Article
Declot
Dr. Chris Beck • Updated Sep 16, 2021 • 9k hits
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.
Table of Contents
Pre-Procedure Prep
Procedure Steps
Post-Procedure
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
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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 toward the venous anastomosis.
• Many operators use US for access
• Many operators 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
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
Additional resources
[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
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