A N G I O G R A P H Y O F T R A U M A T I C A R T E R I O - V E N O U S F I S T U L A E

DENNIS BELL, M.B., Ch.B., D.M.R.D,, and W. P E T E R COCKSHOTT, M.D., D.M.R.D. Ed.

From the Department of Radiology, University of Ibadan, lbadan, Nigeria

THIs communication describes the radiological features to be found in patients with traumatic arterio-venous fistulae (A.V.F.), both in the acute and chronic phases, with especial emphasis on the haemodynamic and morphological changes.

A wealth of descriptive literature relating to experimental A.V.F. in animals is available but little has been published on the radiological aspects of A.V.F. in man.

The first description of an arterio-venous fistula has been attributed to Galen (Rob, 1962). William Hunter in 1764 provided the first good clinical account of the condition based on a study of two patients who developed the lesion from blood letting in the cubital fossa. The brachial artery and the basilic vein communicated and Hunter recognised certain characteristic physical signs such as dilatation of the feeding artery, dilatation and varicosity of the superficial veins and the existence of a thrill and bruit.

Two types of A.V.F. are recognised--those in which direct communication exists between the artery and vein and those fistulae complicated by the presence of an aneurysm. The direct type is termed an aneurysmal varix whilst the other form is described as a varicose aneurysm.

AETIOLOGY

Superficial or deep wounds may cause A.V.F. A superficial injury is liable to result in a fistula in anatomical sites where an artery and vein lie close together such as the temple, elbow and groin. In deep wounds, particularly puncture wounds due to stabbing, glass splinters, or gunshot, a communi- cation may develop which is not at first clinically apparent. Deep wounds are more likely to cause varicose aneurysms than superficial wounds.

Surgical accidents are well recognised as a cause of A.V.F. Fistulae may complicate certain ortho- paedic procedures, particularly those around the knees (menisectomy), the spine (operations on prolapsed discs) and the hips. Angiographic investigations may also occasionally lead to the formation of a fistula as has been recorded as a sequel to percutaneous puncture of a vertebral artery. (Sutton, 1962.)

CIRCULATORY P A T H O L O G Y

The presence of the fistula permits the rapid passage of blood from the arterial side to the venous circulation. In consequence of the greatly increased venous return the cardiac output is raised,

FIG. 1 Case l - -Chest Radiographs. (A) At time of admission following a gunshot wound. (B) Two months later there is marked cardiac

enlargement. (c) Two weeks following closure of A.V.F. heart has returned to normal size.

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242 C L I N I C A L R A D I O L O G Y

the pulse pressure is increased, and tachycardia develops. Temporary obliteration of the feeding artery by pressure closes the shunt and reflex slowing of the pulse rate is at once evident. If the fistula size is small relative to the calibre of the main artery, or there is considerable fibrosis from an organised haematoma around the A.V.F., the increasing load on the heart can be compensated by slight dilatation and hypertrophy (Holman a~d Taylor, 1952). However, if the fistula is initially large, or an increasing degree of shunting occurs, as a result of secondary local changes that will be discussed later, the cardiac burden becomes severe and deeompensation and failure may rapidly ensue. Prompt surgical treatment can correct the failure with dramatic reduction in the size of the heart. (Fig. 1).

The alterations that take place in the circulation around a fistula are complex (Table 1.). The haemodynamics of the condition have been extensively studied in experimental animals but much of tke resulting data is both confusing and contradictory.

Holman (1949) recorded that in a small experimental A.V.F. (the diameter of the fistula being less than that of the feeding artery) the flow of blood is in the normal direction but that in large fistulae immediate retrograde flow occurs in the artery distal to the A.V.F. from anastamotic arteries situated distally (Fig. 2). On the other hand Pinotti (1956) denied the presence of retro- grade arterial flow in a recently created fistula but admitted that this may take place in a chronic fistula. Schenk (1957) was not able to detect significant retrograde flow in the distal artery in a femoral A.V.F. but observed considerable retro- grade flow in the distal artery of a 'carotid-jugular'

FIG. 2 Diagramatic representation of flow patterns in (a)

Large sized fistula find (b) Small A.V.F.

A.V.F. He also noticed differences in the flow pattern of the proximal and distal veins in these two anatomical sites of A.V.F. which he attributed to the absence of valves in the jugular system. These observations were restricted to acute fistulae and Schenk admitted that his findings were not necessarily pertinent to chronic fistulae.

Henrie (1959) studied large A.V.F. in animals and recorded venous congestion distal to the fistula but found no retrograde venous flow. Distal to the fistula the arterial flow was reduced and collateral arterial vessels were formed. A recent angiographic investigation of experimental fistulae (Hol and Ingebrigsten, 1960) supported Holman's findings. These workers also demonstrated the presence of many venous and arterial collateral channels around a fistula.

From this brief review of the experimental approach to the study of A.V.F. it is clear that no consistent pattern emerges. This is not surprising

TABLE 1

SUMMARY OF LOCAL CHANGES CONSEQUENT ON A.V.F.

Artery Vein

Changes Dilates. Dilates. in Collaterals originate. Anastomotic veins dilate

Vessels and join distal collaterals.

Changes Normal direction. Normal direction. in Increased flow. Increased flow.

Haemodynamics Venous congestion.

Changes No change in calibre. Valves eventually rendered in Proximal collaterals incompetent.

Vessels communicate. Veins dilate and become tortuous. ! !

Changes Normal or Reversed Reversal of flow in vein in depending on size of distal to A.V.F. when valves

i I Haemodynamics A.V.F. andits duration, fail or are absent. I

A N G I O G R A P H Y OF T R A U M A T I C A R T E R I O V E N O U S F I S T U L A E 243

FIG. 4 A FIG. 5 B

FIG. 4. Case 1--Femoral Arteriogram. Normal arterial flow and contrast passing into dilated vein. Distal venous reflux only as far as competent valves. FIG. 5. Case 2--Arch Aortogram. Varicose Aneurysm between transverse cervical artery and intcrnal~ jugular vein. (A) Jet of contrast entering dilated jugular vein. (B) Unopacified arterial blood diluting contrast in jugular vein ia

later phase of examination.

244 CLINICAL RADIOLOGY

upon consideration oE the many variables that may influence the flow patterns. The eventual morpho- logical and haeatodynamic disturbances are determined by the size of the fistula, its duration, the presence or absence of venous valves and the anatomical site.

In order to provide a general working hypothesis on the local vascular alterations brought about by the presence of an A.V.F. the following schematic sequence of events, based on a review of the literature and our personal experience, is proposed.

The first response to a fistula seems to be an increase in the diameter of the proximal artery which permits a greater volume of blood to pass tlu'ough the fistula in a given time and this may also increase the flow down the distal artery (Fig. 3a).

Collateral arterial vessels open up bridging the fistula and allowing blood to flow into the distal part of the artery. The presence of an A.V.F. appears to be a stimulus for these new vascular arterial channe!s but the exact mechanism involved is not certain. Probably variations in pressure between the proximal and distal artery are mainly responsible (Fig. 3b).

The passage of a large volume of arterial blood at a high pressure through the fistula into the proximal vein causes it to dilate and raises the pressure locally. Initially the competence of the venous valves prevents significant retrograde flow of arterial blood distally but with the passage of time the distal vein distends and the valves become incompetent (Fig. 3c). Should the fistula be situated where the veins are valveless ( i .e .-- the cranial circulation) dilatation and retrograde venous flow occur at once.

As the valves are rendered incompetent super- ficial veins become varicose and a complex network of collateral veins appears (Fig. 3d). The raised venous pressure and the varicosities are accom- panied by oedema of the limb. The arterial collateral channels may, as they increase in number and calibre, lead to significant reversal of flow in the distal part of the artery through the fistula and into the vein and so add to the cardiac load.

R A D I O L O G I C A L C H A N G E S Plain radiographic investigations do not as a rule

provide much specific aid to the anatomical diagnosis. Oedema of the soft tissues in the vicinity of a fistula is usually clearly seen and foreign bodies may be evident in the adjacent tissues. In long established varicose aneurysms calcification may be detected. In a chronic A.V.F. pulmonary

osteoar thropathy of the affected limb has been known to devetop.

A n g i o g r a p h y . - - W e prefer to study patients with A.V.F. by catheter techniques rather than direct needle puncture of the proximal vessels. As large a catheter as is convenient is introduced by standard Seldinger technique so that it is possible to inject rapidly a large bolus of contrast. I t is important to inject at least double the quanti ty of contrast one would normaly use for the particular artery if all the vascular channels are to be delineated, since most of the medium will be directly shunted through the fistula into the vein.

Because of the rapid circulation rapid serial films (six per second) are desirable if one is to visualise and interpret all the phenomena present. At times biplane filming is an advantage as this facilitates anatomical interpretation. The radio- graphic beam should not be colliminated strictly to the site of the fistula, but should be opened up sufficiently to show the origin and course of collateral vessels.

In order to illustrate the haemodynamic changes we have described earlier the angiographic findings in five patients will be described.

CASE REPORTS Case 1. Recent Small A.V.F. in Limb.--Following a

gunshot wound of the right thigh of this young man oedema of the leg developed. Examination revealed a thrill and bruit over the wound. Angiography was performed two and a half weeks after the injury and showed a small A.V.F. (Fig. 4). Contrast passed in a normal direction down the distal artery. The femoral vein was dilated but the valves remained competent and consequently there was only retrograde venous flow as far as the first set of valves. There were no arterial or venous collaterals.

Case 2. Recent Varicose Aneurysm of Neck.--A few days following a gunshot wound of the neck this man became aware of a murmur in his left ear. On examination a thrill and bruit were present in the anterior !ri.angle of the neck. Arteriography two weeks after the InJury showed a varicose aneurysrn between the transverse cervical artery and the internal jugular vein (Fig. 5). In the early phases of the examination contrast is seen as a jet entering the dilated jugular vein. Owing to the absence of limiting valves in the jugular system there is reversal of flow up the vein. Collaterals have not yet appeared.

Case 3. Chronic A.V.F. of Neck.--Four years before this 20-year-old man had an operation on his neck else- where but the reason for this and details of the surgical procedure could not be obtained. After the operation he noticed that the veins on his face were becoming prominent and that a murmur had developed in his left ear. This gradually became worse and he was referred to U.C.H., Ibadan. On examination the veins over the left side of the neck were very obvious. Pressure over

A N G I O G R A P H Y OF T R A U M A T I C A R T E R I O V E N O U S F ISTULAE 245

FIo. 6 Case 3--(a and b). Selective innominate arteriogram. Dilatecl comlTiOn carotid artery with contrast passing into the internal jugular vein which shows aneurysmal bulges. In (b) the arterial collaterals arising fram suprascapular and thyra- cervical trunk are demonstrated. (c) Aortic arch injection demonstrates the dilatation of the innominate artery. (d) Lateral view shows the block of the external carotid artery, large varicose veins, nuchal and ophthalmic plexuses of

collaterals.

246 C L I N I C A L R A D I O L O G Y

FIG. 7 Case 4--Left Common carotid arteriogram. (a) Arterial phase showing tortuous dilated superficial temporal veins with retrograde flow. (b) Frontal projection showing site of temporal A.V.F. (c) At a later phase many collateral venous channels

are seen.

FIG. 8 Femoral Arteriogram. (a) Dilated femoral artery with contrast in aneurysm and retrograde flow into distal femoral vein. (b) Dilated proximal femoral vein and filling of arterial collaterals from the profunda. (c and d) Retrograde flow in distal femoral

artery. Aneurysm and dilated proximal vein still shown.

A N G I O G R A P H Y OF TRAUMATIC ARTERIOVENOUS FISTULAE

a b e

247

examination when contrast is seen passing in a cephelad direction in the popliteal and femoral artery having presumably reached the vessels via the profunda collaterals.

FIG. 9 Effects of surgical procedures on dynamics of A.V.F. (a) Ideal operation. (b) Quadruple ligation. (c) Effect of ligation of

proximal artery only.

the internal jugular vein at the level of the clavicle caused an alarming bulging of dilated veins.

An aortic arch arteriogram demonstrated a dilated innominate and common carotil artery, an eneurysm at the origin of the external carotid artery, many collateral vessels and an A.V.F. involving the internal jugular vein (Fig. 6). A selective innominate arteriogram showed the dilated feeding artery, the collateral circulation and reversed flow in the internal jugular vein. It is presumed that the external carotid artery had been ligated at the original operation.

Case 4. Temporal Aneurysmai V a r i x . - A youth received a small laceration of his left temple from a broken bottle. This bled profusely but the haemorrhage was controlled by manual compression. A short while following the accident his temporal veins became prominent, tortuous and pulsatile (arteriolisation of veins). Percutaneous carotid arteriography carried out after the injury revealed an A.V.F. between the superficial temporal aitery and vein (Fig. 7). No contrast entered the temporal arteries probably because of thrombosis, though reversal of flow in these vessels cannot be entirely excluded. If an aortic arch injection had been performed it might have shown collateral arterial circulation possibly originating from the occipital artery. A venous collateral circulation is evident in the nuchal area in late films.

Case 5. Chronic Varicose Aneurysm of a l i m b . - Following a penetrating wound of the thigh, this trader developed a large pulsatile swelling of the thigh. The mass was deep to a small healed entry wound. A metallic fragment was noted in plain radiographs of this area.

A femoral arteriogram carried out eight months later disclosed an A.V.F. and a large varicose aneurysm (Fig. 8) The femoral vein valves have become incompetent with reversal of the normal direction of flow in the vein. Arterial collateral vessels originate from the profunda femoris artery. Contrast does not enter the segment of femoral artery distal to the fistula until late in the

T H E R A P Y

The a im of the surgeon is to close or excise the fistula and to restore arterial and venous continuity (Fig. 9a). If this is not possible classical quadruple l igation leaving the collateral venous and arterial circulations intact is permissible (Fig. 9b). How- ever, l igation of the feeding artery only must be avoided as then distal ischaemia and gangrene is inevitable (Fig. 9c) (Rob, 1962). Angiography provides the surgeon with valuable anatomical and haemodynamic informat ion to guide him in his approach and treatment of an A.V.F.

S U M M A R Y

Work on experimental A.V.F. is briefly reviewed.

The probable course of the anatomical and haemodynamic changes resulting from the presence of an A.V.F. are described.

The angiographic findings in different forms of A.V.F. are i l lustrated and tabulated.

Acknowledgements.--We wish to thank Professor Richards and Mr. Victor Ngu for permission to describe their cases.

We are grateful to Mr. Parnis and Dr. Banjo of Adeoyo Hospital, Ibadan, for referring their patients to us to investigate.

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stone. SCHENK, Jr., W. G., BAHN, R. A., CORDELI, A. R. &

STEPHENS, J. G. (1957). Surg. Gynec. Obstet. 105, 733.