UNASSIGNED: Oscillatory wall shear stress and related metrics have been identified as potential predictors of dialysis access outcomes; however, the absence of a simple non-invasive method for measuring these haemodynamic forces has been prohibitive to their adoption into routine clinical practice. We present a computationally enhanced, single patient case study, offering a unique insight into the haemodynamic environment surrounding the development of flow limiting neointimal hyperplasia within the efferent vein of a previously functional arteriovenous fistula (AVF).
UNASSIGNED: Computational fluid dynamics (CFD) simulations were used to create a quantitative map of oscillatory shear stress as well as enabling visualisation of streamline patterns within the AVF. CFD data was compared to ultrasound-based turbulence quantification and examined alongside structural and functional changes in the access site over time.
UNASSIGNED: This work further supports the notion that flow limiting neointimal hyperplasia development in vascular access fistulae, occurs in response to oscillatory wall shear stress, and provides proof of concept for the idea that non-invasive ultrasound turbulence quantification tools could play a role in predicting vascular access outcomes.
UNASSIGNED: In addition to providing insight into the haemodynamic environment surrounding the development of flow limiting neointimal hyperplasia, we hope that this paper will promote discussion and further thinking about how our learnings from in-silico studies can be incorporated into clinical practice through novel uses of existing diagnostic tools.

Dialysis access thrombosis is a common complication in the process of care. With the introduction of endovascular AV-fistulas [AVF]s the situation gained complexity with new potential thrombosis localizations. Several thrombectomy methods are available for recanalization of thrombosed AVFs ranging from invasive surgical methods to minimal invasive endovascular approaches. Early assessment, diagnosis and treatment is crucial for prolonging the life span of an AVF and preventing the need for placement of central venous catheters. To our best knowledge, we present the first case in which an obstructed antecubital communicating vein (aka perforating vein) of an endovascular created AVF was re-opened via interventional thrombectomy with the Rotarex® System (BD Interventional). The procedure was performed primarily under ultrasound guidance with fluoroscopic support. Our case report shows that this method, if done correctly and successfully, may prevent loss of the dialysis access. Additionally, we point towards the central role of ultrasound in this method.

UNASSIGNED: Cardiovascular disease is a major cause of morbidity and mortality in patients with end-stage kidney disease. Arterio-venous fistulas (AVF), the gold standard for hemodialysis vascular access, are known to alter cardiac morphology and circulatory hemodynamics. We present a prospective case series of patients after creation of an AVF, explore the timeline for changes in their cardiac morphology, and detail considerations for clinicians.
UNASSIGNED: Patients were recruited in 2010 at multiple centers immediately prior to the creation of an upper-arm AVF and the initiation of hemodialysis. Cardiovascular magnetic resonance images were taken at intake before the creation of the AVF, 6-month follow-up, and 12-month follow-up. Image segmentation was used to measure left ventricular volume and mass, left atrial volume, and ejection fraction.
UNASSIGNED: Eight patients met eligibility criteria. All eight patients had a net increase in left ventricular mass over enrollment, with a mean increase of 9.16 g (+2.96 to +42.66 g). Five participants had a net decrease in ejection fraction, with a mean change in ejection fraction of -5.4% (-21% to +5%). Upon visual inspection the patients with the largest ejection fraction decrease had noticeably hypertrophic and dilated ventricles. Left atrial volume change was varied, decreasing in five participants, while increasing in three participants. Changes in morphology were present at 6-month follow-up, even in patients who did not maintain AVF patency for the entirety of the 6-month period.
UNASSIGNED: All patients included in this prospective case series had increases in left ventricular mass, with variability in the effects on the ejection fraction and left atrial volume. As left ventricular mass is an independent predictor of morbidity and mortality, further research to determine appropriate vascular access management in both end-stage kidney disease and kidney transplant populations is warranted.

The Surfacer Inside-Out Access Catheter System (Surfacer) is a novel approach to restore access in total central vein occlusion (TCVO). We report a series of three cases, with mean 18-months follow up, in our institution where this technique was safely and effectively used in tandem with Hemodialysis Reliable Outflow (HeRO) graft for creation of upper limb vascular access in patients with TCVO. Although there have been reports describing the simultaneous combination of Surfacer and HeRO graft, to our knowledge, this is the first time where the outcomes with 18-months mean follow-up are reported. All three patients had failed prior conventional attempts at TCVO crossing and had exhausted most conventional upper limb vascular access methods. The above technique yielded a 100% technical success rate with mean operative time of 140 min. Cannulation rate was 100% with all undergoing successful early cannulation by post-operative day 3. Mean primary patency of 199 days was achieved. Average intervention rate of 1.2 a year was required to maintain patency. The Surfacer device used together with HeRO graft is a feasible technique to avoid femoral catheter in patients where conventional attempts to cross the TCVO have failed.

Arteriovenous fistula (AVF) thrombosis occurs less often when compared to arteriovenous grafts. Since the number of AVFs has increased in the United States, AVF thrombosis is seen more frequently today. AVF thrombectomy can be tedious, requires physician ingenuity, and many times results in failure. Substantial clot burden in megafistulas and aneurysms is considered a relative contraindication to endovascular thrombectomy. Usually, it results in surgical referral for open thrombectomy or, at times, abandonment of the fistula altogether. Herein, we describe the technique, results, and cautions of combining a continuous infusion of recombinant tissue plasminogen (rTPA) followed by angioplasty of the culprit stenotic lesion that was successful in opening five of six AVFs with a substantial clot burden.

The open surgical venous cut-down technique is widely performed in cases of long-term treatment including administration of chemotherapy, parenteral nutrition, or replacement therapies. However, it has been recommended to avoid this technique considering the resultant unpredictable alterations in the veins draining the relevant site, especially in patients who may need central venous cannulation (CVC) during disease progression. We aimed to report on CVC in a 5-year-old child who had previously undergone bilateral internal jugular venous access by the open venous cut-down technique, in order to highlight the importance of performing the Rapid Central Vein Assessment protocol prior to any intervention and considering to abandon the use of the open surgical venous cut-down technique by gaining experience with ultrasound-guided percutaneous techniques.

Dialysis access steal syndrome is a well-recognised complication, affecting 1%-8% of all patients who undergo arteriovenous fistula formation particularly those that are brachial based. We present a case of ongoing steal syndrome following a DRIL procedure via retrograde flow in the ulnar artery. This was managed via a hybrid procedure and the use of an Amplatzer plug. This case demonstrates a novel use for the Amplatzer occlusion device, it is also a reminder that failure to occlude the vessel close to the fistula anastomosis can result in continued steal despite a functioning DRIL bypass.

Patients with end-stage kidney disease are at increased risk of death from coronavirus disease 2019 (COVID-19). In addition, severe COVID-19 has been associated with an increased risk of arterial and venous thromboses. In this report, we describe the case of a hemodialysis patient who developed an otherwise-unexplained thrombosis of an arteriovenous fistula during a symptomatic COVID-19 infection. Despite prompt treatment with three technically successful thrombectomies along with systemic intravenous heparin and two rounds of catheter-directed thrombolysis with tissue plasminogen activator, the fistula rapidly re-thrombosed each time and he required tunneled dialysis catheter placement. He subsequently required admission for hypoxemia from COVID-19 pneumonia and ultimately developed a catheter-related blood stream infection that likely contributed to his death. As the fistula had been previously well functioning and no angiographic explanation for the thrombosis was found, we speculate in this case the recurrent thromboses were related to the hypercoagulable state characteristic of severe COVID-19. Interventionalists performing hemodialysis access procedures should be aware of the prothrombotic state associated with COVID-19 and should consider it when deliberating how to best plan and approach access interventions in patients with symptomatic COVID-19.

The creation of an arteriovenous fistula instead of a synthetic vascular graft is a smart decision in hemodialysis patients who do not have a suitable superficial vein. Basilic vein transposition (BVT) is a viable option in most cases, except in patients who do not have a proper basilic vein. In patients with inadequate superficial veins, another source of the autogenous vein is the brachial vein, a deep vein of the upper arm. Most surgeons choose a full medial arm incision to perform brachial vein exploration. We describe a patient in whom BVT was not possible and so brachial vein transposition using skip incisions was performed, with good results.

This retrospective, single center, case report describes the first use of the Ellipsys Vascular Access System for percutaneous arteriovenous fistula (pAVF) creation in children. Two adolescent (<20 year of age) patients (18 and 19-year-old females), one of whom was developmentally delayed, were not considered candidates for traditional surgical arteriovenous fistula creation. pAVF creation was successful in both patients using the Ellipsys device and physiologic maturation of the fistula was achieved within 8 weeks of creation with subsequent 2 needle cannulation. No complications or adverse events were encountered. pAVF creation with the Ellipsys device can be safely performed in adolescents. Further studies will be needed to validate the expanded use of these devices in children.