Iatrogenic common femoral artery pseudoaneurysm

Clinical History

A 60 year old male developed a femoral artery pseudoaneurysm (FAP) following a therapeutic cardiac catheterization.

Imaging Findings

A 60 year old man presented after the onset of substernal chest pain, with electrocardiographic changes of anterior wall myocardial infarction. The patient underwent thrombolysis and subsequent cardiac catheterization with angioplastic repairment of the anterior descending branch. Six days following the procedure, a persistent palpable mass with a bruit was noted in the right groin.
The patient underwent ultrasound examination. The ultrasound confirmed a right FAP (femoral artery pseudo aneurysm).The gray scale sonography (Fig 1) revealed a hypoechoic cystic structure adjacent to the supplying common femoral artery. The size of the pseudoaneurysmal sac was 25x12.4 mm.
Colour Doppler imaging established the diagnosis. A swirling pattern of blood flow in the lumen was revealed with the characteristic ‘yin-yang ’pattern (Fig 2). The tract connecting the artery to the pseudoaneurysm was demonstrated (Fig 3). At the track colour Doppler examination (Fig 4) revealed the typical ”to-and-from“(bidirectional) waveform. Substraction angiography also was performed (Fig 5a,b) as an interventional therapeutic procedure but finally the patient operated one day later (Fig 6).

Discussion

A pseudoaneurysm is a confined collection of thrombus and blood in the extravascular space, containing less than three and often no layers of the arterial wall. It differs from a true aneurysm in that it occurs as a “pouch” attached to an artery lack a fibrous wall, while a true aneurysm is a circumferential thinning or weakness of an arterial wall. Iatrogenic vessel injury is the most common cause of pseudoaneurysm. Iatrogenic pseudoaneurysms form when an arterial puncture site fails to seal, allowing arterial blood flow through the open puncture site to collect and form a pocket within the surrounding tissue and form a pulsative hematoma.
Vascular complications following PTCA (percutaneous transluminal coronary angioplasty) and related procedures include hematoma formation, pseudoaneurysms, arterio-venous (A-V) fistulas, blood loss requiring transfusion, retroperitoneal bleed and acute ischemia of the lower limb. Certain factors may contribute to the development of a pseudoaneurysm. These include both predisposing patient factors and operator factors (large bore catheter and poor technique). Predisposing patient factors include vigorous anticoagulation, age greater than 70, female gender, low nadir platelet count, hypertension, atherosclerosis and aortic insufficiency. The incidence of vascular complications after PTCA is 2%-5%. The incidence of post-catheterization pseudoaneurysms of the femoral artery is 0.7%.
Pseudoaneurysms may be clinically silent, or manifest with local or systemic signs and symptoms. Local effects include a palpable thrill, audible bruit or pulsatile mass with associated pain secondary to compression on local neurovascular structures. Ischemia of the surrounding tissue secondary to vascular compromise may be evident. Systemic signs and symptoms may be related to rupture as pseudoaneurysms are susceptible to growth and rupture, manifesting as life threatening sock. Conventional angiography remains the standard of reference for diagnosis; however, ultrasonography should be attempted first.
The diagnosis can be made using gray scale ultrasound combined with colour Doppler ultrasound (CUS). The lesion is seen as a hypoechoic or anechoic fluid collection within the soft tissue adjacent to or surrounding the parent vessel. CUS reveals bidirectional flow giving the "yin and yang" sign. A neck connecting the artery and fluid collection is needed to make the diagnosis. The flow in the neck of the pseudoaneurysm has a to-and-fro pattern. CUS is a non-invasive method of diagnosing pseudoaneurysm that enables the differentiation of various postangiographic complications, such as hematoma, pseudoaneurysm, arteriovenous fistula, or abscess. The inflow and outflow characteristics within the neck of a simple pseudoaneurysm have been described angiographically by Kreipke et al. Sonographically, Abu-Yousef et al have described a systolic inflow jet with diastolic washout (Doppler “to-and-fro” sign). This finding has been explained by the fact that, during systole, arterial pressure exceeds that of the pseudoaneurysm, leading to inflow of blood, whereas, in systemic diastole, the pressure within the pseudoaneurysm exceeds the pressure of the parent artery, resulting in pseudoaneurysm decompression. The size of the pseudoaneurysm, neck length, and neck diameter should be noted.
Treatment options include observation, compression, percutaneous ultrasound guided injection of Thrombin, and open surgical repair.

Differential Diagnosis List

Final Diagnosis

Iatrogenic common femoral artery pseudoaneurysm

URL:	https://eurorad.org/case/7737
DOI:	10.1594/EURORAD/CASE.7737
ISSN:	1563-4086