In this episode, Dr. Chris Beck interviews vascular access surgeon Dr. Ari Kramer about his management of arteriovenous (AV) access for dialysis patients. We cover his preferred imaging for identifying and deciding to treat stenoses, the protracted angioplasty technique, and the evolution of research in drug coated balloons (DCB) and stent grafts.

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SHOW NOTES

Dr. Kramer starts by describing his vascular access practice. He is the sole operator within a hospital-based practice where he creates and maintains AV access. When evaluating a patient for possible intervention, duplex ultrasound, physical exam findings, patient history, and information from the dialysis center all play roles in determining whether the patient is eligible for a fistulagram. Dr. Kramer offers fistulagram tips: he obtains access above the arterial anastomosis in order to avoid occlusion of outflow, and he first shoots contrast into the venous tract first and works his way up to the arterial system. Depending on the findings of the fistulagram, stenotic lesions in the venous outflow tract can be treated. Dr. Kramer generally treats the lesion if the stenosis limits flow by more than 50%. Additionally, he treats any lesion resulting in a luminal diameter of 2mm or less.

In an AV fistula circuit, Dr. Kramer describes his procedure, which is largely informed by the most current clinical trials. He first employs the FLEX Vessel Prep system to reduce circumferential fibromuscular tension. Next, he performs protracted plain old balloon angioplasty (POBA) for 90 seconds. This helps Then, he re-images the vessel to ensure there was no injury and utilizes a DCB to deliver paclitaxel. We discuss the clinical trials outcomes of the two current DCBs that have been approved for use in AV management, IN.PACT and Lutonix. Dr. Kramer also notes the significant cost of DCBs and lack of access to treatment for the most at-risk patients. He encourages clinicians to unite to advocate for increased reimbursement for this treatment that has been proven to show the highest standard of care.

Additionally, we address treatment of non-autogenous AV circuits with stent grafts. Dr. Kramer prefers self-expanding covered stents, such as Viabahn or Covera, since they are conformable and resistant to kinks. Overall, Dr. Kramer emphasizes the importance of the operator staying up to date on clinical trials that show data for diverse tools with various indications, knowing their own skill and comfort, and incorporating the best treatments based on their patient and practice context.

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RESOURCES

Ep. 139 AV Fistula Graft Management:
https://www.backtable.com/shows/vi/podcasts/139/av-fistula-graft-maintenance

FLEX Vessel Prep System:
https://www.venturemedgroup.com/

KDOQI Clinical Practice Guideline for Vascular Access, 2019 Update:
https://www.ajkd.org/article/S0272-6386(19)31137-0/fulltext

Fahrtash, F., Kairaitis, L., Gruenewald, S., Spicer, T., Sidrak, H., Fletcher, J., Allen, R., & Swinnen, J. (2011). Defining a significant stenosis in an autologous radio-cephalic arteriovenous fistula for hemodialysis. Seminars in dialysis, 24(2), 231–238.

Haskal, Z. J., et al. (2010). "Stent graft versus balloon angioplasty for failing dialysis-access grafts." New England Journal of Medicine 362(6): 494-503.

Bard Peripheral Vascular. Covera vascular covered stent instructions for use. Rev.4 / 08-18.
http://www.bardpv.com/eifu/uploads/BAWB05872R4-Covera-Vascular-Covered-Stent-IFU.pdf.

The Fight Doctors:
https://thefightdoctors.com/about/

Find this episode on BackTable.com for all resources mentioned in this podcast, including references to journal articles.