Measurement of Tremor on Arteriovenous Fistulas with a Flexible Capacitive Sensor

Arteriovenous fistula (AVF) is a widely used vascular access for hemodialysis in clinical. It is a great challenge to monitoring the status of AVF in daily life due to acute AVF stenosis may occur on unnoticeable occasions, such as sleeping. Inspiring tremor is almost always accompanied by a healthy AVF, which can be adopted as an essential physiological sign for AVF monitoring. Hence, a fistula tremor measurement system based on a flexible capacitive pressure sensor is designed in this study. The sensor consists of polydimethylsiloxane(PDMS) dielectric layers, electrode layers, ground layers, and shielding layers. The PDMS layers are fabricated as cross superposition transverse microstructure film to enhance dielectric constant and sensitivity of the sensor. The isolation shielding layers and ground layers guarantee the sensing chain is noise-free. A microcontroller embedded AD7746 measurement circuit is designed for signal acquisition. We test our prototype on the wrists of healthy volunteers and AVF on dialysis patients separately. The pulse signals and AVF tremor signals are clear and distinguishable. The sensor and measurement system have excellent potential in wearable AVF monitoring.

Sharp Needle Recanalization Technique for Peripheral Hemodialysis Arteriovenous Fistula Occlusion

PURPOSE

To determine the efficacy of a percutaneous sharp needle recanalization technique for the treatment of peripheral hemodialysis arteriovenous fistula (AVF) occlusion.

MATERIALS AND METHODS

This study included 13 patients (14 procedures) between May 2010 and February 2020 with non-thrombotic AVF occlusion wherein guidewire passage through the occluded segment had failed. We successfully passed the guidewire through the occluded segment using a sharp needle recanalization technique with Chiba or Colapinto needles, under ultrasound or fluoroscopic guidance. The type of AVF, site and length of occlusion, technical success, complications, and long-term patency were analyzed.

RESULTS

Technical success was achieved in 12 (85.7%) out of 14 procedures. The procedure failed in two patients due to the poor angle of approach in the axillary area and diffuse severe stenosis in the draining cephalic vein. In eight procedures, sharp needle recanalization was performed under ultrasound guidance, while the other six procedures were performed under fluoroscopic guidance. Chiba and Colapinto needles were used in five and nine procedures, respectively. The mean length of occlusion was 2.7 cm (range 1.8-4.2 cm). There was one case of mild complication, that is, mild contrast extravasation, which was treated by stent deployment. The post-intervention primary patency rates at 6 months, 1 year, and 2 years were 81.8%, 36.4%, and 18.2%, respectively.

CONCLUSION

The results of this limited series suggest that the sharp needle recanalization technique is a simple and effective method for the treatment of peripheral non-thrombotic AVF occlusion.

Comparison of pharmacomechanical and surgical interventions for thrombosed native arteriovenous fistulas

Background

This study aims to compare success and patency rates of pharmacomechanical thrombectomy versus open surgical thrombectomy for thrombosed native arteriovenous fistulas.

Methods

A total of 96 patients (56 males, 40 females; mean age 61±11.7 years; range, 26 to 82 years) with a thrombosed native arteriovenous fistula between January 2016 and December 2018 were retrospectively analyzed. The patients were divided into two groups as pharmacomechanical thrombectomy (n=42) and open surgical thrombectomy (n=54). Primary failure rate and primary patency rate at 6 and 12 months were recorded.

Results

Of 42 patients in the pharmacomechanical thrombectomy group, 41 (98%) had additional interventions, and primary failure occurred in four patients (10%). Primary failure was seen in 15 (28%) patients in the surgical group. The primary patency rates at 6 and 12 months were significantly higher in the pharmacomechanical treatment group than the surgical group (85% vs. 67% and 78% vs. 55%, respectively; p<0.05).

Conclusion

Pharmacomechanical thrombectomy procedure yields higher primary patency rates than open surgical thrombectomy for thrombosed native arteriovenous fistula.

Patency Rates After Successful Arteriovenous Fistula Thrombectomy: Relevance of the Flow/d-Dimer Ratio in the Decision-Making

OBJECTIVES

Surgical thrombectomy for acute arteriovenous fistula (AVF) thrombosis is one of the primary salvage intervention. The independent risk factors affecting the patency of AVF after a successful thrombectomy are yet unknown. Here, the author aimed to report the results of surgically corrected AVFs and the independent risk factors which may cause early failure following the surgical salvage.

METHODS

The study cohort comprised 24 patients who had acute AVF thrombosis and underwent successful surgical thrombectomy in the first 24 to 48 hours between January 2016 and April 2020 in our center. The study group was divided into patients with recurrent AVF thrombosis (n = 11, 45.8%) and without recurrent AVF thrombosis (n = 13, 54.1%) following surgical thrombectomy with a follow-up of 22.4 ± 6.8 months. Postthrombectomy primary and secondary patency of AVF were also evaluated.

RESULTS

The mean age of the cohort was 58.1 ± 15.2 years. A simple thrombectomy was performed for all cases. Only 2 cases have required a revision at the anastomosis due to severe intimal hyperplasia. Postthrombectomy primary patency rate was 45.5% for 18 months. Receiver operating characteristic analysis was performed with a resulting area under the curve value of 0.81 (95% CI: 0.35-0.94, P = .006) for flow (mL)/d-dimer (ng/mL) <0.63 in predicting recurrent AVF thrombosis following surgical thrombectomy.

CONCLUSIONS

Flow (mL)/d-dimer (ng/mL) <0.63 was independent predictor of recurrent thrombosis (RT) of a surgically salvaged AVF. The patients at risk for RT or who may benefit from further intervention should be identified with predictive parameters.

Comparative efficacy and safety of local and peripheral venous thrombolytic therapy with urokinase for thrombosed hemodialysis arteriovenous fistulas

Arteriovenous fistula (AVF) thrombosis is a common complication in patients undergoing hemodialysis, and early intervention is required. Urokinase has been used as a thrombolytic agent for declotting the thrombosed access. However, the optimal route for infusing urokinase remains to be determined. In the present retrospective observational study, 49 patients who underwent local venous infusion and 57 patients with peripheral venous infusion of urokinase were included. A urokinase dosage of 300,000 U was administered until successful thrombolysis, which was a maximum of three times. Age, sex, period of dialysis, time of AVF placement, systolic and diastolic blood pressure and thrombus age were similar between the two groups. The efficacy of urokinase infusion via the two routes in resolving thrombosed AVFs, defined as successful fibrinolysis, and the safety, defined as the number of bleeding events, was compared. The cumulative thrombolysis success rate following three sessions of thrombolytic therapy in the local venous thrombolysis group was higher compared with that in the peripheral venous thrombolysis group (85.7 vs. 68.4%; P=0.04). The local thrombolysis group exhibited less ecchymosis (4.1 vs. 14.0%; P=0.07), epistaxis (2.0 vs. 10.5%; P=0.08) and gingival bleeding (4.1 vs. 19.3%; P=0.02) events compared with the peripheral thrombolysis group. Further analyses demonstrated that systolic [odds ratio (OR)=1.10; 95% confidence interval (CI), 1.03-1.17; P<0.01] and diastolic (OR=1.08; 95% CI, 1.02-1.14; P<0.05) blood pressure were protective factors, whereas thrombus age (OR=0.91; 95% CI, 0.84-0.99; P<0.05) was a risk factor for thrombolysis success among patients who underwent local thrombolytic therapy. Overall, the results suggest that local venous infusion of urokinase is superior to peripheral venous infusion for the treatment of patients with thrombosed fistulas.

Restoration of Autologous Arteriovenous Fistula by Removal of the Occluded Short Venous Part and Venovenous End-To-End Anastomosis in a Hemodialysis Patient

Standard salvage procedures for occuluded autologous arteriovenous fistula (AVF) in a hemodialysis patient are endovascular and/or surgical therapy. When endovascular therapy and thrombectomy prove unsuccessful, it is most likely that creating a new AVF or arteriovenous graft will be considered. However, if the occuluded venous part is short, we have adopted an operative technique for repair of AVF by removal of the occluded short venous part and venovenous end-to-end anastomosis. To our knowledge, the efficacy and clinical course of restoration of AVF by the technique have not been reported to date. Here, we describe the technique and report the successful treatment of a hemodialysis patient who developed AVF occlusion.

A novel technique for duplex-guided office-based interventions for patients with acute arteriovenous fistula occlusion

OBJECTIVE

The purpose of the study was to aggressively salvage acutely occluded arteriovenous fistulas (AVFs) using duplex imaging as the sole imaging modality for percutaneous transluminal angioplasty of acutely thrombosed AVF.

METHODS

Over a period of 12 months, 14 patients with acute thrombosis of their AVFs underwent 18 procedures in a single center for AVF salvage. All 14 patients presented with chronic renal failure, and six were diabetic. All patients were treated under duplex guidance alone. Treatment included simple balloon dilation and maceration (group A; n =10 procedures [56%]) for subacute thrombosis or pharmacomechanical thrombectomy (group B; n = 8 procedures [44%]) for more hypoechoic thrombus. A successful procedure was defined as immediate restoration of flow through the AVF.

RESULTS

Of the 18 procedures, 13 (72%) were successful. Of the 14 patients, thrombus was located at the perianastomotic AVF in 6 (43%), proximal-mid AVF in 6 (43%), mid AVF in 1 (7%), and distal AVF in 1 (7%). From group A, six (60%) were successful. From group B, seven (88%) were successful. Among the unsuccessful procedures, one group B patient was hypercoagulable (polycythemia vera). Of the 18 procedures, 16 (89%) were treated within 2 weeks from when duplex revealed the presence of thrombus. Early rethrombosis (<1-month patency) occurred in three cases (17%), and these patients received new fistulas. Full restoration of the fistula flow was established in 14 cases (78%). Of these 14 patients, 8 (57%) are currently on hemodialysis via fistula, 3 patients (21%) had newly placed fistulas after failed interventions, 2 patients (14%) are not on dialysis yet, and 1 patient (7%) with polycythemia vera disorder is on dialysis via a Tesio catheter (MedComp, Harleysville, Pa).

CONCLUSIONS

The sole use of duplex ultrasound imaging to salvage acutely occluded AVFs using percutaneous transluminal angioplasty is a safe and effective alternative to traditional treatment of thrombosed failing/maturing AVF.

Factors Affecting Patency following Successful Percutaneous Intervention for Dysfunctional Hemodialysis Vascular Access

BACKGROUND

This study aimed to investigate the patency following initial successful percutaneous transluminal angioplasty (PTA) for untreated dysfunctional hemodialysis vascular access and to identify predictors of PTA durability.

METHODS

This retrospective observational study included data of 132 consecutive initial PTA of hemodialysis vascular access in 126 patients who showed immediate technical and clinical success and had at least 1 year of follow-up data.

RESULTS

The mean duration of primary and secondary patency post-PTA was 16 and 27 months, respectively. On multivariate adjusted Cox regression analysis, dyslipidemia (P < 0.001), use of insulin (P = 0.016), and arteriovenous graft (AVG) (P = 0.016) were significantly associated with shorter primary patency. Dyslipidemia (P < 0.001), use of antiplatelet medication (P = 0.013), and failed vascular access (P = 0.004) were significant predictors of secondary patency loss. Use of statin was the only clinical variable associated with increased primary and secondary patency (P < 0.001). According to a subgroup analysis on the type of vascular access and dysfunction, primary and secondary patency rates were significantly higher in the arteriovenous fistula (AVF) and failing vascular access groups than AVG and failed vascular access groups, respectively. Early dysfunction (within 6 months) was significantly higher in the AVG and failed vascular access groups after initial PTA, but there was no significant difference after multiple PTAs.

CONCLUSIONS

Post-PTA primary and secondary patency rates were significantly higher with AVF and failing vascular access. The use of statin was associated with increased primary and secondary patency after initial successful PTA in this study.

Preemptive Open Surgical vs. Endovascular Repair for Juxta-Anastomotic Stenoses of Autogenous AV Fistulae: A Meta-Analysis

Purpose

There is controversy about the best mode of preemptive repair of juxta-anastomotic stenoses in radial-cephalic arteriovenous fistula (AVFs). The aim of the present review was to compare the outcome of surgical vs. endovascular repair of those AVF stenoses.

Methods

A systematic review and meta-analysis was performed for studies comparing the outcome of open surgical vs. endovascular preemptive repair of AVF stenoses located in the juxta-anastomotic region. A search was carried out in April 2015. The analyzed outcome measures were the primary patency at 12 and 18 months and the assisted primary patency at 24 months. In addition, assessment of the methodological quality of the included studies was carried out.

Results

Four non-randomized cohort studies (297 patients) were analyzed. A random effects model was used to pool the data. The pooled odds ratio (OR and 95% confidence intervals) for the primary patency at 12 and at 18 months was 0.42 (0.25-0.72) and 0.33 (0.2-0.56), respectively, showing statistically significant higher patency of the surgically repaired group. The pooled OR for the assisted primary patency at 24 months was 0.53 (0.28-0.98) also in favor of the surgically repaired group (p<0.04)

Conclusions

The available evidence, based on non-randomized cohort studies, suggests that surgery is the best way to treat ‘juxta-anastomotic’ stenotic lesions in distal radial-cephalic AVFs, although angioplasty remains a valuable but less durable option in this location of the stenosis.

Surgical versus endovascular management of thrombosed autogenous arteriovenous fistulae

A best evidence topic in vascular surgery was written according to a structured protocol. The question addressed was: In patients undergoing haemodialysis with thrombosed autogenous arteriovenous fistulae, does surgical management as compared to endovascular management improve clinical outcomes? A total of 130 papers were identified using the search protocol described, of which four represented the best evidence available to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Three of the four studies demonstrated no significant difference between the initial success rates of surgical or endovascular management. However, one study illustrated that hybrid surgery (a combination of endovascular and surgical techniques) significantly improved initial success rates, shortened hospital stays and decreased total monetary costs. Furthermore, three studies showed that subsequent fistula patency rates were significantly higher when surgical management was instigated. Nevertheless, one study suggested that surgery worsened subsequent patency rates and that in fact surgical patients were more likely to require temporary dialysis catheters than endovascular patients. Therefore, the clinical bottom line is that with careful patient and fistula selection, surgery provides a number of benefits over endovascular management of thrombosed autogenous arteriovenous fistulae, particularly in the medium to long term. However, further appropriately powered and randomised Level 1 studies are necessary to clarifying this important issue.