Arterial Stent Placement in Arteriovenous Dialysis Access by Interventional Nephrologists

Arterial stenoses in patients with arteriovenous dialysis access can create a variety of problems including access dysfunction, thrombosis, and hand ischemia. While percutaneous balloon angioplasty is largely successful in the management of arterial stenoses, elastic recoil can present a real predicament to this treatment. In this report, we present two cases of arterial stenosis that demonstrated elastic recoil after angioplasty and required endovascular stent insertion. Both cases were treated successfully without any complications on an outpatient basis. This report describes arterial stent placement in patients with arteriovenous access and discusses anticoagulation considerations in such cases.     

Intra-operative central vein angioplasty during arteriovenous access creation

Central vein stenosis or occlusion due to prior use of central vein hemodialysis catheters may lead to disabling extremity edema or cause early failure after arteriovenous access construction. Our integrated program for arteriovenous access management enables us to identify these stenoses pre-operatively. We carried out intra-operative angiography and angioplasty during arteriovenous access creation in 3 patients with good immediate and long-term results. Intra-operative endovascular therapy is a new application of peripheral vascular surgery techniques for patients with significant central vein stenosis undergoing access surgery, which exploits the high postoperative flow state to maintain patency after angioplasty. It may also be applicable in situations such as proximal arterial stenosis with anticipated steal syndrome and other conditions that may compromise access patency.     

Endovascular management of vascular complications in pancreatic transplants

Vascular complications after pancreatic transplantation carry a high rate of graft loss. Endovascular management of these complications is confined to stent placement for iliac artery inflow disease and embolization for arteriovenous fistulae (AVFs), pseudoaneurysms, or active bleeding. The current study describes the endovascular management of pancreatic transplant venous thrombosis (N = 1), arterial stenosis (N = 5), thrombosis (N = 3), pseudoaneurysms (N = 1), and AVF (N = 2). In addition, embolization of nonfunctioning grafts is described as an endovascular alternative to pancreatectomy.     

Salvage of thrombosed dialysis access grafts with venous anastomosis stents

BACKGROUND: Thrombosis of arteriovenous (AV) grafts caused by stenosis at the venous anastomosis is a well-described problem. Surgical thrombectomy and conventional angioplasty with mechanical thrombectomy have provided good success rates in achieving immediate graft patency but with generally dismal graft survival rates in the range of 11% to 36% at 6 months' follow-up. The role of intravascular stents in patients who have failed angioplasty or surgical revision at the venous anastomosis has not been fully elucidated, particularly in older grafts that have previously undergone multiple procedures. METHODS: In this series, 34 patients had self-expanding nitinol stents placed at the venous anastomosis following graft thrombectomy and angioplasty procedures. Patients were selected for stent placement if conventional angioplasty alone was unsuccessful due to immediate elastic recoil or residual stenosis. All patients were followed after stent placement and evaluated for duration of graft patency and need for repeated endovascular procedures. RESULTS: The average graft age at the time of stent placement was 17.9 months. Eight-eight percent of grafts were functioning at 6 months' follow-up, and 63% of the entire group had survived without the need for additional procedures. Among those with need for repeat interventions, 81% had new lesions outside of the stent, and 57% had new lesions within the stent. In 38% of cases, new stenoses were located both outside and within the stent. Among grafts no longer being used, only 19% of the time was it due to disease recurring within the stent. CONCLUSION: Polytetrafluoroethylene (PTFE) graft longevity is improved when venous anastomosis stenoses are treated with stents in selected cases of older grafts that would have normally undergone abandonment or surgical revision.     

Surgical versus percutaneous care of arteriovenous access

Current clinical practice patterns have led to the performance of many percutaneous vascular procedures outside the traditional operating room and led to significant changes in management strategies for treatment of complications of arteriovenous access. In an effort to identify optimal treatment for failed or failing arteriovenous fistulas and grafts, percutaneous and surgical techniques are analyzed. Assessment of the functioning or failing access by physical examination is critical in determining proper treatment and in assessing outcomes of interventions. Percutaneous and surgical techniques are available for the treatment of AV access thrombosis and venous stenosis. Techniques for percutaneous thrombectomy and stent placement for venous stenosis and AV graft pseudoaneurysms are reviewed. Management of arterial inflow disease, steal syndrome and nonmaturing AV fistulas is also addressed. Overall, percutaneous techniques are assuming an increasingly important role in the treatment of failed or failing AV fistulas and grafts. Ongoing analysis of outcomes of both percutaneous and surgical interventions is necessary to continue to identify optimum treatment algorithms.     

Understanding the dialysis access steal syndrome. A review of the etiologies, diagnosis, prevention and treatment strategies

Distal hypoperfusion ischemic syndrome (DHIS), commonly referred to as hand ischemia or 'steal' after dialysis access placement, occurs in 5-10% of cases when the brachial artery is used, or 10 times that of wrist arteriovenous fistulas (AVFs) using the radial artery. It is typically seen in elderly women with diabetes, and may carry severe morbidity including tissue or limb loss if not recognized and treated. Three distinct etiologies include (1) blood flow restriction to the hand from arterial occlusive disease either proximal or distal to the AV access anastomosis, (2) excess blood flow through the AV fistula conduit (true steal), and (3) lack of vascular (arterial) adaptation or collateral flow reserve (ie atherosclerosis) to the increased flow demand from the AV conduit. These three causes of steal may occur alone or in concert. The diagnosis of steal is based on an accurate history and physical examination and confirmed with tests including an arteriogram, duplex Doppler ultrasound (DDU) evaluation with finger pressures and waveform analysis. Treatment of steal includes observation of developing symptoms in mild cases. Balloon angioplasty is the appropriate intervention for an arterial stenosis. At least three distinct surgical corrective procedures exist to counteract the pathophysiology of steal. The ultimate treatment strategy depends on severity of symptoms, the extent of patient co-morbidity, and the local dialysis access technical team support and skills available.     

Treatment of steal syndrome in a distal radiocephalic arteriovenous fistula using intravascular coil embolization

Steal syndrome is a well-described complication of arteriovenous fistulas used for hemodialysis access. Although distal revascularization with interval ligation appears to offer the greatest likelihood of symptom relief and vascular access salvage, not all fistulas are amenable to this procedure, particularly distal radiocephalic arteriovenous fistulas. In this report, we describe the treatment of steal syndrome in a patient with a distal radiocephalic arteriovenous fistula using a percutaneous approach and endovascular coils. After coil embolization of the distal radial artery and multiple collateral vessels, steal was no longer visualized using angiography, and the patient's symptoms resolved.     

Drug-coated balloon angioplasty for dialysis access fistula stenosis

Maintaining vascular access patency represents a tremendous challenge in hemodialysis patients. Although “native” arteriovenous fistula (AVF) is currently recommended as primary vascular access, neointimal hyperplasia stenoses frequently develop, with a risk for AVF thrombosis and vascular access loss. For years, first-line treatment of AVFs stenoses has been percutaneous transluminal angioplasty, generally with high-pressure or cutting uncoated balloons. However, restenosis and reintervention rates remain incredibly high and occur, according to recent studies, in up to 60% and 70% of patients at 6 and 12 months, respectively. Drug-coated balloons delivering paclitaxel at the angioplasty site have proved their superiority in the treatment of coronary and peripheral arterial stenoses. Paclitaxel reduces neointimal hyperplasia and drug-coated balloons, therefore, it represents an attractive option for AVF stenoses. Because data are scarce, the aim of this paper was to review the concepts and current results of drug-coated balloons in AVF stenosis management.     

Upper extremity ischemia and hemodialysis vascular access.

Digital ischemia in dialysis patients due to arteriovenous fistulas (AVF) is a rare condition, occurring in 4% of patients. The etiology is different from lower limb ischemia. Blood shunting through the AVF may cause stealing of blood and hypoperfusion in distal tissues, leading to pain, discolorisation and ulcers. High-flow AVFs have greater risk on ischemia than normal flow AVFs, however combined with peripheral arteriosclerotic disease the latter may also leads to ischemia. A non-invasive and angiographic diagnosis is of importance to determine treatment options. Augmentation of arterial inflow by interventional techniques and/or AVF bloodflow-reducing surgical procedures may eliminate pain and heal ulcers. The best results are obtained by bypassing the arteriovenous anastomotic site and interruption of steal phenomenon by ligation of the artery distal to the AV anastomosis.     

Transjugular venous approach for endovascular intervention in upper-extremity dialysis access fistulae and grafts

A transjugular venous access is an alternative approach for endovascular intervention in upper-extremity dialysis arteriovenous fistulae and grafts. The transjugular access is recommended for patients who have an unfavorable anatomy for the direct arm access approach. Ultrasound evaluation of the arteriovenous access is essential before intervention and includes evaluation of the inflow artery and outflow vein diameters, arteriovenous anastomosis, and the entire outflow vein, specifically looking into potential problem areas. Patency of the ipsilateral internal jugular vein needs to be assessed. If patency of the ipsilateral internal jugular vein is confirmed, it can be used for access. Retrograde access into the outflow vein is obtained with a reverse-curve catheter and a Glidewire. In some cases, puncture of the outflow vein is necessary along with the use of snares to direct the catheter system into the outflow vein. The techniques for intervention are described. Successful access into the outflow vein is possible in >95% of cases. The technique is useful for fistula maturation, declotting procedure, and arteriovenous fistula and graft maintenance. If intervention is unsuccessful, the transjugular access offers the possibility of placement of a dialysis catheter for temporary or long-term dialysis.     

Improvements in dialysis access survival with increasing use of arteriovenous fistulas in a Veterans Administration medical center

BACKGROUND: Native arteriovenous fistulas (AVFs) have been found to exhibit higher survival rates and lower complication rates than prosthetic grafts (AVGs). METHODS: Between August 2001 and December 2003, 93 patients with end stage renal disease (ESRD) had primary dialysis access placed at a single Veterans Administration medical center. Of these 93 patients, 67 had AVFs created and 26 patients had AVGs implanted. RESULTS: The percentage of patients who did not require additional intervention was 84% (56 of 67) for AVF and 78% (21 of 26) for AVG after 4 to 31 months of follow-up evaluation. In the AVF group, repeat interventions were as follows: collateral ligation (4), angioplasty owing to central stenosis (2), AVF ligation due to arterial steal phenomenon (1), and new AVF creation owing to clotting (1). Four AVFs were later converted to AVG. In the AVG group there were 4 venous anastomosis stenosis seen in 3 patients who required angioplasty. Two patients needed thrombectomy and revision, and 1 graft was removed because of infection. AVF prevalence in our dialysis patients was 63%, with 33% AVG and 4% temporary catheter. CONCLUSIONS: The National Kidney Foundation-Dialysis Outcome Quality Initiative (NKF-DOQI) guidelines for dialysis access reawakened interest in maximizing the use of renal veins for AVF. AVFs created by using the patient's native vein provides the best vascular access for dialysis when compared with prosthetic grafts. AVF has better long-term patency with fewer complications.     

Dialysis access-associated steal syndrome: the role of ultrasonography

BACKGROUND: Ischemic steal syndrome is an infrequent, but potentially disabling complication of hemodialysis (HD) access creation. We analyzed the ability of duplex Doppler ultrasonography to reveal potential causes of ischemic steal syndrome in antebrachial accesses. METHODS: We performed 212 examinations on 121 patients. Ten patients suffered from ischemic steal syndrome. Complete length access evaluation was performed by a linear array 7.5 MHz ultrasound probe. RESULTS: Hand ischemia was explained by inflow artery stenosis in five cases. Excessive fistula flow due to large arteriovenous anastomosis was the suspected cause in two cases. The remaining two cases were characterized by high-resistant minimal flow in the ulnar artery with bi-directional flow in the distal part of the radial artery, suggesting stenoses located in the arcus palmaris. Duplex Doppler ultrasound had not revealed the etiology of clinically apparent hand ischemia in one case. Isolated inflow artery stenoses were treated successfully by percutaneous transluminal angioplasty. Patients with ischemic steal syndrome and high fistula flow were treated successfully by outflow vein banding. CONCLUSIONS: Duplex Doppler ultrasonography is a valuable tool for diagnosing the cause of ischemic steal syndrome and can probably replace angiography in some cases.     

Stealsyndrom nach Dialysezugang

After creation of a dialysis access a steal phenomenon (retrograde flow in the artery distal to the arteriovenous anastomosis) and mild symptoms of ischemia are frequently observed, whereas severe clinically relevant steal syndromes rarely occur. A thorough examination of the venous and arterial vascular systems allows the individual risk of developing a steal syndrome to be estimated. This should be taken into account when planning an arteriovenous access in order to minimize the risk as details of the access creation can play an important role during the later course. After development of a relevant steal syndrome the necessity of a correction of the arteriovenous access is determined by the character and extent of complaints. All therapeutic efforts aim at a relief of symptoms of peripheral ischemia while preserving a functional arteriovenous access. Flow and location of an arteriovenous access determine the correct procedure for correction. The underlying principles are the termination of the retrograde flow distal to the arteriovenous anastomosis, the creation of large caliber artificial collaterals (bypass) and the transposition of the arteriovenous anastomosis to a bigger, more proximal feeding artery.     

Case of cervical paraspinal arteriovenous fistulae with a huge intracanalicular varix successfully treated with transvenous embolization

Paraspinal arteriovenous fistulas (AVFs), with the fistulas draining into the epidural veins alone, are relatively rare and few cases have been reported until now. We reported a case of cervical paraspinal AVFs draining only into the epidural venous plexus without reflux into the intradural venous system. The patient showed myelopathy due to direct compression of the spinal cord by a large varix. A 57-year-old man presented with gait disturbance. Neurological findings on admission revealed that tetraparesis, sensory disturbance of four extremitas below the C5 level and bladder bowel dysfunction. Magnetic resonance imaging and computed tomography at the cervical level disclosed remarkable compression of the spinal cord by a large venous pouch at the C6 level. Digital subtraction angiography (DSA) revealed paraspinal arteriovenous fistulas fed by bilateral C6 radicular arteries, the right ascending cervical arteries, and the right deep cervical artery in the right C6 intervertebral foramen. Three-staged transarterial embolization was performed by selective catheterization of the multiple feeders with n-butylcyanoacrylate, followed by transvenous embolization. During transvenous embolization, motor evoked potential (MEP) monitoring was performed. After retrograde catheterization of the epidural venous plexus, the large varix was occluded with Guglielmi detachable coils. The AV fistulas were completely occluded without any change in MEP monitoring during the procedure. The patient's gait improved well after the procedure and follow up DSA six months later showed no recurrence of the paraspinal AVFs.     

Primary arteriovenous fistula inflow proximalization for patients at high risk for dialysis access-associated ischemic steal syndrome

Establishing a functional vascular access while minimizing the risk of dialysis access-associated ischemic steal syndrome (DASS) may present a challenging problem in patients with severe peripheral vascular disease where even a low-flow arteriovenous fistula (AVF) may lead to severe symptoms and physical findings of DASS. Proximalization of arterial inflow for an existing vascular access is established as an effective treatment for DASS. We hypothesized that a primary proximal arterial inflow procedure for vascular access in patients judged to be at high risk for DASS would result in a successful hemodialysis access and mitigate the risk of steal syndrome. We report four such patients considered to be at significant risk for DASS after construction of a new vascular access. An axillary artery AVF inflow anastomosis was constructed in each patient. The access outflow configuration varied with the available venous outflow conduit identified during the preoperative ultrasound evaluation. In all four patients in this report, a functional autogenous dialysis access was established without DASS.     

Symptomatic superior vena cava syndrome in hemodialysis patients: mid-term results of primary stenting

This clinical report details the results of endovascular treatment of symptomatic superior vena cava syndrome due to central vein stenosis or obstruction (CVSO) by stent angioplasty in patients with dialysis-dependent end-stage renal disease. A 3-year retrospective review of two institutional registries identified 25 chronic hemodialysis patients (17 men, 8 women) affected by CVSO who received endovascular treatment. The majority of the patients (n = 19) presented with symptomatic arm, breast, and facial swelling; and 6 patients presented with dialysis-access dysfunction and venous-line hypertension. The etiology of CVSO was before central venous catheter in all but 2 patients. Venography showed 19 cases of stenosis (4 stenoses of superior vena cava, 3 brachiocephalic, 10 subclavian, and 2 axillary veins) and 6 occlusions of the superior vena cava. After percutaneous transluminal angioplasty and primary stent angioplasty, there was an immediate regression of symptoms and arteriovenous fistula preservation in 21 cases; 4 patients received a new arteriovenous fistula after interventional treatment. No procedural major complications or patient deaths occurred. During the follow-up period, we recorded a primary patency rate of 95%, 80%, and 70%, respectively, at 6, 12, and 18 months; and a secondary patency rate of 100%, 95%, and 90%, respectively, at 6, 12, and 18 months. In conclusion, endovascular treatment with primary stenting has proven to be a durable treatment option for hemodialysis patients with CVSO, and this treatment should be considered before dialysis access placement in patients with catheter-induced central vein obstruction.     

Cutting balloon angioplasty for resistant venous anastomotic stenoses

Conventional angioplasty of stenoses at the venous anastomosis has been demonstrated to be an important endovascular adjunct to mechanical thrombectomy of clotted arteriovenous dialysis grafts. In some cases, however, severe venous anastomosis stenosis is resistant to angioplasty. Cutting balloon angioplasty may have an advantageous role in these difficult situations in order to avoid surgical revision. In this series of 350 patients receiving percutaneous, endovascular declotting procedures, 9 patients had high-grade venous anastomotic stenoses (opening less than 2 mm) that could not be remedied with either conventional or high-pressure noncompliant peripheral angioplasty balloons. These nine patients had the lesions opened with the use of 4 mm x 10 mm cutting balloons and placement of self-expanding nitinol stents at the venous anastomosis during the same angiography procedure. Patients were followed for patency and functionality of the graft. In all cases, immediate technical success occurred. Among these patients, the vessels have remained patent for as long as 20 months of follow-up and grafts have remained functional. Cutting balloon angioplasty may have a potential therapeutic role in resistant venous anastomotic stenoses.     

Two cases of iatrogenic vertebral arteriovenous fistulas successfully treated by surgery

Cervical vertebral arteriovenous fistulas (AVFs) are very rare. The most frequent cause is trauma including iatrogenesis which result from vertebral artery penetration during central venous catheterization. Some endovascular techniques have been reported for this type of lesion. However, several potential problems exist, such as possibility of recurrence of AVFs and VA occlusion with endovascular treatment. In this article, we review two cases with iatrogenic vertebral AVFs which were successfully treated surgically and report the advantages of surgical treatment.     

A Meta‐analysis of Stent Placement vs. Angioplasty for Dialysis Vascular Access Stenosis

Dysfunction of arteriovenous fistulas (AVF) and arteriovenous grafts (AVG) contribute significantly to morbidity and hospitalization in the dialysis population. Despite advances in endovascular techniques, the incidence of vascular access stenosis remains problematic. Currently, the role of endovascular stent placement in the treatment of vascular access stenosis is poorly defined. This meta‐analysis compares the primary patency rates of stenotic vascular access treated with stent placement vs. angioplasty. We searched Medline for English language publications from 1980 through December 2013, along with national conference proceedings and reference lists of all included publications. Inclusion criteria were a measure of primary patency, secondary patency, or access dysfunction. Studies were excluded if they were not in English or if they included pediatric patients. Ten studies with a total of 860 subjects met the inclusion criteria, including six experimental studies and four observational studies. There was significantly higher overall primary patency in those receiving stent placement than in those treated with angioplasty (pooled relative risk [RR] = 0.79; 95% confidence interval [CI]: 0.65–0.96). The estimate did not differ by study design. The effect of treatment differed significantly (p = 0.001) by the type of stents used, however. In studies including nitinol stents (six studies, 678 patients), 6‐month patency was significantly better for stent placement than angioplasty (pooled RR = 0.67; 95% CI: 0.54–0.84), whereas there was no significant differences between stent placement and angioplasty in those studies using bare metal stents exclusively (four studies, 182 patients; pooled RR = 1.09; 95% CI: 0.91–1.32). There was significant heterogeneity between studies (I² = 70.6%; p < 0.0001). Our results suggest that stent placement may confer an advantage over balloon angioplasty in primary patency of dialysis access stenoses.     

Frequency of critical stenosis in primary arteriovenous fistulae before hemodialysis access: Should duplex ultrasound surveillance be the standard of care?

OBJECTIVE: Increasing use of primary arteriovenous fistulae (pAVFs) is a desired goal in hemodialysis patients (National Kidney Foundation /Dialysis Outcome Quality Initiative guidelines). However, in many instances, pAVFs fail to adequately mature due to ill-defined mechanisms. We therefore investigated pAVFs with color duplex ultrasound (CDU) surveillance 4 to 12 weeks postoperatively to identify hemodynamically significant abnormalities that may contribute to pAVF failure. METHODS: From March 2001 to October 2003, 54 upper extremity pAVFs were subjected to CDU assessment before access. A peak systolic velocity ratio (SVR) of >/=2:1 was used to detect >/=50% stenosis involving arterial inflow and venous outflow, whereas an SVR of >/=3:1 was used to detect >/=50% anastomotic stenosis. CDU findings were compared with preoperative vein mapping and postoperative fistulography when available. RESULTS: Of 54 pAVFs, there were 23 brachiocephalic, 14 radiocephalic, and 17 basilic vein transpositions. By CDU surveillance, 11 (20%) were occluded and 14 (26%) were negative. Twenty-nine (54%) pAVFs had 38 hemodynamically significant CDU abnormalities. These included 16 (42%) venous outflow, 13 (34%) anastomotic, and 2 (5%) inflow stenoses. In seven (18%), branch steal with reduced flow was found. In 35 of 54 (65%) pAVFs, preoperative vein mapping was available and demonstrated adequate vein size (>/=3 mm) and outflow in 86% of cases. Twenty-one fistulograms (38%) were available for verifying the CDU abnormalities. In each fistulogram, the arterial inflow, anastomosis, and venous outflow were compared with the CDU findings (63 segments). The sensitivity, specificity, and accuracy of CDU in detecting pAVF stenoses >/=50% were 93%, 94%, was 97%, respectively. CONCLUSIONS: Before initiation of hemodialysis, an unexpectedly high prevalence of critical stenoses was found in patent pAVFs using CDU surveillance. These de novo stenoses appear to develop rapidly after arterialization of the upper extremity superficial veins and can be reliably detected by CDU surveillance. Turbulent flow conditions in pAVFs may play a role in inducing progressive vein wall and valve leaflet intimal thickening, although stenoses may be due to venous abnormalities that predate AVF placement. Routine CDU surveillance of pAVFs should be considered to identify and correct flow-limiting stenoses that may compromise pAVF long-term patency and use.