Dialysis Access Intervention — RadCall Procedure Guide

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Indications & Contraindications

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Presenting Problem → Indication

Thrombosed AVG: pulseless, no thrill/bruit, duplex confirmed — same-day preferred but technically feasible months to years after thrombosis (clot is inert in grafts)
Thrombosed AVF: same-day declot strongly preferred — thrombus incites inflammatory reaction; adherent clot and progressive vessel damage make declot harder with every passing day
Recurrent thrombosis (>2×/month): refer for new access creation; endovascular salvage has very low long-term patency in this setting
Non-thrombosed dysfunction: venous pressure >200 mmHg during dialysis, blood flow <300 mL/min (AVF) or <600 mL/min (AVG), Kt/V decline, prolonged post-dialysis bleeding >20 min, duplex PSV ratio >3 at stenosis

Stenosis by Location — Know Before You Start

Inflow / juxta-anastomotic: within 2 cm of AV anastomosis; most common AVF failure site; retrograde access; PTA preferred, stenting near anastomosis avoided
Venous outflow: draining vein and graft-vein anastomosis (most common AVG stenosis site); antegrade access; PTA ± covered stent if refractory/recurring
Central venous: subclavian, innominate, SVC; nearly universal with prior CVC/PICC history on access arm (occult in up to 50%); stent if recurrence within 3 months after PTA

Absolute Contraindications (Declot)

Access infection — bacteremia, septic emboli risk; uremia masks clinical signs; infection 10× more common in AVG; erythema/warmth in thrombosed AVF mimics infection
Pulmonary hypertension or poor cardiopulmonary reserve — radiographic PE in up to 59% of declot cases; deaths reported from PE in poor reserve patients
Known right-to-left shunt (PFO with R→L flow) — paradoxical embolism/stroke risk
Recent access creation <4 weeks — fresh suture line; arterial anastomotic disruption can cause catastrophic hemorrhage; surgical cause should be corrected surgically
Severe ipsilateral ischemic steal syndrome; overlying skin ulceration or erosion

Relative Contraindications

Mega-fistula (estimated >200 mL clot burden) — symptomatic PE risk; consider surgical declot
Contrast allergy — use CO₂ or 13-hour IV steroid premedication

Temporary Contraindications (Address Before Proceeding)

K⁺ >6 mEq/L or EKG changes → dialyze via temporary catheter first; K⁺ 5–6 without EKG changes: temporize with IV insulin/glucose, then may proceed
Fluid overload — patient cannot safely lie supine
Hemodynamic instability
Coagulopathy: INR >4 or platelets <25k — correct before proceeding
Recent ICH, active major bleeding, or CPR — may proceed only without heparin or TPA

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Pre-Procedure

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K⁺ check (declot): K⁺ >6 or EKG changes → dialyze via temp catheter first. K⁺ 5–6 without EKG changes: temporize with IV insulin/glucose, then may proceed. Hyperkalemia is cumulative from multiple missed sessions, not just one.

tPA instillation prior to access (thrombosed access): For thrombosed AVG/AVF, instill rtPA (alteplase) 2 mg/2 mL into each limb of the access via 21G butterfly needle before going to the IR suite. Allow 30–60 minutes dwell time. This softens and partially lyses thrombus, significantly improving success of mechanical declot. Alternative: rtPA 4 mg total split between arterial and venous limbs. Do NOT use if active bleeding at access site.

Physical exam — localize before you start:

No thrill/bruit → thrombosed
Pulsatile (hyperdynamic) outflow vein without bruit → downstream (outflow) stenosis
Arm/chest wall collaterals or ipsilateral arm edema → central venous stenosis/occlusion
Low flow, no augmentation → inflow (juxta-anastomotic) stenosis

Duplex US: confirm thrombosis vs. stenosis; estimate thrombus burden; locate arterial anastomosis (critical before declot); assess for through-and-through puncture risk.

Access history: access age, prior interventions at each site, previous CVL/PICC on same arm (→ assume some central stenosis), date of last successful dialysis.

Consent: obtain consent for both the declot/angioplasty AND for possible temporary dialysis catheter placement if the access cannot be restored.

Labs (elective stenosis/PTA): CBC, BMP, INR. For emergent thrombectomy: K⁺ is the critical one — may proceed without others if clinically stable.

Antibiotics: for prosthetic graft interventions: cefazolin 1–2g IV or vancomycin 500mg IV (occult graft infection is common). Not routine for AVF. Consider broad-spectrum empiric coverage for all declot cases given high rate of occult access infection.

Dialysis team coordination: confirm patient does not urgently require dialysis during the procedure window. If access cannot be restored, dialysis catheter placement must follow immediately.

Fluid overload check: can patient lie supine for the procedure? If no → temporary catheter and dialysis first.

Heparin (declot): prepare IV heparin: bolus 2,000–4,000 U (40–60 U/kg), then 1,000 U/hr during procedure. Use bivalirudin for HIT history.

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Relevant Anatomy

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Access Types

AV Fistula types: Radiocephalic (RC, wrist), Brachiocephalic (BC, antecubital), Brachiobasilic (BB, requires transposition); mature AVF requires 6–8 weeks for development
AV Graft types: forearm loop graft (PTFE/ePTFE, between brachial artery and antecubital vein), upper arm straight graft, thigh graft; graft usable immediately after placement (usually 2–4 weeks)
Access cannulation zones: the graft/fistula body punctured by dialysis needles; identify “arterial” end (from anastomosis) vs “venous” end (toward draining vein)

Critical Segments

Juxta-anastomotic area: within 2 cm of AV anastomosis; most common site of fistula stenosis
Graft-vein anastomosis: most common site of AV graft stenosis (venous outflow anastomosis)
Central veins: subclavian → innominate → SVC; compressed/stenosed from prior CVC use; may not be apparent until access flow increases. Always image to SVC on every fistulogram.
Stents at thoracic outlet MUST be flexible (Wallstent, Fluency) not rigid — fracture risk with thoracic movement

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Technique

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Supplies (Fistulogram + Angioplasty)

Micropuncture set ×2 (declot) or ×1 (PTA) 6 Fr sheath ×2 (antegrade + retrograde for declot) Angled hydrophilic catheter (Kumpe or Berenstein) 0.035″ angled Glidewire + stiff exchange wire (Amplatz/Rosen) Multisidehole infusion catheter (Cragg-McNamara) — declot only rtPA 2–6 mg in 10–20 mL NS — pulse-spray or lyse-and-wait Fogarty arterial embolectomy catheter 4 Fr — arterial plug (grafts) Balloons: 5–6 mm (inflow/underdilate), 7–8 mm (outflow), 10–14 mm (central veins) High-pressure balloons (Atlas Gold, Conquest) 20–30 atm Stents: Fluency/Wallstent (central); covered Flair/Viabahn (graft anastomosis)

Stenosis Treatment Decision — Three Categories (Turmel-Rodrigues)

✔ Fully Dilate

Graft venous anastomosis stenosis (primary failure site in AVG)
Arterial pre-anastomotic stenosis causing distal ischemia
Symptomatic central vein stenosis (debilitating arm/facial edema, OR retrograde IJ flow toward cerebral sinus)

⚠ Deliberately Underdilate

Juxta-anastomotic stenosis in upper arm AVF: start with 5–6 mm balloon; increase by 1 mm at each subsequent session if no ischemia develops
Any stenosis in patients at high steal risk: diabetics, smokers, elderly with arterial disease
Any stenosis where concurrent asymptomatic central vein stenosis exists — full dilation may overwhelm collateral drainage and precipitate arm edema

✖ Do Not Dilate

Asymptomatic central vein stenosis — if collaterals adequately drain the arm and there is no edema, dilation triggers faster/more severe restenosis and may obliterate protective collaterals (Turmel-Rodrigues, Levit, Renaud data)
Protective juxta-anastomotic stenosis in hyperflow AVF — serves as resistance to prevent high-output failure and steal; only dilate if lumen <2 mm or access flow critically low after outflow treatment
Stenosis in access <1 month old — anastomotic suture line disruption risk

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Access planning

Antegrade (from arterial end, toward outflow) for venous outflow stenosis; retrograde (from venous end, toward anastomosis) for juxta-anastomotic stenosis. For central veins: antegrade required (wire must travel centrally). For thrombosed access: both sheaths needed (see declot protocol below).

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Micropuncture access under US guidance

Single-wall puncture only (avoid through-and-through — hematoma risk with heparin/TPA). In thrombosed access there is no flashback; US confirmation of intra-lumen position is mandatory before advancing wire.

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Complete fistulogram — full circuit, every time

Advance catheter to anastomosis. Image: anastomosis → entire access body → draining vein → axillary → subclavian → SVC/RA junction. Never stop short of central veins. Stenosis distribution: forearm AVF — 49% juxta-anastomotic; upper arm AVF — 55% downstream of cannulation zone, 22% cephalic arch; grafts — 85% venous anastomosis/outflow (Turmel-Rodrigues 2000).

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Identify and interpret stenoses before treating

>50% luminal reduction = hemodynamically significant. Always correlate angiographic findings with clinical presentation. Take two orthogonal views of any questioned stenosis. Venous spasm from the sheath can mimic stenosis — confirm with post-procedure image.

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Cross stenosis → balloon angioplasty

Advance angled Glidewire through stenosis; exchange to stiff wire for balloon tracking. Size balloon to adjacent normal vessel (see category table above for underdilation cases). Inflate to rated burst pressure for minimum 3 minutes (prolonged inflation up to 5 min for resistant). For resistant stenosis: advance to high-pressure balloon (Atlas Gold/Conquest, 20–30 atm). Central veins: 10–14 mm balloon. Goal: <30% residual stenosis.

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Stenting — indications by location

Graft venous anastomosis: covered stent (Flair or Viabahn) after ≥2 PTA failures or as primary treatment for avulsive rupture; bare-metal stents not used here (rapid neointimal ingrowth)
Central vein: self-expanding flexible stent only (Wallstent, Fluency Plus); no balloon-expandable stents at the costo-clavicular space or across the humeroglenoid joint — fracture risk; stent if recurrence <3 months after PTA
AVF outflow vein: stenting reserved for rupture or recurrent failure; preserve surgical options

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Completion fistulogram → confirm thrill

Document residual stenosis at all treated sites. Confirm stent position and absence of in-stent thrombus. Confirm thrill/bruit by palpation before removing sheaths.

Thrombosed Access — Declot Protocol

5 Golden Rules (Quencer & Friedman 2017): (1) Never flush sheaths after placement — increased pressure pushes clot into feeding artery. (2) Two sheaths always: antegrade just downstream from anastomosis; retrograde ≥10 cm downstream from first (AVF) or just upstream from venous anastomosis (AVG). (3) Clear outflow before inflow — perturbed thrombus flows centrally (safe) not into feeding artery (dangerous). (4) Systemic heparin: 2,000–4,000 U bolus + 1,000 U/hr; facilitates clot clearance, blunts pulmonary emboli effects. (5) US-guided single-wall puncture only.

Method Options (choose based on resource/operator preference):

Pulse-spray pharmacomechanical thrombolysis (PMT): TPA 2–6 mg in 10–20 mL NS via Cragg-McNamara multisidehole catheter. Small forceful aliquots (0.2 mL/injection), start centrally, work back toward sheath. Use ~75% of TPA volume through antegrade sheath, remainder retrograde. After ~10 min dwell: 6–7 mm balloon maceration, start centrally, work back. Do not push partially inflated balloon toward anastomosis.
Lyse-and-wait: TPA injected in pre-procedure area (20G angiocath) while compressing both anastomoses; patient waits 30 min–2 hr; bring to suite for balloon maceration and arterial plug removal. Advantage: faster in-room time.
Thromboaspiration: 8–9 Fr sheaths; angled-tip guide catheter with 20–30 mL syringe suction while rotating/rapidly moving catheter; eject clot on gauze. Advantage: no TPA. Arterial plug often resistant — use Fogarty embolectomy balloon for plug regardless of aspiration method chosen.
Arrow-Trerotola PTD (mechanical): rotating basket maceration; 90-day patency 15% as sole technique (below KDOQI target) — use as adjunct for chronic/laminated clot only, not primary method.

Arterial Plug Removal — AVG MANDATORY, AVF when plug present:

Through retrograde sheath: advance angled catheter → cannulate feeding artery with Glidewire → exchange for 4 Fr Fogarty embolectomy balloon
Advance deflated Fogarty through arterial anastomosis into feeding artery; inflate with 1.0–1.5 cc air; pull balloon + plug into access body
Repeat 2–3 passes, increasing air volume by 0.5 cc each pass, until pulse/arterial flow restored
If plug immovable: instill rtPA 2 mg directly at anastomosis via catheter; wait 20 min; reattempt. If still fixed: surgical consultation.

Clinical success (≥1 successful HD session after procedure): 94% AVG; 80–90% AVF. Primary patency at 6 months: 25–50% both types.

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Troubleshooting

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Persistent Stenosis After Angioplasty

Elastic Recoil — Residual >30% After Adequate Inflation

Causes: Elastic/fibrous/calcified stenosis; undersized balloon; insufficient inflation time. Stepwise approach: (1) Ensure minimum 3-minute inflation at rated pressure. (2) Upsize to high-pressure balloon (Atlas Gold or Conquest 20–30 atm). (3) Prolonged inflation up to 5 min. (4) If recurs >2×: covered stent — Flair/Viabahn for graft venous anastomosis; Wallstent/Fluency for central vein. Accept deliberate residual stenosis in upper arm juxta-anastomotic areas to avoid precipitating steal or hyperflow.

Cannot Cross Outflow Occlusion

Total Venous Outflow or Central Venous Occlusion

Step 1: Exchange to angled hydrophilic wire (Glidewire Advantage). Step 2: Try co-axial support catheter to direct wire. Step 3: Exchange to stiff wire (Amplatz). Central chronic occlusion: may require dedicated complex recanalization session; sharp recanalization techniques (Outback catheter or needle-tipped wire) for true occlusions. If truly unrecanalizable: discuss access options with nephrology — collateral patency may allow access function without treatment.

Arterial Plug Will Not Come Out

Dense Fibrin Plug Fixed at AV Anastomosis (Graft)

Cause: Organized fibrin plug can become tightly adherent, especially in chronic (weeks–months) thrombosis. Approach: (1) Instill rtPA 2 mg via catheter tip positioned directly against plug; wait 20–30 min. (2) Re-attempt Fogarty maneuver with incremental air increase (start 1.0 cc → 1.5 → 2.0 cc). (3) Gentle thromboaspiration with 20 mL syringe. (4) If truly immovable: do not force — arterial embolization risk; surgical consultation for open embolectomy and access revision.

Arterial Embolization — Ischemic Hand/Fingers

Hand or Digit Ischemia After Thrombectomy (0.4–3% Incidence)

Prevention first: Never flush sheaths; clear outflow before inflow; keep balloons deflated when moving toward anastomosis; no retrograde injection through antegrade sheath while occluding outflow. If embolization occurs — step-up ladder (Quencer Table 4, in order of invasiveness):

Observation — for asymptomatic emboli with close follow-up
Backbleeding* — Fogarty balloon in feeding artery proximal to anastomosis; inflate; patient exercises hand; collateral retrograde flow pushes clot through access (requires patent access)
Endovascular balloon embolectomy* — Fogarty through retrograde sheath, advance beyond clot in artery, inflate, pull clot into access (requires patent access)
Thromboaspiration — angled guide catheter, 20–30 mL syringe; gentle manipulation; does NOT require patent access
Lytic infusion — rtPA via catheter in artery at embolus; often limited efficacy (arterial plug is platelet-rich fibrin, not fresh thrombus)
Surgical embolectomy — when all above fail; emergent vascular surgery

No Flow After Successful Declot

Re-Thrombosis on Table or Absent Thrill After Apparent Technical Success

Missed outflow stenosis: repeat complete fistulogram — recheck central veins. Missed inflow problem: undilated arterial anastomotic or pre-anastomotic stenosis; needs retrograde access. Untreatable central occlusion: if central outflow is occluded and cannot be recannalized, declot will fail — access must be abandoned or outflow must be surgically revised. Residual clot: balloon maceration does not remove clot but disperses it — repeat thromboaspiration or additional PMT passes.

Arm Edema Develops or Worsens After PTA

Asymptomatic Central Stenosis Unmasked by Flow Increase

Mechanism: Treating outflow stenosis increased access flow, overwhelming previously compensating collaterals draining around a silent central stenosis. Next step: Complete central venogram; treat central stenosis with large (10–14 mm) balloon PTA; self-expanding stent if elastic recoil or recurrence <3 months. Prevention: before treating outflow stenosis, always evaluate central veins; deliberate underdilation of outflow stenosis when significant central disease is present.

Venous Rupture During PTA

Contrast Extravasation, Hematoma, or Access Site Bleeding

Immediate: inflate balloon at rupture site as tamponade (5–7 min sustained). If persistent extravasation: covered stent (Viabahn 7 mm or Flair) deployed across rupture site. If skin over stenosis is thin/necrotic: balloon dilation carries skin-vein combined rupture risk; consider balloon tamponade + cutaneous suture + covered stent followed by semi-elective surgical revision. Major hemorrhage/expanding hematoma: proximal balloon occlusion in feeding artery + emergency surgery.

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Complications

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Immediate

Arterial embolization (hand/finger ischemia, 1–2%)
Venous rupture from oversize balloon
Access site hematoma
Arteriovenous steal exacerbation after declot

Delayed

Re-thrombosis (50% AV graft thrombosis recurrence within 6 months)
Central venous stenosis progression
Stent fracture at thoracic outlet (Wallstent preferred over rigid stents)
Access infection post-graft intervention

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Post-Procedure

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Immediate Post-Procedure

Confirm thrill/bruit at end of procedure (document in report)
Radial pulse check bilaterally
Dialysis nursing team notified of access restoration and any restrictions
Duplex US at 1 week (surveillance)
Next dialysis session: clinical assessment at dialysis unit

Surveillance Program (KDOQI Guidelines)

AV graft: fistulogram at first sign of dysfunction (elevated VP, low Kt/V, prolonged bleeding)
AV fistula: duplex US-based surveillance q6 months or with clinical change
Access arm protection: no blood draws, no BP cuffs on access side — remind all clinical staff
Target access flow: >500 mL/min for fistula, >600 mL/min for graft

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Critical Pearls

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✦

Never flush the sheaths. After placing sheaths in a thrombosed access, do not flush them. Added volume and pressure push clot retrograde into the feeding artery → arterial embolization. This is the single most avoidable cause of ischemic complications during declot.

✦

Clear outflow before inflow — every time. Disturbed thrombus pushed centrally into the pulmonary circulation is generally well-tolerated. The same clot pushed into the feeding radial or brachial artery is catastrophic. Always start centrally with the antegrade sheath, then move to inflow via the retrograde sheath.

✦

AVF thrombosis is a time-sensitive emergency. AVF thrombus triggers an inflammatory reaction that causes clot to adhere and damages the vein wall; every hour makes declot harder and less likely to succeed. Same-day declot strongly preferred. AVG clot is biologically inert — graft declot can succeed even months to years later.

✦

Asymptomatic central vein stenosis: do not dilate. If collaterals adequately drain the arm (no edema, no symptoms), treating an asymptomatic central vein stenosis triggers faster and more severe restenosis, obliterates protective collaterals, and precipitates the very arm edema the patient did not have. Treat only when symptomatic. Exception: retrograde flow toward cerebral sinus → must treat.

✦

The protective juxta-anastomotic stenosis. In a hyperflow or upper arm AVF, a mild-moderate juxta-anastomotic stenosis acts as a resistor that keeps access pressure and flow in check — protecting against steal, cardiac failure, and central vein congestion. Dilating it "because it looks like a stenosis" can precipitate all three. Only dilate if lumen <2 mm or access flow is critically low after outflow lesions have been treated.

✦

Image the entire circuit every time. Every fistulogram must reach the SVC. A fistulogram that ends at the axillary vein is incomplete. A patient with arm edema, chest wall collaterals, or a history of prior ipsilateral CVL has central venous disease until proven otherwise.

✦

No balloon-expandable stents at the costo-clavicular space. The subclavian and brachiocephalic veins pass through the costo-clavicular space and are subject to repetitive chest wall movement. Rigid balloon-expandable stents fracture here. Use only self-expanding flexible stents (Wallstent, Fluency Plus) for central venous stenosis.

✦

3–5 minute balloon inflation minimum for venous stenosis. A 30-second inflation is unlikely to achieve durable results. Evidence supports prolonged inflation for resistant venous stenoses. For elastic recoil: upsize balloon first, then extend inflation to 5 min before declaring a high-pressure balloon is needed.

✦

Covered stent for graft venous anastomosis; flexible stent for central veins. Bare metal stents at graft venous anastomosis fail rapidly from neointimal hyperplasia — use covered stent (Flair or Viabahn). At the cephalic arch or central veins, flexible self-expanding stents resist repetitive deformation. Use the right stent for the location.

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References

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Key Guidelines

Lok CE, et al. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis. 2020;75(4 Suppl 2):S1–S164.
SIR Standards of Practice Committee. Quality Improvement Guidelines for Dialysis Access. J Vasc Interv Radiol. 2016.

Primary References

Quencer KB, Friedman T. Declotting the Thrombosed Access. Tech Vasc Interv Rad. 2017;20:38–47. [Source for declot techniques, contraindication classification, arterial embolization ladder]
Turmel-Rodrigues L, Renaud CJ. Diagnostic and Interventional Radiology of Arteriovenous Accesses for Hemodialysis. Springer-Verlag France, 2013. [Source for dilation decision framework, stenosis categories, underdilation principles, cephalic arch stenosis, central vein management]
Nikolic B, et al. Dialysis Access Interventions. Tech Vasc Interv Rad. 2008;11:156–166. [Source for stenosis localization, PTA outcomes, access surveillance]
Turmel-Rodrigues L, et al. Treatment of stenosis and thrombosis in haemodialysis fistulas and grafts by interventional radiology. Nephrol Dial Transplant. 2000;15:2029–2036. [Stenosis location distribution data: forearm AVF 49% juxta-anastomotic; grafts 85% venous anastomosis]
Haskal ZJ, et al. Stent graft versus balloon angioplasty for failing dialysis-access grafts. N Engl J Med. 2010;362:494–503.
Maya ID, et al. Outcomes of stent placement for dialysis access–related central venous stenosis. Semin Dial. 2007;20:355–361. [Central vein stent: 19% primary, 64% secondary patency at 1 year]