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Treatment of Arm Swelling in Hemodialysis Patients with Ipsilateral Arteriovenous Access and Central Vein Stenosis: Conversion to the Hemodialysis Reliable Outflow Graft versus Stent Deployment
CLINICAL STUDY
Treatment of Arm Swelling in Hemodialysis Patients with Ipsilateral Arteriovenous Access and Central Vein Stenosis: Conversion to the Hemodialysis Reliable Outflow Graft versus Stent Deployment Brendan C. Cline, MD, Shawn M. Gage, PA, James Ronald, MD, PhD, Waleska M. Pabon-Ramos, MD, Ellen D. Dillavou, MD, Tony P. Smith, MD, Jeffrey H. Lawson, MD, PhD, and Charles Y. Kim, MD
ABSTRACT Purpose: To compare outcomes after conversion of arteriovenous (AV) access to Hemodialysis Reliable Outflow (HeRO) graft vs stent deployment in patients with arm swelling owing to ipsilateral central vein stenosis. Materials and Methods: This single-center retrospective study comprised 48 patients (19 men, mean age 58 y) with arm swelling ipsilateral to AV access and central vein stenosis over a 13-year period who had clinical follow-up and without prior central stents. Twenty-one patients underwent placement of a HeRO graft with anastomosis of the HeRO graft to the existing graft or fistula, and 27 patients underwent central venous stent deployment. Symptomatic improvement in arm swelling and access patency rates after intervention were ascertained from medical records. Results: Improvement in swelling within 1 month after HeRO conversion and stent deployment was found in 95% and 89%, respectively (P ¼ .62). Swelling eventually recurred in 16 patients (59%) treated with stents compared with 1 patient (5%) who underwent HeRO conversion (P < .001). Primary access patency was statistically significantly longer after HeRO conversions than stent deployments, with 6- and 12-month primary patency rates of 89% and 72% vs 47% and 11% (P < .001). HeRO conversions also resulted in longer 6- and 12-month secondary access patency rates (95% and 95% vs 79% and 58%, P ¼ .006). Mean number of interventions per 1,000 access days to maintain secondary patency was 2.7 for the HeRO group vs 6.3 for the stent group. Conclusions: Although stent deployment and HeRO graft conversion are effective for alleviating arm swelling in the short term in patients receiving hemodialysis with clinically significant arm swelling and functioning AVaccess, the HeRO graft has more durable results.
ABBREVIATIONS AV ¼ arteriovenous, HeRO ¼ Hemodialysis Reliable Outflow, SVC ¼ superior vena cava
Central venous stenosis is a common condition in patients receiving hemodialysis with an estimated prevalence of 25%–40% (1,2). When stenosis develops within the central
venous outflow of an existing arteriovenous (AV) fistula or graft or when an AV access is created in the presence of a pre-existing central stenosis or occlusion, the dramatically
From the Divisions of Interventional Radiology (B.C.C., J.R., W.M.P.-R., T.P.S., C.Y.K.) and Vascular Surgery (E.D.D., J.H.L.) and Physician Assistant Program (S.M.G.), Duke University Medical Center, Durham, North Carolina; InnAVasc Medical, Inc (S.M.G.), Durham, North Carolina; and Humacyte, Inc (J.H.L.), Durham, North Carolina. Received March 14, 2019; final revision received June 11, 2019; accepted June 13, 2019. Address correspondence to C.Y.K., Division of Interventional Radiology, Duke University Medical Center, 2301 Erwin Road, Durham, NC 27710; E-mail: [email protected]; Twitter handle: @dukeir
paid employee of Humacyte, Inc. S.M.G. is a paid employee of InnAVasc Medical, Inc (Durham, North Carolina). C.Y.K. is a paid consultant for Applied Clinical Intelligence, LLC (Bala Cynwyd, Pennsylvania) as a clinical trial committee member for Humacyte Inc. None of the other authors have identified a conflict of interest.
S.M.G. is a paid consultants for Humacyte, Inc (Durham, North Carolina). J.H.L. is a paid consultant for Merit Systems, Inc (South Jordan, Utah) and is a
From the SIR 2018 Annual Scientific Meeting. © SIR, 2019 J Vasc Interv Radiol 2019; ▪:1–8 https://doi.org/10.1016/j.jvir.2019.06.010
2 ▪ HeRO Graft versus Stent
EDITORS’ RESEARCH HIGHLIGHTS Arm swelling resulting from a central vein stenosis or occlusion ipsilateral to an arteriovenous (AV) access is a common and debilitating condition that may lead to access failure. This single-center retrospective study compared 21 patients who received a Hemodialysis Reliable Outflow (HeRO) graft with 27 patients who received stent placement.
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Table 1. Comparison of Baseline Characteristics between Treatment Groups HeRO (n ¼ 21) Patient age, y, average
55
58
.63
16 (59%)
.85
31
20
.17
6 (29%)
15 (56%)
.06
Right-sided access
9 (43%)
10 (37%)
.48
Autogenous fistula
14 (67%)
15 (56%)
.43
Age of access, mo, average Complete venous occlusion
Primary and secondary patency rates were significantly higher and mean interventions to maintain secondary patency were significantly lower in patients treated with the HeRO graft. One patient (5%) died owing to HeRO graft complications, whereas no adverse events were recorded in patients treated with stents.
Stenotic ipsilateral venous segments
increased venous flow will typically induce symptomatic severe arm swelling that can be debilitating (1,3,4). Angioplasty is a commonly performed initial treatment for patients receiving hemodialysis with symptomatic central vein stenosis, with a 6-month patency of 42%–62% (5–7). Repeated intervention is often required to maintain patency (1). For angioplasty-resistant lesions or lesions with early recurrence, stent or stent graft deployment can be performed to preserve AV access, with 6-month stent patency rates of 38%–81% (7–11). In severely symptomatic patients, AV access ligation or occlusion can be performed to terminate the arterialized flow to the extremity’s venous system, which will typically result in resolution of swelling. The Hemodialysis Reliable Outflow (HeRO) graft (Merit Medical Systems, Inc, South Jordan, Utah) was introduced as an AV access option for patients with central venous stenosis as a last resort for patients with end-stage renal disease with failing AV access (12). For primary HeRO placement, the inflow end of the graft is typically anastomosed to the brachial or axillary artery with the outflow end connected to a tunneled nitinol-reinforced silicone outflow catheter component that courses through the central veins with the tip terminating in the right atrium. The HeRO graft can also be directly anastomosed to an AV graft or fistula for purposes of access salvage, which has been reported to result in resolution of arm swelling in the presence of a central vein stenosis (13). The purpose of this study was to compare outcomes of stent deployment versus conversion of the AV access to a HeRO graft in patients with upper extremity swelling owing to angioplasty-refractory central vein stenosis. The primary outcome was resolution of arm swelling, and secondary outcomes included rates of
P Value*
13 (62%)
Female sex
Although relief of arm swelling was similar up to 3 months, after 6 months recurrent swelling was much more frequent in patients treated with stents, most of which were bare metal.
Although reported numbers are small, in a center where HeRO use is common, equivalent or better outcomes might be achievable than with bare metal stent central vein recanalizations.
Stent (n ¼ 27)
Subclavian vein
14 (67%)
11 (41%)
.09
Brachiocephalic vein Superior vena cava
8 (38%) 9 (43%)
16 (59%) 4 (15%)
.24 .05
Multiple central vein segments
9 (43%)
3 (11%)
.02
HeRO ¼ Hemodialysis Reliable Outflow. *Continuous variables were compared with Student t test; categorical values were compared with c2 or Fisher exact test.
recurrent swelling and primary and secondary access patency after intervention.
MATERIALS AND METHODS Patient Population Institutional review board approval and a waiver of informed consent were obtained for this single-institution retrospective study. Over a 10-year period between 2006 and 2015, 192 patients underwent HeRO graft insertion. Previous literature has described HeRO patency rates in a portion of this cohort (14–16). Inclusion criteria were HeRO graft insertions performed for the indication of clinically significant arm swelling in a patient with a central vein stenosis or occlusion ipsilateral to an autogenous AV fistula or prosthetic AV graft, where the HeRO graft was anastomosed directly to the AV access specifically to salvage the arterial anastomosis and cannulation segments. Patients without at least 1 month of clinical followup were excluded. From this cohort, 21 patients (8 men and 15 women, mean age 55 y) were included (Table 1). Over the same period, the interventional radiology procedural database was reviewed for cases of stent deployment in patients with AV access. Patients who had documented clinically significant arm swelling ipsilateral to the AV access who underwent stent deployment to treat a central vein stenosis or occlusion were included. Patients with prior central vein stents or who lacked documented clinical follow-up of changes in arm symptoms were excluded. There were 27 patients (11 men and 16 women, mean age 58 y) with stent deployment identified. In both treatment groups, the diagnosis of arm swelling was made based on subjective assessment by the referring clinician in accordance with physical examination findings and patient symptoms;
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this diagnosis was deemed clinically significant if severe enough to warrant treatment specifically to address the swelling. The superior vena cava (SVC), brachiocephalic veins, and subclavian veins were considered central veins. The treatment modality was chosen based on referring physician, interventionalist, and patient preference. Although infrequently documented, some of the reasons why conversion of the access to a HeRO graft were recommended included concern for limited access longevity based on the poor angiographic and physical appearance of the cannulation segment; presence of pacemaker leads that would be entrapped by the stent; or predicted poor patency of stents owing to suspicion of bony compression, excessive length or multifocality of stenosis, early aggressive restenosis after recent angioplasty, or perceived high risk or futility for subclavian vein recanalization. Some of the reasons why stent deployment was recommended included lesions that were deemed optimal for stent deployment (ie, short segment, unifocality), involved vein segments that would not jeopardize future HeRO graft insertion, extremely severe arm swelling where rapid relief was of highest priority, and situations where the patient was unlikely to have timely vascular surgical consultation and/or surgery. Analysis was performed on 21 patients who underwent conversion to a HeRO graft and 27 patients who underwent stent or stent graft deployment for treatment of a central venous stenosis or occlusion. The patients in the 2 treatment groups had similar age and sex breakdown (Table 1). The 2 groups were also similar in terms of average age of access, occlusion versus stenosis, laterality, and autogenous fistula proportion. However, patients undergoing HeRO conversion were statistically significantly more likely to have > 1 stenotic segment than the stent group (43% vs 11%, P ¼ .02). Patients receiving a HeRO graft were also more likely to have SVC occlusions than the stent group, although this difference was only marginally significant (43% vs 15%, P ¼ .05).
HeRO Implantation Technique HeRO graft implantation was routinely performed in a singlestage operation in patients with patent but stenotic central veins. For patients with complete central venous occlusion, a 2-stage approach was routinely used, involving central venous recanalization and catheter access across the central veins by interventional radiology followed by surgical graft implantation and outflow component placement on a separate day as described in earlier literature (12,15–17). Briefly, after guide wire access was achieved to the right atrium, the HeRO venous outflow component was inserted via a peel-away sheath and then tunneled laterally near the deltopectoral groove. After the existing AV fistula or graft was dissected and exposed, the polytetrafluoroethylene graft component was cut to the appropriate length and anastomosed to the preexisting fistula or graft in an end-to-end fashion. The graft was then coupled to the outflow component using the titanium connector. Technical success was defined as
3
Table 2. Stent Types and Diameters N Stent type S.M.A.R.T. self-expanding stent
24
iCast balloon expandable covered stent
6
VIABAHN endoprosthesis
1
WALLSTENT endoprosthesis
2
Stent diameter, mm 9
2
10 12
9 9
13
1
14
10
16
2
documented patency of the HeRO graft on completion of the implantation.
Stent Deployment Technique All procedures were performed using moderate sedation by an attending interventional radiologist (mean 12 y of experience; range, 1–24 y) or a fellow under the direct supervision of an attending interventional radiologist. Angioplasty of the central vein was initially performed in all patients in this group using a high-pressure noncompliant 10- to 16-mm-diameter angioplasty balloon (ATLAS or CONQUEST; Bard Peripheral Vascular, Inc, Tempe, Arizona). Stent deployment was performed only for lesions refractory to angioplasty either owing to immediate flowlimiting elastic recoil, defined as residual stenosis > 50% with concurrent filling of collateral veins, or owing to early recurrent stenosis within 3 months after prior angioplasty. The type and size of stent were chosen at the discretion of the operator and included S.M.A.R.T self-expanding stent (Cordis Corp, Milpitas, California) (n ¼ 24), iCast balloon expandable covered stent (Atrium Medical Corp, Hudson, New Hampshire) (n ¼ 6), VIABAHN endoprosthesis (W.L. Gore & Associates, Flagstaff, Arizona) (n ¼ 1), and WALLSTENT endoprosthesis (Boston Scientific, Marlborough, Massachusetts) (n ¼ 2) devices (Table 2). The balloon and stent diameters used were 1 mm or 10% larger than the perceived normal diameter, with a maximum of 16 mm in the SVC, 14 mm in the brachiocephalic veins, and 12 mm in the subclavian veins. Owing to long-segment lesions, 4 patients required 2 stents, and 1 patient required 3 stents for adequate coverage. All stents were post-dilated to their labeled diameter. Technical success was defined as improved luminal diameter with < 30% residual luminal stenosis with nonfilling of significant collateral veins on completion venography.
Outcomes Baseline patient characteristics and outcomes were determined based on review of documentation in the electronic
4 ▪ HeRO Graft versus Stent
medical record. Relevant baseline characteristics included age, sex, age of AV access, AV access type, access laterality, and comorbidities. The outcomes of interest were symptomatic improvement in arm swelling (which defined clinical success) and primary access patency and secondary access patency. Symptomatic improvement in swelling was based on follow-up documentation in the medical record and classified as partial improvement, complete resolution, or no improvement within 1 month of the procedure or surgery, based on maximal results. Primary access patency after intervention was defined as the interval following the initial percutaneous intervention on the index intragraft stenosis until the next access thrombosis or percutaneous intervention for a lesion anywhere within the access circuit (18). The number of additional interventions to maintain patency, including angioplasty, thrombectomy, or additional stent deployment at any location within the AV access circuit, was ascertained. Complications within 30 days were reviewed and categorized according to the Society of Interventional Radiology (SIR) guidelines (19).
Statistical Analysis Statistical analyses were performed with IBM SPSS Version 24 software (IBM Corp, Armonk, New York). Categorical and continuous variables were compared with c2 and t test, respectively. Patency rates were estimated with the KaplanMeier technique and compared with the log-rank test. To assess for potential confounding by factors that differed between groups, multivariable analysis for correlation with patency was performed using Cox proportional hazards test. The number of subsequent interventions per unit time in the stent versus HeRO group was compared using negative binomial regression. A P value < .05 was considered statistically significant.
RESULTS Symptom Control All HeRO graft insertions and stent deployments were technically successful. After stent deployment for a central vein stenosis, improvement or resolution in arm swelling was found in 86% of patients compared with 95% after conversion to a HeRO graft (P ¼ .35) (Table 3). Complete resolution of arm swelling was identified in 14 patients (52%) after stent deployment and 11 patients (52%) after HeRO conversion (P ¼ 1.0). Swelling recurred within 1 year in 16 patients (59%) treated with stents compared with 1 patient (5%) who underwent HeRO conversion (P < .001).
Access Patency The median primary access patency (Fig 1) was statistically significantly longer for HeRO conversions than stent deployments (15.6 months vs 5.4 months, P < .001). Primary patency for HeRO graft placement at 6, 12, and 24 months was 89%, 72%, and 9% and for stent deployment was 47%, 11%, and 0%. Secondary patency (Fig 2) was also longer for HeRO conversions than for
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Table 3. Outcomes HeRO (n ¼ 21)
Stent (N ¼ 27)
P Value*
Arm swelling changes Improved
20 (95%)
24 (89%)
.62
Resolved
11 (52%)
14 (52%)
1.00
1/20 (5%)
16/24 (67%)
< .001 < .001
Recurrent arm swelling Primary access patency Median, mo
15.6
5.4
6 mo
89%
47%
12 mo
72%
11%
24 mo
9%
0
Secondary access patency Median, mo
Not reached
29.4
6 mo
95%
79%
12 mo 24 mo
95% 89%
58% 51%
Interventions to maintain secondary patency, mean
2.6
3.4
Interventions per 1,000 access days, mean
2.9
6.2
.006
.009
HeRO ¼ Hemodialysis Reliable Outflow. *Continuous variables were compared with Student t test; categorical values were compared with c2 or Fisher exact test; median patency rates were compared with Kaplan-Meier analysis and log-rank test.
stent deployment (P ¼ .006) (Fig 2), with 6-, 12-, and 24month secondary patency rates of 95%, 95%, and 89% for HeRO grafts and 79%, 58%, and 51% for stent deployment (Table 3). The mean number of interventions to maintain secondary patency was 2.9 per 1,000 access days for HeRO conversions and 6.2 per 1,000 access days for stent deployments, with a higher rate of interventions in the stent group (incidence rate ratio ¼ 2.12, P ¼ .009) (Table 3). Given differences in group demographics, a multivariable analysis of HeRO versus stent, presence of SVC stenosis, or multisegment involvement revealed that only HeRO versus stent grouping correlated in a statistically significant manner with primary and secondary patency (P ¼ .001 and P ¼ .027, respectively).
Complications There was 1 severe complication in the HeRO group, consisting of an anastomotic dehiscence 1 week after HeRO surgery requiring graft ligation. The patient died 10 days later of myocardial infarction. No severe complications occurred in the stent group. At repeat venography and reintervention for stent occlusion, no instances of stent deformation secondary to bony compression were noted.
DISCUSSION Given the substantial morbidity that is incurred with AV access–associated central venous stenosis and need to preserve access options in patients receiving hemodialysis,
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5
Figure 1. Kaplan-Meier curve of primary patency in HeRO graft versus stent deployment. Cum ¼ cumulative.
successful management strategies are important. The data presented here suggest that both stent deployment and conversion to a HeRO graft are effective for short-term mitigation of swelling. However, conversion to a HeRO graft was less likely to incur subsequent return of arm swelling and resulted in longer primary and secondary patency rates than stent deployment. The average number of interventions to maintain secondary patency was lower in the HeRO group. Considering that both treatments prolong access patency while improving symptoms, both of these options should be preferable to access ligation. The 1-year HeRO graft primary patency rate of 72% in this study is substantially higher than the range of 9.1%– 49% reported in the literature (16,20,21). As all AV accesses converted to HeRO grafts in this study were already functioning, the study population lacks cases where HeRO failure occurred owing to inadequate arterial inflow to support patency, which skews primary patency rates to be higher. The generally high level of HeRO implantation experience at the authors’ institution may also improve outcomes. The secondary patency rate of 95% in this study is also high compared with the literature (45.5%–91% at 1 y), also likely for the same reasons (16,20,21). The access patency rates after stent deployment in the current study were generally low, with 12-month primary and secondary patency rates of 11% and 58%, respectively. Primary access patency rates after stent deployment for the
central veins are rarely reported (in favor of lesion patency rates); at 12 months, the primary access patency rates after stent deployment have been reported to be 0–29% (8,22,23). As access patency includes lesions anywhere within the circuit, the access age is an important factor (20 months on average in the current study), considering that the mean primary and secondary access patency after creation is 42.7% and 59.5% for AV fistulae and 31.5% and 56.8% for AV grafts at 1 year, based on a recent large study comprising > 90,000 patients (24). Thus, conversion of an existing access to a HeRO graft may have additional benefit to access patency by excluding the impact of venous outflow stenosis, venous anastomosis stenosis, and intragraft stenosis that would otherwise affect access patency in the stent group. Notably, whereas most studies on central vein stents in patients receiving hemodialysis report lesion patency rates based on postintervention angiography, access patency rates were instead assessed in the current study because this metric is not valid after HeRO graft insertion. By definition, access patency is always worse than lesion patency. Furthermore, access patency may be more important in this population because AV access ligation or abandonment may be required for unremitting arm swelling. Also of note, stent deployment was performed only after failed angioplasty, which enriches this group with more aggressive lesions that would skew toward worse patency rates after stent deployment; in contradistinction, many studies reporting patency
6 ▪ HeRO Graft versus Stent
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Figure 2. Kaplan-Meier curve of secondary patency in HeRO graft versus stent deployment. Cum ¼ cumulative.
after central stents include primary stent deployment, which would be expected to have higher patency rates. Finally, self-expanding bare metal stents (S.M.A.R.T.) were used in most of the stent group, which are not necessarily representative of all stents and stent grafts, particularly given emerging stents designed for use in veins as well as promising performance of covered stents in AV access (9,25–28). Although the purpose of this study was to compare outcomes after stent deployment versus conversion to a HeRO graft, the treatment choice in practice is not always binary. Depending on the location of central vein stenosis, conversion of an AV access to a HeRO graft may be completely feasible after initial stent deployment to mitigate arm swelling; similarly, initial conversion to a HeRO graft also might not preclude subsequent ipsilateral stent deployment after HeRO removal. For example, in a patient with patent central veins except for a subclavian vein stenosis, stent deployment within the subclavian vein will not impair insertion of a HeRO graft via the internal jugular vein. However, it is possible that stent deployment may make ipsilateral HeRO graft insertion difficult or impossible if the stent or stent graft obstructs a pathway to the right atrium in the setting of impassable stent occlusion. It is important to consider future permanent and catheter access options when deploying stents and stent grafts in the central veins of patients receiving hemodialysis (25); these results suggest that it may be prudent to also strategically plan for future HeRO access options to optimize long-term outcomes.
A statistically significant percentage of patients (59%) developed recurrent arm swelling after stent deployment compared with 1 patient after HeRO conversion. The intimal hyperplasia that leads to central vein stenosis can impair patency after stent or stent graft deployment by growing through stent interstices, formation within the stent graft lumen, or growing at the stent margin, thus leading to progressive restenosis and return of arm swelling (4,29). However, there have been no reports of stenosis or neointimal hyperplasia development within the HeRO outflow component. It is also known that the central veins can be subject to bony compressive forces, such as the thoracic outlet (4). On one hand, these sites would be expected to respond poorly to angioplasty alone and would be expected to respond suboptimally to stents owing to the compressive force. On the other hand, the HeRO outflow component contains braided nitinol reinforcement that resists compressive forces, which may represent a less morbid procedure than rib resection, particularly given the abundance of pressurized collateral veins in this region. Although this study examined only outcomes, an important consideration in the choice of treatment is overall cost. Compared with endovascular management, HeRO graft implantation would additionally incur anesthesia costs, operating room costs, and inpatient costs. In a cost analysis of the HeRO graft and associated interventions to maintain patency, the annual costs were estimated at $34,713.63 per patient/y (30). However, it is notable that the primary
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patency rate in that study was 8.4% at 12 months compared with 72% in the current study, which underscores the variability in outcomes based on institution experience. In another cost analysis study, the HeRO graft was shown to have lower costs on an annual basis than with tunneled hemodialysis catheters (31). Financial analyses of stent deployment for endovascular management of central venous occlusions are not currently published in the medical literature; a formal cost analysis would be helpful in ascertaining the optimal treatment algorithm. This study is limited by its nature as a retrospective, single-center study. The sample size for both groups was modest, which limits subset analyses and could exacerbate bias. For example, a variety of stents and stent grafts were used in the stent group. Although a much larger number of patients underwent central vein stent deployment at the authors’ institution, documented clinical follow-up of arm symptoms was not routinely available in many patients who were referred from unaffiliated outpatient dialysis centers, which substantially reduced the sample size in the stent deployment group. Selection bias was likely present, as stent deployment may be avoided in cases where bony compression was presumed to be present. This may explain why the HeRO group had a higher number of patients with SVC stenosis/occlusion and stenosis of > 1 central vein. Finally, given the relatively high-level experience with HeRO grafts at this center, results achieved in this study may not be entirely generalizable to other centers, as HeRO graft experience is not ubiquitous. In conclusion, for patients with upper extremity swelling owing to central venous stenosis in the setting of AV hemodialysis access, both central stent deployment and conversion of access to a HeRO graft are effective for addressing arm swelling. Although this is an inherently limited, retrospective study, these data suggest that conversion to a HeRO graft incurs a lower incidence of recurrent swelling and results in longer access patency rates, with fewer interventions to maintain secondary patency. However, as these 2 treatments are not mutually exclusive, there may be an optimal sequence of therapy that optimizes AV access longevity and maximizes future access options based on lesion and patient factors.
7
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
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FLUENCY Plus Stent Graft: technical and 180-day patency results. J Vasc Interv Radiol 2012; 23:479–487. 26. 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.e3. 27. Falk A, Maya ID, Yevzlin AS; RESCUE Investigators. 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. 28. Shemesh D, Goldin I, Zaghal I, Berlowitz D, Raveh D, Olsha O. Angioplasty with stent graft versus bare stent for recurrent cephalic arch
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stenosis in autogenous arteriovenous access for hemodialysis: a prospective randomized clinical trial. J Vasc Surg 2008; 48:1524–1531, 1531.e1–1531.e2. 29. Cejna M, Virmani R, Jones R, et al. Biocompatibility and performance of the Wallstent and several covered stents in a sheep iliac artery model. J Vasc Interv Radiol 2001; 12:351–358. 30. Torrent DJ, Maness MR, Kachare SD, et al. Examining Hemodialysis Reliable Outflow catheter performance and cost in hemodialysis access. J Surg Res 2014; 192:1–5. 31. Al Shakarchi J, Inston N, Jones RG, Maclaine G, Hollinworth D. Cost analysis of the Hemodialysis Reliable Outflow (HeRO) graft compared to the tunneled dialysis catheter. J Vasc Surg 2016; 63: 1026–1033.
Treatment of Arm Swelling in Hemodialysis Patients with Ipsilateral Arteriovenous Access and Central Vein Stenosis: Conversion to the Hemodialysis Reliable Outflow Graft versus Stent Deployment Brendan C. Cline, MD, Shawn M. Gage, PA, James Ronald, MD, PhD, Waleska M. Pabon-Ramos, MD, Ellen D. Dillavou, MD, Tony P. Smith, MD, Jeffrey H. Lawson, MD, PhD, and Charles Y. Kim, MD
ABSTRACT Purpose: To compare outcomes after conversion of arteriovenous (AV) access to Hemodialysis Reliable Outflow (HeRO) graft vs stent deployment in patients with arm swelling owing to ipsilateral central vein stenosis. Materials and Methods: This single-center retrospective study comprised 48 patients (19 men, mean age 58 y) with arm swelling ipsilateral to AV access and central vein stenosis over a 13-year period who had clinical follow-up and without prior central stents. Twenty-one patients underwent placement of a HeRO graft with anastomosis of the HeRO graft to the existing graft or fistula, and 27 patients underwent central venous stent deployment. Symptomatic improvement in arm swelling and access patency rates after intervention were ascertained from medical records. Results: Improvement in swelling within 1 month after HeRO conversion and stent deployment was found in 95% and 89%, respectively (P ¼ .62). Swelling eventually recurred in 16 patients (59%) treated with stents compared with 1 patient (5%) who underwent HeRO conversion (P < .001). Primary access patency was statistically significantly longer after HeRO conversions than stent deployments, with 6- and 12-month primary patency rates of 89% and 72% vs 47% and 11% (P < .001). HeRO conversions also resulted in longer 6- and 12-month secondary access patency rates (95% and 95% vs 79% and 58%, P ¼ .006). Mean number of interventions per 1,000 access days to maintain secondary patency was 2.7 for the HeRO group vs 6.3 for the stent group. Conclusions: Although stent deployment and HeRO graft conversion are effective for alleviating arm swelling in the short term in patients receiving hemodialysis with clinically significant arm swelling and functioning AVaccess, the HeRO graft has more durable results.
ABBREVIATIONS AV ¼ arteriovenous, HeRO ¼ Hemodialysis Reliable Outflow, SVC ¼ superior vena cava
Central venous stenosis is a common condition in patients receiving hemodialysis with an estimated prevalence of 25%–40% (1,2). When stenosis develops within the central
venous outflow of an existing arteriovenous (AV) fistula or graft or when an AV access is created in the presence of a pre-existing central stenosis or occlusion, the dramatically
From the Divisions of Interventional Radiology (B.C.C., J.R., W.M.P.-R., T.P.S., C.Y.K.) and Vascular Surgery (E.D.D., J.H.L.) and Physician Assistant Program (S.M.G.), Duke University Medical Center, Durham, North Carolina; InnAVasc Medical, Inc (S.M.G.), Durham, North Carolina; and Humacyte, Inc (J.H.L.), Durham, North Carolina. Received March 14, 2019; final revision received June 11, 2019; accepted June 13, 2019. Address correspondence to C.Y.K., Division of Interventional Radiology, Duke University Medical Center, 2301 Erwin Road, Durham, NC 27710; E-mail: [email protected]; Twitter handle: @dukeir
paid employee of Humacyte, Inc. S.M.G. is a paid employee of InnAVasc Medical, Inc (Durham, North Carolina). C.Y.K. is a paid consultant for Applied Clinical Intelligence, LLC (Bala Cynwyd, Pennsylvania) as a clinical trial committee member for Humacyte Inc. None of the other authors have identified a conflict of interest.
S.M.G. is a paid consultants for Humacyte, Inc (Durham, North Carolina). J.H.L. is a paid consultant for Merit Systems, Inc (South Jordan, Utah) and is a
From the SIR 2018 Annual Scientific Meeting. © SIR, 2019 J Vasc Interv Radiol 2019; ▪:1–8 https://doi.org/10.1016/j.jvir.2019.06.010
2 ▪ HeRO Graft versus Stent
EDITORS’ RESEARCH HIGHLIGHTS Arm swelling resulting from a central vein stenosis or occlusion ipsilateral to an arteriovenous (AV) access is a common and debilitating condition that may lead to access failure. This single-center retrospective study compared 21 patients who received a Hemodialysis Reliable Outflow (HeRO) graft with 27 patients who received stent placement.
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Table 1. Comparison of Baseline Characteristics between Treatment Groups HeRO (n ¼ 21) Patient age, y, average
55
58
.63
16 (59%)
.85
31
20
.17
6 (29%)
15 (56%)
.06
Right-sided access
9 (43%)
10 (37%)
.48
Autogenous fistula
14 (67%)
15 (56%)
.43
Age of access, mo, average Complete venous occlusion
Primary and secondary patency rates were significantly higher and mean interventions to maintain secondary patency were significantly lower in patients treated with the HeRO graft. One patient (5%) died owing to HeRO graft complications, whereas no adverse events were recorded in patients treated with stents.
Stenotic ipsilateral venous segments
increased venous flow will typically induce symptomatic severe arm swelling that can be debilitating (1,3,4). Angioplasty is a commonly performed initial treatment for patients receiving hemodialysis with symptomatic central vein stenosis, with a 6-month patency of 42%–62% (5–7). Repeated intervention is often required to maintain patency (1). For angioplasty-resistant lesions or lesions with early recurrence, stent or stent graft deployment can be performed to preserve AV access, with 6-month stent patency rates of 38%–81% (7–11). In severely symptomatic patients, AV access ligation or occlusion can be performed to terminate the arterialized flow to the extremity’s venous system, which will typically result in resolution of swelling. The Hemodialysis Reliable Outflow (HeRO) graft (Merit Medical Systems, Inc, South Jordan, Utah) was introduced as an AV access option for patients with central venous stenosis as a last resort for patients with end-stage renal disease with failing AV access (12). For primary HeRO placement, the inflow end of the graft is typically anastomosed to the brachial or axillary artery with the outflow end connected to a tunneled nitinol-reinforced silicone outflow catheter component that courses through the central veins with the tip terminating in the right atrium. The HeRO graft can also be directly anastomosed to an AV graft or fistula for purposes of access salvage, which has been reported to result in resolution of arm swelling in the presence of a central vein stenosis (13). The purpose of this study was to compare outcomes of stent deployment versus conversion of the AV access to a HeRO graft in patients with upper extremity swelling owing to angioplasty-refractory central vein stenosis. The primary outcome was resolution of arm swelling, and secondary outcomes included rates of
P Value*
13 (62%)
Female sex
Although relief of arm swelling was similar up to 3 months, after 6 months recurrent swelling was much more frequent in patients treated with stents, most of which were bare metal.
Although reported numbers are small, in a center where HeRO use is common, equivalent or better outcomes might be achievable than with bare metal stent central vein recanalizations.
Stent (n ¼ 27)
Subclavian vein
14 (67%)
11 (41%)
.09
Brachiocephalic vein Superior vena cava
8 (38%) 9 (43%)
16 (59%) 4 (15%)
.24 .05
Multiple central vein segments
9 (43%)
3 (11%)
.02
HeRO ¼ Hemodialysis Reliable Outflow. *Continuous variables were compared with Student t test; categorical values were compared with c2 or Fisher exact test.
recurrent swelling and primary and secondary access patency after intervention.
MATERIALS AND METHODS Patient Population Institutional review board approval and a waiver of informed consent were obtained for this single-institution retrospective study. Over a 10-year period between 2006 and 2015, 192 patients underwent HeRO graft insertion. Previous literature has described HeRO patency rates in a portion of this cohort (14–16). Inclusion criteria were HeRO graft insertions performed for the indication of clinically significant arm swelling in a patient with a central vein stenosis or occlusion ipsilateral to an autogenous AV fistula or prosthetic AV graft, where the HeRO graft was anastomosed directly to the AV access specifically to salvage the arterial anastomosis and cannulation segments. Patients without at least 1 month of clinical followup were excluded. From this cohort, 21 patients (8 men and 15 women, mean age 55 y) were included (Table 1). Over the same period, the interventional radiology procedural database was reviewed for cases of stent deployment in patients with AV access. Patients who had documented clinically significant arm swelling ipsilateral to the AV access who underwent stent deployment to treat a central vein stenosis or occlusion were included. Patients with prior central vein stents or who lacked documented clinical follow-up of changes in arm symptoms were excluded. There were 27 patients (11 men and 16 women, mean age 58 y) with stent deployment identified. In both treatment groups, the diagnosis of arm swelling was made based on subjective assessment by the referring clinician in accordance with physical examination findings and patient symptoms;
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this diagnosis was deemed clinically significant if severe enough to warrant treatment specifically to address the swelling. The superior vena cava (SVC), brachiocephalic veins, and subclavian veins were considered central veins. The treatment modality was chosen based on referring physician, interventionalist, and patient preference. Although infrequently documented, some of the reasons why conversion of the access to a HeRO graft were recommended included concern for limited access longevity based on the poor angiographic and physical appearance of the cannulation segment; presence of pacemaker leads that would be entrapped by the stent; or predicted poor patency of stents owing to suspicion of bony compression, excessive length or multifocality of stenosis, early aggressive restenosis after recent angioplasty, or perceived high risk or futility for subclavian vein recanalization. Some of the reasons why stent deployment was recommended included lesions that were deemed optimal for stent deployment (ie, short segment, unifocality), involved vein segments that would not jeopardize future HeRO graft insertion, extremely severe arm swelling where rapid relief was of highest priority, and situations where the patient was unlikely to have timely vascular surgical consultation and/or surgery. Analysis was performed on 21 patients who underwent conversion to a HeRO graft and 27 patients who underwent stent or stent graft deployment for treatment of a central venous stenosis or occlusion. The patients in the 2 treatment groups had similar age and sex breakdown (Table 1). The 2 groups were also similar in terms of average age of access, occlusion versus stenosis, laterality, and autogenous fistula proportion. However, patients undergoing HeRO conversion were statistically significantly more likely to have > 1 stenotic segment than the stent group (43% vs 11%, P ¼ .02). Patients receiving a HeRO graft were also more likely to have SVC occlusions than the stent group, although this difference was only marginally significant (43% vs 15%, P ¼ .05).
HeRO Implantation Technique HeRO graft implantation was routinely performed in a singlestage operation in patients with patent but stenotic central veins. For patients with complete central venous occlusion, a 2-stage approach was routinely used, involving central venous recanalization and catheter access across the central veins by interventional radiology followed by surgical graft implantation and outflow component placement on a separate day as described in earlier literature (12,15–17). Briefly, after guide wire access was achieved to the right atrium, the HeRO venous outflow component was inserted via a peel-away sheath and then tunneled laterally near the deltopectoral groove. After the existing AV fistula or graft was dissected and exposed, the polytetrafluoroethylene graft component was cut to the appropriate length and anastomosed to the preexisting fistula or graft in an end-to-end fashion. The graft was then coupled to the outflow component using the titanium connector. Technical success was defined as
3
Table 2. Stent Types and Diameters N Stent type S.M.A.R.T. self-expanding stent
24
iCast balloon expandable covered stent
6
VIABAHN endoprosthesis
1
WALLSTENT endoprosthesis
2
Stent diameter, mm 9
2
10 12
9 9
13
1
14
10
16
2
documented patency of the HeRO graft on completion of the implantation.
Stent Deployment Technique All procedures were performed using moderate sedation by an attending interventional radiologist (mean 12 y of experience; range, 1–24 y) or a fellow under the direct supervision of an attending interventional radiologist. Angioplasty of the central vein was initially performed in all patients in this group using a high-pressure noncompliant 10- to 16-mm-diameter angioplasty balloon (ATLAS or CONQUEST; Bard Peripheral Vascular, Inc, Tempe, Arizona). Stent deployment was performed only for lesions refractory to angioplasty either owing to immediate flowlimiting elastic recoil, defined as residual stenosis > 50% with concurrent filling of collateral veins, or owing to early recurrent stenosis within 3 months after prior angioplasty. The type and size of stent were chosen at the discretion of the operator and included S.M.A.R.T self-expanding stent (Cordis Corp, Milpitas, California) (n ¼ 24), iCast balloon expandable covered stent (Atrium Medical Corp, Hudson, New Hampshire) (n ¼ 6), VIABAHN endoprosthesis (W.L. Gore & Associates, Flagstaff, Arizona) (n ¼ 1), and WALLSTENT endoprosthesis (Boston Scientific, Marlborough, Massachusetts) (n ¼ 2) devices (Table 2). The balloon and stent diameters used were 1 mm or 10% larger than the perceived normal diameter, with a maximum of 16 mm in the SVC, 14 mm in the brachiocephalic veins, and 12 mm in the subclavian veins. Owing to long-segment lesions, 4 patients required 2 stents, and 1 patient required 3 stents for adequate coverage. All stents were post-dilated to their labeled diameter. Technical success was defined as improved luminal diameter with < 30% residual luminal stenosis with nonfilling of significant collateral veins on completion venography.
Outcomes Baseline patient characteristics and outcomes were determined based on review of documentation in the electronic
4 ▪ HeRO Graft versus Stent
medical record. Relevant baseline characteristics included age, sex, age of AV access, AV access type, access laterality, and comorbidities. The outcomes of interest were symptomatic improvement in arm swelling (which defined clinical success) and primary access patency and secondary access patency. Symptomatic improvement in swelling was based on follow-up documentation in the medical record and classified as partial improvement, complete resolution, or no improvement within 1 month of the procedure or surgery, based on maximal results. Primary access patency after intervention was defined as the interval following the initial percutaneous intervention on the index intragraft stenosis until the next access thrombosis or percutaneous intervention for a lesion anywhere within the access circuit (18). The number of additional interventions to maintain patency, including angioplasty, thrombectomy, or additional stent deployment at any location within the AV access circuit, was ascertained. Complications within 30 days were reviewed and categorized according to the Society of Interventional Radiology (SIR) guidelines (19).
Statistical Analysis Statistical analyses were performed with IBM SPSS Version 24 software (IBM Corp, Armonk, New York). Categorical and continuous variables were compared with c2 and t test, respectively. Patency rates were estimated with the KaplanMeier technique and compared with the log-rank test. To assess for potential confounding by factors that differed between groups, multivariable analysis for correlation with patency was performed using Cox proportional hazards test. The number of subsequent interventions per unit time in the stent versus HeRO group was compared using negative binomial regression. A P value < .05 was considered statistically significant.
RESULTS Symptom Control All HeRO graft insertions and stent deployments were technically successful. After stent deployment for a central vein stenosis, improvement or resolution in arm swelling was found in 86% of patients compared with 95% after conversion to a HeRO graft (P ¼ .35) (Table 3). Complete resolution of arm swelling was identified in 14 patients (52%) after stent deployment and 11 patients (52%) after HeRO conversion (P ¼ 1.0). Swelling recurred within 1 year in 16 patients (59%) treated with stents compared with 1 patient (5%) who underwent HeRO conversion (P < .001).
Access Patency The median primary access patency (Fig 1) was statistically significantly longer for HeRO conversions than stent deployments (15.6 months vs 5.4 months, P < .001). Primary patency for HeRO graft placement at 6, 12, and 24 months was 89%, 72%, and 9% and for stent deployment was 47%, 11%, and 0%. Secondary patency (Fig 2) was also longer for HeRO conversions than for
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Table 3. Outcomes HeRO (n ¼ 21)
Stent (N ¼ 27)
P Value*
Arm swelling changes Improved
20 (95%)
24 (89%)
.62
Resolved
11 (52%)
14 (52%)
1.00
1/20 (5%)
16/24 (67%)
< .001 < .001
Recurrent arm swelling Primary access patency Median, mo
15.6
5.4
6 mo
89%
47%
12 mo
72%
11%
24 mo
9%
0
Secondary access patency Median, mo
Not reached
29.4
6 mo
95%
79%
12 mo 24 mo
95% 89%
58% 51%
Interventions to maintain secondary patency, mean
2.6
3.4
Interventions per 1,000 access days, mean
2.9
6.2
.006
.009
HeRO ¼ Hemodialysis Reliable Outflow. *Continuous variables were compared with Student t test; categorical values were compared with c2 or Fisher exact test; median patency rates were compared with Kaplan-Meier analysis and log-rank test.
stent deployment (P ¼ .006) (Fig 2), with 6-, 12-, and 24month secondary patency rates of 95%, 95%, and 89% for HeRO grafts and 79%, 58%, and 51% for stent deployment (Table 3). The mean number of interventions to maintain secondary patency was 2.9 per 1,000 access days for HeRO conversions and 6.2 per 1,000 access days for stent deployments, with a higher rate of interventions in the stent group (incidence rate ratio ¼ 2.12, P ¼ .009) (Table 3). Given differences in group demographics, a multivariable analysis of HeRO versus stent, presence of SVC stenosis, or multisegment involvement revealed that only HeRO versus stent grouping correlated in a statistically significant manner with primary and secondary patency (P ¼ .001 and P ¼ .027, respectively).
Complications There was 1 severe complication in the HeRO group, consisting of an anastomotic dehiscence 1 week after HeRO surgery requiring graft ligation. The patient died 10 days later of myocardial infarction. No severe complications occurred in the stent group. At repeat venography and reintervention for stent occlusion, no instances of stent deformation secondary to bony compression were noted.
DISCUSSION Given the substantial morbidity that is incurred with AV access–associated central venous stenosis and need to preserve access options in patients receiving hemodialysis,
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5
Figure 1. Kaplan-Meier curve of primary patency in HeRO graft versus stent deployment. Cum ¼ cumulative.
successful management strategies are important. The data presented here suggest that both stent deployment and conversion to a HeRO graft are effective for short-term mitigation of swelling. However, conversion to a HeRO graft was less likely to incur subsequent return of arm swelling and resulted in longer primary and secondary patency rates than stent deployment. The average number of interventions to maintain secondary patency was lower in the HeRO group. Considering that both treatments prolong access patency while improving symptoms, both of these options should be preferable to access ligation. The 1-year HeRO graft primary patency rate of 72% in this study is substantially higher than the range of 9.1%– 49% reported in the literature (16,20,21). As all AV accesses converted to HeRO grafts in this study were already functioning, the study population lacks cases where HeRO failure occurred owing to inadequate arterial inflow to support patency, which skews primary patency rates to be higher. The generally high level of HeRO implantation experience at the authors’ institution may also improve outcomes. The secondary patency rate of 95% in this study is also high compared with the literature (45.5%–91% at 1 y), also likely for the same reasons (16,20,21). The access patency rates after stent deployment in the current study were generally low, with 12-month primary and secondary patency rates of 11% and 58%, respectively. Primary access patency rates after stent deployment for the
central veins are rarely reported (in favor of lesion patency rates); at 12 months, the primary access patency rates after stent deployment have been reported to be 0–29% (8,22,23). As access patency includes lesions anywhere within the circuit, the access age is an important factor (20 months on average in the current study), considering that the mean primary and secondary access patency after creation is 42.7% and 59.5% for AV fistulae and 31.5% and 56.8% for AV grafts at 1 year, based on a recent large study comprising > 90,000 patients (24). Thus, conversion of an existing access to a HeRO graft may have additional benefit to access patency by excluding the impact of venous outflow stenosis, venous anastomosis stenosis, and intragraft stenosis that would otherwise affect access patency in the stent group. Notably, whereas most studies on central vein stents in patients receiving hemodialysis report lesion patency rates based on postintervention angiography, access patency rates were instead assessed in the current study because this metric is not valid after HeRO graft insertion. By definition, access patency is always worse than lesion patency. Furthermore, access patency may be more important in this population because AV access ligation or abandonment may be required for unremitting arm swelling. Also of note, stent deployment was performed only after failed angioplasty, which enriches this group with more aggressive lesions that would skew toward worse patency rates after stent deployment; in contradistinction, many studies reporting patency
6 ▪ HeRO Graft versus Stent
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Figure 2. Kaplan-Meier curve of secondary patency in HeRO graft versus stent deployment. Cum ¼ cumulative.
after central stents include primary stent deployment, which would be expected to have higher patency rates. Finally, self-expanding bare metal stents (S.M.A.R.T.) were used in most of the stent group, which are not necessarily representative of all stents and stent grafts, particularly given emerging stents designed for use in veins as well as promising performance of covered stents in AV access (9,25–28). Although the purpose of this study was to compare outcomes after stent deployment versus conversion to a HeRO graft, the treatment choice in practice is not always binary. Depending on the location of central vein stenosis, conversion of an AV access to a HeRO graft may be completely feasible after initial stent deployment to mitigate arm swelling; similarly, initial conversion to a HeRO graft also might not preclude subsequent ipsilateral stent deployment after HeRO removal. For example, in a patient with patent central veins except for a subclavian vein stenosis, stent deployment within the subclavian vein will not impair insertion of a HeRO graft via the internal jugular vein. However, it is possible that stent deployment may make ipsilateral HeRO graft insertion difficult or impossible if the stent or stent graft obstructs a pathway to the right atrium in the setting of impassable stent occlusion. It is important to consider future permanent and catheter access options when deploying stents and stent grafts in the central veins of patients receiving hemodialysis (25); these results suggest that it may be prudent to also strategically plan for future HeRO access options to optimize long-term outcomes.
A statistically significant percentage of patients (59%) developed recurrent arm swelling after stent deployment compared with 1 patient after HeRO conversion. The intimal hyperplasia that leads to central vein stenosis can impair patency after stent or stent graft deployment by growing through stent interstices, formation within the stent graft lumen, or growing at the stent margin, thus leading to progressive restenosis and return of arm swelling (4,29). However, there have been no reports of stenosis or neointimal hyperplasia development within the HeRO outflow component. It is also known that the central veins can be subject to bony compressive forces, such as the thoracic outlet (4). On one hand, these sites would be expected to respond poorly to angioplasty alone and would be expected to respond suboptimally to stents owing to the compressive force. On the other hand, the HeRO outflow component contains braided nitinol reinforcement that resists compressive forces, which may represent a less morbid procedure than rib resection, particularly given the abundance of pressurized collateral veins in this region. Although this study examined only outcomes, an important consideration in the choice of treatment is overall cost. Compared with endovascular management, HeRO graft implantation would additionally incur anesthesia costs, operating room costs, and inpatient costs. In a cost analysis of the HeRO graft and associated interventions to maintain patency, the annual costs were estimated at $34,713.63 per patient/y (30). However, it is notable that the primary
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patency rate in that study was 8.4% at 12 months compared with 72% in the current study, which underscores the variability in outcomes based on institution experience. In another cost analysis study, the HeRO graft was shown to have lower costs on an annual basis than with tunneled hemodialysis catheters (31). Financial analyses of stent deployment for endovascular management of central venous occlusions are not currently published in the medical literature; a formal cost analysis would be helpful in ascertaining the optimal treatment algorithm. This study is limited by its nature as a retrospective, single-center study. The sample size for both groups was modest, which limits subset analyses and could exacerbate bias. For example, a variety of stents and stent grafts were used in the stent group. Although a much larger number of patients underwent central vein stent deployment at the authors’ institution, documented clinical follow-up of arm symptoms was not routinely available in many patients who were referred from unaffiliated outpatient dialysis centers, which substantially reduced the sample size in the stent deployment group. Selection bias was likely present, as stent deployment may be avoided in cases where bony compression was presumed to be present. This may explain why the HeRO group had a higher number of patients with SVC stenosis/occlusion and stenosis of > 1 central vein. Finally, given the relatively high-level experience with HeRO grafts at this center, results achieved in this study may not be entirely generalizable to other centers, as HeRO graft experience is not ubiquitous. In conclusion, for patients with upper extremity swelling owing to central venous stenosis in the setting of AV hemodialysis access, both central stent deployment and conversion of access to a HeRO graft are effective for addressing arm swelling. Although this is an inherently limited, retrospective study, these data suggest that conversion to a HeRO graft incurs a lower incidence of recurrent swelling and results in longer access patency rates, with fewer interventions to maintain secondary patency. However, as these 2 treatments are not mutually exclusive, there may be an optimal sequence of therapy that optimizes AV access longevity and maximizes future access options based on lesion and patient factors.
7
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
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