too much or too little flow - chiang mai university€¦ · too much or too little flow: steal...

Dr John Swinnen

Vascular Surgeon

Dialysis Access Specialist

MSF Trauma Surgeon University Of SydneyWestmead Hospital

Too Much or Too Little flow:

Steal Syndrome and the Giant Fistula

Advanced Course in Vascular Access 2019

Convenor: Professor Kittipan Rerkasem

2 – 3 May 2019, Chiang Mai, Thailand

The Native Fistula

• A PATHOLOGY, a disease!

• A disease useful for Hemodialysis

AVF of Interest to 3 Parties

• The DIALYSIS PUMP:

Adequate Dialysis / RRT

• The FISTULA LIMB:

Adequate Perfusion

• The HEART:

Adequate Cardiac Function

AVF Acted on by 2 Forces

• Fistula Stenosis:

Driven by the body’s healing response

• Fistula Growth:

Driven by the inflow artery

Common Clinical Assumption

“Once a fistula becomes big enough for

adequate dialysis, all is well”

Not True!

• It may be too big !

• It may become too big !

• It may stenose and become too small !

• It may deprive the hand of adequate perfusion

Fistula Surveillance

• The Pathology that is the native AVF is unstable, and changes over time.

• Surveillance & possible revision is essential throughout the patient’s life to maintain good & uncomplicated function.

Role of the Access Specialist

Ensure that all fistulas are:

• Big enough for adequate hemodialysis

• Not too big and a burden to the heart

• The donor limb is adequately perfused

Qa: Fistula Flow

Fistula Flows

• Blood Flow Required by AVF: > 500mls/min

• Blood Flow Needed by forearm: > 200mls/min

therefore

• Blood Flow in Brachial artery: > 700mls/min

Measuring Qa

• On dialysis: eg Transonic

• With Ultrasound

• During angiography

Fistula Flows

Qa < 500ml/min - Too Small

Qa > 2000ml/min - Too Big

Qa 500 – 2000ml/min - Just Right!

• A common problem

• Poorly understood:

“The proximal fistula long a mystery to me!!”

• Better understanding from:

Fistulography, endovascular treatment,

Fistula duplex ultrasound & IVUS

Pressure & flow studies during intervention

THE GIANT FISTULA

NOTA BENE !

Giant Fistula ≠ Fistula vein aneurysm

THE GIANT FISTULA

VENOUS ANEURYSM/S

Venous aneurysm 32 mm

Feeding Radial artery 5 mm

Fistula flow Qa: 900 mls/min

THE GIANT FISTULA

Fistula vein 28 mm

Inflow brachial artery 11 mm

Fistula flow Qa: 3,500 mls/min

• Most AVF grow throughout their life

• The entire circuit, from L ventricle to R atrium

• Growth is artery driven

• Fistulas do not stop growing just because they have become adequate for dialysis !!!!

PATHOPHYSIOLOGY

GIANT FISTULA

Large fistula vein

Large inflow artery 9mm

Normal outflow artery 5mm

• Functional AVF: RC radial artery 3-5 mm

BC brachial artery 4-7mm

• Functional AVF: RC flow Qa : 500mls/min

BC flow Qa : 1000mls/min

• Giant AVF: Brachial artery ♂ > 8mm ♀ > 7mm

BC flow > 1500mls/min

DEFINITIONS

• Proximal fistulas (Brachiocephalic)

• Male sex

• Large patient / Large donor artery

• Large anastomosis (>5mm)

• Genetic factors

ETIOLOGY

• Asymptomatic

• Covert high-output cardiac failure

• Overt high-output cardiac failure

PRESENTATION

• Hypertensive fistula

• “Outflow” Problem:

High Venous Return Pressures

Prolonged Venous Bleeding

PRESENTATION

BRACHIAL ARTERY 1.82 CM

GIANT FISTULA

• Synthetic “choke” to swing vein

• Sacrifice fistula

• Giant Fistula must be treated:

BEFORE it becomes a problem!

TREATMENT

GIANT FISTULA: INFLOW CHOKE

“CHOKE” PROCEDURE: PRINCIPLE

• Synthetic patch stitched around swing vein

• Close to anastomosis without mobilisation

• Patch stitched over endovascular balloon

• Balloon size 3 – 5 mm pending indications

“CHOKE” PROCEDURE: TECHNICAL

• Straighten swing vein to avoid kinks

• Use long balloon (60-80mm): Melon seeding

• Anchor patch to vein proximally & distally

• Rifampicin soaking & systemic Vancomycin

“CHOKE” PROCEDURE

BC anastomosis

“CHOKE” PROCEDURE

“CHOKE” PROCEDURE

“CHOKE” PROCEDURE

“CHOKE” PROCEDURE

“CHOKE” PROCEDURE

CHOKE

DUPLEX U/S FOLLOW UP

DUPLEX U/S FOLLOW UP

DUPLEX U/S FOLLOW UP

COMPLICATIONS

• Not tight enough

• Too tight

• Occluded fistula

• Thrombo-embolism from poor flow

• (Infection)

CHOKE TOO TIGHT

Large RC AVF, anginaChoke too tight, 0,9mmInadequate dialysis

CHOKE TOO TIGHT

Angioplasty on 014” system with 3 x20 coronary balloon

CHOKE TOO TIGHT

Final run; choke lumen 2,8 mm

• Mrs PL, 74 yrs old

• BC AVF Queensland 2000, now in Sydney

• Qb: 300, -100, +160

• Duplex ultrasound assessment:

Flow 2387 mls/min

Brachial artery 8.8mm

Anastomosis 7.7mm

Elective Choke Procedure

GIANT AVF: CASE 1

GIANT AVF: CASE 1

CHOKE DOWN

TO 4mmm

POST-OP VISIT

• No more SOB !

• I can do the shopping again!

• So much more energy !

• Sleep better at nite !

• Qb: 300, -100, +120

GIANT AVF: CASE 1

+ 0.30cm

GIANT AVF: CASE 1

GIANT AVF: CASE 1

Giant fistula ligated at St Elsewhere

Brachial artery 14 mm with laminated thrombus

GIANT AVF: CASE 2

Brachial artery 14 mm

Excision & LSV bypassof brachial artery

• Generally MISUNDERSTOOD

• A lot of Access done by NON – Vascular Surgeons

Take Home Message:

“ Steal is an INFLOW problem ie Brachial a problem”

Steal Syndrome

Subclavian Steal Syndrome

Arm at Rest

Brain: Low Resistance

Arm:High Resistance

Very Limited Flow thru SCA Stenosis

Subclavian Steal Syndrome

Arm:Very Low Resistance

Brain: Low Resistance

Arm Exercising

Very Limited Flow thru SCA Stenosis

• Present in most fistulas

• Arm “claudication” – common

• Critical ischemia - uncommon with native AVF

• Seen mainly in diabetics

• ?Commoner with proximal anastomoses

Steal Syndrome in AVF

• Less common in the native fistula

• Native fistula growth gradual, allowing for collateralisation, inflow artery growth.

• AVG is sudden diversion of blood supply –

Steal more common

Steal Syndrome in AVF

Patho-Physiology

At rest: Brachial arteryblood flow 100-200 mls/min

Exercise: Brachial arteryblood flow 1000 mls/min

A - Brachial artery inflow

B - Fistula flow (LOW resistance)

C - Forearm / hand (HIGH resistance)

BRACHIO-CEPHALIC FISTULANORMAL

NORMAL

BRACHIO-CEPHALIC FISTULA

Increase in size / flow

inflow brachial artery ++++

Increased flow in

fistula vein +++

Small / modest decrease

in forearm flow +

NO significant increase in

size/flow brachial a due to disease

Increased flow in

fistula vein +++

Severe decrease

in forearm flow +++

CLINICAL STEAL SYNDROME

DUE TO

FAILURE OF BRACHIAL A GROWTH

Physiology of Steal

1. Blood flow to BC fistula

(Minimum 500ml/min)

2. Blood flow hand/forearm

(Minimum 200ml/min)

3. Blood flow R upper limb

(Minimum 700ml/min)

1

2

3

1. 1600mls/min

Normal BC AVF 2. 1400mls/min

3. 200mls/min

1. 1100mls/min

BC AVF & STEAL 2. 1080mls/min

3. 20mls/min

Diseased runoff vessels

with high resistance

Diseased bra a +++

limiting inflow

1

2

3

Physiology of Steal

Severely diseased, calcified brachial artery

Algorithm

• Diagnosis (Accurate diagnosis!!)

• Is steal limb threatening?

• NO: Conservative Management

• YES: Duplex scan & Volume flow Brachial a

(Not fistulography!)

Diagnosis

• All patients have a “steal”

• Diagnosis of clinically significant steal

• Steal largely a problem of Diabetics

• Accurate dx on Clinical Grounds DIFFICULT !

Diagnosis

Ischemic rest pain vs other symptoms

• Diabetic Neuropathy

• Carpal Tunnel syndrome

• “Median Nerve Neuropathy”

• Other neuropathy: cervical

• Peripheral Nerve damage

• History

• Physical Examination: Berger’s sign

• Finger Plethysmography

• Nerve conduction studies

DIAGNOSIS

BERGER’S SIGN

HANDS UP

R HAND WHITE

BERGER’S SIGN

HANDS DOWN

R HAND RED

ISCHEMIA

Severe Ischemia: Westmead, Sydney

Severe Ischemia: SIUT, Karachi, Pakistan

50 year old DMLost his fistula

& His hand!

Finger Plethysmography

Finger Plethysmograpy

• Absolute Pressures, not ratios to the Brachial a

• Both hands

Pressures < 30mm Hg

Pressures >> lower Fistula hand

• Significant Steal Pressures lower on Radial side

Flattened wave forms

Unrecordable pressure / wave

Nerve Conduction Study

Two scenarios:

• “High Flow Steal” (Qa > 1000mls/min)

“Choke” procedure

• “Low Flow Steal” (Qa < 800mls/ min)

Ligate fistula

Other? (Low life expectancy!)

STEAL: Treatment

Flow in fistula vein

limited by choke (3mm)

Small increase

in forearm flow eliminating

critical ischemia

TREATMENT OF CLINICAL STEAL

WITH INFLOW CHOKE

“High Flow Steal” : CHOKE

1. 1200mls/min

BC AVF & STEAL 2. 1180mls/min

3. 20mls/min

1. 1200mls/min

BC AVF & CHOKE 2. 600mls/min

3. 600mls/min

11

2 2

33

CHOKE FOR STEAL

• Choke needs to be tight: 3mm balloon

• Risk of occlusion / inadequate dialysis

• Creating new fistula high risk ischemia

• Patients with limited life: Vascath

TREATMENT OF STEAL: ANGIOPLASTY

LOCALISED INFLOW STENOSIS

Angioplasty +/- stent

OUTFLOW STENOSIS

Angioplasty +/- stent

“Low Flow Steal” : LIGATE FISTULA

1. 400mls/min

BC AVF & STEAL 2. 300mls/min Inadequate inflow to upper limb

3. 100mls/min

1

2

3

PERSONAL EXPERIENCE

46 “CHOKE” Procedures

30 Giant Fistula 16 Critical Ischemia

26/30 Fistula Saved 9/16 Fistula Saved

PERSONAL EXPERIENCE

16 Critical Ischemia

4 Ligated 2 Brach a Angioplasty 10 Choked

2/2 Saved 7/10 Fistula Saved

Conclusions

• Steal is a problem of the inflow Brachial a

• Almost always in the Diabetic

• Accurate diagnosis CRITICAL

• Finger Plethysmography essential

Conclusions

• High Flow steal treated with Choke

• Accurate Choke a difficult operation!

• Low Flow steal treated with Ligation

OR

• ? Improving INFLOW to upper limb

Dr Ruth Carter, GP

Aboriginal Health

Tennant Creek

Sydney

Tennent Creek

3,600 km

Sally Swinnen

English, Bahasa Indonesia

Official Bahasa Translator

Australian National University

2018 Strategic Studies Tour

Kalimantan, Indonesia

Tui Swinnen

English, Spanish

Emergency Nutrition Network,

Project Manager,

Niamey, Niger, Africa

Lucy Swinnen

Turkish, Arabic

Journalist,

Currently in London