Arterio venous fistula is defined as an abnormal communication between an artery and vein. It is of two types
1.Congenital - is arteriovenous malformations
2.Acquired - Trauma is the main cause.
It is commonly seen in limbs , either whole or part, toes , fingers, lungs, brain, other organs like bowel and liver
3. ARTERIOVENOUS FISTULA
(AVF)
DEFINITION
ā¢ It is an abnormal
communication betweenan
arteryand vein.
TYPES
ā¢ 1. Congenitalāis
arteriovenous malformation.
2. Acquired (Trauma is
commoncause).
4. SITE
ā¢ Limbs, either part or
whole of the limb is
involved.
ā¢ It may be localisedto toes
or fingers.
ā¢ Lungs.
ā¢ Braināincircle of Willis.
ā¢ Other organs likebowel,
liver.
5. CLINICALFEATURES
ā¢ Structural changes in the
limb:
ā
Limbis lengtheneddue to
increasein blood flow
ā
since developmental period.
ā
Limb girthis also increased.
ā
Limb is warm.
ā
Continuous thrill & continuous
machinerymurmur all over the
lesion.
ā
Dilatedarterialised varicose
veins
ā
due to increasedblood flow &
valvular incompetence.
ā
bone erosionor extensionof
AVF into the bone as such.
6. ā¢ Physiological changes
ā
Because of the hyperdynamic
circulation
ā
there is increasedcardiacoutput
ā
congestive cardiac failure
COMPLICATION
ā¢ Haemorrhage
ā¢ Thrombosis
ā¢ Cardiac failure (CCF)
8. ACQUIREDARTERIOVENOUS
FISTULA
CAUSES
ā¢ Trauma in (most common
cause): Femoral region.
Popliteal region. Brachial
region. Wrist. Aortaā
vena caval. Abdomen.
ā¢ After surgical intervention
of major vessels.
ā¢ Therapeutic: For renal
dialysis, AVF is created
(Cimino fistula) to achieve
arterialisation of veins and
also to have hyperdynamic
circulation.
ā¢ It is done to have easy and
adequatevenous accessfor
long time haemodialysis.
ā¢ Common sites
ā¢ Wrist
ā¢ Brachial
ā¢ Femoral region
9. PATHOPHYSIOLGY
Physiological changes:
ā¢ Cardiac failure due to
hyperdynamiccirculation.
Structural changes:
ā¢ Changes at theLevel of
Fistula
ā
Blood flows fromhighpressure
arteryto low pressurevein
ā
causing diversion of most of the
blood.
ā
Between the artery and vein, at
the site of fistula
10. ā
dilatation develops with
formation of fibrous sac called
as Aneurysmal sac.
ā
This presents as warm, pulsatile,
smooth, soft, compressible
swelling at the site
ā
with continuous thrill and
continuous machinerymurmur
11. ā¢ Changes Belowthe Level of
the Fistula
ā
Because of diversionof arterial
blood distal part
ā
becomes ischaemic
ā
Because of highpressure
arterialisationof veins
ā
& valvular incompetence occurs
causing varicoseveins.
12. ā¢ Changes Proximal to the
Fistula
ā
Hyperdynamiccirculation
causes cardiac failure.
ā
Cardiac failure may be very
severe in traumaticAVF
ā
If pressure is appliedto the
arteryproximal to the fistula,
ā
swelling will reduce in size
ā
thrill and bruit will disappear,
pulserate and pulsepressure
becomes normal.
ā
This is calledas Nicoladoniās
signor Branhamās sign.
13. INVESTIGATION
ā¢ Doppler
ā¢ Angiogram.
ā¢ ECG
ā¢ Echocardiography.
TREATMENT
ā¢ Excision of fistula and
reconstructionof artery
and vein with graft.
ā¢ Done in early stagesā
larger vessels.
ā¢ Venous or Dacrongraft is
used.
14. REFERENCE
1. SRB's Manual of Surgery
by SriramBhat M
2. A Manual on Clinical
Surgery by Das
3. A Concise textbookof
Surgery by Das