of 2.4% ± 0.3%, which is comparable to that of current carotid endarterectomy.5, 6, 7, 8, 9 Most interventionists prefer to use the transfemoral approach for access. This method provides adequate access in most situations and allows traversal of the arch and negotiation of acute angles at the ostia of the great vessels. Femoral access is not possible in some patients. Extensive atherosclerotic disease in the aortic arch, atypical aortic arch anatomy, dissection of the thoracic aorta, iliofemoral occlusive disease, and infection in the groin are some of the limitations for femoral access. In such cases, alternate access sites need to be considered, such as transcervical, transbrachial, or transradial. The transcervical approach is more invasive because it usually requires a small cervical incision to prevent potentially disastrous access site complications and ensure hemostasis due to the lack of percutaneous carotid puncture closure systems at present. The transbrachial approach may also be difficult to perform and can result in severe complications, including brachial sheath hematoma, compartment syndrome, injury to the median nerve, or ischemia to the hand.10 Major access site complications were more frequently encountered during coronary artery stenting (CAS) after transbrachial and transfemoral puncture compared with transradial access according to the Access study.11 Significant benefit in favor of transradial access was found in the multicenter randomized Access study comparing transfemoral, transbrachial, and transradial approaches for coronary artery stenting. Radial access was associated with fewer major complications (2.0 % for transfemoral, 2.3% for transbrachial, 0% for transradial) and had the same technical success rate (91% to 92%) as transfemoral and transbrachial access. Percutaneous transradial coronary angioplasty led to asymptomatic loss of the radial pulse in approximately 3% of patients. As carotid stenting devices become increasingly more pliable and lower in profile, the percentage of periprocedural radial artery occlusions is expected to decrease. The right transradial approach is particularly efficacious for cannulation of the right CCA or the left CCA in the presence of a bovine arch because it minimizes the risk of particulate embolization. The advantage of the right transradial approach is the avoidance of catheter manipulations in the aortic arch, because there is no need to negotiate the ostia of the arch vessels. The incidence of cerebral embolization during CAS procedures using a transfemoral approach was analyzed by Hammer et al.12 Their study demonstrated that 40% of the patients had new ischemic lesions in postoperative diffusion-weighted MRI, and that 62% of the cases with positive diffusion-weighted MRI had embolic lesions that were found outside the vascular territory of the treated internal carotid artery, thus suggesting embolization from the aortic arch. Cannulation of the left CCA in patients with type I arch anatomy may be more difficult or impossible through the right radial artery. If this is the case, standard femoral access can be used for CAS procedure. We now perform preoperative CTA and MRA to evaluate aortic arch anatomy that might preclude successful transradial access. The use of the transradial approach for coronary angiography was first described by Lucien Campeau in 1989.13 The safety and feasibility of this approach in coronary angioplasty and stenting have been reported in several studies.14, 15 As a consequence of these favorable initial results and reduced bleeding risk, despite use of potent antithrombotic and platelet therapy, transradial access for coronary intervention has gained widespread worldwide acceptance. Transradial access provides excellent postoperative comfort for the patient, with practically immediate ambulation after the procedure. Researchers have even found a cost reduction in several studies because of the low incidence of complications, no need for a closure devices, and reduced length of stay.16, 17 Use of transradial access for CAS has been reported in sporadic case reports.18, 19 Despite excellent results, this method has not gained widespread acceptance. The reasons for the infrequent use of transradial access for CAS may have been the large, inflexible, first-generation stenting systems and sheaths. Devices have quickly been developed, however, that are hydrophilic, flexible, kink-resistant, and that have low profiles (5F to 6F). These technical improvements should facilitate use of TRA access. The mean radial artery internal diameter is 3.1 ± 0.60 mm in men and 2.8 ± 0.60 mm in women.20 Further downsizing of carotid stents should theoretically allow most patients to accommodate the procedure through transradial access. Similar to every method in the beginning, the transradial access technique also has a learning curve. The puncture of this relatively small-caliber artery is not always easy. The radial artery is very vasoreactive and tends to spasm; therefore, it is important to try to achieve entry on the first puncture. The radial artery has a small lumen, but its muscular wall dilates to accommodate 8F diameter sheaths.21, 22 It is very important to administer spasmolytic medication (isosorbide dinitrate, lidocaine, or verapamil) intra-arterially immediately after the puncture. This will decrease the incidence of vasospasm and radial artery occlusion from 60% to 3%.2 Periprocedural pain and paresthesias may be considerably reduced by the use of micropuncture systems to access the radial artery. Complications at the radial artery puncture site are extremely rare owing to the anatomy of the wrist. The median nerve courses apart from the artery in this location; therefore, it is almost impossible to cause an injury to the nerve. There have been reports of inflammatory reaction with granuloma formation in patients who had transradial coronary artery catheterization using hydrophilic sheaths. This complication occurred in 1.6% of patients during a 3-year period, but despite severe initial pain, there were no adverse long-term sequelae.23 The artery lies very superficially on the radius; therefore, it is relatively easy to access and compress. Ease and effectiveness of compressibility are vital for interventions where patients have received anticoagulation medication. In cases of postoperative bleeding after radial access, patients are able to recognize and control the bleeding themselves. Even when the radial artery occludes, the hand is not jeopardized because of the dual blood supply through the ulnar artery and palmar arch. Most patients remained asymptomatic despite radial artery occlusion if they had a negative (normal) Allen’s test, and it is notable that the radial pulse had returned to normal at the 1-month follow-up in half of the patients.2 A properly performed and documented Allen’s test is imperative before use of transradial access. The contraindications to use of transradial access are a nonpalpable radial pulse, a positive (abnormal) Allen’s test, calcinosis, and need to maintain the radial artery for dialysis access. Radial artery size and degree of calcinosis can be determined by preoperative duplex evaluation. In this pilot study, we did not perform duplex evaluation of our patients’ radial arteries; however, after further review of our results and the literature, we now recommend obtaining a duplex study to evaluate size and suitability of the radial artery before sheath insertion. Contrary to public perception, Saito et al20 have published that there is no relationship between radial artery internal diameter and weight, height, or patient body surface area. Stella et al2 also comment that there is no correlation between gender and postprocedural radial artery occlusion.2 We perform transradial access in patients with noncalcified arteries sized ≥2.5 mm on duplex because that size will accommodate the outer diameter of a 6F sheath. Conclusion Our early experience with transradial access confirms that CAS can be effectively performed through this approach with acceptable morbidity and with high technical success and patient satisfaction. We propose that transradial access is a safe, ideal alternative to transfemoral access and do not restrict its use just to patients with difficult femoral access. We preferentially perform CAS with transradial access in patients with right-sided carotid lesions and left-sided carotid lesions in the presence of bovine or type II or III arch anatomy (Fig 2). We recommend obtaining imaging of the aortic arch and supra-aortic trunks with CTA and MRA, as well as a duplex scan of radial artery before attempting CAS when using transradial access. With this approach, patients with unfavorable aortic arch and radial artery characteristics that impact procedural success can be excluded. A multicenter, randomized, controlled trial is needed to definitively answer whether transradial access can replace transfemoral access routinely during CAS. Author contributions Conception and design: LP, CC, ZR, RK Analysis and interpretation: LP, CC, CB, RK Data collection: LP, CC, CB Writing the article: LP, CC Critical revision of the article: LP, CC, ZR, RK Final approval of the article: RK Statistical analysis: LP, CC Obtained funding: Not applicable Overall responsibility: RK LP and CC contributed equally to this work. References 1. 1Yadav JS, Wholey MH, Kuntz RE, Fayad P, Katzen BT, Mishkel GJ, et al. ; Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy Investigators. Protected carotid-artery stenting versus endarterectomy in high-risk patients N Engl J Med. 2004;351:1493–1501. 2. 2Stella PR, Kiemeneij F, Laarman GJ, Odekerken D, Slagboom T, van der Wieken R. Incidence and outcome of radial artery occlusion following transradial artery coronary angioplasty. Cathet Cardiovasc Diagn. 1997;40:156–158. MEDLINE |
CrossRef
3. 3North American Symptomatic Carotid Artery Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991;325:445–453. MEDLINE 4. 4Lin SC, Trocciola SM, Rhee J, Dayal R, Chaer R, Morrissey NJ, et al. Analysis of anatomic factors and age in patients undergoing carotid angioplasty and stenting. Ann Vasc Surg. 2005;19:798–804. Abstract | Full Text |
Full-Text PDF (593 KB)
|
CrossRef
5. 5Burton KR, Lindsay TF. Assessment of short-term outcomes for protected carotid angioplasty with stents using recent evidence. J Vasc Surg. 2005;42:1094–1100. Abstract | Full Text |
Full-Text PDF (171 KB)
|
CrossRef
6. 6Ouriel K, Hertzer NR, Beven EG, O’Hara PJ, Krajewski LP, Clair DG. Preprocedural risk stratification: identifying an appropriate population for carotid stenting. J Vasc Surg. 2001;33:728–732. Abstract | Full Text |
Full-Text PDF (71 KB)
|
CrossRef
7. 7Stoner MC, Abbott WM, Wong DR, Hua HT, LaMuraglia GM, Kwolek CJ. Defining the high risk patient for carotid endarterectomy: an analysis of the prospective national surgical quality improvement database. J Vasc Surg. 2006;43:285–296. Abstract | Full Text |
Full-Text PDF (186 KB)
|
CrossRef
8. 8Goodney PP, Schermerhorn ML, Powell RJ. Current status of carotid artery stenting. J Vasc Surg. 2006;43:406–411. Abstract | Full Text |
Full-Text PDF (115 KB)
|
CrossRef
9. 9Ahmadi R, Willfort A, Lang W, Schillinger M, Alt E, Gschwandtner ME. Carotid artery stenting: effect of learning curve and intermediate-term morphological outcome. J Endovasc Ther. 2001;8:539–546. MEDLINE |
CrossRef
10. 10Heenan SD, Grubnic S, Buckenham TM, Belli AM. Transbrachial arteriography: indications and complications. Clin Radiol. 1996;51:205–209. Abstract |
Full-Text PDF (2985 KB)
|
CrossRef
11. 11Kiemeneij F, Laarman GJ, Odekerken D, Slagboom T, van der Wieken R. A randomized comparison of percutaneous transluminal coronary angioplasty by the radial, brachial and femoral approaches: the Access study. J Am Coll Cardiol. 1997;29:1269–1275. Abstract | Full Text |
Full-Text PDF (183 KB)
|
CrossRef
12. 12Hammer FD, Lacroix V, Duprez V, Grandin C, Verhelst R, Peeters A. Cerebral microembolization after protected carotid artery stenting in surgical high risk patients: results of a 2-year prospective study. J Vasc Surg. 2005;42:847–853. Abstract | Full Text |
Full-Text PDF (126 KB)
|
CrossRef
13. 13Campeau L. Percutaneous radial artery approach for coronary angiography. Cathet Cardiovasc Diagn. 1989;16:3–7. MEDLINE |
CrossRef
14. 14Kiemeneij F, Laarman GJ, de Melker E. Transradial artery coronary angioplasty. Am Heart J. 1995;129:1–7. Abstract |
Full-Text PDF (798 KB)
|
CrossRef
15. 15Kiemeneij F, Laarman GJ. Percutaneous transradial artery approach for coronary stent implantation. Am Heart J. 1995;128:167–174. MEDLINE |
CrossRef
16. 16Cooper CJ, El-Shiekh RA, Cohen DJ, Blaesing L, Burket MW, Basu A, et al. Effect of transradial access on quality of life and cost of cardiac catheterization: a randomized comparison. Am Heart J. 1999;138:430–436. Abstract | Full Text |
Full-Text PDF (214 KB)
|
CrossRef
17. 17Slagboom T, Kiemeneij F, Laarman GJ, van Der Wieken R, Odekerken D. Actual outpatient PTCA: Results of the OUTCLAS pilot study. Catheter Cardiovasc Interv. 2001;53:204–208. MEDLINE |
CrossRef
18. 18Levy EI, Kim SH, Bendok BR, Qureshi AI, Guterman LR, Hopkins LN. Transradial stenting of the cervical internal carotid artery: technical case report. Neurosurgery. 2003;53:448–451. 19. 19Yoo BS, Lee SH, Kim JY, Lee HH, Ko JY, Lee BK, et al. A case of transradial carotid stenting in a patient with total occlusion of distal abdominal aorta. Catheter Cardiovasc Interv. 2002;56:243–245. MEDLINE |
CrossRef
20. 20Saito S, Ikei H, Hosokawa G, Tanaka S. Influence of the ratio between radial artery inner diameter and sheath outer diameter on radial artery flow after transradial coronary intervention. Catheter Cardiovasc Interv. 1999;46:. 21. 21Loubeyre K, Fajadet J, Laborde JC, Jorgan C, Cassagneau B, Laurent JP. Transradial angioplasty: experience with 7F guiding catheters. Eighth Complex Coronary Angioplasty Course. 1997;259–267. 22. 22Wu SS, Galani RJ, Bahro A, Moore JA, Burket MW, Cooper CJ. 8 French transradial coronary interventions: clinical outcome and late effects on the radial artery and hand function. J Invas Cardiol. 2000;12:605–609. 23. 23Kozak M, Adams DR, Ioffreda MD, Nickolaus MJ, Seery TJ, Chambers CE, et al. Sterile inflammation associated with transradial catheterization and hydrophilic sheaths. Catheter Cardiovasc Interv. 2003;59:207–213. MEDLINE |
CrossRef
Department of Vascular Surgery and Endovascular Interventions, Augusta Hospital, Düsseldorf, Germany.  Reprint requests: Laszlo Pinter MD Augusta Krankenhaus, Amalien Strasse 9, Dusseldorf 40472, Germany.
Competition of interest: none. PII: S0741-5214(07)00322-9 doi:10.1016/j.jvs.2007.02.035 © 2007 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. | |
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