Quality improvement guidelines for percutaneous management of the thrombosed or dysfunctional dialysis access. Standards of Practice Committee of the Society of Cardiovascular & Interventional Radiology

Rotational thrombectomy versus balloon maceration in dialysis access salvage

BACKGROUND

Although end stage renal disease patients who undergo hemodialysis frequently experience dialysis-associated thrombotic complications, there remains a paucity of literature comparing the efficacy of different endovascular salvage techniques for grafts and fistulas. This study aims to compare primary patency in dialysis access following salvage mechanical thrombolysis/thrombectomy with a rotational thrombolysis device versus balloon maceration.

METHODS

Using a database of patient records at a tertiary medical center, all patients who underwent rotational thrombectomy with the Cleaner XT™ Rotational Thrombectomy System for endovascular salvage of arteriovenous fistula or arteriovenous graft from August 2016 to July 2022 were included in the population. Fourteen patients who underwent balloon maceration for endovascular salvage were matched to the patients in the rotational thrombectomy group based on date of procedure. The primary patency of the fistula or graft for the two groups was measured.

RESULTS

A total of 13 patients who underwent dialysis access salvage with rotational thrombectomy (10 grafts, 3 fistulas) were matched with 14 patients who underwent balloon maceration for dialysis access salvage (10 grafts, 4 fistulas). Six patients in both groups required additional graft access salvage (46% rotational thrombectomy; 43% balloon maceration). The median time to next dialysis salvage was 51 days for rotational thrombectomy and 43.5 days for balloon maceration (W + 9, critical value 1; compatible with statistically significant difference).

CONCLUSION

Endovascular access salvage by rotational thrombectomy may provide longer primary patency compared to salvage by balloon maceration. However, a longer follow-up prospective study of a larger study population is necessary to clarify the safety and efficacy of rotational thrombectomy using the Cleaner XT™ device.

Central vein stenosis in hemodialysis vascular access: clinical manifestations and contemporary management strategies

Central venous stenosis is a significant and frequently encountered problem in managing hemodialysis (HD) patients. Venous hypertension, often accompanied by severe symptoms, undermines the integrity of the hemodialysis access circuit. In central venous stenosis, dialysis through an arteriovenous fistula is usually inefficient, with high recirculation rates and prolonged bleeding after dialysis. Central vein stenosis is a known complication of indwelling intravascular and cardiac devices, such as peripherally inserted central catheters, long-term cuffed hemodialysis catheters, and pacemaker wires. Hence, preventing this challenging condition requires minimization of central venous catheter use. Endovascular interventions are the primary approach for treating central vein stenosis. Percutaneous angioplasty and stent placement may reestablish vascular function in cases of elastic and recurrent lesions. Currently, there is no consensus on the optimal treatment, as existing management approaches have a wide range of patency rates.

Duplex ultrasound-guided angioplasty of hemodialysis vascular access

OBJECTIVE

Duplex ultrasound-guided angioplasty (DA) for hemodialysis vascular accesses remains questionable regarding its feasibility and safety. Minor complications (requiring no more treatment than nominal therapy) might be over-reported. Our hypothesis is that this procedure has no significant differences between observed rates and the recommended threshold of main outcomes of the procedure defined by the standards of arteriovenous fistulas (AVF) angioplasty.

METHODS

In a single-center retrospective study, 298 DA performed on 141 patients from 2015 to 2019 were analyzed. Occluded AVF or concomitant use of radiographic guidance were excluded. Duplex ultrasound parameters were collected up to 1 month before, at the end of angioplasty, and on day 30 after the procedure. Complications were registered, and patency rates were studied at 24 months of follow-up.

RESULTS

Anatomical success was achieved in 142 procedures (47.7%), clinical success in 284 (95.3%), and hemodynamic success in 283 (95.0%). Major complications-requiring at least a specific therapy-were reported in 8 procedures (2.7%) and minor complications-requiring no adjunctive therapy-in 157 (52.7%). At 24 months, overall postintervention primary patency was 34.0%, primary-assisted patency 87.4%, and secondary patency 92.5%. There were no significant differences of patency rates between groups with or without minor complications (P value for primary patency, 0.08; primary-assisted patency, 0.08; secondary patency, 0.23) or 30% residual stenosis (P value for primary patency, 0.82; primary-assisted patency, 0.46; secondary patency: 0.63). Duplex parameters further improved at postoperative day 30 after angioplasty.

CONCLUSIONS

DA of AVF is feasible, safe-despite over-reported minor complications having no impact on postintervention patency rates-and efficient. A minor complication can be seen as an event without bad or good consequences. Anatomical definition of success does not fit on DA for hemodialysis vascular access. Further studies are required to define the duplex parameter threshold for efficacy.

Migration of covered stents in thoracic central vein obstruction procedures in patients with hemodialysis: Case report and literature review

OBJECTIVE

The objective of the study is to present a case of hemodialysis in which the covered stent that had migrated into the right ventricle was retrieved by exploratory thoracotomy, and to review the literature on the diagnosis and treatment of stent migration in thoracic central vein obstruction (TCVO) procedures for hemodialysis patients.

METHOD

A systematic search of the PubMed database was performed to identify clinical presentations, imaging strategies, stent types, and treatment modalities for stent migration in hemodialysis patients.

RESULTS

A total of 14 case reports on stent migration in TCVO procedures for hemodialysis patients were included and analyzed. Ten cases included migration to the cardiac chambers and the remainder migration to the pulmonary artery. The common symptoms of stent migration in TCVO procedures are reported to be chest pain and dyspnea, while three of the cases studied involved no symptoms. Echocardiography, chest X-ray, and computed tomography are the commonly used methods for the diagnosis of stent migration and identification of the precise positioning of the stent. Stent migration to the right subclavian or innominate veins was the most prevalent case (seven cases). All were bare stents. Seven cases involved retrieval by interventional surgery, while four cases involved retrieval by open heart surgery. However, there were three cases in which the "wait-and-see" approach was adopted since the patients were asymptomatic.

CONCLUSIONS

Stent migration in TCVO procedures is a rare but extremely serious complication. The causes are not fully understood. The current treatment strategies include interventional surgery, open heart surgery, and the "wait-and-see" approach.

Results of Prompt Surgical Intervention in Hemodialysis Radiocephalic Fistula Secondary Dysfunction

Radiocephalic fistula (RCF) dysfunction is a common problem due to low maturation and patency rates of these fistulas. The most common procedure in such cases is to place a temporary catheter for the dialysis. Temporary catheter placement and undergoing dialysis with this catheter cause complications, reduce the chance for fistula, and deteriorate the quality of life. The aim of this study was to demonstrate that immediate intervention in RCF dysfunctions can increase fistula success for the patient and can reduce the need for a catheter. Furthermore, the hemodialysis treatment can continue without affecting the quality of life. A total of 295 patients who were admitted for RCF dysfunction and who underwent early surgical intervention without any catheter placement were evaluated for postoperative complications, patency rates, and rates and durations of temporary catheter use over a mean time of 47 months of follow-up (range: 4–79 months). Of the patients, 77.2% (n = 228) underwent new proximal anastomosis (NEO; the radial artery and cephalic vein were reached with an incision created proximal to the previous anastomosis), 14.2% (n = 42) underwent brachiocephalic arteriovenous fistula (AVF), 8.4% (n = 25) underwent side-to-side brachiobasilic AVF + superficialization of the basilic vein. In 88.8% (n = 262) of the patients, successful cannulations were performed within the first 24 to 48 hours without any catheter requirement or complications. Temporary catheter was used for 15.1 ± 10.7 days in 11.2% (n = 33) of the patients. In RCF dysfunctions, early surgical interventions performed in the forearm and elbow provide early cannulation and thus decrease the catheter requirement, also prevent the complications of temporary catheters (infection, decreasing the fistula success, vascular injuries, etc.), increase the autogenous fistula success, and allow for the continuation of dialysis without disturbing the quality of life.

The Cleaner XT™ Device as an Endovascular Adjunct for Pharmacomechanical Thrombolysis of Thrombosed Arteriovenous Fistulas and Grafts

Objective: This paper documents our experience using the Cleaner XT™ device (Argon Medical Devices, Plano, TX, USA) for pharmacomechanical thrombolysis (PMT) of thrombosed haemodialysis arteriovenous grafts (AVG) and fistulas (AVF). Materials and Methods: This was a retrospective case series (n=17) over six months at Singapore General Hospital. We evaluated demographics, procedural data, technical and procedural success, patency rates and complications. Results: There were 8 (47%) males and the patients' mean age was 66 (± 5.7) years. The mean age of AVF/AVG was 1605 (± 1099) days. All procedures were performed under local anaesthetic. PMT was performed within a mean time of 40 (±34.3) hours from the presentation. Technical, clinical and procedural success was 15/17 (88%). The thrombolysis agents used were tissue plasminogen activator (52.9%) and urokinase (41.2%). Mean primary patency time was 114 (± 116) days, with a 65% 1-month and 47% 3-month primary patency rates. The mean secondary patency time was 155 (±132) days, with 76% one-month and 65% three-month secondary patency rates, respectively. AVF rupture occurred in 3/17 (18%) cases but did not involve loss of the access circuit. Conclusion: The Cleaner XT™ device is a safe, minimally invasive endovascular tool for PMT in thrombosed AVF/AVG, with relatively high success and low complication rates.

Use of Paclitaxel Coated Drug Eluting Technology to Improve Central Vein Patency for Haemodialysis Access Circuits: Any Benefit?

Purpose

Central venous stenosis is a recurring problem affecting dialysis access patency. Increasing evidence suggests that the use of drug-coated balloons (DCBs) improves target lesion primary patency (TLPP) in dialysis access. However, few studies have investigated the use of DCBs specifically in central venous stenosis. Thus, this study presents our initial experience with DCBs in the central vein of a dialysis access circuit.

Materials and Methods

This is a retrospective cohort study of all hemodialysis patients who underwent central vein angioplasty with DCB between February 2017 and March 2018 at Singapore General Hospital. We compared the primary patency post DCB angioplasty to the primary patency of the patient’s previous plain old balloon angioplasty (POBA).

Results

We observed a 100% anatomic and procedural success rate with no complications. The median follow-up period was 151 days (interquartile range, 85.5-234 days) and no patients were lost to follow-up. The 30- and 90-day TLPPs after DCB were 93.3% and 75.7%, respectively. The mean primary patency in our study group post-DCB during the follow-up period was 164 days (vs. 140 days in the POBA group). However, no statistically significant difference was detected.

Conclusion

DCB showed a similar TLPP to that for POBA in treating central venous stenosis with a trend toward a longer re-intervention-free period for DCB. However, there were numerous confounding factors and a well-designed randomized controlled trial is warranted to assess the true utility of DCB in treating central venous stenosis.

Predictors of primary patency after percutaneous balloon angioplasty for stenosis of Brescia-Cimino hemodialysis arteriovenous fistula

OBJECTIVE

Percutaneous transluminal balloon angioplasty (PTA) is recommended as the first choice to treat stenosis of Brescia-Cimino arteriovenous fistulas (B-C AVFs). The ability to predict which B-C AVFs are at risk for recurrent stenosis post-PTA would allow closer monitoring of patients, and possibly result in surgical intervention rather than repeat PTA. The purpose of this study was to identify predictive factors of primary patency after PTA in B-C AVFs.

METHODS

Patients diagnosed with B-C AVF primary stenosis and treated by PTA between November 2013 and March 2018 were included in the study. Patient and stenotic lesion characteristics and PTA procedure factors were included in the analysis. The Kaplan-Meier method was used to analyze the primary patency rate. Cox proportional hazard regression analysis was used to identify factors predictive of decreased primary patency.

RESULTS

74 patients (35 males, 39 females) with a mean age of 61.68 ± 11.44 years (range, 36-84 years) were included in the study. The mean B-C AVF age was 16.34 ± 12.93 months (range, 2-84 months), and the median primary patency time was 7.79 ± 0.48 months. Cox proportional hazard regression analysis revealed stenosis location at the inflow artery [hazard ratio (HR)=3.83, 95% confidence interval (CI): 1.46-10.09] or anastomosis (HR = 1.90, 95% CI: 1.09-3.32), dilation >2 times during PTA (HR = 2.30, 95% CI: 1.22-4.34), and residual stenosis >30% (HR = 2.42, 95% CI: 1.26-4.63) were significantly associated with decreased patency.

CONCLUSION

In conclusion, the primary patency rate of PTA for B-C AVF dysfunction is reduced by dilation >2 times, residual stenosis >30%, and stenosis located at the inflow artery or anastomosis. These results may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with AVF dysfunction.

ADVANCES IN KNOWLEDGE

A number of studies have been conducted to examine the predictors of primary patency after PTA, however, no definitive conclusions have been reached. Our study revealed that stenosis location at the inflow artery or anastomosis, dilation >2 times during PTA, and residual stenosis >30% were the predictors of primary patency after PTA, which may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with arteriovenous fistulas dysfunction.

Safety and efficacy of the AngioJet device in the treatment of thrombosed arteriovenous fistula and grafts: A systematic review

PURPOSE

The AngioJet Hemolytic Thrombectomy Device "AngioJet" (Boston Scientific, Malborough, MA, USA) is a rheolytic thrombectomy device that can be used in the treatment of hemodialysis arteriovenous fistula and graft thrombosis. We aim to appraise the current evidence on AngioJet thrombectomy in hemodialysis vascular access thrombosis, and to determine its safety, including complications and efficacy.

MATERIALS AND METHODS

An electronic literature search was performed on the MEDLINE and Embase databases. References of retrieved articles were also reviewed. Articles using AngioJet for the treatment of arteriovenous fistula or graft were included. Patients less than 18 years old, non-English articles, single case reports, small case series (<5 cases), conference publications, and nonhuman models were excluded.

RESULTS

A total of 688 articles were initially evaluated and 10 articles fulfilled the inclusion criteria, which included 836 patients with 431 grafts and 234 fistulas. Results were heterogeneously reported. The adjusted mean primary patency rates for 1, 3, 6, and 12 months were 64.6%, 43.8%, 42.5%, and 30.5%, respectively; adjusted mean secondary patency rates for 3, 6, and 12 months were 76.5%, 75.1%, and 74.5%, and assisted primary patency rates were 61.9%, 47.3%, and 35.3%, respectively. There were 126 complications, most were minor. There were seven deaths, but were unable to be attributable to the AngioJet.

CONCLUSION

The AngioJet is an effective and safe treatment option for thrombosed fistulas and grafts. However, the quality of the current evidence is poor. Further research with prospective randomized controlled trials using standardized data reporting methods is needed to prove its safety and efficacy.

Radiological Central Vein Treatment in Vascular Access

In the last decades, the percutaneous interventional approach for the treatment of central venous obstructions (CVO) has become increasingly popular as the treatment of first choice because of its minimal invasiveness and reported success rates. CVOs are caused by a diverse spectrum of diseases which can be broadly categorized into two principal eliciting genera, either benign or malignant obstructions. The large group of benign venous obstructions includes the increasing number of end-stage renal disease patients with vascular access related complications. Due to the invasiveness and complexity of thoracic surgery for benign CVOs, the less invasive percutaneous interventional therapy can generally be considered the preferred treatment option. Initially, the radiological intervention consisted of balloon angioplasty alone, subsequently additional stent placement was applied. This was advocated as either primary placement or secondary in cases of elastic recoil or residual stenosis after percutaneous transluminal angioplasty (PTA). The efficacy of angioplasty of CVO in patients with vascular accesses, either with or without stenting, has been addressed by various studies. Overall, reports indicate an initial technical and clinical success rate above 95% and satisfactory patency rates. However, systematic follow-up and frequent re-interventions are necessary to maintain vascular patency to achieve long-term success.

Restoration of Acutely Thrombosed Arterio-Venous Fistulae by rTPA and Percutaneous Angioplasty

Acute thrombosis in native arterio-venous fistulae (AVF) results in considerable patient morbidity. Interventional radiology (IR) comprising thrombolysis and percutaneous transluminal angioplasty (PTA) is well established in the management of thrombosed polytetrafluoroethylene (PTFE) grafts. However its role in thrombosed AVF is uncertain. We looked retrospectively at the role of IR in re-establishing blood flow in acutely thrombosed AVF.

Between 1992–2000, 21 episodes of acutely thrombosed AVF in 15 patients (9 females; age range 29–80yrs) were referred for intervention. All fistulae were being used for haemodialysis at the time. Diagnosis was established by angiography and thrombolysis with recombinant tissue plasminogen activator (rTPA) was attempted in all patients. Discrete stenoses when present (n=12) were then treated with PTA and resistant or recurrent stenoses were managed by stent insertion (n=3). Patients were then heparinised for 24 hours.

Technical success as defined by radiological patency was achieved in 86% cases. Clinical success i.e. the ability to reuse of the fistula for haemodialysis was achieved in 62% of the interventions, where patency rates at 3 and 6 months were 92% and 69% respectively. Five patients had recurrence of thrombosis >3 months after the primary procedure, 3 had successful re-intervention. Minor local bleeding was the only complication.

Our retrospective study shows rTPA and PTA is successful in the management of acutely thrombosed AVF. We advocate the routine use of IR as a valuable technique for prolonging the life of native AVF in patients on maintenance haemodialysis.

Complications Related to Percutaneous Thrombectomy of Hemodialysis Grafts

Purpose

To retrospectively review the complications reported during percutaneous thrombectomy procedures performed on polytetrafluoroethylene hemodialysis grafts.

Materials and Methods

A retrospective review revealed that 935 percutaneous thrombectomy procedures were performed at our institution between January 1993 and June 2001. The type and number of procedures include: Arrow PTD (527), pulse-spray with urokinase (240), Amplatz Thrombectomy Device (96), AngioJet (17), Oasis (15), Hydrolyser (10), Endovac (7), Lyse and Wait (7), Thrombex (6), Cragg brush (6), Castaneda brush (4). Complications were reported to have occurred in 31 patients. The radiology reports and medical records of these patients were reviewed.

Results

The overall complication rate was 3.3%. The type and number of complications included: rupture of a vein during angioplasty (13), severe cardiopulmonary distress (4), arterial emboli (4), rigors related to urokinase (3), minor bleeding (2), hypoxia with chest pain (2), other assorted complications (3). There was one death resulting from a fall from the angiography table immediately following the procedure. There were 12 minor complications, requiring minimal treatment, and 19 major complications that altered the course of the procedure or treatment of the patient.

Conclusion

The most common complication was angioplasty-induced rupture of the vein or graft. The most severe complications occurred immediately following dislodgement of the arterial plug and were likely due to acute pulmonary embolization.

Vascular Rupture during Angioplasty of Hemodialysis Graft-Related Stenoses

Purpose

To retrospectively determine the incidence and outcome of angioplasty-induced ruptures that occurred during treatment of hemodialysis graft-related stenoses.

Materials and Methods

During a five year period 1222 patients with dysfunctional or thrombosed polytetrafluoroethylene (PTFE) hemodialysis grafts underwent angioplasty procedures at our institution. Angioplasty-induced vascular ruptures occurred in 24 (2.0%) patients. The locations of these ruptures were: basilic vein (10), venous anastomosis (7), cephalic vein (5), brachial vein (1) and intragraft (1). The mean length of the treated stenoses was 2.4 centimeters.

Results

Manual compression was used to treat the vascular rupture in ten patients. One patient was treated with endovascular balloon tamponade and one patient underwent stenting of the rupture site. Despite the rupture, 15 patients had completion of the angioplasty procedure. In nine patients the procedure was abandoned due to persistent stenosis at the rupture site. There were no major complications as a result of these ruptures. Follow-up was available in ten of these patients. All ten underwent at least one successful hemodialysis treatment. In five of these patients the hemodialysis graft failed within 30 days after the rupture. The mean primary patency following rupture in the ten patients with follow-up was 87.5 days (range 5 – 225 days).

Conclusion

The incidence of angioplasty-induced vascular rupture of hemodialysis-related stenoses is low and despite the injury, the majority (62%) of procedures can be completed. However, in our experience the long-term patency of the vascular access was suboptimal.

Percutaneous transluminal balloon angioplasty in stenosis of native hemodialysis arteriovenous fistulas: technical success and analysis of factors affecting postprocedural fistula patency

PURPOSE

We aimed to determine the predictors of technical success and patency after percutaneous transluminal angioplasty (PTA) of de novo dysfunctional hemodialysis arteriovenous fistulas (AVF).

METHODS

We performed a retrospective analysis of first time PTA in 228 patients (129 men, 99 women; mean age, 56.8±14.6 years). Anatomical (location, length, grade, and number of stenoses) and clinical variables (sex, age, prior AVF, diabetes mellitus, AVF age, side, and location) were reviewed.

RESULTS

A total of 330 stenoses were found in 228 patients. PTA was technically successful in 96.3% of the stenoses (n=319). Clinical success was achieved in 97.2% (n=321). Early dysfunction (within six months) was positively correlated with patient age (P < 0.001) and diabetes (P < 0.005). Older age (P < 0.001) and diabetes (P = 0.002) were associated with a lower primary patency rate. Patient age (P %lt; 0.001), presence of diabetes (P = 0.023), length of stenosis (P = 0.003), early recurrence (P = 0.003) and presence of residual stenosis (P = 0.014) were associated with a lower secondary patency rate.

CONCLUSION

Patency of dysfunctional hemodialysis fistulas can be maintained safely with continuous follow-up and repeated interventions without shortening the venous segment by surgical revision. Percutaneous approach to hemodialysis access stenosis is an alternative to the conventional surgical approach and PTA is an effective treatment method for dysfunctional AVF.

Does Technical Success of Angioplasty in Dysfunctional Hemodialysis Accesses Correlate with Access Patency?

PURPOSE

To study if <30 % residual stenosis post angioplasty (PTA) correlates with primary access circuit patency, and if any variables predict technical success.

MATERIALS AND METHODS

A prospective observational study was performed between January 2009 and December 2012, wherein 76 patients underwent 154 PTA events in 56 prosthetic grafts (AVG) and 98 autogenous fistulas (AVF). Data collected included patient age, gender, lesion location and laterality, access type and location, number of prior interventions, and transonic flow rates pre- and postintervention. Impact of technical outcome on access patency was assessed. Univariate logistic regression was used to assess the impact of variables on technical success with significant factors assessed with a multiple variable model.

RESULTS

Technical success rates of PTA in AVFs and AVGs were 79.6 and 76.7 %, respectively. Technical failures of PTA were associated with an increased risk of patency loss among circuits with AVFs (p < 0.05), but not with AVGs (p = 0.7). In AVFs, primary access patency rates between technical successes and failures at three and 6 months were 74.4 versus 61.9 % (p = 0.3) and 53.8 versus 23.8 % (p < 0.05), respectively. In AVGs, primary access patency rates between technical successes and failures at three and six months were 72.1 versus 53.9 % (p = 0.5) and 33.6 versus 38.5 % (p = 0.8), respectively. Transonic flow rates did not significantly differ among technically successful or failed outcomes at one or three months.

CONCLUSION

Technical failures of PTA had a significant impact on access patency among AVFs with a trend toward poorer access patency within AVGs.

Postintervention Patency Rates and Predictors of Patency after Percutaneous Interventions on Intragraft Stenoses within Failing Prosthetic Arteriovenous Grafts

PURPOSE

To determine postintervention patency rates after endovascular interventions on intragraft stenosis within failing prosthetic arteriovenous (AV) grafts, as well as predictors of patency.

MATERIALS AND METHODS

Retrospective review of percutaneous interventions on prosthetic AV grafts presenting with first-time intragraft stenoses over a 7-year period revealed 183 patients (81 male; mean age, 59.7 y). "Intragraft" was defined as 2 cm or more from the arterial or venous anastomosis. Procedural imaging was retrospectively reviewed. Patency rates were estimated by Kaplan-Meier test. Predictors of patency were calculated by Cox proportional-hazards model.

RESULTS

Two-hundred twenty-nine intragraft stenoses were identified in 183 grafts. Intragraft stenoses were treated at a median of 20.7 months (interquartile range, 12.0-33.9 mo) after graft creation. Graft thrombosis was present in 62%. The anatomic success rate of angioplasty was 85%. Fifteen percent required stent or stent-graft deployment because of inadequate response to angioplasty. A concurrent nonintragraft stenosis within the access circuit was identified in 76% of grafts. At 3, 6, and 12 months, postintervention primary patency rates were 56%, 40%, and 23%, respectively. Secondary patency rates were 84%, 77%, and 67%, respectively. The lesion-specific patency rates were 89, 75%, and 63%, respectively. Graft thrombosis (hazard ratio [HR], 1.43; P = .048) and concurrent nonintragraft lesion (HR, 1.51; P = .047) were independent negative predictors of primary patency. Graft thrombosis (HR, 1.81; P = .029) was a negative predictor of lesion patency, and stent or stent-graft deployment (HR, 0.42; P = .045) was a positive predictor of lesion patency.

CONCLUSIONS

Endovascular interventions on intragraft stenoses resulted in primary, secondary, and lesion-specific patency rates of 40%, 77%, and 75%, respectively, at 6 months. Stent or stent-graft deployment may prolong lesion patency.

Efficacy of percutaneous transluminal angioplasty on dysfunctional fistulae because of inflow stenosis

PURPOSE

Autogenous fistulas are the preferential vascular access for hemodialysis. The aim of this retrospective study was to determine the efficacy of angioplasty for dysfunctional fistulas because of inflow dysfunction. 


METHODS

We reviewed all the angiographic procedures performed on our institution between April 2007 and April 2009. Procedures performed in dysfunctional fistulas because of inflow stenoses were analyzed. Fistulas with stenoses out of these areas were excluded. The following data were collected: patient age and sex, fistula age at the time of intervention, location of fistula, number and location of stenosis, angiography referral criteria, clinical findings (presence or absence of thrills, bruits and pulsatility) and date of reintervention or failure. 


RESULTS

During the study period 215 fistulas were submitted to angiography of which, seventy-one presented inflow stenosis (33%). Mean follow-up was 21.72±9.26 months, and average age was 7.03 months. Two groups were considered: 31 fistulas comprising ≤6 months old, and 40 fistulas >6 months old. Primary patency rates±SE for older fistulas at 6, 12, 18 and 24 months, respectively, was 91.3%± 0.04%, 80.7%± 0.07%, 53.8% ±0.10% and 34.2±0.1% versus 91.7±0.08%, 57.1±0.14%, 23±0.14%, 11.4%± 0.1% for younger fistulas (P=0.04). Fistulas ≤6 months old and multiple stenosis were associated with a poorer primary patency rate (P=0.005).


CONCLUSIONS

Inflow stenosis is frequently associated with fistula dysfunction. In this study we only analyzed AVF with inflow stenosis and we have shown that angioplasty can have great patency results, particularly for single lesions in matured fistulas.

Pictorial essay: Interventional radiology in the management of hemodialysis vascular access - A single-center experience

Chronic kidney disease (CKD) is a worldwide public health problem and is associated with high morbidity and mortality. The majority of patients with CKD stage 5 (CKD-5), who cannot undergo renal transplant, depend on maintenance hemodialysis by surgically created access sites. Native fistulae are preferred over grafts due to their longevity. More than half of these vital portals for dialysis access will fail over time. Screening procedures to select high-risk patients before thrombosis or stenosis appears have resulted in aggressive management. These patients are referred for angiographic evaluation and/or therapy. We present the patterns of dialysis-related interventions done in our institution.

Long-term results of stent-graft placement to treat central venous stenosis and occlusion in hemodialysis patients with arteriovenous fistulas

PURPOSE

To determine the effectiveness of stent-grafts for the treatment of central venous disease in hemodialysis patients with functioning arteriovenous (AV) fistulas.

MATERIALS AND METHODS

Between October 2004 and March 2010, 42 VIABAHN stent-grafts were deployed in central veins of 30 patients (16 men, 14 women; mean age 60 y) with functioning AV fistulas and central venous disease that did not respond to percutaneous transluminal angioplasty (PTA). Eighteen patients had central vein stenosis and 12 had occlusion. Previous PTA and/or bare metal stent placement had been performed in 23 patients (77%). Surveillance was carried out at 3, 6, 9, 12, 18, and 24 months with diagnostic fistulography. The mean follow-up was 705 days (range, 66-1,645 d). Statistical analysis included Kaplan-Meier and log-rank studies.

RESULTS

Technical success rate was 100%. Primary patency rates were 97%, 81%, 67%, and 45% at 3, 6, 12, and 24 months, respectively. Primary assisted patency rates were 100%, 100%, 80%, and 75% at 3, 6, 12, and 24 months, respectively. Patients without previous procedures had significantly shorter times to repeat intervention (P = .018) than those who had undergone PTA or bare metal stent placement previously. Patients with occlusive lesions had a significantly shorter primary patency interval (P = .05) than patients with stenoses. Occluded veins were more likely to require further stent-grafts (P = .02). Twelve patients required further stent-grafts to maintain patency. There was one minor complication.

CONCLUSIONS

Stent-graft placement to treat central venous disease in hemodialysis patients with autogenous AV fistulas is safe and effective if PTA fails to maintain luminal patency.

Treatment of hemodialysis graft pseudoaneurysms with stent grafts: institutional experience and review of the literature

Hemodialysis access grafts are an important component of the treatment of patients with renal failure. Because access sites are limited, maximizing graft lifespan is of major importance to dialysis patients. Pseudoaneurysm formation is a rare, but important complication potentially limiting the longevity of dialysis grafts. With rapidly advancing technology, placement of stent grafts in patients with end-stage renal disease is an important step in prolonging the life of the graft. We conducted a review of the literature regarding stent-graft use for hemodialysis access. In addition, we looked at our experience utilizing the Viabahn(®) (W. L. Gore & Associates, Newark, DE) stent graft in pseudoaneurysm repair. Our patients achieved primary patency of their grafts for 1, 5, and 9 months, respectively. No complications related to stent-graft implementation have been encountered in six stent-graft implants over the course of 29 months.

Optimizing function and treatment of hemodialysis grafts and fistulae

We are entering a new era for the management of hemodialysis grafts and fistulae. The hallmark of this new era will be the use of quantitative, hemodynamic parameters to optimize vascular access function and improve the results of our endovascular interventions. The implementation of vascular access surveillance programs has not only decreased the incidence of vascular access thrombosis, but also has provided new insights into the hemodynamic performance of grafts and fistulae. The measurement and analysis of intra-access blood flow has proven useful for the early detection of developing stenosis, and also provides a quantitative method to assess the results of our endovascular interventions. In the future, the use of quantitative hemodynamic measurements will play an increasingly important role in our evaluation and treatment of hemodialysis grafts and fistulae.

Clinical Outcome of Overlapping Stents in Hemodialysis Access

Purpose

Endovascular stents have recently been shown to extend access patency in thrombosed and stenotic arteriovenous grafts. Given this improved patency, stent placement has outpaced balloon angioplasty in hemodialysis (HD) access interventions. However, concern remains over localized corrosion and increased neointimal hyperplasia of overlapping stents in the access circuit and whether this promotes premature stent failure.

Methods

This is a retrospective analysis of HD patients referred for access dysfunction during a 2-yr period. Using a prospectively collected, vascular access database, we identified 76 patients seen for follow-up angiography due to access dysfunction after stent placement. We compared the outcomes of overlapping vs. non-overlapping stents in measured primary assisted patency and mean percent luminal diameter as a marker of lesion severity.

Results

The two groups did not differ significantly in demographics or comorbid conditions. Only gender had a significant discrepancy between the two groups, with 65.5% vs. 42.9% male (p=0.01) in the overlapping vs. non-overlapping stent groups, respectively. The mean percent luminal stenosis was found to be 83.7 ± 17.3 and 85.5 ± 12.6 (p=0.55) for the overlapping vs. non-overlapping stent groups, respectively. For overlapping and non-overlapping stents, 30-day primary patency was 94% and 89%, respectively, 60-day primary patency was 77% and 63%, respectively, and 90-day primary patency was 68% and 50%, respectively. Using multiple regression analysis, no risk factors were identified to be associated with the severity of luminal stenosis. No identifiable risk factors were found to be associated with improved primary patency. In particular, overlapping vs. non-overlapping stents were not identified as a statistically significant factor influencing primary (assisted) patency (hazards ratio 0.60; 95% cI 0.34 to 1.06; p>0.05).

Conclusions

This study provides evidence that the theoretical concern of metal on metal corrosion and increased neointimal hyperplasia that can be seen with overlapping stents does not play a significant clinical role.

Central venous disease in hemodialysis patients: prevalence, etiology and treatment

A common problem in the management of hemodialysis patients is central venous occlusive disease. There has been extensive literature on the treatment of this important and prevalent problem. Treatment options to date include percutaneous balloon angioplasty, bare metal stents and surgical bypass. Unfortunately, all the available treatment options have poor long-term patency, requiring repetitive intervention. More recently, covered stents have been mentioned in the literature for the treatment of central venous stenosis and obstruction. There is very little data to date on this technology, and further randomized controlled trials will be needed to compare the efficacy of percutaneous balloon angioplasty, bare metal stents and covered stents. It appears prevention of this difficult problem is paramount, by limiting venous access or intervention of the central venous system.

Use of a rosch-uchida needle for recanalization of refractory dialysis-related central vein occlusion

OBJECTIVE

The purpose of this study was to evaluate our experience with the use of a Rösch-Uchida needle technique to recanalize central vein occlusion that cannot be traversed with a guidewire.

MATERIALS AND METHODS

We retrospectively evaluated 33 recanalization procedures performed with a Rösch-Uchida needle on 20 men and 13 women with central vein occlusion during the period January 1999-December 2008. The occlusions were in the subclavian vein (n = 29) and the brachiocephalic vein (n = 4). A 9- or 10-French Rösch-Uchida introducer sheath was advanced centrally to abut the occlusion. The Rösch-Uchida needle was directed and advanced toward a transfemoral angiographic catheter placed on the central side of the occlusion. After passage of a guidewire through the occlusion, balloon angioplasty and stent insertion were performed. The outcome measures evaluated were technical success rate, primary and secondary patency, and complication rate.

RESULTS

The mean occlusion length was 1.73 +/- 0.8 cm. The rate of technical success of recanalization was 93.9% (31 of 33 procedures). The 3-, 6-, and 12-month primary patency rates were 43.6%, 24%, and 8%, and the 3-, 6-, and 12-month secondary patency rates were 77.4%, 68.8% and 55.9%. One patient reported shoulder pain lasting 2 weeks, which resolved with conservative treatment.

CONCLUSION

Use of a Rösch-Uchida needle to recanalize central vein occlusion refractory to a traditional procedure is feasible and safe and can preserve the involved extremity for long-term hemodialysis.

Incidence and management of percutaneous transluminal angioplasty-induced venous rupture in the "fistula first" era

PURPOSE

Percutaneous transluminal angioplasty (PTA)-induced venous rupture is a common complication of hemodialysis access interventions. The authors sought to determine if venous rupture rates and management differed between grafts and fistulas, and in the fistula subset, between transposed and nontransposed fistulas.

MATERIALS AND METHODS

Patients experiencing venous rupture during hemodialysis PTA over a 5-year period were identified. Of 1,985 hemodialysis interventions, 75 ruptures occurred in 69 patients (46 women) with a mean age of 63 years (range, 31-88 y). Rupture rates, proportion of successful treatments, and treatment type and number (ie, balloon tamponade, stent, covered stent) were determined.

RESULTS

Rupture was more common in fistulas overall (5.6%, 39 of 693) compared with grafts (2.8%, 36 of 1,292; P = .002), in transposed (10.7%, 20 of 187) compared with nontransposed fistulas (3.8%, 19 of 506; P = .001), and in transposed fistulas compared with grafts (P = .0001). There was no significant difference between nontransposed fistulas and grafts. Treatment success (ie, resolution of extravasation) was the same among groups: 69% (27 of 39) in fistulas overall, 70% (14 of 20) in transposed fistulas, 68% (13 of 19) in nontransposed fistulas, and 72% (26 of 36) in grafts. There was a greater need for stents in grafts (38.9%, 14 of 36) compared with fistulas (12.8%, five of 39; P = .003).

CONCLUSIONS

PTA-induced rupture is more common in fistulas than grafts, and this effect seems nearly entirely driven by transposed fistulas. Although rupture treatment in fistulas of all types yielded similar success to grafts, and graft ruptures were more difficult to treat than fistula ruptures, the high rupture rates in transposed fistulas attest to the increased difficulty of treating this subset of fistulas.

Stent placement versus angioplasty improves patency of arteriovenous grafts and blood flow of arteriovenous fistulae

BACKGROUND

While endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery intervention, its role in the salvage of thrombosed and stenotic hemodialysis access remains controversial.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We compared the effects of stent versus angioplasty on primary patency rates in the treatment of stenotic arteriovenous fistulae (AVF) and arteriovenous grafts (AVGs). Moreover, we compared access flow (Qa) and urea reduction ratio (URR) between the two groups as a metric of the effect of stent placement versus angioplasty on dialysis delivery.

RESULTS

Cox regression analysis revealed that the primary assisted AVG patency was significantly longer for the stent group compared with angioplasty, with a median survival of 138 versus 61 d, respectively (aHR = 0.17; 95% confidence interval, 0.07 to 0.39; P < 0.001). The primary AVG patency for stent versus angioplasty was 91% versus 80% at 30 d, 69% versus 24% at 90 d, and 25% versus 3% at 180 d, respectively. The primary assisted AVF patency did not differ significantly between the stent and angioplasty groups. In patients dialyzing via AVF, multiple regression analysis revealed that stent placement was associated with improved after intervention peak Qa, 1627.50 ml/min versus 911.00 ml/min (beta = 0.494; P = 0.008), change in Qa from before to after intervention, 643.54 ml/min versus 195.35 ml/min (beta = 0.464; P = 0.012), and change in URR from before to after intervention, 5.85% versus 0.733% (beta = 0.389; P = 0.039).

CONCLUSIONS

Our results suggest that stent placement is associated with improved AVG primary assisted patency and improved AVF blood flow, which may significantly impact on dialysis adequacy.

How I do it: directional atherectomy for in-stent restenosis of a PTFE arteriovenous graft

We describe the use of directional atherectomy (DA) to restore patency of a thrombosed polytetrafluoroethylene arteriovenous graft with an in-stent restenosis at the venous anastomosis. Technically, the procedure described is not an atherectomy per se, but rather the removal of fibrosis and intimal hyperplasia with sharp endoluminal dissection. Certainly, the operator must be cautious when performing DA directly adjacent to a previously deployed stent. Nevertheless, our report suggests that there may be a role for DA in the treatment of severe, resistant in-stent stenosis. Further investigation is necessary to evaluate the safety and efficacy of the described technique.

Use of nitinol stents following recanalization of central venous occlusions in hemodialysis patients

PURPOSE

To retrospectively review the patency of endovascular interventions with nitinol stent placement for symptomatic central venous occlusions in hemodialysis patients.

METHODS

A retrospective review of all patients who underwent endovascular interventions for dysfunctional hemodialysis grafts and fistulas was performed from April 2004 to August 2006. A total of 6 patients presented with arm and/or neck and facial swelling and left brachiocephalic vein occlusion. The study group consisted of 3 men and 3 women with a mean age of 79.5 years (SD 11.2 years). Of these 6 patients, 1 had a graft and 5 had fistulas in the left arm. The primary indication for nitinol stent placement was technical failure of angioplasty following successful traversal of occluded central venous segments. Patency was assessed from repeat fistulograms and central venograms performed when patients redeveloped symptoms or were referred for access dysfunction determined by the ultrasound dilution technique. No patients were lost to follow-up.

RESULTS

Nitinol stent placement to obtain technically successful recanalization of occluded venous segments was initially successful in 5 of 6 patients (83%). In 1 patient, incorrect stent positioning resulted in partial migration to the superior vena cava requiring restenting to prevent further migration. Clinical success was observed in all patients (100%). Over the follow-up period, 2 patients underwent repeat intervention with angioplasty alone. Primary patency was 83.3% (95% CI 0.5-1.2) at 3 months, and 66.7% at 6 and 12 months (0.2-1.1, 0.1-1.2). Secondary patency was 100% at 12 months with 3 patients censored over that time period. Mean primary patency was 10.4 months with a mean follow-up of 12.4 months. No complications related to recanalization of the occluded central venous segments were observed.

CONCLUSION

Our initial experience has demonstrated that use of nitinol stents for central venous occlusion in hemodialysis patients is associated with good mid-term patency and may exceed historical observations with prior use of Wallstents.

Ultrahigh-pressure versus High-pressure Angioplasty for Treatment of Venous Anastomotic Stenosis in Hemodialysis Grafts: Is There a Difference in Patency?

PURPOSE

Ultrahigh-pressure (UHP) balloon catheters were compared with high-pressure (HP) balloon catheters to determine if there was a difference in patency after percutaneous transluminal angioplasty (PTA) of venous anastomotic stenoses.

MATERIALS AND METHODS

A retrospective study was conducted from January 2001 to September 2005 that included 22 patients with synthetic hemodialysis grafts who underwent 110 PTA procedures for venous anastomotic stenoses. Data collected included graft configuration and location, percent stenosis, balloon type used, residual stenosis, and total access blood flow before and after intervention. Patency from time of initial PTA to the next intervention was estimated with the Kaplan-Meier technique, with initial failures included in the analysis.

RESULTS

A total of 55 PTAs were performed in each group. Technical success rate was 96% (n = 106) and clinical success rate was 100%. Median survival times were 4.6 months for the UHP cohort and 5.4 months for the HP group. When each event was considered independent, the difference was significant (P = .014). However, when each PTA event was considered dependent on earlier PTA events, no significant difference in patency was observed (P = .64). The mean increases in access blood flow rate by ultrasound dilution (available for 71 events) after PTA were 264 mL/min with UHP and 524 mL/min with HP (P = .14, Student t test). One minor complication (0.9%) of focal extravasation after PTA occurred and resolved with prolonged balloon inflation.

CONCLUSION

Routine use of UHP for PTA of venous anastomotic stenoses in synthetic hemodialysis grafts was not associated with any significant change in patency compared with routine HP balloon angioplasty.

Diagnostic imaging of and radiologic intervention for bovine ureter grafts used as a novel conduit for hemodialysis fistulas

OBJECTIVE

The objectives of our study were to review the appearances on diagnostic imaging and amenability to imaging-guided intervention of a novel bovine ureter graft (Syner-Graft 100 [SG 100]) for use as a conduit for hemodialysis fistulas.

CONCLUSION

The SG 100 shows initial promise as a conduit for hemodialysis fistulas in patients with difficult vascular access. The SG 100 has characteristic appearances on diagnostic imaging and is prone to similar pathologic processes that affect autogenous venous and synthetic grafts. These grafts are readily amenable to imaging-guided percutaneous intervention, which plays a major role in prolonging graft function.

Patency of Endovascular Treatment for Central Venous Stenosis: Is There a Difference Between Dialysis Fistulas and Grafts?

PURPOSE

To determine if there is a difference in intervention patency for central venous stenosis (CVS) and occlusion between patients with autogenous hemodialysis fistulas and those with grafts.

MATERIAL AND METHODS

A retrospective study was performed from March 1998 to September 2005 identifying all patients with autogenous fistulas and synthetic grafts who underwent percutaneous angioplasty and/or stent placement for CVS. This study cohort consisted of 38 patients (22 with fistulas and 16 with grafts). Age, sex, type of access, location and side of the access, location and side of the CVS, presence of diabetes, previous hemodialysis catheter placement, date and type of interventions, and outcomes were recorded. The patency of each intervention was estimated by using the Kaplan-Meier survival curves. Univariate and multivariate analysis of the variables were performed.

RESULTS

Eighty-nine interventions were performed; 83 were angioplasties and six were stent placements. Previous catheter placement on the side of the CVS occurred in 29 of the 38 patients (76%). Technical and clinical success of the interventions were 93.3% and 94.4% respectively. The intervention or primary patency rates +/- standard errors at 3, 6, and 9 months in the fistula group were 88.5% +/- 4.8, 59.4% +/- 7.6, and 46% +/- 7.9, respectively. In the graft group, the rates were 78.1% +/- 7.3, 40.7% +/- 9, and 16% +/- 7.3, respectively. With multivariate analysis, intervention patency remained significantly longer for fistulas (P .014) and in patients who did not have a previous catheter (P .001).

CONCLUSION

Longer intervention-free survival for CVS was observed in patients with autogenous fistulas compared with grafts and in patients who did not previously undergo hemodialysis catheter insertion.

Percutaneous treatment of failed native dialysis fistulas: use of pulse-spray pharmacomechanical thrombolysis as the primary mode of therapy

Objective

To determine the efficacy and outcome of percutaneous treatment in restoring the function of failed native arteriovenous fistulas (AVFs) where pulse-spray pharmacomechanical thrombolysis was used as the primary mode of therapy.

Materials and Methods

From June 2001 to July 2005, 14 patients who had thrombosis of native AVFs underwent percutaneous restoration following 20 episodes of thrombosis. These included 6 repeated episodes in one forearm AVF and two episodes in another forearm AVF. All patients except one were treated with urokinase injection utilizing the pulse-spray technique and had subsequent balloon angioplasty. One patient was treated by percutaneous angioplasty alone. We retrospectively evaluated the feasibility of percutaneous treatment in restoring the function of the failed AVFs. The primary and secondary patencies were calculated by using a Kaplan-Meier analysis.

Results

Both technical and clinical success were achieved in 15 (75%) of 20 AVFs. Four of the five technical failures resulted from a failure to cross the occluded segment. One patient refused further participation in the trial through a brachial artery access following failure to cross the occluded segment via an initial retrograde venous puncture. There were no major precedure related complications observed. Including the initial technical failures, primary patency rates at six and 12 months were 64% and 55%, respectively. Secondary patency rates at six and 12 months were 71% and 63%, respectively.

Conclusion

Pulse-spray pharmacomechanical thrombolysis for treatment of the thrombosed AVFs is safe, effective and durable. This procedure should be considered as an option for the management of failed AVFs prior to surgical intervention.

Salvage of nonmaturing native fistulas by using angioplasty

PURPOSE

To retrospectively review outcomes following angioplasty of nonmaturing autogenous hemodialysis fistulas.

MATERIALS AND METHODS

Institutional review board exemption was received for this HIPAA-compliant retrospective study; informed consent was waived. During 48 months, 101 patients underwent fistulography for percutaneous salvage of nonmaturing native fistulas. Clinical and technical success, need for secondary interventions, and complications were recorded according to consensus definitions. Patency following angioplasty was estimated with the Kaplan-Meier technique. Patient age, sex, ethnicity, fistula age, fistula type, number of stenoses, maximal angioplastic balloon diameter used, and presence of palpable thrill following angioplasty were examined as predictors of primary patency of the fistula following intervention by using Cox proportional hazards model.

RESULTS

Mean patient age was 58 years; 35% were women. Median time from fistula creation to fistulography was 2.5 months. Hemodynamically significant (>50%) stenoses were identified in 88% (89 of 101) of patients; angioplasty was attempted in 96% (85 of 89). Technical success was achieved in 92% (78 of 85) of fistulas following angioplasty; clinical success of normal hemodialysis with total access blood flow of more than 500 mL/min occurred following 88% (75 of 85) of angioplastic interventions. No major and two minor complications occurred. Mean primary unassisted patency at 3, 6, and 12 months was 60%+/-6% (95% confidence interval), 45%+/-6%, and 34%+/-6%, respectively. Additional angioplasty (n=12), stent placement (n=1), or thrombectomy (n=1) during subsequent interventions resulted in mean secondary patency at 3, 6, and 12 months of 82%+/-4%, 79%+/-5%, and 75%+/-6%, respectively. Patients without thrill following angioplasty were more than twice as likely to lose patency as patients with thrill (P=.035). No relationship was seen between primary patency and other predictors examined.

CONCLUSION

Early fistulography enables identification of underlying areas of stenosis in nonmaturing fistulas, which can be safely and effectively treated with angioplasty. With continued surveillance and repeat interventions, functional patency can be sustained in the majority of fistulas.

Radiological Intervention to Maintain Vascular Access

Stenoses and thromboses of dialysis grafts and fistulae are common problems in patients with end stage renal disease (ESRD). Timely recognition and treatment of access-related complications are essential to achieve long-term access function. Minimally invasive percutaneous interventions are techniques of growing importance for the interventional community. While stenoses can typically be treated by balloon angioplasty (PTA), thrombotic lesions may necessitate the combination of mechanical devices and/or thrombolytic agents with ancillary PTA. In this article, interventional treatments for the failing arteriovenous (AV) access are presented and reviewed.

Angioplasty Balloon Inflation Pressures during Treatment of Hemodialysis Graft–related Stenoses

PURPOSE

This two-part prospective investigation was designed to determine the balloon inflation pressures required to dilate stenoses associated with hemodialysis grafts and evaluate the burst pressures of five different angioplasty balloons.

MATERIALS AND METHODS

Eighty-nine patients with dysfunctional hemodialysis grafts were enrolled and underwent fistulography. The diagnostic studies revealed 104 stenoses, which were treated with balloon angioplasty. The characteristics of these stenoses and the balloon inflation pressures required to dilate the lesions were recorded. In part two of this investigation, the burst pressures of five different angioplasty balloons were evaluated immediately after their use during angioplasty procedures. Twenty-five balloons of each type were inflated until the balloon burst or 30 atm of pressure was achieved. Several different statistical tests were used to analyze the data set.

RESULTS

The mean balloon inflation pressure required to dilate all 104 stenoses was 17.2 atm. Subgroup analysis revealed that the mean balloon inflation pressure required to dilate 75 venous anastomotic stenoses was 17.9 atm and that a mean pressure of 15.6 atm was required to dilate 29 stenoses located within the native outflow veins. The angioplasty balloon burst pressure experiments revealed that the majority of the tested balloons can be inflated to pressures 5-6 atm greater than the manufacturers' rated burst pressures. However, the margin of safety for overinflation was variable among the balloons tested, and angioplasty balloons experience fatigue with repeated inflations.

CONCLUSION

The majority of stenoses associated with hemodialysis grafts can be successfully dilated with use of available high-pressure angioplasty balloons.

Salvage of immature arteriovenous fistulas with percutaneous transluminal angioplasty

The purpose of this study was to assess the value of percutaneous transluminal angioplasty (PTA) for the salvage of arteriovenous fistulas (AVFs) that fail to mature. From November 1998 to February 2003, 19 patients who were treated with PTA due to immature forearm AVFs were selected. Fistulography and PTA were performed via a retrograde transvenous approach after direct puncture of the fistular vein. Technical success was defined as less than a 30% residual stenosis, whereas clinical success was defined as the ability to perform at least one session of normal hemodialysis after PTA. Findings of fistulograms, success rates of PTA, and patency rates were evaluated. On initial fistulograms, stenoses were observed in all cases and 68% (13/19) of the stenoses were located in the perianastomotic area of these immature AVFs. The initial technical success rate was 84% (16/19). Technical failures comprised two patients with diffuse narrowing and segmental thrombosis of the cephalic veins and one case of elastic recoil of the anastomotic site stenosis after PTA. Two patients were immediately lost on follow-up. The remaining 14 cases underwent successful hemodialysis 0 to 33 (mean = 15) days after PTA, showing 74% (14/19) clinical success. Although accessory branch veins were noted in most cases (74%, 14/19), leaving them alone did not affect the maturation of AVFs following PTA. There was no significant procedural or late complication. Primary and secondary patency rates at 1 year were 61 and 82%, respectively. For those AVFs that failed to mature, there were stenoses along their vascular courses as underlying causes. For the percutaneous procedure, the retrograde transvenous approach was a reasonable one. As PTA is effective and quick for the salvation of immature AVFs, it can be considered a primary method for salvaging these immature AVFs.