Is surgical salvage of arteriovenous grafts feasible after unsuccessful percutaneous mechanical thrombectomy?

Hybrid Simultaneous Treatment of Thrombosed Prosthetic Grafts for Hemodialysis

Purpose

The aim of the study was to evaluate our experience in the hybrid simultaneous treatment (open and endovascular) of acute thrombosis of prosthetic grafts for hemodialysis.

Methods

Between January 2011 and June 2013, 23 patients with acute thrombosis of a prosthetic graft for hemodialysis were urgently treated with a hybrid simultaneous treatment in order to obtain a prompt restoration of the flow. A new puncture of the graft was scheduled after 24 hours.

Results

Intraoperative technical success was 100% with a completion angiography showing the restored patency of the graft. As adjunctive procedures, in 6 patients (26.1%) locoregional thrombolysis was necessary and in all cases further endovascular manoeuvres (angioplasty/stenting) were immediately performed to solve a significant stenosis of the venous anastomosis/first tract of the vein. At 24 hours when the first puncture was done, three grafts were occluded resulting in a primary patency of 87%. During the follow-up (mean duration 5.6 months) four reocclusions occurred. In-stent restenosis occurred in all patients undergone stenting. At 1 year the rates of primary patency, primary assisted patency and secondary patency were 58.7%, 78.3% and 87%, respectively.

Conclusions

In our series the combined simultaneous hybrid approach in urgency maximizes the use of different available techniques, which appeared to improve overall success rate to save a thrombosed graft for hemodialysis. The great difference showed between primary and primary assisted patency demonstrates the necessity of a close follow-up.

Sharp Needle Recanalization for Salvaging Hemodialysis Accesses with Chronically Occluded Peripheral Outflow

Purpose

To assess the effectiveness of sharp needle recanalization (SNR) for treatment of chronically occluded venous outflow in hemodialysis access.

Methods

A retrospective analysis of patient records from January 2006 to March 2010 was conducted. Forty-four hemodialysis patients (31 fistulas, 13 grafts) were referred for arm swelling (18%), excessive bleeding after dialysis (29%), and thrombosis (53%). All patients had chronic occlusion of the outflow vein which failed conventional recanalization techniques. A new outflow pathway was established by advancing a 21g needle and dilating the subcutaneous tract to bridge the fistula body to a juxtaposed patent vein. If necessary, uncovered or covered stents were utilized to maintain patency of the newly formed subcutaneous tract.

Results

Forty-four patients underwent 45 SNR procedures, with restoration of normal function and complete relief of symptoms in 40 (91%) patients. The average tract length was 15 mm (range, 1 to 32) and the average dilatation diameter was 8 mm. During the initial SNR procedure, bare metal (n=21) or covered (n=5) stents were inserted in 26 patients. The average follow-up was 18.4 months (range, 0.2 to 48 months). No major complications were observed with the procedure. At 12 months, the primary access, primary tract, and secondary access patencies were 10%, 51%, and 92%, respectively. Percutaneous thrombectomy procedures were performed at a rate of 1.16 per access-year and the number of interventions within the tract was 0.94 per access-year.

Conclusions

Sharp needle recanalization is an effective percutaneous treatment for restoring function to hemodialysis accesses with chronically occluded venous outflow pathways.

Hemodialysis vascular access monitoring: current concepts

Most arteriovenous grafts fail due to irreversible thrombosis, and most clotted grafts have an underlying stenotic lesion. These observations raise the plausible hypothesis that early detection of graft stenosis with preemptive angioplasty will reduce the likelihood of graft thrombosis. A number of noninvasive methods can be used to detect hemodynamically significant graft stenosis with a high positive predictive value. These tests include clinical monitoring, as well as surveillance by static dialysis venous pressures, flow monitoring, or duplex ultrasound. However, these surveillance tests have a much lower positive predictive value for graft thrombosis in the absence of preemptive angioplasty. In other words, none of the currently available surveillance tests can reliably distinguish between stenosed grafts destined to clot, and those that will remain patent without intervention. As a consequence, any program of graft surveillance necessarily results in a substantial proportion of unnecessary angioplasties. Moreover, a substantial proportion of grafts thrombose despite a normal antecedent surveillance test. Numerous observational studies have found an impressive reduction of graft thrombosis after implementation of a stenosis surveillance program. In contrast, 5 of 6 randomized clinical trials failed to show a reduction of graft thrombosis in patients undergoing graft surveillance, as compared with those receiving only clinical monitoring. The lack of benefit of surveillance is largely attributable to the rapid recurrence of stenosis after angioplasty. Thus, routine surveillance for graft stenosis, with preemptive angioplasty, cannot be recommended for reduction of graft thrombosis. Future research should be directed at pharmacologic interventions to prevent graft stenosis.

Prosthetic arteriovenous grafts for hemodialysis

INTRODUCTION

Prosthetic arteriovenous (AV) grafts are indicated in patients with failed AV fistula (AVF), exhausted superficial veins or unsuitable vessels. Increasing the proportion of prevalent hemodialysis (HD) patients using autogenous AVF should reduce the need for AV grafts and associated morbidity. This paper reviews the current role of prosthetic AV grafts in vascular access for HD.

TECHNICAL CONSIDERATIONS

Prior to the insertion of a prosthetic AV graft, a comprehensive review of previous access procedures and full physical examination in addition to vessel mapping is required. Anastomotic technique should take into account the flow diffuser concept, graft geometry and an anastomotic angle of 15 degrees in order to reduce the incidence of intimal hyperplasia.

RESULTS

Many authors report 1 and 2-yr cumulative graft patency rates of 59-90% and 50-82%, respectively. The major drawbacks with synthetic grafts include: thrombosis, a five-fold increase in infection risk and steal syndrome. The choice between surgical and percutaneous methods of dealing with blocked AV grafts remains controversial, though percutaneous techniques are assuming an increasingly important role. Percutaneous strategies are successful in declotting access in 67-95% of cases. Stenting of stenotic lesions following thrombectomy improves secondary patency rates. Strategies for dealing with AV graft infection include antibiotic prophylaxis, partial, subtotal or total graft excision and the use of biological prosthesis.

CONCLUSIONS

Though more prone to complications than autogenous AVFs, AV grafts offer a short maturation period and are more amenable to thrombectomy by radiological or surgical means. Complex AV grafts may be appropriate in patients with exhausted access sites.

Outcomes of brachiocephalic fistulas, transposed brachiobasilic fistulas, and upper arm grafts

BACKGROUND AND OBJECTIVES

An upper arm vascular access is often placed in patients with a failed forearm fistula or with vessels unsuitable for a forearm fistula. The aim of this study was to compare the outcomes of three upper arm access types: brachiocephalic fistulas, transposed brachiobasilic fistulas, and grafts.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A prospective, computerized access database was queried retrospectively to identify the clinical outcomes of upper arm accesses placed in 678 patients at a large dialysis center, including 322 brachiocephalic fistulas, 67 brachiobasilic fistulas, and 289 grafts.

RESULTS

Primary access failures were less common for brachiobasilic fistulas and grafts compared with brachiocephalic fistulas (18%, 15%, and 38%; hazard ratio of brachiocephalic fistulas versus brachiobasilic fistulas 2.76; 95% confidence interval 1.41 to 5.38; P < 0.003). For the subset of patients receiving a brachiocephalic fistula, a multiple variable logistic regression analysis including age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, prior access, surgeon, arterial diameter, and venous diameter found that only vascular diameters predicted primary failure (P < 0.001). When primary failures were excluded, cumulative access survival was similar for brachiobasilic and brachiocephalic fistulas, but superior to that of grafts. Total access interventions per year were lower for brachiobasilic and brachiocephalic fistulas than for grafts (0.84, 0.82, and 1.87, respectively, P < 0.001).

CONCLUSIONS

Transposed brachiobasilic fistulas may be preferred, due to (1) a lower primary failure rate (similar to grafts), and (2) a lower intervention rate (similar to brachiocephalic fistulas). However, this advantage must be balanced against the more complex surgery.