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Radiology
Percutaneous
closure of a traumatic subclavian arteriovenous fistula with the use of a
covered stent-graft
A 19-year-old man suffered injuries to the left shoulder region and left hand in an industrial accident caused by a cylinder explosion. Following the injury, the patient developed dyspnea and lacerations at the site of injuries. He had difficulty in using his left upper limb.
On examination, there was a bruit over the left supraclavicular region & feeble pulses in the left upper limb. His blood pressure was 90/ 60 mm. of Hg in left upper limb and 120/84 on the right.
A plain radiograph of the chest revealed metallic fragments and suture materials impacted in the left shoulder region (Fig.1). A CT scan showed a metallic foreign body in the region of thoracic outlet in relation to the neuro-vascular bundle (Fig.2). An arch aortogram revealed a pseudoaneurysm of subclavian artery with an anrteriovenous communication between the subclavian artery and vein (Fig.3).
An open vascular surgery was attempted by which the metallic foreign bodies were extracted, but was unsuccessful in treating the fistula because of a large surrounding hematoma and its intrathoracic extension. An endovascular approach was then decided on.
ENDOVASCULAR TREATMENT:
A 7Fr.transfemoral arterial access was obtained under local anesthesia. The lesion was crossed using amplatz superstiff exchange wire (0.035, 260 cms) and a 10 X 80mm stent- graft (Wallgraft, Boston Scientific) was placed across the fistula. Then stentgraft was positioned such that it did not occlude the major branches of the subclavian and axillary arteries (Fig 4). Balloon dilatation of waist in the stentgraft was then carried out using a 10x40 mm. balloon catheter (Meditech, Boston scientific). Post-stenting angiogram revealed complete closure of the arteriovenous fistula and good antegrade flow into the axillary artery distal to the site of the fistula (Fig .5).
During the procedure, the patient received 5000 IU of heparin and 5000IU every 8 hourly for the next 48 hours. One week following the procedure, the patient's blood pressure improved to 110/80 mm of Hg.in left upper limb. His left axillary, brachial and radial pulses were well felt. His limb functioning and breathlessness had markedly improved. He was put on clopidrogel 75mg for 1month and 75mg aspirin for six months.
DISCUSSION:
An arteriovenous fistula is an abnormal communication between the arterial and venous system of various etiology. The most common cause of acquired fistulae is trauma due to knives, bullets, catheters injuring adjacent arteries and veins. Neoplasms, infections and atherosclerotic aneurysms, although quite rare can sometimes be a cause of arteriovenous fistulae.
The pathophysiology may be divided into peripheral, central and local effects. Initially, ischemia may develop in portions of the limb distal to the fistula. Even when peripheral vasodilatation is unable to avert ischaemia by compensating the short circuit produced by the fistula, the demands of the heart may be excessive leading to cardiac failure. The major determinant of the systemic effects is the size of the shunt, which is measured in terms of percentage of cardiac output that flows through the fistula. Other factors include duration of the shunt and any other cardiac abnormalities. Lesser shunts over a longer period may lead to ventricular dilatation, myocardial hypertrophy and congestive cardiac failure. Massive shunts may quickly lead to hypotension, heart failure and death. Finally the blood vessels leading to and draining the fistula suffer degenerative changes.
A machinery murmur over the site of the fistula is a useful diagnostic sign. Doppler examination can aid in reaching the diagnosis and is mandatory in confirming the diagnosis as well as to clarify the anatomic details of the fistula and homodynamic changes.
The traditional treatment of arteriovenous fistulas has been by open surgery by ligation proximal and distal to the fistula. if the fistula arises from a nonessential peripheral artery. A bypass graft may also be used. This requires a wide area of exposure and is fraught with risks such as infections, blood loss, venous thrombosis and inconveniences such as a prolonged hospital stay. The same result can be achieved by a percutaneous approach using detachable balloons, embolisation coils proximal and distal to the fistula or by using glue at the site of the fistula.
Endovascular treatment in the form of a percutaneous stent graft system has been recently advocated and has the advantages of a minimally invasive approach, local anesthesia, reduced risk of infection and a significant decrease in post operative morbidity and mortality. As a percutaneous approach, the advantage of the stent graft system is its introduction from an area remote in the vascular system. This advantage is particularly obvious when there is scarring, infection or a hematoma around the lesion as was in this case. Complications of stentgraft systems include stent graft migration/ dislodgement, leak around the stent graft, compromise of subsequent surgical procedures and obstruction of side branches. Though long-term results of such stents have not yet been documented, initial results have been extremely promising. With widespread and cheaper availability and utilization of such stents, percutaneous approach will soon become the mainstay of treatment for arteriovenous fistulas.
Case 16 : Contributed
by Dr. Joseph Lazar
Other Cases
A 19-year-old man suffered injuries to the left shoulder region and left hand in an industrial accident caused by a cylinder explosion. Following the injury, the patient developed dyspnea and lacerations at the site of injuries. He had difficulty in using his left upper limb.
On examination, there was a bruit over the left supraclavicular region & feeble pulses in the left upper limb. His blood pressure was 90/ 60 mm. of Hg in left upper limb and 120/84 on the right.
A plain radiograph of the chest revealed metallic fragments and suture materials impacted in the left shoulder region (Fig.1). A CT scan showed a metallic foreign body in the region of thoracic outlet in relation to the neuro-vascular bundle (Fig.2). An arch aortogram revealed a pseudoaneurysm of subclavian artery with an anrteriovenous communication between the subclavian artery and vein (Fig.3).
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Fig.1
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Fig.2
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Fig.3
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An open vascular surgery was attempted by which the metallic foreign bodies were extracted, but was unsuccessful in treating the fistula because of a large surrounding hematoma and its intrathoracic extension. An endovascular approach was then decided on.
ENDOVASCULAR TREATMENT:
A 7Fr.transfemoral arterial access was obtained under local anesthesia. The lesion was crossed using amplatz superstiff exchange wire (0.035, 260 cms) and a 10 X 80mm stent- graft (Wallgraft, Boston Scientific) was placed across the fistula. Then stentgraft was positioned such that it did not occlude the major branches of the subclavian and axillary arteries (Fig 4). Balloon dilatation of waist in the stentgraft was then carried out using a 10x40 mm. balloon catheter (Meditech, Boston scientific). Post-stenting angiogram revealed complete closure of the arteriovenous fistula and good antegrade flow into the axillary artery distal to the site of the fistula (Fig .5).
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Fig.4
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Fig.5
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During the procedure, the patient received 5000 IU of heparin and 5000IU every 8 hourly for the next 48 hours. One week following the procedure, the patient's blood pressure improved to 110/80 mm of Hg.in left upper limb. His left axillary, brachial and radial pulses were well felt. His limb functioning and breathlessness had markedly improved. He was put on clopidrogel 75mg for 1month and 75mg aspirin for six months.
DISCUSSION:
An arteriovenous fistula is an abnormal communication between the arterial and venous system of various etiology. The most common cause of acquired fistulae is trauma due to knives, bullets, catheters injuring adjacent arteries and veins. Neoplasms, infections and atherosclerotic aneurysms, although quite rare can sometimes be a cause of arteriovenous fistulae.
The pathophysiology may be divided into peripheral, central and local effects. Initially, ischemia may develop in portions of the limb distal to the fistula. Even when peripheral vasodilatation is unable to avert ischaemia by compensating the short circuit produced by the fistula, the demands of the heart may be excessive leading to cardiac failure. The major determinant of the systemic effects is the size of the shunt, which is measured in terms of percentage of cardiac output that flows through the fistula. Other factors include duration of the shunt and any other cardiac abnormalities. Lesser shunts over a longer period may lead to ventricular dilatation, myocardial hypertrophy and congestive cardiac failure. Massive shunts may quickly lead to hypotension, heart failure and death. Finally the blood vessels leading to and draining the fistula suffer degenerative changes.
A machinery murmur over the site of the fistula is a useful diagnostic sign. Doppler examination can aid in reaching the diagnosis and is mandatory in confirming the diagnosis as well as to clarify the anatomic details of the fistula and homodynamic changes.
The traditional treatment of arteriovenous fistulas has been by open surgery by ligation proximal and distal to the fistula. if the fistula arises from a nonessential peripheral artery. A bypass graft may also be used. This requires a wide area of exposure and is fraught with risks such as infections, blood loss, venous thrombosis and inconveniences such as a prolonged hospital stay. The same result can be achieved by a percutaneous approach using detachable balloons, embolisation coils proximal and distal to the fistula or by using glue at the site of the fistula.
Endovascular treatment in the form of a percutaneous stent graft system has been recently advocated and has the advantages of a minimally invasive approach, local anesthesia, reduced risk of infection and a significant decrease in post operative morbidity and mortality. As a percutaneous approach, the advantage of the stent graft system is its introduction from an area remote in the vascular system. This advantage is particularly obvious when there is scarring, infection or a hematoma around the lesion as was in this case. Complications of stentgraft systems include stent graft migration/ dislodgement, leak around the stent graft, compromise of subsequent surgical procedures and obstruction of side branches. Though long-term results of such stents have not yet been documented, initial results have been extremely promising. With widespread and cheaper availability and utilization of such stents, percutaneous approach will soon become the mainstay of treatment for arteriovenous fistulas.