Case of the week - superficial femoral artery pseudoaneurysm

Case of the week :

A case of Superficial femoral artery

Pseudoaneurysm

Dr.Abdalla Mutwakil, Dr. Mabroka Ellaffi

Radiology Department

Sebha Medical Center

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Presentation outline

• The case

• Pseudoaneurysms

• Imaging of pseudoaneurysms

• Treatment of pseudoaneurysms

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The case

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The case

• 16 years old male, victim of a stab wound in the back of the right thigh was

brought to the emergency department of sebha medical center one month

ago for treatment and was discharged on antibiotics and analgesia after the

stab wound was treated and dressed.

• On the 7th of April 2014, he came to the radiology department for an

Ultrasound image of the site of the stab because he was still complaining of

pain and difficulty in walking and moving the affected limb. His ultrasound

scan showed the following image :

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What is the Differential

diagnosis ?

• Abscess

• Hematoma

• Cyst

• Pseudoaneurysm

• True aneurysm

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Flow mode

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Note ! This image is taken from the web to illustrate the Ying-Yang sign in the

lesion (We missed the opprtunity store the image from our case during

examination)

Pseudoaneurysms

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Definition

• A false aneurysm (also known as a pseudoaneurysms, Pulsatile

haematoma and communicating haematoma) is when there is a breach in

the vessel wall such that blood leaks through the wall but is contained by

the adventitia or surrounding perivascular soft tissue. A direct

communication of blood flow exists between the vessel lumen and the

aneurysm lumen through the hole in the vessel wall.

• The risk of rupture is higher than that of a true aneurysm of comparable size

due to poor support of the aneurysm wall and thus false aneurysms

generally require treatment.

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Causes

• Trauma

• Iatrogenic

• spontaneous dissection

• Myocardial infarction

• Vasculitis

• Other causes like regional inflammatory process, Fibromuscular dysplasia

(dissection), Mycotic aneurysm (inflammatory digestion of the vessel wall)

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Clinical presentation

• Painful, tender, pulsatile mass (the patient may note that the pulsatile mass

is gradually expanding)

The overlying skin is sometimes erythematous (red).

• The patient may describe a history of catheterization or trauma, and they

may note that the pulsatile mass is gradually expanding.

• Because of the pain, tendernes, redness of skin a pseudoaneurysm is

sometimes confused with abscesses

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Location

- They can involve any arterial segment or even a cardiac chamber.

• Femoral artery pseudoaneurysm - relatively common site due to femoral

punctures

• Examples include

– Carotid artery.

– Aorta.

– Left ventricle .

– Visceral artery.

– Femoral artery.

– Peripheral arteries (limb).

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Carotid artery pseudoaneurysm

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Aortic pseudoaneurysm

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Left ventricular pseudoaneurysm

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Visceral arterial pseudoaneurysm

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Femoral artery pseudoaneurysm

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Imaging of pseudoaneurysms

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What are the options ?

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Ultrasound

- Normal USG

- Flow mode (yin-yang sign)

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Ultrasound

What is the yin-yang?

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CT

• Unenhanced CT scans may demonstrate a well define hypodense lesion

structure arising from the donor artery. Intermediate or high attenuation

(haemorrhage) adjacent to the pseudoaneurysm may been seen and

indicates pseudoaneurysmal rupture, which may vary in attenuation

dependant on being chronic or acute. The pseudoaneurysmal wall is usually

smooth and well defined except in a mycotic pseudoaneurysm, where the

wall can be thickened, irregular, or ill defined.

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CT

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Contrast enhanced CT

The patent portion of the lumen of the aneurysmal vessel demonstrates

increased attenuation, due to contrast enhancement whereas a part of the

lumen shows reduced attenuation due to a mural thrombus (yin-yang sign)

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CT angiography

May demonstrate a contrast filled sac. However, the entire pseudoaneurysm

however may not fill with contrast material. If a low-attenuation area remains

within the pseudoaneurysm, it usually indicates partial thrombosis . A

communication with a donor artery is adjacent to the pseudoaneurysm can

usually be seen.

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CT angiography

MRI & MRI angiography

• MR angiography can depict the pseudoaneurysm as a well-delineated

rounded structure originating from the donor artery. High-signal-intensity

thrombus may be seen within the sac on fat-suppressed T1-weighted MR

images.

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MRI & MRI angiography

• A 77-year-old male with a history of

dyslipidemia and hypertension was

admitted to our Emergency

Department for unstable

angina. While obtaining a complete

history, the patient reported that 20

years ago he was in a motor vehicle

accident where he suffered a severe

precordial thump but suffered no

known permanent effects.

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MRI & MRI angiography

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Angiography

• Angiography is the criterion standard to determine diagnosis and treatment.

Digital subtraction provides high-resolution imaging of small arteries and

allows percutaneous vascular intervention in the same setting. If the patient

is hemodynamically stable, performing a preoperative angiogram helps to

confirm the diagnosis. Angiography defines the character—unique or

otherwise—of the lesion and allows therapeutic planning. Angiography

greatly facilitates identification of the location and serves as a topographic

guide for the pseudoaneurysm, which aids in operative proximal and distal

control of the bleeding vessel.

• Preoperative angiography may constitute an opportunity to gain temporary

control over the bleeding vessel by performing transcatheter embolization,

thus providing a time window for the surgeon to operate on a high-risk

patient under optimum clinical conditions

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Angiography

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Treatment of pseudoaneurysms

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Treatment options

Many options exist for the treatment of pseudoaneurysms. While surgery was

the gold-standard treatment in the past, several less invasive treatment options

are popular today.

1 - Covered stent

2 - Ultrasound probe compression

3 - Ultrasound-guided thrombin injection

4 - Surgical ligation (with or without distal bypass)

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• 1 - Covered stent – Since the pseudoaneurysm communicates with an artery through a hole in the arterial wall, a

covered stent may be placed endovascularly across this hole to "exclude it," or to prevent it from

receiving blood flow from the artery.

• 2 - Ultrasound probe compression – Another option for treatment is ultrasound probe compression of the neck of the

pseudoaneurysm. The "neck" of the pseudoaneurysm is the narrow path of blood flow between

the artery, through the arterial wall, and into the pseudoaneurysm cavity. The artery, neck, and

pseudoaneurysm are seen on ultrasound. The ultrasound probe can be pushed firmly against the

patient's skin to compress the neck of the pseudoaneurysm for usually about 20 minutes. During

this time, the blood within the pseudoaneurysm clots; after the probe is then removed, the

pseudoaneurysm will hopefully remain clotted and will not continue to expand.

• 3 - Ultrasound-guided thrombin injection – In addition to covered stent placement, another popular, minimally-invasive technique used today

is ultrasound-guided thrombin injection. Thrombin (factor IIa in the coagulation cascade)is a

clotting factor that converts fibrinogen into fibrin, which then polymerizes to form a blood clot.

Under ultrasound guidance, thrombin can be injected directly into a pseudoaneurysm, causing it

to clot

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• 4 - Surgical ligation (with or without distal bypass) – Open surgery may also be performed to remove pseudoaneurysms or prevent them from

expanding. If the artery is small and "expendable" - the tissues it supplies have adequate

collateral blood flow - then the artery supplying the pseudoaneurysm may be ligated both

proximally and distally to the pseudoaneurysm. The pseudoaneurysm may or may not be

removed. If the tissues supplied by the artery do not have sufficient collateral flow (the artery is

not expendable), then a vein or synthetic graft would have to be anastomosed proximally and

distally to allow for continued blood flow around the pseudoaneurysm

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