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Results of Stent Graft Placement to Treat Cephalic Arch Stenosis in Hemodialysis Patients with Dysfunctional Brachiocephalic Arteriovenous Fistulas
CLINICAL STUDY
Results of Stent Graft Placement to Treat Cephalic Arch Stenosis in Hemodialysis Patients with Dysfunctional Brachiocephalic Arteriovenous Fistulas Robert G. Jones, MRCP, FRCR, Andrew P. Willis, MRCS, FRCR, Karen Tullett, RGN, and Peter L. Riley, MRCP, FRCR
ABSTRACT Purpose: To determine effectiveness of the VIABAHN (W.L. Gore & Associates, Flagstaff, Arizona) stent graft to treat cephalic arch stenosis in patients with dysfunctional brachiocephalic arteriovenous fistulas after inadequate venoplasty response. Materials and Methods: Between 2012 and 2015, patients with failed venoplasty of symptomatic cephalic arch stenosis received a VIABAHN stent graft. Follow-up venography was performed at approximately 3, 6, and 12 months. Data were retrospectively analyzed with patency estimated using Kaplan-Meier and log-rank methodology. There were 39 patients included. Results: Technical and clinical success was 100%. Primary target lesion patency was 85% (95% confidence interval [CI], 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency with regard to sex or age (P ¼ .8 and P ¼ .6, respectively). Primary assisted patency was 95% (95% CI, 82%–99%) at 3, 6, and 12 months. Access circuit primary patency was 85% (95% CI, 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency between patients with the stent graft as the first treatment episode in the cephalic arch and those that had previous intervention at this site (P ¼ .98). There were 48 repeat venoplasty procedures performed in the cephalic arch to maintain patency, including 7 repeat VIABAHN insertions. No complications were encountered. Conclusions: The VIABAHN stent graft is a safe, effective, and durable device for treating cephalic arch stenosis when venoplasty fails.
ABBREVIATION CI ¼ confidence interval
Cephalic arch stenosis is the most common cause of brachiocephalic fistula failure with a reported incidence of up to 70% in this patient group (1,2). Percutaneous venoplasty is considered the standard treatment for dialysis arteriovenous fistula stenosis associated with access From the Departments of Interventional Radiology (R.G.J., A.P.W., P.L.R.) and Renal Services (K.T.), Queen Elizabeth Hospital Birmingham, University Hospital, Edgbaston, Birmingham B152WB, United Kingdom. Received March 17, 2017; final revision received June 12, 2017; accepted June 16, 2017. Address correspondence to R.G.J.; E-mail: [email protected] R.G.J. has received honoraria from W.L. Gore & Associates (Flagstaff, Arizona), Boston Scientific (Marlborough, Massachusetts), and Merit Medical Systems, Inc (South Jordan, Utah). A.P.W. has received an honorarium from Boston Scientific. Neither of the other authors has identified a conflict of interest. Crown Copyright © 2017 Published by Elsevier, Inc., on behalf of SIR. All rights reserved. J Vasc Interv Radiol 2017; ▪:1–5 http://dx.doi.org/10.1016/j.jvir.2017.06.023
dysfunction (3). Although venoplasty is associated with good technical results, primary patency rates are poorer than in other parts of the dialysis access circuit and reported as 42% at 6 months (4). Factors influencing this include the extrinsic compression of the vein from multiple fascial layers, the curvature of the vein in this region, and the hemodynamic effects of arterialization of the vein (5). Bare metal stents used to treat cephalic arch stenosis have not been shown to result in improved patency compared with venoplasty alone (6,7). The stent graft is emerging as a potentially more durable device in vascular access preservation and maintenance compared with venoplasty and bare metal stents with promising results reported in several randomized, prospective trials (8–10). More specifically, several small retrospective studies and 2 small randomized controlled trials have shown encouraging patency results and demonstrated superiority with the use of stent grafts to treat cephalic arch stenosis compared with venoplasty and/or bare metal stents (6,11,12). The purpose of this study
2 ▪ Stent Graft to Treat Cephalic Arch Stenosis
was to examine the durability, performance, and safety of the VIABAHN stent graft (W.L. Gore & Associates, Flagstaff, Arizona) to treat cephalic arch stenosis in patients with dysfunctional ipsilateral brachiocephalic fistulas.
METHODS AND MATERIALS This study is a retrospective review of patients treated with a VIABAHN stent graft after failed venoplasty of symptomatic cephalic arch stenosis at a single institution between 2012 and 2015. This study received institutional review board approval.
Jones et al ▪ JVIR
Massachusetts), a VIABAHN stent graft was deployed (Fig 1a–c). All balloon and stent graft diameters were up to 10% larger than the normal adjacent segment of the cephalic vein. Intravenous heparin was not administered in any of the cases. If stenosis involved the very medial aspect of the cephalic arch near its junction with the axillary vein, the stent graft was extended into the subclavian vein by no more than 1–3 mm to avoid occlusion of the central vein. Completion venography was performed, and hemostasis was achieved with manual pressure or a purse-string suture.
Surveillance and Follow-up Patients All patients had mature brachiocephalic fistulas and ipsilateral cephalic arch stenosis (> 50%) with clinical symptoms and/or dysfunctional dialysis and were treated by 1 of 3 interventional radiologists with 41 years’ collective experience (R.G.J., A.P.W., P.L.R.). Patients with de novo cephalic arch stenosis and previous interventions in the cephalic arch were included. The study included 39 patients (15 women) and the mean age at stent graft insertion was 64 years (range, 18–86 y). Of patients, 36 had cephalic arch stenosis, and 3 had occlusion. Before the date of the initial stent graft insertion, 16 patients had no previous interventions in the cephalic arch, and 23 patients had undergone at least 1 venoplasty. Stent graft dimensions ranged from 7 mm 5 cm to 13 mm 5 cm and 6 mm 10 cm to 10 mm 10 cm.
Procedural Details After access was obtained, digital subtraction venography was performed, and cephalic arch stenosis identified. The cephalic arch was considered the terminal portion of the cephalic vein from the lateral extent of its horizontal segment to include the more medially situated insertion with the axillary vein (5). Venoplasty was carried out and if > 30% recoil was observed after full inflation of a high pressure balloon (Mustang; Boston Scientific, Marlborough,
Surveillance was carried out with diagnostic fistulography. Patients were scheduled for fistulography at 3, 6, and 12 months after stent graft insertion, but not all patients adhered to this schedule. Any evidence of restenosis (> 50%) in association with the cephalic arch stent graft or any other de novo access circuit stenosis was recorded. Patients were also examined with fistulography with a view to repeat the intervention if symptoms recurred. The decision to treat angiographic, yet asymptomatic restenosis was made on a case-by-case basis with discussion at multidisciplinary rounds. Pressure gradient measurements were used in some cases as an adjunct to support the decision to repeat venoplasty or stent graft placement.
Definitions and Statistical Analysis Definitions used in this study were based on the Society of Interventional Radiology (SIR) guidelines for dialysis access intervention (13). Technical success was defined as satisfactory deployment, appropriate position, and expansion of the stent graft to exclude the stenosis. Clinical success was defined as resumption of normal dialysis and/or resolution of patient symptoms. Primary target lesion patency was defined as time interval from initial stent graft deployment until next intervention within the stent graft or within 5 mm of its edge. Access circuit primary patency was defined as time interval from initial stent graft deployment
Figure 1. (a) Digital subtraction venography of left cephalic arch in an 86-year-old woman with an ipsilateral brachiocephalic fistula presenting with high venous pressures on dialysis. Imaging demonstrates significant multilevel stenosis (arrows). (b) Venography after high-pressure balloon inflation demonstrating recoil stenosis (arrows). (c) Venography after 8 mm 5 cm VIABAHN stent graft deployment and dilation. Satisfactory exclusion of cephalic arch stenosis is demonstrated with no compromise to the central vein owing to positioning of the medial aspect of the stent graft at the cephalic-axillary vein junction (arrows). Also note anatomic conformity of the stent graft through the arch (arrowheads). Corresponding normalization of venous pressure on subsequent dialysis was observed.
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to next access intervention regardless of the anatomic site. Primary assisted patency was defined as interval from initial stent graft placement regardless of the number of repeat interventions. Data were collected using Microsoft Excel (Microsoft Corp, Redmond, Washington). Statistical analysis was performed using SAS software (SAS Institute Inc, Cary, North Carolina). Patency over time was estimated using the Kaplan-Meier method. Means and SDs were used for continuous variables.
RESULTS Technical and clinical success was 100%. All patients had dysfunctional ipsilateral brachiocephalic arteriovenous fistulas at the time of referral for initial treatment (Table). Primary target lesion patency was 85% (95% confidence interval [CI], 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months (Fig 2). There was no significant difference in patency with regard to sex or age (P ¼ .8 and P¼ .6, respectively). Primary assisted patency was 95% (95% CI, 80%–99%) at 3, 6, and 12 months. Access circuit primary patency was 85% (95% CI, 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency between patients with the stent graft as first intervention and patients with the stent graft and previous intervention (P ¼ .98) (Fig 2). During the study period, there were 48 repeat venoplasty procedures performed within the cephalic arch, including 7 repeat VIABAHN stent grafts to maintain patency in 23 of the 39 patients. There was 1 thrombectomy procedure. Of these reinterventions, 21 (44%) were clinically driven with recurrence of the original symptoms; the remainder were angiographically driven, in which the detection of restenosis on surveillance fistulography prompted venoplasty. Pressure gradient measurement across the recurrent stenosis was used as an adjunct to support reintervention in 10 patients, 3 in the clinically driven group and 7 in the angiographically driven group. A value of 10 mm Hg was deemed a significant gradient. The pattern of restenosis observed was that of “edge” stenosis at the interface of the stent graft and the normal adjacent vein or within 5 mm of its margin (Fig 3). The overall site of
Table. Indications for Patient Referral for Initial Procedure Indication High venous pressure on dialysis
Number of Patients 14
Prolonged bleeding time after dialysis
9
Arm swelling
6
Low clearance
4
Recirculation
2
Thrombosis Indication information lost
2 5
restenosis was at the lateral edge in 25 episodes (52%), both edges in 14 (29%), the medial edge in 8 (17%), and true in-stent in 1. The initial stent graft protruded into the subclavian vein 1–3 mm in 20 patients (51%). In this subgroup, there were 21 reinterventions, including 6 repeat stent grafts. The site of restenosis was at the lateral edge of the stent graft in 10 episodes, the medial edge in 7, both edges in 3, and true in-stent in 1. In the group in which the stent graft did not protrude into the subclavian vein (n ¼ 19), the site of restenosis was at the lateral edge in 15 episodes, both edges in 11, and the medial edge in 1. There were 27 repeat reinterventions in this subgroup, including 1 repeat stent graft. No complications were encountered. There were 3 patients lost to follow-up, 2 of whom received renal transplantation in the study period. One patient required fistula ligation, but the stent graft was patent at that time. There were 6 deaths during the study period unrelated to the procedures.
DISCUSSION The cephalic arch is situated in an anatomically complex region within the deltopectoral groove and passes beneath the deep fascia behind the clavicular head of the pectoralis major muscle and then passes through the clavipectoral fascia to join the axillary vein. These constraints help explain the pathophysiology of venous stenosis and poor response to venoplasty. Other contributing factors are the abnormal wall shear stress caused by the curvature of the vein, which promotes intimal hyperplasia and hypertrophic remodeling secondary to arterialization of the vein (5,14). Cephalic arch stenosis in patients with a functioning brachiocephalic fistula can lead to high venous pressures, prolonged bleeding after dialysis, dysfunctional dialysis, fistula thrombosis, and fistula failure. Venoplasty alone performed in this region provides a primary patency of 42% at 6 months (4,15). Owing to the recalcitrant and recurrent nature of stenosis after venoplasty, a more durable percutaneous solution is highly desired. Bare metal stent placement after venoplasty has been described with variable results (6,7). In a retrospective study of 45 cases, a median patency of 152 days with bare metal stents compared with 91.5 days with venoplasty alone was demonstrated, although these results are difficult to interpret in context, as no clear definition of patency or procedural description was provided (7). Shemesh et al (6) compared the application of bare metal stents with stent grafts in cephalic arch stenosis. The primary patency at 6 months with stent grafts was 82% compared with 39% with bare metal stents, and at 1 year patency decreased to 32% and 0%, respectively. There were also fewer reinterventions in the stent graft group (0.9 interventions/y vs 1.9 interventions/y). Stent grafts in general are proving effective and appear to offer a superior patency solution over venoplasty alone in
4 ▪ Stent Graft to Treat Cephalic Arch Stenosis
Jones et al ▪ JVIR
Figure 2. Primary target lesion patency estimation with Kaplan-Meier method, with and without previous intervention for cephalic arch stenosis (P ¼ .98).
Figure 3. Digital subtraction venography demonstrating edge stenosis (arrows) in a cephalic arch stent graft placed 6 months previously. In this case, the stenosis is seen at both edges of the stent graft.
arteriovenous access interventions (8–11,16–18). A prospective randomized trial by Rajan and Falk (11) compared the VIABAHN stent graft with venoplasty in cephalic arch stenosis. Results showed primary target lesion patency at 6 and 12 months to be 0% and 0% for venoplasty and 100% and 29% for the VIABAHN stent graft (P < .01). The main
drawback of this study was the relatively small number of subjects with only 14 patients enrolled (5 in venoplasty group and 9 in stent graft group) owing to early termination of the study because of poor recruitment over an extended period of time. In a retrospective study of 11 patients with cephalic arch stenosis treated with VIABAHN, primary access circuit patency was 81% and 72% at 6 and 12 months (12). In this report, there is no clear definition of the followup, and no follow-up with venography was mentioned. In addition, no information was provided on target lesion patency, and there was a mixed patient group with some applications for rupture as opposed to stenosis resistant to venoplasty. The results of the present study are comparable to these 2 reported studies. In the present study, primary assisted patency results were 95% at both 6 and 12 months, which may be explained by the aggressive follow-up and subsequent repeat intervention rate of 48 venoplasties and placement of 7 further stent grafts in the cephalic arch. The use of venographic followup in arteriovenous access intervention is of questionable benefit, but this has been historical practice at our institution. A drawback and criticism of venographic follow-up is the dilemma of knowing what to do when a restenosis is detected and there is little or no clinical correlation. In these circumstances, pressure gradient measurement can be helpful in supporting the decision for reintervention. A pressure gradient of 10 mm Hg was considered an adjunct to deciding to proceed to intervention, and this has been reported previously (19). In the present study, there was a mixture of clinically driven and venographically driven
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reinterventions, which were decided on after careful multidisciplinary discussion taking into account the risks of leaving a significant restenosis in the absence of clinical symptoms versus the risk of accelerating the stenosis process further by creating more intimal hyperplasia with the trauma of repeat venoplasty. With this in mind and despite 27 angiographically driven reinterventions, acceptable patency rates were observed. When deploying the VIABAHN in the cephalic arch, several technical aspects need to be taken into account. The highest incidence of stenosis in the cephalic arch is at its most medial aspect where it joins the axillary vein (5). Therefore, in this scenario it would be almost impossible to effectively land a stent graft without some extension into the subclavian vein. In the present series, devices were extended into the axillary vein by no more than 1–3 mm in 20 of the 39 original interventions. There is the potential for this to predispose to stenosis at the axillary-subclavian vein junction and impede venous return from the upper limb, which may become symptomatic, especially if a further access is created in the future using the ipsilateral basilic vein. In this study, accurate retrospective quantification of central venous stenosis was not possible, but no clinically apparent central vein stenosis was encountered. Another important consideration when extending a stent graft into the central vein is the position of the lateral aspect of the device, as there is a tendency for it to “stand up” in the apex of the arch predisposing to further stenosis, especially when the guide wire is removed after deployment. This was observed in 1 case that required a second stent graft positioned more laterally with overlap to overcome this. This may also explain the use of 5 10-cm devices in cases where the shorter 5-cm devices could not adequately treat the very medial cephalic arch stenosis and also extend through the extent of the arch smoothly. The pattern of restenosis was that of edge stenosis with most occurring at the lateral edge of the stent graft (Fig 3). The limitations of this study include, first, its retrospective nature and, second, the relatively low number of patients, although this study represents the largest reported series to date. Third, follow-up using venography was a potential limitation in that the patency rates may have been underestimated owing to detection of subclinical restenosis. In conclusion, this study demonstrates and adds support to the current body of evidence that the use of a stent graft in the treatment of cephalic arch stenosis associated with dysfunctional brachiocephalic fistulas is safe and effective. A large-volume prospective trial on its application in this anatomically complex region is needed.
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ACKNOWLEDGMENTS W.L. Gore & Associates provided support with statistical analysis.
REFERENCES 1. Kian K, Asif A. Cephalic arch stenosis. Semin Dial 2008; 21:78–82. 2. Hammes M, Funaki B, Coe FL. Cephalic arch stenosis in patients with fistula access for hemodialysis: relationship to diabetes and thrombosis. Hemodial Int 2008; 12:85–89. 3. Clinical practice guidelines for vascular access. Am J Kidney Dis 2006; 48(Suppl 1):S176–S247. 4. Rajan DK, Clark TW, Patel NK, et al. Prevalence and treatment of cephalic arch stenosis in dysfunctional autogenous hemodialysis fistulas. J Vasc Interv Radiol 2003; 14:567–573. 5. Bennett S, Hammes MS, Blicharski T, et al. Characterization of the cephalic arch and location of stenosis. J Vasc Access 2015; 16:13–18. 6. Shemesh D, Goldin I, Zaghal I, et al. Angioplasty with stent-graft versus bare stent for recurrent cephalic arch stenosis in autogenous arteriovenous access for hemodialysis: a prospective randomized clinical trial. J Vasc Surg 2008; 48:1524–1531. 7. Dukkipati R, Lee L, Atray N, et al. Outcomes of cephalic arch stenosis with and without stent placement after percutaneous balloon angioplasty in hemodialysis patients. Semin Dial 2015; 28:E1–E7. 8. Haskal ZJ, Trerotola S, Dolmatch B, et al. Stent graft versus balloon angioplasty for failing dialysis-access grafts. N Engl J Med 2010; 362: 494–503. 9. Vesely T, DaVanzo W, Behrend T, et al. Balloon angioplasty versus Viabahn stent graft for treatment of failing or thrombosed prosthetic hemodialysis grafts. J Vasc Surg 2016; 64:1400–1410. 10. Falk A, Maya ID, Yevzlin AS, et al. A prospective, randomized study of an expanded polytetrafluoroethylene stent graft versus balloon angioplasty for in-stent restenosis in arteriovenous grafts and fistulae: two-year results of the RESCUE study. J Vasc Interv Radiol 2016; 27:1465–1476. 11. Rajan DK, Falk A. A randomized prospective study comparing outcomes of angioplasty versus VIABAHN stent-graft placement for cephalic arch stenosis in dysfunctional hemodialysis accesses. J Vasc Interv Radiol 2015; 26:1355–1361. 12. Shawyer A, Fotiadis NI, Namagondndlu G, et al. Cephalic arch stenosis in autogenous haemodialysis fistulas: Treatment with the Viabahn stentgraft. Cardiovasc Intervent Radiol 2013; 36:133–139. 13. Gray RJ, Sacks D, Martin LG, et al. Reporting standards for percutaneous interventions in dialysis access. J Vasc Interv Radiol 2003; 14:S433–S442. 14. Remuzzi A, Ene-Iordache B. Novel paradigms for dialysis vascular access: upstream hemodynamics and vascular remodelling in dialysis access stenosis. Clin J Am Soc Nephrol 2013; 8:2186–2193. 15. Heerwagen ST, Lonn L, Schroeder TV, et al. Cephalic arch stenosis in autogenous brachiocephalic hemodialysis fistulas: results of cutting balloon angioplasty. J Vasc Access 2010; 11:41–45. 16. Haskal ZJ, Saad TF, Hoggard JG, et al. Prospective, randomized, concurrently-controlled study of a stent-graft versus balloon angioplasty for treatment of arteriovenous access graft stenosis: 2-year results of the RENOVA study. J Vasc Interv Radiol 2016; 27:1105–1114. 17. Jones RG, Willis AP, Jones C, et al. Long-term results of stent-graft placement to treat central venous stenosis and occlusion in hemodialysis patients with arteriovenous fistulas. J Vasc Interv Radiol 2011; 22:1240–1245. 18. Anaya-Ayala JE, Smolock CJ, Colvard BD, et al. Efficacy of covered stent placement for central venous occlusive disease in hemodialysis patients. J Vasc Surg 2011; 54:754–759. 19. Funaki B, Kim R, Lorenz J, et al. Using pullback pressure measurements to identify venous stenoses persisting after successful angioplasty in failing hemodialysis grafts. AJR Am J Roentgenol 2002; 178:1161–1165.
Results of Stent Graft Placement to Treat Cephalic Arch Stenosis in Hemodialysis Patients with Dysfunctional Brachiocephalic Arteriovenous Fistulas Robert G. Jones, MRCP, FRCR, Andrew P. Willis, MRCS, FRCR, Karen Tullett, RGN, and Peter L. Riley, MRCP, FRCR
ABSTRACT Purpose: To determine effectiveness of the VIABAHN (W.L. Gore & Associates, Flagstaff, Arizona) stent graft to treat cephalic arch stenosis in patients with dysfunctional brachiocephalic arteriovenous fistulas after inadequate venoplasty response. Materials and Methods: Between 2012 and 2015, patients with failed venoplasty of symptomatic cephalic arch stenosis received a VIABAHN stent graft. Follow-up venography was performed at approximately 3, 6, and 12 months. Data were retrospectively analyzed with patency estimated using Kaplan-Meier and log-rank methodology. There were 39 patients included. Results: Technical and clinical success was 100%. Primary target lesion patency was 85% (95% confidence interval [CI], 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency with regard to sex or age (P ¼ .8 and P ¼ .6, respectively). Primary assisted patency was 95% (95% CI, 82%–99%) at 3, 6, and 12 months. Access circuit primary patency was 85% (95% CI, 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency between patients with the stent graft as the first treatment episode in the cephalic arch and those that had previous intervention at this site (P ¼ .98). There were 48 repeat venoplasty procedures performed in the cephalic arch to maintain patency, including 7 repeat VIABAHN insertions. No complications were encountered. Conclusions: The VIABAHN stent graft is a safe, effective, and durable device for treating cephalic arch stenosis when venoplasty fails.
ABBREVIATION CI ¼ confidence interval
Cephalic arch stenosis is the most common cause of brachiocephalic fistula failure with a reported incidence of up to 70% in this patient group (1,2). Percutaneous venoplasty is considered the standard treatment for dialysis arteriovenous fistula stenosis associated with access From the Departments of Interventional Radiology (R.G.J., A.P.W., P.L.R.) and Renal Services (K.T.), Queen Elizabeth Hospital Birmingham, University Hospital, Edgbaston, Birmingham B152WB, United Kingdom. Received March 17, 2017; final revision received June 12, 2017; accepted June 16, 2017. Address correspondence to R.G.J.; E-mail: [email protected] R.G.J. has received honoraria from W.L. Gore & Associates (Flagstaff, Arizona), Boston Scientific (Marlborough, Massachusetts), and Merit Medical Systems, Inc (South Jordan, Utah). A.P.W. has received an honorarium from Boston Scientific. Neither of the other authors has identified a conflict of interest. Crown Copyright © 2017 Published by Elsevier, Inc., on behalf of SIR. All rights reserved. J Vasc Interv Radiol 2017; ▪:1–5 http://dx.doi.org/10.1016/j.jvir.2017.06.023
dysfunction (3). Although venoplasty is associated with good technical results, primary patency rates are poorer than in other parts of the dialysis access circuit and reported as 42% at 6 months (4). Factors influencing this include the extrinsic compression of the vein from multiple fascial layers, the curvature of the vein in this region, and the hemodynamic effects of arterialization of the vein (5). Bare metal stents used to treat cephalic arch stenosis have not been shown to result in improved patency compared with venoplasty alone (6,7). The stent graft is emerging as a potentially more durable device in vascular access preservation and maintenance compared with venoplasty and bare metal stents with promising results reported in several randomized, prospective trials (8–10). More specifically, several small retrospective studies and 2 small randomized controlled trials have shown encouraging patency results and demonstrated superiority with the use of stent grafts to treat cephalic arch stenosis compared with venoplasty and/or bare metal stents (6,11,12). The purpose of this study
2 ▪ Stent Graft to Treat Cephalic Arch Stenosis
was to examine the durability, performance, and safety of the VIABAHN stent graft (W.L. Gore & Associates, Flagstaff, Arizona) to treat cephalic arch stenosis in patients with dysfunctional ipsilateral brachiocephalic fistulas.
METHODS AND MATERIALS This study is a retrospective review of patients treated with a VIABAHN stent graft after failed venoplasty of symptomatic cephalic arch stenosis at a single institution between 2012 and 2015. This study received institutional review board approval.
Jones et al ▪ JVIR
Massachusetts), a VIABAHN stent graft was deployed (Fig 1a–c). All balloon and stent graft diameters were up to 10% larger than the normal adjacent segment of the cephalic vein. Intravenous heparin was not administered in any of the cases. If stenosis involved the very medial aspect of the cephalic arch near its junction with the axillary vein, the stent graft was extended into the subclavian vein by no more than 1–3 mm to avoid occlusion of the central vein. Completion venography was performed, and hemostasis was achieved with manual pressure or a purse-string suture.
Surveillance and Follow-up Patients All patients had mature brachiocephalic fistulas and ipsilateral cephalic arch stenosis (> 50%) with clinical symptoms and/or dysfunctional dialysis and were treated by 1 of 3 interventional radiologists with 41 years’ collective experience (R.G.J., A.P.W., P.L.R.). Patients with de novo cephalic arch stenosis and previous interventions in the cephalic arch were included. The study included 39 patients (15 women) and the mean age at stent graft insertion was 64 years (range, 18–86 y). Of patients, 36 had cephalic arch stenosis, and 3 had occlusion. Before the date of the initial stent graft insertion, 16 patients had no previous interventions in the cephalic arch, and 23 patients had undergone at least 1 venoplasty. Stent graft dimensions ranged from 7 mm 5 cm to 13 mm 5 cm and 6 mm 10 cm to 10 mm 10 cm.
Procedural Details After access was obtained, digital subtraction venography was performed, and cephalic arch stenosis identified. The cephalic arch was considered the terminal portion of the cephalic vein from the lateral extent of its horizontal segment to include the more medially situated insertion with the axillary vein (5). Venoplasty was carried out and if > 30% recoil was observed after full inflation of a high pressure balloon (Mustang; Boston Scientific, Marlborough,
Surveillance was carried out with diagnostic fistulography. Patients were scheduled for fistulography at 3, 6, and 12 months after stent graft insertion, but not all patients adhered to this schedule. Any evidence of restenosis (> 50%) in association with the cephalic arch stent graft or any other de novo access circuit stenosis was recorded. Patients were also examined with fistulography with a view to repeat the intervention if symptoms recurred. The decision to treat angiographic, yet asymptomatic restenosis was made on a case-by-case basis with discussion at multidisciplinary rounds. Pressure gradient measurements were used in some cases as an adjunct to support the decision to repeat venoplasty or stent graft placement.
Definitions and Statistical Analysis Definitions used in this study were based on the Society of Interventional Radiology (SIR) guidelines for dialysis access intervention (13). Technical success was defined as satisfactory deployment, appropriate position, and expansion of the stent graft to exclude the stenosis. Clinical success was defined as resumption of normal dialysis and/or resolution of patient symptoms. Primary target lesion patency was defined as time interval from initial stent graft deployment until next intervention within the stent graft or within 5 mm of its edge. Access circuit primary patency was defined as time interval from initial stent graft deployment
Figure 1. (a) Digital subtraction venography of left cephalic arch in an 86-year-old woman with an ipsilateral brachiocephalic fistula presenting with high venous pressures on dialysis. Imaging demonstrates significant multilevel stenosis (arrows). (b) Venography after high-pressure balloon inflation demonstrating recoil stenosis (arrows). (c) Venography after 8 mm 5 cm VIABAHN stent graft deployment and dilation. Satisfactory exclusion of cephalic arch stenosis is demonstrated with no compromise to the central vein owing to positioning of the medial aspect of the stent graft at the cephalic-axillary vein junction (arrows). Also note anatomic conformity of the stent graft through the arch (arrowheads). Corresponding normalization of venous pressure on subsequent dialysis was observed.
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to next access intervention regardless of the anatomic site. Primary assisted patency was defined as interval from initial stent graft placement regardless of the number of repeat interventions. Data were collected using Microsoft Excel (Microsoft Corp, Redmond, Washington). Statistical analysis was performed using SAS software (SAS Institute Inc, Cary, North Carolina). Patency over time was estimated using the Kaplan-Meier method. Means and SDs were used for continuous variables.
RESULTS Technical and clinical success was 100%. All patients had dysfunctional ipsilateral brachiocephalic arteriovenous fistulas at the time of referral for initial treatment (Table). Primary target lesion patency was 85% (95% confidence interval [CI], 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months (Fig 2). There was no significant difference in patency with regard to sex or age (P ¼ .8 and P¼ .6, respectively). Primary assisted patency was 95% (95% CI, 80%–99%) at 3, 6, and 12 months. Access circuit primary patency was 85% (95% CI, 69%–93%), 67% (95% CI, 50%–80%), and 42% (95% CI, 25%–57%) at 3, 6, and 12 months. There was no significant difference in patency between patients with the stent graft as first intervention and patients with the stent graft and previous intervention (P ¼ .98) (Fig 2). During the study period, there were 48 repeat venoplasty procedures performed within the cephalic arch, including 7 repeat VIABAHN stent grafts to maintain patency in 23 of the 39 patients. There was 1 thrombectomy procedure. Of these reinterventions, 21 (44%) were clinically driven with recurrence of the original symptoms; the remainder were angiographically driven, in which the detection of restenosis on surveillance fistulography prompted venoplasty. Pressure gradient measurement across the recurrent stenosis was used as an adjunct to support reintervention in 10 patients, 3 in the clinically driven group and 7 in the angiographically driven group. A value of 10 mm Hg was deemed a significant gradient. The pattern of restenosis observed was that of “edge” stenosis at the interface of the stent graft and the normal adjacent vein or within 5 mm of its margin (Fig 3). The overall site of
Table. Indications for Patient Referral for Initial Procedure Indication High venous pressure on dialysis
Number of Patients 14
Prolonged bleeding time after dialysis
9
Arm swelling
6
Low clearance
4
Recirculation
2
Thrombosis Indication information lost
2 5
restenosis was at the lateral edge in 25 episodes (52%), both edges in 14 (29%), the medial edge in 8 (17%), and true in-stent in 1. The initial stent graft protruded into the subclavian vein 1–3 mm in 20 patients (51%). In this subgroup, there were 21 reinterventions, including 6 repeat stent grafts. The site of restenosis was at the lateral edge of the stent graft in 10 episodes, the medial edge in 7, both edges in 3, and true in-stent in 1. In the group in which the stent graft did not protrude into the subclavian vein (n ¼ 19), the site of restenosis was at the lateral edge in 15 episodes, both edges in 11, and the medial edge in 1. There were 27 repeat reinterventions in this subgroup, including 1 repeat stent graft. No complications were encountered. There were 3 patients lost to follow-up, 2 of whom received renal transplantation in the study period. One patient required fistula ligation, but the stent graft was patent at that time. There were 6 deaths during the study period unrelated to the procedures.
DISCUSSION The cephalic arch is situated in an anatomically complex region within the deltopectoral groove and passes beneath the deep fascia behind the clavicular head of the pectoralis major muscle and then passes through the clavipectoral fascia to join the axillary vein. These constraints help explain the pathophysiology of venous stenosis and poor response to venoplasty. Other contributing factors are the abnormal wall shear stress caused by the curvature of the vein, which promotes intimal hyperplasia and hypertrophic remodeling secondary to arterialization of the vein (5,14). Cephalic arch stenosis in patients with a functioning brachiocephalic fistula can lead to high venous pressures, prolonged bleeding after dialysis, dysfunctional dialysis, fistula thrombosis, and fistula failure. Venoplasty alone performed in this region provides a primary patency of 42% at 6 months (4,15). Owing to the recalcitrant and recurrent nature of stenosis after venoplasty, a more durable percutaneous solution is highly desired. Bare metal stent placement after venoplasty has been described with variable results (6,7). In a retrospective study of 45 cases, a median patency of 152 days with bare metal stents compared with 91.5 days with venoplasty alone was demonstrated, although these results are difficult to interpret in context, as no clear definition of patency or procedural description was provided (7). Shemesh et al (6) compared the application of bare metal stents with stent grafts in cephalic arch stenosis. The primary patency at 6 months with stent grafts was 82% compared with 39% with bare metal stents, and at 1 year patency decreased to 32% and 0%, respectively. There were also fewer reinterventions in the stent graft group (0.9 interventions/y vs 1.9 interventions/y). Stent grafts in general are proving effective and appear to offer a superior patency solution over venoplasty alone in
4 ▪ Stent Graft to Treat Cephalic Arch Stenosis
Jones et al ▪ JVIR
Figure 2. Primary target lesion patency estimation with Kaplan-Meier method, with and without previous intervention for cephalic arch stenosis (P ¼ .98).
Figure 3. Digital subtraction venography demonstrating edge stenosis (arrows) in a cephalic arch stent graft placed 6 months previously. In this case, the stenosis is seen at both edges of the stent graft.
arteriovenous access interventions (8–11,16–18). A prospective randomized trial by Rajan and Falk (11) compared the VIABAHN stent graft with venoplasty in cephalic arch stenosis. Results showed primary target lesion patency at 6 and 12 months to be 0% and 0% for venoplasty and 100% and 29% for the VIABAHN stent graft (P < .01). The main
drawback of this study was the relatively small number of subjects with only 14 patients enrolled (5 in venoplasty group and 9 in stent graft group) owing to early termination of the study because of poor recruitment over an extended period of time. In a retrospective study of 11 patients with cephalic arch stenosis treated with VIABAHN, primary access circuit patency was 81% and 72% at 6 and 12 months (12). In this report, there is no clear definition of the followup, and no follow-up with venography was mentioned. In addition, no information was provided on target lesion patency, and there was a mixed patient group with some applications for rupture as opposed to stenosis resistant to venoplasty. The results of the present study are comparable to these 2 reported studies. In the present study, primary assisted patency results were 95% at both 6 and 12 months, which may be explained by the aggressive follow-up and subsequent repeat intervention rate of 48 venoplasties and placement of 7 further stent grafts in the cephalic arch. The use of venographic followup in arteriovenous access intervention is of questionable benefit, but this has been historical practice at our institution. A drawback and criticism of venographic follow-up is the dilemma of knowing what to do when a restenosis is detected and there is little or no clinical correlation. In these circumstances, pressure gradient measurement can be helpful in supporting the decision for reintervention. A pressure gradient of 10 mm Hg was considered an adjunct to deciding to proceed to intervention, and this has been reported previously (19). In the present study, there was a mixture of clinically driven and venographically driven
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reinterventions, which were decided on after careful multidisciplinary discussion taking into account the risks of leaving a significant restenosis in the absence of clinical symptoms versus the risk of accelerating the stenosis process further by creating more intimal hyperplasia with the trauma of repeat venoplasty. With this in mind and despite 27 angiographically driven reinterventions, acceptable patency rates were observed. When deploying the VIABAHN in the cephalic arch, several technical aspects need to be taken into account. The highest incidence of stenosis in the cephalic arch is at its most medial aspect where it joins the axillary vein (5). Therefore, in this scenario it would be almost impossible to effectively land a stent graft without some extension into the subclavian vein. In the present series, devices were extended into the axillary vein by no more than 1–3 mm in 20 of the 39 original interventions. There is the potential for this to predispose to stenosis at the axillary-subclavian vein junction and impede venous return from the upper limb, which may become symptomatic, especially if a further access is created in the future using the ipsilateral basilic vein. In this study, accurate retrospective quantification of central venous stenosis was not possible, but no clinically apparent central vein stenosis was encountered. Another important consideration when extending a stent graft into the central vein is the position of the lateral aspect of the device, as there is a tendency for it to “stand up” in the apex of the arch predisposing to further stenosis, especially when the guide wire is removed after deployment. This was observed in 1 case that required a second stent graft positioned more laterally with overlap to overcome this. This may also explain the use of 5 10-cm devices in cases where the shorter 5-cm devices could not adequately treat the very medial cephalic arch stenosis and also extend through the extent of the arch smoothly. The pattern of restenosis was that of edge stenosis with most occurring at the lateral edge of the stent graft (Fig 3). The limitations of this study include, first, its retrospective nature and, second, the relatively low number of patients, although this study represents the largest reported series to date. Third, follow-up using venography was a potential limitation in that the patency rates may have been underestimated owing to detection of subclinical restenosis. In conclusion, this study demonstrates and adds support to the current body of evidence that the use of a stent graft in the treatment of cephalic arch stenosis associated with dysfunctional brachiocephalic fistulas is safe and effective. A large-volume prospective trial on its application in this anatomically complex region is needed.
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ACKNOWLEDGMENTS W.L. Gore & Associates provided support with statistical analysis.
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