Ushinsky A, Kiani AZ, Shenoy S. Intravascular Arterial Lithotripsy of Medial Calcinosis Causing Low Flow in Dialysis Arteriovenous Fistulae. J Vasc Interv Radiol. 2025 Nov;36(11):1730-1734. doi: 10.1016/j.jvir.2025.08.006. Epub 2025 Aug 9. PMID: 40789567.
Tell us about you, your team, and your institution.
Alexander Ushinsky, MD
Alexander Ushinsky, MD: I am an associate professor of radiology at Washington University in Saint Louis, Mallinckrodt Institute of Radiology. My co-authors on this paper are from the Transplant Surgery section. This effort is a product of a long-standing collaboration in vascular access (dialysis access) between the Interventional Radiology and Transplant Surgery Sections within Washington University in Saint Louis, under the leadership of our senior author, Dr. Surendra Shenoy.
Why did you pursue this topic?
Dr. Ushinsky: Our group has been focused on developing surgical and interventional techniques to improve vascular access options for patients with end stage kidney disease. Many of our patients are referred to us after multiple unsuccessful prior accesses or have significant surgical or technical risk factors. When such "high risk" accesses are created, patients may not reach functional fistula maturation without secondary interventions, especially if the access is created on a diseased artery or a small vein.
After creation, the interventional radiology team performs a variety of endovascular interventions to augment maturation and maintain fistulas which are at risk of failure. Arterial inadequacy secondary to medial calcinosis has historically been a challenge due to limited endovascular tools addressing arteriosclerosis. Recently, intravascular lithotripsy (IVL) has been demonstrated to fracture medial calcium and improve arterial compliance in the coronary and peripheral vascular circulation.
Drawing from our experience treating patients with peripheral vascular disease using IVL, we reasoned that a similar effect should be seen in the inflow arteries supplying low flow fistulas. We implemented this clinically, and, seeing an improvement for our patients, retrospectively investigated our results.
Figure 1 (a) Brachial artery angiogram of the functionally immature radiocephalic fistula. The distal radial artery was not well opacified due to preferential flow into the fistula. (b) Spot radiograph during the intravascular lithotripsy showed the balloon (arrow) inflated in the radial artery during treatment. Lithotripsy was performed throughout the inflow radial artery. Medial calcinosis was evident throughout the radial artery (white arrowheads). (c) Completion angiogram after lithotripsy of the entire radial artery inflow showed increased flow and washout of the radial artery and fistula.
Source: JVIR
What are the key takeaways from your research?
Dr. Ushinsky: Primarily, we have demonstrated that IVL in the upper extremity can be safely performed with a high technical success rate. We did not observe any adverse events and delineated a consistent methodology to administer treatment. Secondarily, we believe that our data demonstrates potential for efficacy. As this is a retrospective study, we cannot determine definite claims of efficacy or effectiveness.
What prompted your team to explore intravascular lithotripsy as a potential solution for maturation arrest in distal radiocephalic AVFs?
Dr. Ushinsky: Our group has significant experience using IVL in our peripheral arterial disease practice. Concurrently, we treat a large number of such "high risk" distal radiocephalic AV fistula patients with maturation arrest. Previously we would investigate dialysis access patients with low flow rates with arteriography and treatment with plain balloon angioplasty for any luminal stenoses. We lacked an effective treatment for those with heavy medial calcium burden (arteriosclerosis, causing poor compliance and inability to dynamically dilate) but who did not have luminal stenosis (atherosclerosis). Routinely treating both vascular beds, the clinical premise to use IVL for these low flow AV fistulas became readily apparent.
Were there any specific technical considerations or challenges when performing IVL in small-caliber radial arteries?
Dr. Ushinsky: Firstly, as IVL balloons are intended for the lower extremity vasculature or the coronary vasculature, the smallest balloon size (2.5mm) may still exceed the nominal diameter of the distal part of the radial artery. This may limit use of these devices in some patients or so-called "snuffbox" distal access. Because the IVL balloon is more rigid than a regular angioplasty ballon, this limited the ability to track in retrograde through the fistula anastomosis and into the proximal radial artery. A trans-femoral approach proved to be consistently deliverable. The newer generation of IVL balloons have somewhat improved in this matter. Finally, due to the risk of distal arterial occlusion we abandoned the distal radial access approach due to concerns for increasing risk of hemodialysis access induced distal ischemia (HAIDI).
How might this research influence treatment, practice or clinical processes in interventional radiology?
Dr. Ushinsky: This approach delineates a role for interventional therapies in low flow distal AV Fistulas where medial calcinosis is present. This expands on prior approaches to address maturation arrest, such as treatment of luminal stenoses of the vein or inflow artery, or "Balloon Assisted Maturation" of the cannulation segment. The capability of interventional radiologists to subsequently address inadequate flows secondary to medial calcinosis may give the access surgeon confidence to create distal forearm AV fistulas on patients with borderline arteries. In this manner, previously excluded patients may be candidates for this preferred type of dialysis access.
How might your findings influence future approaches to managing nonmaturing fistulas with arterial calcification?
Dr. Ushinsky: We would advocate for additional investigation into IVL for immature AV fistulas with medial calcinosis to grow the body of literature and better understand the effect of this approach. There are multiple additional vascular lithotripsy technologies on the horizon. Laser atherectomy (355nm laser) has also recently been demonstrated to effect fracture of medial calcium and may also improve compliance.
Any next steps or plans for follow‑up research?
Dr. Ushinsky: A critical near-term step will be an investigational device exemption as the vascular access community looks to prospectively study IVL in the upper extremity. It will be important to understand which patients are in need of IVL therapies. It is technically easy to measure flow rates for these patients; however, we do not have a commonly used approach to measure vessel compliance nor clearly qualify or quantify medial calcium in the radial artery.
