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BackTable / VI / Topic / Procedure
Declot
Declot is a common interventional procedure that occurs in arteriovenous fistulae (fistula declot) and grafts. A declot is done to remove any clogging or narrow passages in arteriovenous fistulas and grafts to improve blood flow. It can be performed by a range of specialists including interventional radiology, interventional nephrology, cardiology and vascular surgery. When dialysis access sites thrombose, every effort should be made to restore dialysis quality flow in a timely fashion. The declot procedure can range in complexity and time investment. Learning a few key concepts will help you understand why access sites thrombose and how to restore flow safely and efficiently.
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Pre-Procedure Prep
Indications
• Thrombosed dialysis graft
Contraindications
• Severe hyperkalemia
• Fluid overloaded
• Infected graft
• Severe coagulopathy or contraindication to thrombolysis (recent stroke, trauma, brain tumor, etc.)
• Severe contrast reaction - consider CO2
• Recently placed graft; < 4 weeks - needs surgical revision
• Severe pulmonary hypertension
Sometimes safest path forward is to place catheter to correct hyperkalemia or fluid imbalance. Bring patient back for declot
Pre-Procedural Evaluation
• Physical exam - evaluate the graft and skin
• Previous studies of the graft
• Dialysis schedule and last successful session
• Allergies
• Evidence of infection
Declot Podcasts
Listen to leading physicians discuss declot on the BackTable VI Podcast. Get tips, tricks, and expert guidance from your peers and level up your practice.
Episode #420
In this episode of the Backtable Podcast, host Dr. Chris Beck interviews guests Dr. Omar Chohan and Dr. Harris Chengazi about dialysis fistula declot procedures and their own experiences with various devices and strategies, including usage of pre-procedure ultrasound, heparinization, and closure techniques. Both Dr. Chohan and Dr. Chengazi are interventional radiologists at Great Lakes Medical Imaging in Buffalo, New York.
Procedure Steps
Antibiotic Prophylaxis
• Not recommended for routine declot
• Special considerations: 1–2 g cefazolin IV in high-risk patients, especially those receiving covered stent
• PCN allergy: Vancomycin recommended
Positioning
Position body and arm so that the whole graft and outflow to the right atrium can be imaged
• Often times, will involve breaking table
• Moveable C-arm with lower profile can have advantages in terms of maneuvering around patient and operator
Access
Many different techniques when declotting a fistula or graft
Give local 1% lidocaine in tissues over the inflow near the arterial anastomosis.
Access with toward the venous anastomosis
• Many operator use US for access
• Many operator use micropuncture needle or an angiocath which can accept an 0.0038" wire
• There will likely be no blood return when puncturing the graft
Advance wire through needle or micropuncture sheath under fluoroscopy
Place venous outflow sheath - 7 Fr
• May be able to use smaller sheath but 7 Fr generally will allow for larger balloons in case of central stenosis
Treat Outflow Stenoses
Advance a 5 Fr catheter centrally to evaluate venous outflow
• Obtain a subclavian venogram to exclude a central stenosis
• Can do pullback venogram to get a sense of clot extent and possible stenoses
• Administer heparin IV
• Treat outflow stenoses
Administer TPA
Run fogarty through the venous limb centrally to clear path for TPA
• Administer 2-4 mg of TPA through venous sheath.
• Ok to mix TPA with contrast. Will give some diagnostic information for potential stenoses or clot extent.
• Option to perform balloon maceration with low resistance angiography or possibly using thrombectomy device
Remove Arterial Plug
Obtain access in the graft/fistula directed towards arterial inflow
• 6 Fr sheath
• Navigate catheter and glidewire combination across arterial anastomosis and direct wire proximally within the artery
• Confirm catheter position with angiogram
• Bring Fogarty balloon across arterial anastomosis. Pull platelet plug. Some operators will pull Fogarty across anastomosis multiple times
• Place Fogarty through venous sheath and push clot centrally
• Check sheaths for blood return. Check dialysis access for pulse
Fistulagram
Gentle fistulagram through venous sheath
• Evaluate for stenoses or residual clot
• Angioplasty stenoses
• Reasonable to stent resistant stenotic lesions when appropriate. Angioplasty should be exhausted before stenting in most circumstances.
Circuit Imaging
Once flow is restored, image entire length of dialysis circuit from inflow artery to right atrium
Remove sheaths
• Hemostasis with gentle compression
• Occlusive pressure can re-thrombose dialysis circuit
• Woggle technique helpful. Leave in place for 30-60 minutes following declot. Allows patient to be discharged without leaving suture in place. Extremely helpful if dialysis RN will remove
Declot Articles
Read our exclusive BackTable VI Articles for quick insights on declot, provided by physicians for physicians.
Arteriovenous fistulas and grafts are dialysis access sites that can thrombose. To restore blood flow in the dialysis circuit, a declot procedure is performed to remove clots and treat any associated stenoses which may be flow-limiting. Interventional nephrologist Dr. Neghae Mawla provides tips and tricks for reducing procedure time, working with two sheaths, performing angioplasty, and using stents vs. drug coated balloons.
Arteriovenous fistulas and grafts are dialysis access sites that can thrombose. To restore blood flow in the dialysis circuit, a declot procedure is performed to remove clots and treat any associated stenoses which may be flow-limiting. In part 2 of this article, interventional nephrologist Dr. Neghae Mawla walks through the remaining steps of the declot procedure including arterial sheath placement (inflow), polish, closure, and follow-up.
Declots are typically added to the case schedule on short notice and can require a substantial amount of time depending on the treatment modality you utilize. Interventional radiologist Dr. Sabeen Dhand walks through his declot technique for dialysis access cases, and how he drastically reduces procedure time using the Argon Cleaner thrombectomy system.
Post-Procedure
Outcomes
• Technical success is flow reestablished and patient able to complete 1 session of dialysis
• Fistulas slightly less successful than grafts
• Technical success for fistulas ranging between 75%-100%
• Primary patency: 34-50% at 12 months
• Consider monitoring/surveillance program for dialysis access to reduce declots
Complications
Major: 1%
Minor: 10%
• Bleeding and/or hematoma
• Vascular dissection or venous rupture
• Embolization of clot into arterial system: avoid; can be difficult to treat
Patients encouraged to go immediately to dialysis with full anticoagulation
Avoid tight dressings
Declot Demos
Watch video walkthroughs of declot on the BackTable VI expanded content network.
References
[1] Chehab MA, Thakor AS, Tulin-Silver S, et al. Adult and Pediatric Antibiotic Prophylaxis during Vascular and IR Procedures: A Society of Interventional Radiology Practice Parameter Update Endorsed by the Cardiovascular and Interventional Radiological Society of Europe and the Canadian Association for Interventional Radiology. J Vasc Interv Radiol. 2018;29(11):1483‐1501.e2. doi:10.1016/j.jvir.2018.06.007
[2] Quencer KB, Friedman T. Declotting the Thrombosed Access. Tech Vasc Interv Radiol. 2017;20(1):38‐47. doi:10.1053/j.tvir.2016.11.007
[3] MacRae JM, Dipchand C, Oliver M, et al. Arteriovenous Access Failure, Stenosis, and Thrombosis. Can J Kidney Health Dis. 2016;3:2054358116669126. Published 2016 Sep 27. doi:10.1177/2054358116669126
[4] El Kassem M, Alghamdi I, Vazquez-Padron RI, et al. The Role of Endovascular Stents in Dialysis Access Maintenance. Adv Chronic Kidney Dis. 2015;22(6):453‐458. doi:10.1053/j.ackd.2015.02.001
[5] National Kidney Foundation. KDOQI Clinical Practice Guideline for Hemodialysis Adequacy: 2015 update [published correction appears in Am J Kidney Dis. 2016 Mar;67(3):534]. Am J Kidney Dis. 2015;66(5):884‐930. doi:10.1053/j.ajkd.2015.07.015
[6] Funaki B. Problematic declots: complications and irritations. Semin Intervent Radiol. 2004;21(2):69‐75. doi:10.1055/s-2004-833679
[7] BackTable, LLC (Producer). (2018, March 21). Ep 25 – Declots and the Argon Cleaner Device [Audio podcast]. Retrieved from https://www.backtable.com/shows/vi
Disclaimer: The Materials available on https://www.BackTable.com/ are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Podcasts
Articles
Tips & Tricks for AV Fistula & Graft Declots
How to Declot AV Fistulas & Grafts Part 2: Finishing Touches & Follow-Up Care
How to Declot AV Fistulas & Grafts Part 1: Patient Prep, Access, Outflow