Dialysis Access Interventions

Dialysis Access Interventions

“Preservation of arteriovenous access”

Matt Hawkins, MDAssistant Professor – Emory University SOM

Introduction

• Understand basic construction and function of AV fistulas and grafts

• Review endovascular interventions for non-thrombosed AV fistulas and grafts

• Review endovascular interventions for thrombosed fistulas and grafts

Construction and Function


• NKF-KDOQI = at least 65% fistulas• All new patients with ESRD

• Typical fistula failure rates after construction = 15%-25%

• Fistula maturity time = 3-4 months• Balloon-assisted maturation = 74-94%

salvage of non-maturing fistulas


• Fistulas are ready to use when:• Flow > 600 mL/min• Vein diameter > 0.6 cm• Depth under the skin < 0.6 cm

• Diameter > 4mm and flow > 500 mL/min = 95% likelihood of successful dialysis1

1:Robbin et al. Hemodialysis arteriovenous fistula maturity: US evaluation. Radiology 2002.


• AV Grafts – looped configuration from brachial artery to brachial vein preferred.

• May be used within 14 days of placement

• Primary 1 yr patency = 40%• Secondary 1 yr patency = 60-90%

• Most common reason for graft failure?


• SURVEILLANCE• Flows < 400 mL/min• Increased bleeding after dialysis• Increased pulsatility• Increased swelling

• 50-90% decrease in thrombosis rate with monitoring and surveillance and with early venous stenosis angioplasty

Endovascular Interventions

• NON-THROMBOSED FAILING ACCESS

• Comparably miserable for surgical and endovascular repair (25% patency at 6 months)


• NON-THROMBOSED FAILING ACCESS• Commonly Venous outflow in FISTULAS• Brachiocephalic = cephalic arch (39%)• Primary patency rate w/ angioplasty

(3, 6, & 12 mos) = 96%, 83%, 75%• Brachiobasilic transposition = “swing”

site• Arterial stenoses = < 15%


• NON-THROMBOSED FAILING ACCESS• PTFE graft angioplasty results:• 50% 6 month primary patency• Angioplasty-enabled patency = 68% at

1 year; 51% at 2 years• Secondary patency rates = 82% at 1

year; 65% at 2 years


• NON-THROMBOSED FAILING ACCESS• PTFE graft angioplasty results:

• NKF-KDOQI endorses Secondary patency of:

• 70% at 1 year• 60% at 2 years• 50% at 3 years


• NON-THROMBOSED FAILING ACCESS• Venous outflow stenosis in a graft,

consider covered stent


• PTFE stent = 38% 6 month patency of circuit• Angioplasty = 20%

• PTFE stent = 32% freedom from intervention

• Angioplasty = 16%


• NON-THROMBOSED FAILING ACCESS• Fistula angioplasty results:• WIDELY VARIABLE• 55% 6 month primary patency• 80% 6 month assisted primary patency• 82% 6 month secondary patency

Clark et al. Outcome and prognostic factors of restenosis after percutaneous treatment of native hemodialysis fistulas. JVIR 2002.


• NON-THROMBOSED FAILING ACCESS

DE-CLOT


• THROMBOSED ACCESS

• Pre-procedure work-up• K+• Right-to-left shunt• Prior procedures


• THROMBOSED ACCESS


• THROMBOSED ACCESS• Outcomes for PTFE grafts:• 90% initial clinical success (at least 1

round of dialysis)• 1 year primary patency = 11-26%• 1 year secondary patency = 51-69%

• Surgical and endovascular methods demonstrate similar patency rates


• THROMBOSED ACCESS• Outcomes for FISTULAS:• Technical success 75-100%• 18-60% primary patency at 6 months• 60-80% primary assisted patency at 6

months


• THROMBOSED ACCESS• Three ways to declot thrombosed access:

1. Pulse-spray thrombolysis2. Lyse-and-wait (“Lyse-and-go”)3. Mechanical thrombectomy

They all work!

How do we declot

dialysis access?


• TECHNIQUE


• TECHNIQUE• Micropuncture access both directions• Infuse 4 mg tPa in 10mL saline• Split between the two catheters

• Wait, prep remainder of equipment


• TECHNIQUE• 6F sheaths, bilaterally (radio-opaque tip)• Wire access both directions• Pull-back venogram to level of venous

outflow clot• Heparin• Venous outflow angioplasty/balloon

maceration (start with 6 mm Conquest)


• TECHNIQUE• Compliant balloon (Python/Fogarty) over

wire in artery (through anastamosis)• Pull back arterial plug into shunt• Repeat venous outflow

angioplasty/maceration• Repeat angiogram• Treat residual stenosis within the dialysis

circuit and centrally


• TECHNIQUE


• OTHER CONSIDERATIONS• Venous collateral embolization• Ischemia/steal syndromes• Venous hypertension (central occlusion)• Aneurysms/pseudoaneurysms


• OTHER CONSIDERATIONS• Current coding: • Access 36147, 36148• Angiography 35476, 75978• Thrombectomy 36870• Stent 37236, 37238• Venous embolization 37241

• TOTAL = 27.52 RVU


• COMPLICATIONS• Arterial embolization (up to 10%)• Peri-graft bleeding• Vein rupture from angioplasty


• SUMMARY• As a general rule: 6 month primary

patency following angioplasty = 50%• Stent grafts may be superior to

angioplasty at the venous anastamosis of grafts

• As a general rule: 50-67% 1 year secondary patency after thrombosis

REFERENCES

Matt Hawkins, MD@MattHawkinsMD

[email protected]

Dialysis Access Interventions

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