Compliance with the provisions in this policy may be monitored and addressed
through post payment data analysis and subsequent medical review audits.  
  
 **History/Background and/or General Information  
  
** Chronic venous disease (CVD) is prevalent in the United States of America
(USA) affecting more than 6 million adults.1 CVD may be defined as any
morphological and functional abnormality of the venous system of long duration
manifested either by symptoms and/or signs indicating the need for
investigation and/or care.2 Symptoms of progression may include leg heaviness,
aching, fatigue, edema, and ulceration.  
  
A common feature in chronic venous disease is the formation of progressive
venous hypertension in which inflammatory and pro-thrombotic mechanisms are
triggered. While the pathophysiology of venous disease is largely related to
stasis and reflux, the sequelae of same may ultimately lead to subsequent
obstruction resulting in the partial or total occlusion of a vein.  
  
Venous thrombosis is the formation of a blood clot in any segment of the deep
or superficial venous system. Venous obstruction is considered to be a partial
or complete blockage of venous flow in any venous segment. The blockage may be
a result of an internal thrombosis or external compression of a vein.  
  
Deep Venous Thrombosis (DVT) refers to the formation of blood clots in at
least one deep vein, usually of the lower or upper extremities. The Centers
for Disease Control and Prevention (CDC) estimates 20-50% of people who
experience DVT develop long-term complications.3 Post-thrombotic syndrome
(PTS), manifesting itself with a myriad of symptoms, is recognized as the most
common long-term complication of DVT.  
  
After DVT is objectively diagnosed, clinical tools used to help define PTS may
include the Villalta scale, Ginsberg measure or the Brandjes scale. Other
tools developed for general chronic venous disease include the Clinical,
Etiological, Anatomic, Pathophysiological (CEAP) classification, Venous
Clinical Severity Score (VCSS) and the Widmer scale.4  
  
Venous stenosis is an abnormal narrowing in a vein. Venous stenosis most
commonly affects the axillary, brachial, cephalic, or brachiocephalic veins of
the upper extremities, or the superior vena cava, but can also affect the
central veins in the abdomen and the pulmonary artery and veins. Common causes
are extrinsic compression, thrombosis from various etiologies including, but
not limited to, trauma and stenosis from placement of central venous
catheters, pacemaker leads or hemodialysis catheters.  
  
Noninvasive conservative management of venous disease and stenosis includes
treatment that improves venous circulation and reduces lower extremity edema
(e.g., elevation, analgesics, diuretics, weight management, exercise, tobacco
cessation or compression and anticoagulant therapy) to prevent thromboembolic
complications.  
  
Failed conservative management of clinically significant symptomatic venous
stenosis may include angioplasty and placement of an endovenous stent. An
endovenous stent may be defined as a synthetic tubular structure implanted in
native or graft vasculature to provide mechanical radial support and enhance
vessel patency. Percutaneous transluminal angioplasty (PTA) delivers the stent
under radiographic guidance to the intended location, where it is expanded
within the luminal space using either a balloon catheter or a self-expanding
mechanism.  
  
In the infancy of stenting, intravascular stents were developed for arterial
obstructions to restore and maintain arterial perfusion. Early venous stenting
extrapolated these indications from arterial use and applied balloon-
expandable and self-expandable stents to veins as an off-label use.  
  
As an initial therapeutic intervention, angioplasty may be performed on near-
obstructed veins to alleviate symptomatic areas of stenosis. In general, the
determination of success for angioplasty is evaluated by using the degree of
residual stenosis, the appearance of the vessel wall, and the absence of a
complication.5  
  
Clinical experience has shown advantages and disadvantages of the different
stent types. Compared to the self-expanding type, balloon-expandable stents
tend to have higher radial force but will not re-expand if crushed or bent. On
the other hand, self-expanding stents, available in larger lengths and
diameters, are reported to conform better to curvatures and deploy easily.
Venous stent technologies are emerging with many questions still unanswered.6  
  
In the search for the optimal endovenous stent, various types, each with their
unique characteristics, have been tried in search of the optimal desired
outcome.  
  
Nitinol stents have also been developed as an adjunct for treatment of venous
stenosis.  
  
Several different stents are currently used in the medical community.  
  
Coverage for placement of endovenous stents depends on the use of a U.S. Food
and Drug Administration (FDA) approved stent. Neither FDA classification and
marketing indication nor American Medical Association (AMA) Current Procedural
Terminology (CPT) category descriptors determine that a product meets Medicare
reasonable and necessary requirements. Each device has specific indications
described by the FDA for approved market uses. All products with FDA
clearance/approval used in accordance with the individualized product
application guidelines will be considered for the purpose of this LCD. Stent
placement is covered by Medicare only when an FDA-approved stent is used for
the FDA-approved indications or for off-label indication(s) supported by the
peer reviewed medical literature. For more details please see the FDA website
at [http://www.fda.gov/.](http://www.fda.gov/)  
  
It is the responsibility of the treating physician/practitioner to:

  * Determine and comply with FDA approval and specific designation for use of any agent or device utilized for the procedure or treatment planned
  * Comply with all applicable State and Federal regulations, laws and licensure related to the use of the agents and devices utilized

  
The central focus of this Local Coverage Determination (LCD) will be on the
indications for placement of stents in a severely symptomatic patient with a
vein which may be partially or near occluded.  
  
 **Covered Indications  
  
** Failed conservative management of CVD may include the need for Percutaneous
Transluminal Angioplasty (PTA). Placement of endovenous stents may be
considered as a planned adjunct to suboptimal or failed angioplasty.  
  
A suboptimal or failed angioplasty is defined as dilation judged by the
physician to be suboptimal or failed due to the presence of unfavorable lesion
morphology such as:

  * Residual stenosis of more than 30 percent for a vein measured at the narrowest point of the vascular lumen at the site of angioplasty or more than 50 percent reduction of luminal diameter.5(p59)
  * A tear that interrupts the integrity of the intima or lumen causing hemorrhage.
  * Abrupt persistent occlusion or dissection at the site of angioplasty, occlusion elastic recoil or refractory spasm.

  
A stent may be placed as a planned adjunct to angioplasty rather than in
response to a suboptimal or failed angioplasty.  
  
Primary endovenous stenting is justified for situations where angioplasty
alone is not expected to provide a durable result.  
  
Endovenous stents may be placed for patients with severely symptomatic venous
obstructions due to any of the following:

  1. Iliac vein compression syndrome also known as May-Thurner or Cockett syndrome.
  2. Iliocaval obstruction.
  3. Iliofemoral obstruction for patients with venous leg ulceration(s) not relieved by conservative therapies and compression. Progression of symptoms may lead to Phlegmasia Cerulea Dolens (PCD), acute inferior vena cava (IVC) thrombosis, and rapid thrombus extension despite anticoagulation as well as anatomically extensive DVT affecting the common femoral and/or iliac vein, or post-thrombotic stenosis with ankle edema of venous origin (i.e., minimum CEAP score 3).
  4. Superior or Inferior Vena Caval Thrombosis including Superior Vena Cava syndrome.
  5. Post-thrombotic syndrome (PTS).
  6. As an adjunct to catheter-directed thrombolysis for acute femoroiliocaval deep vein thrombosis when post thrombolysis imaging identifies symptomatic residual stenosis.
  7. Post radiation venous stenosis.
  8. Symptomatic post-traumatic venous stenosis including those resulting from central venous catheters or transvenous device (e.g., pacemakers, defibrillators,) pacemaker leads or a history of abdominal and/or pelvic surgery.
  9. Salvage of thrombosed or stenotic symptomatic or limited function arteriovenous dialysis access fistulae or grafts with compromised venous outflow, failed angioplasty rapid restenosis, or vessel perforation. This may include treatment of trapping a life threatening thrombus, an aneurysm or pseudoaneurysm that threatens the viability of the AV fistula or graft, or the treatment of a hemodialysis vascular access rupture that cannot be controlled through balloon tamponade.
  10. Thrombotic obstruction of major hepatic veins (Budd-Chiari syndrome).
  11. Transvenous decompression of portosystemic shunts.
  12. Post-operative stenosis or venous narrowing due to repair of congenital cardiac disease, e.g. sinus venosus Atrial Septal Defect (ASD), discordant atrioventricular connection status post Mustard or Senning repair of Transposition of the Great Arteries (TGA).
  13. Pulmonary vein stenosis resulting from congenital malformation, extrinsic compression, sequelae of radiofrequency ablation (RFA), lung transplantation, or status post repair of Total Anomalous Pulmonary Vein Return (TAPVR).

****

**Limitations  
  
** The following are considered not medically reasonable and necessary:

  1. All other uses of endovenous stents not listed as a covered indication in this LCD.
  2. The placement of a stent in a vein for which there is no objective-related symptom or limitation of function is considered to be preventive and, therefore, not covered by Medicare.
  3. Presence of local or systemic infection is a relative contraindication to venous stenting except under unusual circumstances where the benefit of placing the stent may outweigh the risks. In these circumstances, the documentation should reflect the provider's rationale.
  4. Use of stents without U.S. FDA approval.
  5. Stenting of popliteal or tibial veins.
  6. Venous stenosis less than or equal to 50% of diameter of vein or residual stenosis of less than 30% measured after angioplasty.
  7. Venous stenting for idiopathic intracranial hypertension (IIH) is considered investigational and may be considered only in select isolated and unique circumstances upon individual redetermination.
  8. A stent(s) that carries an Investigational Device Exemption (IDE) may be covered under Medicare. Medicare coverage of IDE devices is predicated, in part, upon their status with the FDA. Coverage will cease in the event a manufacturer loses (or violates relevant IDE requirements necessitating FDA's withdrawal of) IDE approval. The FDA issues a special identifier number that corresponds to each device or stent(s) granted an IDE.

**  
Provider Qualifications  
  
** Services will be considered reasonable and necessary only if performed by
appropriately trained physicians.

  1. Physicians who perform endovenous stent procedures must possess the knowledge, skills, training and experience necessary to properly select suitable patients who will benefit from and not be harmed by stent therapy as opposed to other intervention, perform the procedures safely, and recognize and handle complications of stent placement. Physicians who perform and report these services for Medicare payment must have satisfied training and competency guidelines in peripheral vascular medicine and intervention as part of a formal postgraduate training program in radiology, nephrology, cardiology or general/vascular surgery. Alternatively, physicians must have completed supervised training in vascular medicine and intervention as published by a recognized specialty organization of the same stature as the American College of Radiology, American College of Cardiology or American College of Surgery, or American Society of Diagnostic and Interventional Nephrology.
  2. For those physicians who would not have had formal training, i.e. before 2000, Medicare expects that any physician who seeks and receives payment for these services is prepared to substantiate his/her training and experience if asked to do so by Medicare. Substantiation of the training may include ongoing CME and Training events, Medical Staff privileges in order to do the procedures, or attestation by peers.

  
A qualified physician for this service/procedure is defined as:

  * Physician (MD or DO) properly enrolled in Medicare, Licensed by the State with full scope of practice, with

  * Training and experience acquired through tenured practice or within the framework of an accredited residency and/or fellowship training program in the applicable specialty/subspecialty in the United States, reflecting equivalent education, training and expertise endorsed by an academic institution or specialty society in the United States.

**  
Notice:** Services performed for any given diagnosis must meet all of the
indications and limitations stated in this policy, the general requirements
for medical necessity as stated in CMS payment policy manuals, any and all
existing CMS national coverage determinations, and all Medicare payment rules.  
  
The redetermination process may be utilized for consideration of services
performed outside of the reasonable and necessary requirements in this LCD.

**_Technology Assessment_** ** _  
  
_**Agency for Healthcare Research and Quality (AHRQ) Jones, et al. 7 in
conjunction with CMS proposed a technology assessment (TA) on treatment
strategies for lower extremity chronic venous disease (LECVD). This systematic
review includes a narrative review of diagnostic testing modalities and
assesses the comparative effectiveness of exercise training, medical therapy,
weight reduction, mechanical compression therapy, and invasive procedures
(i.e., surgical and endovascular procedures) in patients with LECVD. Eight
studies were included for treatment of adult patients with lower extremity
chronic venous thrombosis/obstruction. In seven of the studies, all patients
were symptomatic at baseline; in one study only a small minority had unclear
symptom severity. Three studies were randomized controlled trials representing
a total of 109 patients. The sample size of the five observational studies
ranged from 20 to 216 patients. All studies assessed the comparative
effectiveness of exercise training, medical therapy, weight reduction,
compression therapy, skin/wound care, endovenous intervention and/or surgical
intervention on functional outcomes, quality of life, and safety events in
patients with lower extremity chronic venous obstruction/thrombosis. Studies
that assessed individual treatment modalities or combinations of treatment
modalities were analyzed; however differences in the treatment comparisons,
outcome measures, and follow-up time points eliminated the possibility that
study results could be pooled for analysis of direct comparisons. There were
no studies reporting results by the following subgroups: age, race/ethnicity,
sex, body weight, CEAP classification, VCSS classification, severity of
disease, anatomic segment affected, presence of ulcer, and known malignancy.
Unfortunately given the small number of studies, heterogeneity in outcomes and
interventions assessed, diverse populations evaluated, and inconsistency in
findings, the evidence was insufficient to support any findings.  
  
 ** _Evidence-Based / Professional Society Guidelines_** ** _  
  
_**The American College of Phlebology, in their practice guidelines on chronic
deep venous obstruction of the femoroiliocaval venous system 8 recommend
venous balloon angioplasty and stenting as an adjunct to catheter-directed
thrombolysis for acute femoroiliocaval deep vein thrombosis in order to
maintain vein patency and flow when a residual stenosis is found on post
thrombolysis imaging. The guidelines state there is robust clinical evidence
in the peer-reviewed medical literature that alleviating venous obstruction
utilizing balloon angioplasty and stenting is feasible in the vast majority of
patients with good to excellent results in terms of stent patency, relief of
symptoms, and recurrent stenosis. The evolution of balloon angioplasty and
stenting of the femoroiliocaval vein obstructions over the past 20 years has
established it as the technique of choice for most severely symptomatic
patients.  
  
The American College of Radiology (ACR) Committee represented by Hohenwalter,
et al.9 developed criteria for radiologic management of iliofemoral venous
thrombosis. The ACR criteria include conventional anticoagulation alone does
not prevent post-thrombotic syndrome and catheter-directed thrombolysis and
pharmacomechanical thrombolysis may decrease the incidence of PTS in patients
with acute iliofemoral DVT with proper patient selection. Patients with
iliofemoral DVT are the subset of patients with the largest thrombus burden
and the highest risk for postthrombotic morbidity; up to 75% have chronic
painful edema, and 40% have venous claudication when treated with
anticoagulant therapy alone. The evidence available favors use of catheter-
directed thrombolysis (CDT) and pharmacomechanical thrombolysis in DVT
patients with clinically severe manifestations of DVT. These severe
manifestations include Phlegmasia Cerulea Dolens (PCD), acute IVC thrombosis,
and rapid thrombus extension despite anticoagulation as well as anatomically
extensive DVT that includes the common femoral and/or iliac vein since this
degree of thrombus carries a higher risk of recurrent DVT and PTS.  
  
The ACR Committee and the Society of Interventional Radiology (SIR)
collaboratively revised the practice parameter for endovascular management of
the thrombosed or dysfunctional dialysis access.10 Endovascular management of
hemodialysis access prosthetic grafts and autogenous fistulae is an
alternative treatment to surgical thrombectomy and revision. It applies to
accesses that have never matured, or accesses that have thrombosed, accesses
that have blood flow insufficient to allow hemodialysis, accesses with
clinical symptoms or noninvasive assessments that indicate the access is at
increased risk of thrombosis, and access complications such as pseudoaneurysm
or steal. Endovascular management results in reduced morbidity compared to
standard surgical therapy, with less post procedure pain and decreased wound
edema. Endovascular management of the thrombosed or dysfunctional hemodialysis
access is usually performed on an outpatient basis, with the patient returning
home or to the dialysis unit for treatment.  
  
The ACR Committee, the Society of Interventional Radiology (SIR), the Society
of Neurointerventional Surgery (SNIS) and the Society for Pediatric Radiology
(SPR) collaboratively revised the practice parameter for interventional
clinical practice and management.11 The practice parameter states
interventional radiology and interventional neuroradiology are clinical
subspecialties of radiology focused on minimally invasive, image-guided
therapy for numerous diseases. An interventional radiologist or interventional
neuroradiologist interacts directly with patients and counsels them regarding
their diseases and therapeutic options.  
  
In 2014, the ACR Committee, the Society of Interventional Radiology (SIR), the
Society for Pediatric Radiology (SPR) collaboratively revised the practice
parameter for reporting and archiving of interventional radiology
procedures.12 This practice parameter is intended to improve patient care by
improving the consistency of medical record content, the written or dictated
reports, and image archiving for vascular/interventional radiology procedures
(exclusive of breast interventional procedures). For endovascular
interventions, the ACR-SIR-SPR recommend predeployment and postdeployment
intervention images should be obtained and archived. Intermediate stages that
are pertinent to the performance of the endovascular procedure may also be
documented with archived images. Images should detail the position of the
device and, when appropriate, the effect of the device on target or nontarget
vessels.  
  
The American Heart Association (AHA) represented by Jaff, et al.13 released a
scientific statement following review of literature for the management of
massive and submassive acute pulmonary embolism (PE), iliofemoral deep vein
thrombosis (IFDVT), and chronic thromboembolic pulmonary hypertension (CTEPH).
The AHA mentions percutaneous transluminal venous angioplasty and stent
placement have been used routinely concomitant with endovascular or surgical
thrombus removal to treat obstructive lesions and prevent rethrombosis in
patients with acute iliofemoral deep vein thrombosis (IFDVT). The AHA states
typically with left common iliac vein stenosis in association with left-sided
IFDVT (i.e., May-Thurner syndrome, Cockett syndrome) the treatment is stent
placement in catheter-directed thrombolysis (CDT) studies. The authors
conclude the body of evidence to guide management for these forms of venous
thromboembolism (VTE) is incomplete, and therefore, some recommendations must
rely on lower levels of evidence or expert opinion. Further clinical trials of
advanced therapies for VTE are strongly advised.  
  
The American Heart Association Scientific Council leadership invited
multidisciplinary experts in Post Thrombotic Syndrome (PTS), represented by
Kahn, et al.4 to form a writing panel for the construction of a scientific
statement. After systematic review of relevant literature on the
pathophysiology, epidemiology, prevention, diagnosis, and treatment of PTS,
the writing panel developed the peer-reviewed evidence-based recommendations.
The authors noted experience with endovascular, surgical, and hybrid
approaches to the treatment of PTS is limited and only the most severely
affected patients are considered for treatment. The panel acknowledged the
body of evidence to guide management of PTS is incomplete and consequently,
many recommendations rely on lower levels of evidence.  
  
The Cardiovascular and Interventional Radiological Society of Europe (CIRSE)
standards of practice guidelines on iliocaval stenting, represented by
Mahnken, et al.14 review the current evidence on iliocaval vein recanalization
and provide standards of practice for iliocaval stenting in primary and
secondary causes of chronic venous disease. Chronic venous disease (CVD)
covers a wide range of symptoms from cosmetic problems to more severe
symptoms, such as ulceration. The role of venous obstruction is increasingly
recognized as a major cause of CVD, with obstructive lesions in the iliocaval
segment being markedly more relevant than lesions at the levels of the crural
and femoral veins. Iliac vein obstruction is most commonly due to insufficient
recanalization following an episode of acute deep venous thrombosis (DVT),
with approximately 70-80% of veins developing a variable degree of
obstruction. Non-thrombotic iliac vein obstruction occurs where it is crossed
by the iliac or hypogastric artery, a condition known as May-Thurner or
Cockett's syndrome. Patients with CEAP clinical class 3-6 and chronic venous
outflow obstructions should be considered for interventional therapy. Stenting
of the iliac veins also should be considered in the presence of nonthrombotic
obstructive venous lesions in the iliocaval segment with a degree of stenosis
of more than 30% and the presence of venous collaterals. Iliocaval stenting
should always be considered as an adjunct to interventional or surgical
management of iliocaval thrombosis. Clinical improvement appears to be long
lasting, although long-term results after treating acute DVT seem to be better
than stenting in chronic venous obstruction. The CIRSE guidelines conclude
stenting in chronic iliocaval obstruction is safe and effective. It provides
excellent long-term results with respect to target vessel revascularization as
well as symptom relief, therefore improving the quality of life. In selected
patients, it appears to even reverse established PTS. During the past decade,
venous outflow obstruction has become recognized as more relevant in CVD than
previously anticipated and endovascular correction of outflow obstructions
should be liberally indicated.  
  
The European Society of Vascular Surgery (ESVS) represented by Wittens, et
al.15  provides Clinical Practice Guidelines for the care of patients with CVD
in the lower extremities. Sixteen articles related to percutaneous
transluminal angioplasty and stenting were reviewed. Consensus recommendation
is that after percutaneous transluminal angioplasty, stent placement should be
considered for patients with chronic deep venous obstruction. The stent should
ideally have a sufficient high radial force and flexibility to preclude recoil
and collapse. It has been shown that in two thirds of patients with post-
thrombotic disease it is necessary to implant stents down to the groin below
the inguinal ligament to improve inflow into the reconstructed iliac veins.
Interventions distal to the groin, including endophlebectomy or stenting
further down into the femoral vein or profunda femoral vein are not yet
validated. There are several forms of congenital deep venous anomalies causing
obstruction of the outflow tract. One severe anomaly is atresia (congenital
absence) of the inferior vena cava (IVC) in which the sub-hepatic segment of
the IVC has not developed. This may cause CVD because of outflow obstruction,
often complicated by recurrent ilio-femoral DVT and subsequent post-thrombotic
problems. Clinical results using dedicated venous stents and comparison
between different types of stent are lacking. The optimal design and material
of a venous stent is presently not known.  
  
The KDOQI 2006 guidelines16 state endovascular stents would seem to be an
ideal method to treat angioplasty failures. Stents can oppose elastic recoil
and optimize endoluminal dimensions, thereby improving intragraft blood flow
and prolonging graft patency. However, the majority of clinical studies showed
that the routine use of stents does not provide an additional benefit compared
with angioplasty alone. The neointimal hyperplastic tissue continues to grow
unabated through the meshwork of the metallic stent. For these reasons, use of
endovascular stents to treat HD-related stenoses continues to be a
controversial subject. A recent study reported that use of nitinol stents
provided superior results compared with stainless steel stents. Continued
improvements in stent design, the use of stent grafts, or the use of drug-
eluting stents may provide better long-term results. Covered stents have been
used to salvage arteriovenous grafts, but efficacy has not been compared with
other strategies.  
  
The Society of Interventional Radiology position statement on the treatment of
acute iliofemoral deep vein thrombosis with use of adjunctive catheter-
directed intrathrombus thrombolysis, represented by Vedantham, et al.17
considers the use of catheter-directed intrathrombus thrombolysis (CDT) as an
adjunct to anticoagulant therapy to represent an acceptable initial treatment
strategy for carefully selected patients with acute iliofemoral deep vein
thrombosis (DVT). Patients with iliofemoral DVT are at particularly high risk
for PTS and late disability. The enhanced effectiveness of CDT compared with
systemic thrombolysis in reestablishing iliofemoral venous patency is thought
to be a result of two main factors: (a) catheter-directed delivery enables a
higher intrathrombus drug concentration to be achieved, enhancing thrombus
removal and reducing the needed dose; and (b) catheter access into the venous
system enables the use of balloon angioplasty and stents to treat underlying
venous obstruction that might otherwise predispose to recurrent DVT.  
  
The Society of Interventional Radiology Position Statement, by Baerlocher, et
al.18 provides reference guidelines for the requirements for safe operation of
interventional radiology (IR) suites. Although the primary focus of the
guidelines is to address staffing issues for IR practice, certain clinical
aspects merit specific mention. IR is a clinical specialty composed of
physicians with extensive knowledge of a broad spectrum of disease that they
treat. In 2012, the American Board of Medical Specialties officially
recognized IR as the 37th medical specialty. In 2014, the Accreditation
Council on Graduate Medical Education approved the new IR residency pathway.
One aspect of this expertise requires admitting privileges. It is the
unequivocal position of the SIR that IR be provided with admitting privileges
and have parity with other admitting physicians. Equally, longitudinal IR care
requires dedicated clinic space, typically separate from the inpatient area,
and resources for outpatient evaluation, examination, consultation, and
charting.  
  
The Society of Interventional Radiology represented by Dolmatch et al.19
identifies four anatomic patterns of obstruction and defines five key
reporting dimensions that allow clinicians to describe thoracic central vein
obstruction (TCVO) in a straightforward and reproducible manner. TCVO often
interferes with vascular access and may cause disability of varying degree
and, on occasion, death. Although thoracic aneurysms rarely cause TCVO today,
there are a multitude of other conditions that do. Thoracic malignancy,
particularly lung cancer and lymphoma, and other neoplastic, infectious, and
inflammatory mediastinal processes may obstruct the thoracic central veins.
Paget-Schroetter syndrome and subclavian venous thrombosis may cause TCVO.
TCVO is frequently associated with the use of indwelling venous devices such
as infusion ports, peripherally inserted central catheters, and transvenous
cardiac rhythm device leads. Chronic central venous catheters in children and
adults have been associated with TCVO. Patients receiving hemodialysis who
have had previous venous catheter access or cardiac rhythm device leads are
known to have a high prevalence of symptomatic TCVO. Some cases of TCVO cannot
be attributed to any particular cause. The type of obstruction should be
reported. Additionally, flow leading up to the obstruction is systemic venous
return or return from an arteriovenous (AV) circuit (in patients with a
working upper-extremity hemodialysis fistula or graft). The type of flow
should be noted. If flow is AV, the side of the AV circuit should be reported.
Whenever possible, stenosis should be quantified as a percentage diameter
narrowing compared with an adjacent nonstenosed venous segment. The guidelines
suggest clinical reporting requirements of TCVO pattern of obstruction, type
of flow, and degree of obstruction. The authors hope this work will guide the
way toward best-practice recommendations, algorithms to track central vein
use, strategies that can reduce the incidence of TCVO, and broader adoption of
common data elements and standardized reporting structures.  
  
The Society for Vascular Surgery (SVS) clinical practice guidelines, for the
surgical placement and maintenance of arteriovenous hemodialysis access, were
developed by Sidawy, et al.20 The SVS involved The Knowledge and Encounter
Research Unit (KER) of the Mayo Clinic College of Medicine, Rochester,
Minnesota. For the management of nonfunctional or failed arteriovenous (AV)
access, the recommendation is open surgery, endovascular means, or a
combination of both to maintain or restore patency in AV access. The
systematic literature reviews reveal a scarcity of high-quality evidence and
many of the recommendations are based on observational studies and consensus
of the committee. Despite the lack of high-quality evidence, some of the
recommendations were graded as strong because of the values and preferences
brought to light by the multidisciplinary committee.  
  
The Society for Vascular Surgery and the American Venous Forum, represented
by Meissner, et al.21 provide clinical practice guidelines for early thrombus
removal strategies for acute deep venous thrombosis. The committee of experts
in venous disease performed a systematic review and meta-analysis of relevant
literature supplemented by less rigorous data as necessary. Regarding
adjunctive use of venous stents, the recommendations are to use self-expanding
metallic stents for treatment of chronic iliocaval compressive or obstructive
lesions that are uncovered by any of the thrombus removal strategies [in the
guidelines] and that stents not be used in the femoral and popliteal veins.
The committee concluded that most data regarding early thrombus removal
strategies are of low quality but do suggest patient-important benefits with
respect to reducing postthrombotic morbidity.  
  
The Society for Vascular Surgery and the American Venous Forum, referenced by
O'Donnell, et al.22 provide clinical practice guidelines including
recommendations for operative and endovenous management of venous disease. In
general, quality of evidence available to support recommendations for
operative and endovascular management is mostly limited to observational
studies or case series. For all patients with venous leg ulcers who require
venous endovascular or operative intervention, outcome assessment should be
performed to determine success of the procedure over time. In a patient with
inferior vena cava or iliac vein chronic total occlusion or severe stenosis,
with or without lower extremity deep venous reflux disease, that is associated
with skin changes at risk for venous leg ulcer (C4b), healed venous leg ulcer
(C5), or active venous leg ulcer (C6) the recommendation is for venous
angioplasty and stent recanalization in addition to standard compression
therapy to aid in venous ulcer healing and to prevent recurrence.  
  
 ** _Summary of Evidence: Endovenous Stenting Articles_** ** _  
  
_**Abou Ali, et al. 23 reviews the role of venous stenting for iliofemoral and
vena cava obstruction in patients with acute or chronic venous outflow
obstruction. The authors describe endovenous balloon angioplasty as a
suboptimal intervention with high level of lesion recurrence. Large-caliber
stents are required in most cases. Although venography is used to confirm deep
venous occlusion, intravascular ultrasound (IVUS) is frequently implemented to
determine the extent of the lesion and the proximal and distal stent landing
zones. IVUS is recommended for adequate placement of the stent and for stent
sizing and determining the extent of disease. Stent sizing is different in
venous practice compared with arterial stents. Although it is agreed that
stent sizing with arterial lesions is in accordance with normal adjacent
vessels, the same approach would lead to significant undersizing with venous
lesions. Undersizing venous stents can lead to iatrogenic stenosis, which
becomes more pronounced when in-stent restenosis (ISR) develops and possible
migration. This finding is particularly important, as 61% of stents in the
iliocaval outflow tract experienced ISR between 20% and 50% at 5-year follow-
up. Until recently, there have been no venous dedicated stents, but two stent
designs have completed clinical trial enrollment in the United States and are
awaiting data analysis and subsequent FDA approval. A prospective multicenter
nonrandomized study (VIRTUS) has completed enrollment and aims to evaluate the
safety and efficacy of venous stents in patients with chronic nonmalignant
iliofemoral venous outflow obstruction.  
  
Attaran24 in Latest Innovations in the Treatment of Venous Disease describes
current modalities of treatment of venous disease and specifically elaborates
on the use of stents in various thrombotic syndromes. The current standard
treatment for May-Thurner Syndrome and/or iliac vein stenosis is angioplasty
and stenting and has achieved favorable patency rates. Stents must be
appropriately selected to avoid undersizing and subsequent stent migration.
The use of iliac intervention for the treatment of symptomatic iliac vein
stenosis has shown favorable long-term patency, as well as improvement in
symptoms including pain, edema, and ulcer healing. The author notes no
conflict of interest.  
  
Aydinli and Bayraktar25 discuss the etiology, pathogenesis and diagnosis of
Budd-Chiari syndrome (BCS). Throughout the world occurrence of BCS is noted to
be rare and a disorder characterized by obstruction of hepatic venous outflow.
Patients present with acute signs and symptoms of abdominal pain, ascites and
hepatomegaly or more chronic symptoms related to long-standing portal
hypertension. The authors review etiology, pathogenesis and diagnosis of BCS
stating most patients with BCS have an underlying condition that predisposes
the patient to blood clotting with obstruction mainly caused by primary
intravascular thrombosis.  
  
Bachleda, et al.26 conducted a study outside of the United States designed to
evaluate the results of hybrid treatment of arteriovenous graft thrombosis
associated with venous anastomotic stenosis. Sixteen patients with
arteriovenous graft (AVG) occlusions were treated. Immediately after the
diagnosis of occlusion was made, the patients underwent thrombectomy. After
thrombectomy, a diagnostic fistulogram was performed and if stenosis was
confirmed at the venous anastomosis of the graft (VAG), it was treated with
balloon angioplasty and stent graft introduction. Lesions were dilated to
reduce the stenosis in the treated area to less than 25%. Primary patency
after 12 months was 32.8%. Primary assisted patency was 44.7%, secondary
patency was 47.6%. Restenosis of the stent graft was seen in two patients.
Recurring AVG occlusion was observed in four patients. The average number of
interventions to maintain AVG patency was 1.18 per patient/1 year of dialysis.
Treatment of AVG thrombosis due to VAG stenosis by hybrid procedure proved to
be effective and improved secondary patency. Although the sample size is
small, it demonstrates that venous anastomosis of the graft (VAG stenosis)
leading to arteriovenous grafts (AVG) thrombosis can be managed by angioplasty
with stent graft introduction.  
  
Bozkaya, et al.27 in Endovascular Treatment of Iliac Vein Compression (May-
Thurner) Syndrome: Angioplasty and Stenting with or without Manual Aspiration
Thrombectomy and Catheter-Directed Thrombolysis, describes treatment
modalities for May-Thurner syndrome (MTS). May-Thurner syndrome, a rare
clinical entity featuring venous obstruction of the left lower extremity is
characterized by chronic pulsatile compression of the left iliac vein in the
region between the right common iliac artery and the lumbar vertebral body.
The study is a retrospective analysis of 23 patients with MTS and to evaluate
the utility of treatment using endovascular techniques. Complete left common
iliac vein patency was achieved in 21 of the 23 patients (technical success
rate: 91.3%). Complete thrombolysis was attained by 14 of the 18 DVT patients
(77.7%). The mean clinical and radiological follow-up time was 15.2  16.1
months. Upon follow-up, complete symptomatic regression was observed in 19 of
the 23 patients (82.6%). Stent patency was complete in 19 of the 21 patients
(90.4%) who received stents. Restenosis occurred in two patients and no
treatment-related mortality or morbidity was observed. The study concludes
that endovascular treatment of MTS is safe and effective and reduces symptoms
in most patients, associated with high medium-term patency rates. The
limitations of the present study were the retrospective nature of the work,
the limited number of MTS patients evaluated, and the loss of some patients to
follow-up (limiting the long-term data). Follow-up periods and control numbers
were not standardized, and follow-up periods were relatively short. Another
potential limitation is the variability in stent type and size. The authors
declare no conflicts of interest.  
  
Brinegar, et al.28 addresses iliac vein compression syndrome and focused on
May-Thurner syndrome (MTS), in which the pathologic compression of the left
common iliac vein by the right common iliac artery, results in left lower
extremity pain, swelling, and deep venous thrombosis. This article is a
summary of the historical aspects of the clinical features of this syndrome as
well as a comprehensive assessment of the literature on the efficacy of
imaging tools available to diagnose MTS. It also provides recommendations to
aid physicians in diagnosing the syndrome through the use of provocative
measures and provides treatment options.  
  
de Graaf, et al.29 conducted an observational study of forty patients treated
for chronic bi-iliocaval obstructions. The study reports on two confluence
stenting techniques, one with self-expandable stents and the other with
balloon-expandable stents (BECS) bridging the common iliac vein confluence.
The total number of legs evaluated was 80 legs with 50 of those for the
endovascular only group. The mean age of participants was 41 (+/- 14.9) years
(range 16-62 years). Each group performed bilateral iliac extensions using
nitinol stents; beginning in 2013 dedicated venous stents were used. Patency
was described as patency of more than 50% of the venous lumen on DUS. The
primary, assisted-primary, and secondary patency rates of treated lower
extremities were 79, 82, and 90% at 12 months and 70, 73, and 78% at three
years respectively. The study mentions although dedicated venous stents are
purported to perform better in venous vasculature, no proof that dedicated
venous stents improve outcome was available at the time of the study. The
authors anticipate the evolution of "confluence-stent" devices as the use is
already recognized in bifurcated aorta repair and may also be shown to support
venous reconstructions in the future.  
  
Dinkin and Patsalides30 presents prospective data after venous sinus stenting
for medically-refractory, medication-intolerant, or fulminant Idiopathic
Intracranial Hypertension (IIH), and suggests that while this may be
considered as an alternative to conventional therapy, concludes that there
remains insufficient evidence to support any surgical procedure for IIH over
another, and a large, multicenter, randomized, physician-blinded, head-to-head
trial comparing venous stenting to shunting is needed to determine the
relative safety and efficacy of these options.  
  
Kurklinsky, et al.31 conducted a single-center, retrospective 30-day, 1-year
and 3-year review on patency of chronically occluded iliofemoral venous
thrombotic lesions treated with stent placement in a case series. Records of
189 consecutive patients treated by interventional radiology for iliofemoral
venous occlusions between March 01, 2003, and December 01, 2008, were
retrospectively reviewed. Eighty-nine patients (27 males, median age 46.2
years) with chronic iliac or iliofemoral deep vein thrombosis without
involvement of the inferior vena cava met criteria for analysis. Eighty-nine
patients (91 limbs) successfully underwent placement of venous self-expanding
stents. Discharge patency was 100%. Following the index procedure, the mean
pressure gradient across the lesion decreased from 5.63 mmHg (95% CI: 3.51 -
7.75) to 0.71 mmHg (95% CI: 0.08 - 1.34) mmHg (p less than 0.0001). There were
no bleeding complications. Median follow-up was 11.3 months (range 0.8 -
72.4). Follow-up at 30 days demonstrated 90 of 91 limbs patent. Primary
patency of treated limbs at 1 and 3 years was 81 and 71% respectively. Primary
patency was lost in 17 (19.1%) cases; interventions to maintain or restore
stent patency were performed in 13 (14.6%) cases. Primary assisted limb
patency at 1 and 3 years was 94% and 90% respectively; secondary patency was
95%.  
  
Neglen, et al.32 reports a study on stenting of the venous outflow in chronic
venous disease. This study reviewed timestamped electronic medical records for
patients with venous disease specifically constructed to prospectively collect
comprehensive standardized information on symptoms and physical findings in
patients with venous disease. This study of 982 (in 870 patients) chronic
nonmalignant obstructive lesions of the femoroiliocaval vein were stented
under intravascular ultrasound guidance. One hundred and twelve patients (13%)
had bilateral treatment with stents for obstruction of the femoroiliocaval
vein. Median age was 54. Clinical score of CEAP (classification of varicose
veins severity) was 2 in 7%, 3 in 47%, 4 in 24%, 5 in 5%, and 6 in 17%;
primary/secondary etiology was 518 limbs/464 limbs, respectively. Stent-
related outcome (morbidity, thrombotic events, patency, in-stent recurrent
stenosis), clinical outcome, quality of life (QOL) as assessed by the Chronic
Venous Insufficiency Quality of Life Questionnaire (ClVlQ), and hemodynamics
were evaluated before and after intervention. Monitoring for 94% of patients
lasted a mean 22 months (range, 1 to 107 months). Stenting was performed with
no mortality (less than 30 days) and low morbidity. Thrombotic events were
rare (1.5%) during the postoperative period (less than 30 days) and during
later follow-up (3%). At 72 months, primary, assisted-primary, and secondary
cumulative patency rates were 79%, 100%, and 100% in nonthrombotic disease and
57%, 80%, and 86% in thrombotic disease, respectively. Cumulative rate of
severe in-stent restenosis (greater than 50%) occurred in 5% of limbs at 72
months (10% in thrombotic limbs, 1 % in nonthrombotic limbs). The main risk
factors associated with stent occlusion were the presence and severity of
thrombotic disease; thrombophilia by itself was not a risk factor. The median
pain score and degree of swelling decreased significantly poststent. The mean
ClVlQ scores improved significantly in all categories. Mean hand-foot pressure
differential decreased and mean ambulatory venous pressure improved in stented
limbs with no concomitant reflux. The hemodynamic response was modified,
depending on the presence of deep and superficial reflux in subsets of
patients with adjunct saphenous procedures. No increase in venous reflux was
observed.  
  
Raju, et al.33 assessed stent-related and clinical outcomes following
treatment by iliac venous stenting alone in symptomatic limbs with a
combination of iliac vein obstruction and deep venous reflux. Over a period of
11 years, a total of 528 limbs in 504 patients, ranging in age from 15 to 87
years (median 55 years) of age, had intravascular ultrasound (IVUS)-guided
vein stent placement to correct obstruction. The etiology of obstruction was
nonthrombotic in 196 (37%) limbs, post-thrombotic in 285 (54%) limbs, and
combined in 47 (9%) limbs. Venography and other functional tests had poor
diagnostic sensitivity to detect obstruction, which was ultimately diagnosed
by IVUS. The IVUS-guided iliac vein stenting was the only procedure performed
and the associated reflux was left uncorrected in this study. The authors
stated use of large-caliber (14-18mm) stents, stent coverage of all lesions
without skip areas, three to five centimeter (cm) extension of braded iliac
stents into inferior vena cava, and extension below the inguinal ligament, as
necessary, are essential technical elements for a successful outcome. There
was no mortality; morbidity was minor. Wallstents (Boston Scientific,
Nantucket, Mass.) were used exclusively in this study. Cumulative secondary
stent patency reported was 88% at five years; no stent occlusions occurred in
nonthrombotic limbs. Cumulative rates of limbs with healed active ulcers,
freedom of ulcer recurrence in legs with healed ulcers and freedom from leg
dermatitis at five years was 54%, 88%, and 81% respectively. Cumulative rate
of substantial improvement of pain and swelling at five years was 78% and 55%
respectively. The study reports quality of life improved significantly and
reflux parameters did not deteriorate after stenting was performed. Iliac
venous stenting alone sufficiently controlled symptoms in the majority of
patients with combined outflow obstruction and deep reflux. The study
concludes partial correction of the pathophysiology in limbs with multisystem
or multilevel disease can provide substantial symptom relief. The authors
state open correction of obstruction or reflux is only required as a "last
resort" due to percutaneous stent technology in concert with other minimally
invasive techniques to address superficial and/or perforator reflux for
patients with advanced CVI and complex venous pathology.  
  
Raju34 retrospectively reviewed a single-arm case series encompassing about
1,500 patients treated for iliac vein stenosis and occlusion. Evidence quality
was judged moderate, with a grade 1B recommendation (benefits outweigh risks)
for patients with disabling symptoms in whom conservative therapy had failed.
A grade 2B recommendation was assigned for patients with less severe symptoms.
The author states iliac vein stenting is safe, with negligible morbidity (less
than1%). Patency was 90% to 100% for nonthrombotic disease and 74% to 89% for
post-thrombotic disease at 3 to 5 years. Clinical relief of pain was 86% to
94%, and relief from swelling was 66% to 89%. From 58% to 89% of venous ulcers
healed. Procedural success in recanalization of chronic total occlusions was
83% to 95%. Approximately 25% of stents occlude in thrombotic cases during a
3- to 5-year period. Secondary patency ranged from 90% to 100% in limbs with
nonthrombotic iliac vein lesions and from 74% to 89% in post-thrombotic limbs
during 4 to 7 years. Patency is somewhat lower, at 66% to 89% at 4 to 7 years,
and stent occlusions higher in the group among chronic total occlusion
recanalizations. Many areas related to iliac vein stenting require further
study and clarification, including the role of IVUS imaging (used in only two
studies), the degree of correctible stenosis, the relationship between silent
and symptomatic obstructions, inter-relationship of obstruction and reflux,
and finally, a hemodynamic metric for obstruction. The author concludes stent
placement to correct iliac-caval-femoral obstructions is emerging as a safe,
effective, and minimally invasive alternative to traditional open procedures
for iliac vein stenting.  
  
Raju and Ward35 reported on clinical research with iliac vein stenting, some
with concurrent saphenous ablation, in patients aged 80 years and older in
whom the dominant issue was deep venous obstruction. During a 13-year period,
iliac vein stenting was performed for 107 limbs in 95 patients who were at
least 80 years old. Three procedures were for recanalizations of chronic total
occlusion; the remainder of the stenting procedures was for correction of
stenosis. Stented patients were seen for follow-up at six weeks, three months,
and at six month intervals by the physician or nurse practitioner; mean
follow-up was 17 months. No post procedure mortality was noted within 30 days.
Among the 95 patients, 45 (47%) were alive at the time the report was written.
Regarding the remaining 50 patients, no information was available for 41 and
nine other patients were deceased. The authors state lack of mobility due to
swelling or orthostatic pain compromises independent living with venous ulcers
and cellulitis also impacting factors. The report lists relief of pain and
suffering to the extent possible in the last stages of life as central to
geriatric care. The authors submit that stenting expertise is widely available
and has the potential to benefit the geriatric population reporting advanced
manifestations of chronic venous disease since the procedure is minimally
invasive with low mortality and morbidity, high patency rate and satisfactory
symptom relief.  
  
Raju,36 in Ten Lessons Learned in Iliac Venous Stenting, discusses iliac vein
stenting as an extension of arterial stent technology. The two share some
technical similarities and much of the hardware; however, the indications for
and purpose of iliac vein stenting are fundamentally different from arterial
practice. Pathophysiologic differences require specific modifications of
techniques as well. Undersizing stents in iliac veins results in residual
symptoms, even though the stent may remain patent. For example, placement of a
14-millimeter (mm) stent in the common iliac vein, seemingly a minor
downsizing, represents an iatrogenic area stenosis of 25% at the outset,
disregarding any in-stent restenosis (ISR) that may develop (25% is common).
In addition to ISR, iliac vein stents are prone to stent compression from the
outside at anatomical choke points or from recurrent post-thrombotic stenosis.
Commensurate with the high patency rate with iliac stenting, a significant
improvement in pain was reported in 74% of limbs (cumulative), with complete
relief in 65% at 5 years. Swelling improved significantly in 62% of limbs,
with complete relief in 32% at 5 years, and 58% of ulcers (cumulative) healed
at 5 years. The author states the iliac vein stent experience is with off-
label use of a Wallstent endoprosthesis, which is designed for extravascular
use. The performance was better than anticipated noting certain deficiencies,
some specific to the iliocaval anatomy. A 3- to 5-cm stent extension into the
IVC is often required to traverse the lesion completely and minimize end
effects, such as coning, and distal migration of the stent. This poses a
potential risk of partial jailing of contralateral iliac flow. Simultaneous or
sequential bilateral stenting with current stent designs are unsatisfactory
and may be technically difficult or impossible. The author purports solutions
to these problems can be improvised and that a dedicated venous stent with
improved performance is clearly desirable. The author discloses multiple
conflicts of interest including stockholder of Venti, Inc., as well as United
States patents for IVUS (diagnosis) and venous stent.  
  
Razavi, et al.37 examined the safety and effectiveness of venous stent
placement in patients with non-thrombotic, acute thrombotic (AT) and chronic
post-thrombotic (CPT) disease pathogenesis. The review consisted of 37 studies
reporting 45 treatment effects (non-thrombotic, acute thrombotic [AT], and
chronic post-thrombotic [CPT]) from 2,869 individual patients (non-thrombotic,
1,122; AT, 629; CPT, 1,118). Main objectives of the review included technical
success, peri-procedural complications (i.e., major bleeding, pulmonary
embolism, early thrombosis, and death), patient symptom resolution (i.e.,
pain, edema, ulcer) at final follow-up, and primary and secondary patency
through five years. A secondary objective of the review was to develop
performance goals to be used as comparators in single-arm clinical trials of
iliofemoral venous stents specifically manufactured for placement in the
venous system. Most studies included were retrospective and performed at a
single institution. Median sample size of each included study ranged between
26 and 38 and the median follow-up timeframe was between 15 and 19 months.
Most often, AT was treated with catheter-directed thrombolysis (with or
without thrombectomy) followed by percutaneous transluminal angioplasty (PTA)
and stent placement. Non-thrombotic and CPT were typically treated with PTA
and stent placement although adjunctive therapies were applied in some cases.
Wallstents (Boston Scientific, Marlborough, MA) were used in 78% of the
studies included. Only one study (3%) used a stent specifically manufactured
for venous applications in three (0.1%) limbs. Technical success rates were
comparable among groups; ranging from 94% for AT and CPT to 96% for non-
thrombotic patients. The authors note at the time of the review no robust
clinical studies with long-term outcomes of stent placement for iliofemoral
venous obstructions were available. The study authors anticipate an increase
in utilization of venous stents in response to emerging evidence in favor of
catheter-based therapies for acute and chronic iliofemoral venous thrombosis.  
  
Seager, et al.38 conducted a systematic review of sixteen studies (14 before-
and-after studies, 1 controlled before-and-after study, and 1 case series)
encompassing successful deep venous stenting in 2,373 and 2,586 post-
thrombotic or nonthrombotic limbs and patients respectively. Meta-analysis was
not possible as the data lacked control groups and was too heterogeneous.
Significant improvements in validated measures of the severity of CVD and
venous disease-specific quality of life were noted. Persistent ulcer healing
rates ranged from 56% to 100% in limbs that had often already failed
conservative management. Primary and secondary stent patency ranged from 32%
to 98.7% and 66% to 96% respectively. The major complication rate ranged from
0 to 8.7% per stented limb. The quality of the evidence for five outcomes was
"Very Low" and one "Low" (ulcer healing) as demonstrated by a GRADE
assessment. The authors concluded the quality of evidence to support the use
of deep venous stenting to treat obstructive CVD is currently weak yet
consistent effects and marked changes in disease course with potential impact
on quality of life. Seager et al. state the treatment does however, appear
promising and is safe and therefore, should be considered as a treatment
option while the evidence base is improved with perhaps a randomized control
trial comparing the practice against conservative measures, with long-term
follow-up and outcome measures including chronic venous disease measures and
quality of life scores.  
  
van Vuuren, et al.39 conducted a prospectively randomized controlled single-
blind, single-center trial in the Netherlands comparing venous stenting with
conservative treatment in patients with deep venous obstruction. One hundred
and thirty patients with post-thrombotic syndrome (PTS) or MTS, eligible for
interventional percutaneous treatment who did not have previous deep venous
intervention, were randomized to conservative treatment or venous stenting and
stratified for the PTS or MTS subgroup. The primary end point was the change
in quality of life (QoL) at 12 months (on the disease-specific Veines QoL/Sym
questionnaire) from baseline. Results are pending and should be interesting.  
  
Yevzlin and Asif,40 in Stent Placement in Hemodialysis Access: Historical
Lessons, the State of the Art and Future Directions, provide a review of stent
placement in hemodialysis access. Recent data have emphasized that
endovascular stents could be used in the treatment of central as well as
peripheral stenotic lesions. In general, a peripheral or central vein lesion
that is elastic or recurs within a three-month period after an initially
successful balloon angioplasty or a stenosis where surgical revision is not
possible are some indications for intravascular stent placement. Recent
reports have expanded the role of stents in the management of pseudoaneurysms
associated with dialysis access. Indeed, recent information from United States
Renal Data System (USRDS) is reporting a marked increase of stent placement in
hemodialysis access. While the total number of access interventions increased
from 52,380 to 98,148 (a 1.8 fold increase), the number of stent placements
has increased from 3,792 to 8,514, a 2.2 fold increase. Of note, the relative
percentage growth of stent placement has outpaced that of angioplasty each
year during the same time period. Studies illustrate that a stent (nitinol
alloy) is safe and effective for treating dialysis-access venous stenosis that
are resistant to standard angioplasty. While the results were encouraging, the
study had several limitations. In addition to the lack of randomization,
arteriovenous grafts and arteriovenous fistulas were mixed in the analysis,
the type of lesion (e.g., inflow, outflow, or central) was not uniform and
patient characteristics (e.g., diabetic or not) were not accounted for in the
analysis. The presence of these confounding factors does not conclusively
establish the superiority of stents over percutaneous balloon angioplasty. The
role of stent placement in the management of hemodialysis access dysfunction
remains controversial. It will remain so until large, multi-center,
prospective, randomized, controlled trials are conducted. The authors disclose
no conflict of interests.

Unlike arterial disease, in most cases, chronic venous disease seldom poses a
threat to limb or life. Consequently, invasive intervention is usually
reserved for lesions with disabling symptoms that do not respond to
conservative treatment.41  
  
Lack of data is noted regarding the proportion of patients that progress from
asymptomatic to symptomatic LECVD, as well as to the safety of treatment
modalities in patients with LECVD in the Medicare population. There is a lack
of data regarding the use of disease specific quality of life surveys and
health outcomes in the care of LECVD.  
  
In general, literature related to venous stenting in chronic venous disease
indicates that there is an overall lack of prospective multicenter randomized
controlled data regarding the proportion of symptomatic patients whose
clinical quality of life outcomes benefit from angioplasty and stenting.
However, the majority of studies, technical analyses, and guidelines seem to
support the judicious use of angioplasty and or venous stenting in appropriate
circumstances for those severely symptomatic patients refractory to
conservative non-invasive measures.