Transradial Approach to Subclavian Artery Stenting

ABSTRACT: Background. Subclavian artery angioplasty has been traditionally performed via the transfemoral approach. Transradial access is becoming increasingly used for coronary as well as for certain peripheral vascular beds. We describe our experience with transradial access for subclavian artery stenting. Methods. We performed a retrospective review of subclavian artery interventions from 2007 to 2009 at our institution. Demographics, clinical data, lesion and procedural characteristics were collected. Safety and efficacy endpoints were recorded, and follow-up was performed at 1 year post intervention. Descriptive statistics were used to analyze the data. Results. Fourteen cases of subclavian artery stenting, including 5 total occlusions, were performed using transradial access. The procedural success was 93%, and there were no complications recorded. All patients remained symptom-free at 1 year follow up. Conclusions. Subclavian artery stenting can be safely performed via transradial access with success rates comparable to the transfemoral approach. J INVASIVE CARDIOL 2010;22:204–206 Subclavian artery stenosis is a rare condition that is usually asymptomatic and may not require intervention. However, treatment is indicated for patients with symptoms of arm ischemia such as upper limb claudication or pain at rest. ¹ It is also indicated for those who experience subclavian steal syndrome, which occurs if the stenosis is severe enough to cause retrograde blood flow in the vertebral artery. These patients can present with neurological symptoms due to cerebral ischemia directly triggered by arm exercise. ² Intervention may also be considered either for patients who have undergone coronary artery bypass graft (CABG) surgery using the left internal mammary artery (LIMA) as a conduit or in those individuals where a LIMA conduit will be utilized for a planned CABG surgery. ^3,4 In these cases, the subclavian artery becomes a functional part of the coronary circulation, and patients can present with coronary steal symptoms such as angina. ⁵ Surgical and endovascular treatments are available options for subclavian artery stenosis. Both procedures are similar in long-term patency and effectiveness. However, endovascular intervention is becoming more favorable due to patient convenience, shorter hospitalization, and decreased complications. ^1,4,5 Traditionally, endovascular subclavian intervention was performed via the femoral approach. In recent years, the transradial approach has evolved as a safer alternative for both cardiac catheterization and percutaneous peripheral interventions particularly because of decreased bleeding complications. ^6-8 The primary objective of this study is to establish the safety and efficacy of transradial angioplasty for subclavian artery stenosis. We describe our initial experience with the ipsilateral radial approach for subclavian artery intervention.

Methods

We reviewed our database for subclavian artery interventions from 2007 to 2009. Subjects who underwent the procedure via a transradial approach were selected for this review. Demographics, clinical presentation, comorbidities, and procedural details were recorded and analyzed. Lesion measurements were made using quantitative vascular analysis software (Version 4.4) provided by the GE Cardiovascular Imaging Workstation (GE Healthcare, Wauwatosa, Wisconsin). The subjects were followed out to 1 year, and telephone interviews were conducted to ascertain the recurrence of symptoms. Data on patency of the subclavian artery at 1 year, as assessed by either routine duplex ultrasonography or angiography performed for non-related reasons, were collected when available. Technique. The ipsilateral radial artery was imaged prior to the intervention via Duplex ultrasound. Once patency of the radial artery was established, access was obtained, and a short 5 French (Fr) introducer sheath was placed in the artery. A diagnostic angiogram was performed using a 5 Fr Multipurpose catheter. Once the anatomy was established, anticoagulation was achieved with non-fractionated heparin, for an activated clotting time of 250–300 seconds. The short radial sheath was then exchanged for a 6 Fr 65 cm-long sheath which was then advanced just distal to the distal end of the subclavian lesion. Nine (64.3%) lesions were crossed using a 0.035 inch stiff, hydrophilic glidewire, which was then exchanged for a 0.035 inch non-hydrophilic wire. Three (21.4%) lesions were crossed with a 0.014 inch guidewire, and 2 (14.3%) total occlusions were attempted using the Crosser® CTO recanalization catheter (FlowCardia, Inc., Sunnyvale, California), one of which (7.2%) could not be crossed. Once the lesion was crossed, a 5 Fr Pigtail catheter was advanced into the transverse aorta, and an aortogram was performed to visualize the aorto-subclavian junction. The diseased subclavian segments were pre-dilated with a balloon with an average diameter of 4.8 mm (range 4.0–7.0 mm). Self-expandable stents were sized 1–2 mm larger in diameter than the estimated reference vessel diameter (RVD), and balloon-expandable stents were sized close to the RVD. The average stent diameter was 8.8 mm (range 7.0–12.0 mm), and the average stent length was 34.5 mm (range 18-80 mm). Post-dilatation with non-compliant balloons 1–2 mm smaller in diameter than the RVD was performed in all cases where a self-expandable stent was placed. A final aortogram was performed at the end of the procedure in all cases. Selective steps of the procedure are illustrated in Figure 1. The sheath was removed at the end of the case, and local compression was applied to the access site for 2–3 hours. All patients were ambulatory at the end of the procedure.

Results

Patient characteristics. Our population consisted of 14 subjects (mean age 67 ± 10 years, 5 males) with subclavian artery stenosis treated via the transradial approach. Indications were subclavian steal syndrome (4 cases), coronary steal syndrome (3 cases), and arm claudication (6 cases). In one additional case, intervention was pursued in order to permit the use of a LIMA conduit for planned CABG surgery. The average body-mass index was 25 ± 4, and 10 (71.4%) subjects had a history of smoking. All subjects had hypertension and hyperlipidemia, and 9 (64.3%) had diabetes mellitus. Eleven (78.6%) had a documented history of coronary artery disease, including 3 (21.4%) with prior CABG surgery. Two (14.3%) patients had a prior stroke, and 3 (21.4%) had at least stage 3 chronic kidney disease. Lesion and procedural characteristics. There were 12 (85.7%) de novo lesions and 2 (14.3%) in-stent restenoses. Five (35.7%) lesions were totally occluded, and 11 (78.6%) lesions involved the ostium of the subclavian artery. Two (14.3%) lesions involved the origin of the vertebral artery. The mean gradient at angiography between the aorta and subclavian artery distal to the stenosis was 57 ± 26 mmHg. Lesion measurements are shown in Table 1. An average of 1.08 stents were deployed for each intervention and the ratio of self-expandable stent to balloon-expandable stent use was 3:1 (9 self-expandable stents vs. 3 balloon-expandable stents). Thirteen of the 14 patients (92.9%) were successfully treated with percutaneous transluminal angioplasty (PTA) and/or stent placement for lesions located in the subclavian artery. One of the total occlusions could not be crossed by either the radial or femoral approach. All lesions were initially accessed from the ipsilateral radial artery only, and in five cases the femoral artery was also accessed. In 3 cases, at the beginning of transradial experience, the femoral access was obtained for aortography and to facilitate stent positioning. This approach was completely abandoned for the later interventions. In the particular case that was not successful via radial access, the femoral approach was also attempted, without success. In one more case, femoral access was required to retrieve a dislodged stent that was placed via the radial artery; a larger stent was then successfully deployed via the radial approach. The final gradient between the aorta and subclavian artery after successful intervention ranged from 0–10 mmHg. There were no angiographic complications of distal embolization, perforation, or spasm. There were two cases of subclavian artery dissection, both occurring while attempting to cross total occlusions. One case was aborted, and one case was successfully completed. The average procedure time was 66.8 ± 39.9 minutes, with an average fluoroscopy time of 23.9 ± 18.9 minutes. The average dye usage was 178.8 ± 88.1 milliliters. There were no post-procedural complications including access site hematoma, myocardial infarction, stroke, or death. Follow up. All patients were contacted at 1 year, and no one reported any recurrence of their initial presenting symptoms. Duplex ultrasound or angiographic follow-up was available on 7 patients (50%) at 1 year confirming patency of the subclavian vessels in all cases. There was one (7.2%) patient who presented with in-stent restenosis that was discovered by symptom-guided repeat duplex ultrasound six months after the procedure was completed; the follow-up duplex ultrasound showed stent patency at 1 year after repeat intervention.

Discussion

Subclavian artery stenosis is relatively rare, but when present, could lead to significant clinical consequences like vertebro-basilar insufficiency and coronary steal syndrome with consequent angina. The current treatment modality is mainly endovascular, with surgical bypass being reserved for failed recanalization of totally occluded subclavian arteries. Among various technical aspects for subclavian angioplasty and stenting, the approach is clearly a topic for discussion. We describe in this small series of patients our approach with trans- radial subclavian intervention. The classical initial access for subclavian angioplasty has been femoral access.4,9 Brachial access has been described particularly for ostial occlusions, but we found no series describing transradial subclavian angioplasty. Although the present cohort is small, our rate of procedural success (93%) is comparable to the 85–91% rate of successful angioplasty that has been reported in larger series using primarily the transfemoral approach.4,9,10 Furthermore, our series suggests that intervention via the radial route can be performed safely with no neurologic or access-site complications, while conferring to the individual complete resolution of symptoms and an acceptable patency rate at 1 year (92.3%), based upon clinical and imaging follow-up. While stent embolization to the iliac artery occurred in one of our cases, this was resolved uneventfully without the need for surgical removal. The transradial approach is particularly beneficial for patients undergoing subclavian artery interventions for multiple reasons. First, the transradial approach virtually abolishes access site complications. ^6-8 Secondly, it provides stable guide support in the proximity of the stenosis. Third, this approach facilitates early ambulation and eventual same-day discharge even in the face of aggressive anticoagulant, and antithrombotic therapy. ^1,5 The limitations of transradial catheterization are mostly due to insufficient operator experience.8 Although the transradial approach for coronary interventions is technically more difficult than the femoral approach and requires more training for the operator, ⁷ the same is not true for the subclavian interventions. Crossover to a transfemoral catheterization is typically due to failure to puncture the radial artery, albeit there were no such cases in our database. Nevertheless, prior knowledge of radial artery patency enhances the success of radial artery puncture to virtually 100%. In the earlier cases of totally occluded subclavian arteries, we used dual radial/femoral access, but we later abandoned this strategy and used only the radial access site with similar success rate. Another concern with the radial approach seems to be related to imaging the location of the ostium of the subclavian artery. Usually, a pigtail catheter can be placed across the lesion in the ascending aorta to perform an aortogram. If the stenosis is too severe, one could predilate the lesion first, and perform the aortogram second. Either way, an aortogram should be performed prior to stent deployment to ensure adequate stent placement. In recent years, the armamentarium of tools to treat peripheral vascular disease has expanded, including stent options. The choice of balloon-epandable stents versus self-expandable stents should be tailored not only to lesion features but also arterial characteristics. The tortuous nature of the subclavian artery and its tendency to deform with movement makes stenting in this location riskier with higher potential for restenosis and fracture. ¹¹ To date, the only series of subclavian stenting with the more rigid balloon-expandable stents showed a primary patency of 95% in 26 patients at 1 year and 87% in 47 patients at 2.5 years. ^4,9 In our series, there were three times more self-expandable stents deployed, but the theoretical long-term benefit of these, given their innate resistance to compression, remains to be seen. While more precise positioning of balloon-expandable stents is an attractive feature, especially for ostial lesions, repositioning of self-expandable stents after partial deployment is possible, if needed, by pulling back the entire system to the desired location. Furthermore, the lower profile of self-expandable stents allows for easier passage through smaller introducer sheaths. Only one of our patients required upsizing of the radial sheath to 7 Fr in order to allow for entry of a larger-sized balloon-expandable stent. This limitation should soon be obsolete since a full range of balloon-expandable stents are now compatible with 6 Fr introducers. Although balloon-expandable stents remain the standard for subclavian artery stenting, our limited experience suggests that, at least in the short term, self-expandable stensts are as effective and safe. In conclusion, transradial angioplasty of the subclavian artery allows success rates comparable with the transfemoral approach, with the advantage of extremely limited access site complications and very early ambulation. Larger comparative series are needed to support these early findings.

References

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_____________________________________________________________________- From St. Vincent's Catholic Medical Center of New York, New York. The authors report no conflicts of interest related to the content herein. Manuscript submitted October 13, 2009, provisional acceptance given December 4, 2009, final version accepted February 8, 2010. Address for correspondence: Dr. Cezar S. Staniloae, St. Vincent's Catholic Medical Center of New York, Cardiology, 170 West 12 Street Spellman 990, New York, NY 10011. E-mail: cstaniloae@aol.com