Steal syndrome solutions proposed amid assessment of ischaemia risks

VIETHsymposium (15–19 November, New York City, USA) has played host to a “mini-symposium” on the risk of steal syndrome and distal ischaemia posed by vascular access for haemodialysis. Moderated by John E Aruny (Dialysis Access Institute, Orangeburg, USA) and Clifford M Sales (Mount Sinai School of Medicine, Summit, USA), it saw prominent vascular access voices tackle the issue and propose means of mitigating it.

First to speak was William Jennings (University of Oklahoma School of Community Medicine, Tulsa, USA), who gave a presentation reviewing his published findings that even patients “at high risk of hand ischaemia” can have “a safe and functional arteriovenous fistula (AVF) established” for vascular access. Haemodialysis access-induced distal ischaemia (HAIDI) is a particular risk, he said, for individuals with peripheral vascular disease, diabetes, a history of any amputation, previous steal syndrome, females, and older patients, among others. Jennings set about outlining methods for minimising the risk of HAIDI, including “more (and more successful) distal radiocephalic AVFs” as well as proximal radial artery inflow. He noted too that “reports of percutaneous AVFs all note a very low incidence of HAIDI,” referencing the 2020 study by Alexandros Mallios (Hôpital Paris Saint-Joseph, Paris, France) et al on the

Ellipsys (Medtronic) system and the 2017 NEAT trial of WavelinQ (BD) published by Charmaine Lok (University of Toronto, Toronto, Canada) et al in the American Journal of Kidney Diseases (AJSN)

Following Jennings came Matthew J Dougherty (Pennsylvania Hospital, Philadelphia, USA), who explored strategies for managing steal syndrome and neuropathy related to dialysis access. Dougherty provided statistics on the prevalence of steal, which affects 10–20% of dialysis patients. Of those, 4–6% require intervention, he said, while also noting that while neuropathy of various aetiologies was experienced by between 10 and 40% of dialysis patients, ischaemic monomelic neuropathy (IMN) affects fewer than 1%.

He differentiated the two conditions, noting that steal has a slower, less conspicuous onset than IMN which is “immediate.” Steal, he said, is associated more with vascular access at the distal brachial level, while IMN is almost exclusively associated with diabetes. Dougherty proposed an algorithm for the work-up and management of neuropathy and steal syndrome, with a diminished emphasis on the distal revascularisation and interval ligation (DRIL) procedure as the dominant option, which was shared by the panel.

Outlining treatment options, Dougherty pointed to ligation, which he described as “simple” and a way of restoring a patient’s baseline anatomy. Banding, meanwhile, he described as “a poor choice for low flow” and “less predictable” than alternative treatments, but said it was better for veins than prosthetics. For low-flow patients, he did suggest DRIL.

He also examined revision using distal inflow (RUDI) but said it shared problems with banding and that clinical data on the procedure were limited. He advocated perhaps most strongly for minimally invasive limited ligation endoluminal-assisted revision (MILLER) as a steal treatment, referring to Gregg Miller (American Access Care of Brooklyn, Brook-

Hypotension and AV access thrombosis: causation or just association?

Aisha Shaikh (Memorial Sloan Kettering Cancer Centre, New York, USA) has staked a claim that, though hypotension is “associated” with arteriovenous access (AV) thrombosis, it should be far from the only consideration in choosing an access modality. She did so while presenting at VEITHsymposium (15–19 November, New York, USA).

SHAIKH BEGAN BY DRAWING ATTENTION TO THE fact that chronic hypotension in ESKD patients is often caused by poor cardiac function, autonomic dysfunction or a combination of both. Chronic hypotension is associated with increased risk of AV access thrombosis, and AV access thrombosis in turn is associated with poor outcomes, Shaikh said. She stated that high AV access flow can lead to heart failure especially in the setting of poor myocardial reserve, which can in turn can lead to hypotension. Therefore, she argued, in patients with chronic hypotension it is peritoneal dialysis (PD) that is the preferred dialysis modality as it causes less blood pressure variability.

She stressed that it is nevertheless important to assess whether a patient is a candidate for PD—as well as whether they are a candidate for a kidney transplant. If they are, then their clinician must also “determine living donor availability and transplant wait-time”. All of these considerations must be taken into account when making modality decisions.

With all of this in mind, she reminded the audience of the three vascular access options for the chronically hypotensive ESKD patients who are not candidates for PD: an arteriovenous fistula (AVF), an arteriovenous graft

(AVG) or a central venous catheter (CVC). Functional AV fistulae carry lower risk of thrombosis and infection compared to AV grafts and CVCs.

Next, Shaikh discussed the findings of a study led by Tara I Chang (Stanford University, Palo Alto, USA) that investigated the association between intradialytic lyn, USA) et al’s 2009 retrospective analysis study in Kidney International which described the “minimally invasive” procedure as “effective and durable.”

Yana Etkin (Zucker School of Medicine at Hofstra/Northwell, Hempstead, USA) followed this with her own presentation examining a modified banding technique as a treatment option for distal ischaemia. She distinguished first between high flow rate steals, adequate and low flow rate steals and severe ischaemia, all of which demand different treatments. Modified banding is only appropriate as a treatment for high flow rate steals, she said, echoing Dougherty.

She stated that overall banding is associated with a “high rate of failure” and complications. Drawing on a Journal of Vascular Surgery (JVS) study by Andrew E Leake (Vascular Surgery Associates of Richmond, Henrico, USA) et al from 2015, Etkin made the claim that banding could benefit from “intraoperative measurement of distal perfusion” as a “simple and effective adjunct” that could be easily performed, requiring no “special equipment or personnel.”

“HAIDI could lead to devastating complications including loss of digits or even limbs in a small group of patients,” Etkin said later to Renal Interventions. “We are continuing to improve our techniques to manage this challenging problem.” hypertension and the risk of AV access thrombosis. In this study, intra-dialytic hypotension increased the risk of AVF thrombosis. Low predialysis and postdialysis systolic blood pressure were associated with increased risk of AVF and AVG thrombosis. Furthermore, patients in the higher quartiles of intradialytic hypotension were older, tended to use AVG more than AVF and were more likely to have heart disease.

The symposium explored a variety of treatments for steal and neuropathy, before a concluding presentation which diverged into vascular access haemorrhage.

She also alluded to another recent study by Mu-Yang Hsieh et al that showed an association between blood pressure variability and higher risk of AVF and AVG thrombosis. Although she said intra-dialytic hypotension, pre- and post-hypotension, as well as blood pressure variability, are all “associated” with increased risk of AV access thrombosis, she was careful to note that “association does not establish causation.” She insisted that, though it is “reasonable” to employ treatment of intra-dialytic hypotension and chronic hypotension for patients with recurrent AV thrombosis, such interventions have not been proven to lower the risk of AV access thrombosis.

In patients with heart failure and chronic hypotension, Shaikh described it as preferable to create a radial arterybased AV fistula. If a brachial artery-based AV fistula is created then AV fistula flow rate should be monitored and flow reduction must be considered if the flow rate exceeds 1.5 L/min. In patients who are at high risk of AV fistula failure, an AV graft is a reasonable AV access choice. In patients with poor life expectancy, a CVC can be used as a permanent vascular access.

Shaikh concluded by stressing that, “association between hypotension and AV access thrombosis… does not establish causation,” The final decision on AV access choice should not solely be based on presence of hypotension. Other factors, including “comorbidities, symptoms, frailty status, life expectancy and patient preference” should all be considered.