Femoral Artery Pseudoaneurysm

Etiology

Femoral PSA can typically be caused by any form of percutaneous intervention that uses the femoral artery as its entry point. Classically, interventions after cardiac catheterization for coronary stenting have been implicated as the culprit. However, any form of femoral artery cannulation and sheath introduction can potentially cause arterial wall dissection with resultant PSA. Hence, ultrasound-guided cannulation with a Seldinger technique under fluoroscopic guidance becomes paramount in any endovascular intervention. Certain risk factors may contribute to PSA formation, for example, the use of large sheath size, poor technique, patient body habitus and obesity, need for anticoagulation, female gender, and patient on hemodialysis. It is also implicated that interventions performed for therapeutic reasons are associated with a higher number of PSA formations than diagnostic ones, as the former typically require a larger size sheath.[4][5][6]

True femoral artery aneurysms are very rare and are mostly found in individuals over the age of 65. They are usually unilateral but may be bilateral in 10% of cases. In at least 30% of cases, the true femoral artery aneurysm is associated with an aneurysm elsewhere in the body. Unlike pseudoaneurysms, the risk of rupture is low; however, these aneurysms can form thrombosis and cause limb ischemia.

Epidemiology

As mentioned, PSAs are the most common complication after percutaneous procedures performed by a cardiologist, interventional radiologist, or vascular surgeon. Some series have reported incidence from 0.5% to up to 9%. There are other rare causes, such as surgical intervention or blunt and penetrating trauma. A few case reports reported femoral artery PSA due to slipped capital femoral epiphysis treatment. However, percutaneous interventions are the leading cause of PSA formation.[7]

History and Physical

While examining a patient for a femoral PSA, the clinician should perform a full vascular exam of the patient and a detailed medical history, including HTN, smoking, hyperlipidemia, recent vascular interventions, or recent/remote trauma. The examiner should then perform a comprehensive vascular examination starting with a cardiovascular examination, followed by listening to any bruit in the neck, recording and examining any peripheral pulses in both upper and lower extremities, and any investigating for pulsatile abdominal mass. A detailed examination should be tailored to a patient with a pulsatile mass in the groin. A patient at this stage should not be mistaken as having an inguinal hernia, as both entities could present with a bulge and pain. A bruit, however, would differentiate between the 2 as it is characteristic of PSA instead of an inguinal hernia.

Evaluation

Imaging modalities for PSAs include a duplex ultrasound (DUS). Usually, the first test one should obtain if PSA is suspected. DUS carries a sensitivity of 92% to 96%. Findings on DUS indicate PSA would consist of a “to-and-fro flow” between the arterial lumen and femoral artery. Ideally, the DUS includes the dimensions and size of the sac and the neck, and treatment is based on those dimensions. Proximal and distal arteries should also be evaluated for thrombus extruding from the aneurysmal sac. Whenever a surgical intervention is planned, CT angiography can be used for pre-operative planning.[1][8][9]

Treatment / Management

Treatment of femoral PSA includes open surgical repair, ultrasound-guided compression, ultrasound-guided thrombin injection, coil embolization, and covered stent placement.[10][11][3](A1)

Surgical repair of PSA is an option when a concomitant arterio-venous fistula exists. It should also be considered when there is ongoing hemodynamic instability or limb ischemia. Surgical principles consist of controlling the artery proximally and distally and primary repair of the arterial defect. When hemorrhagic shock ensues, digital compression of the bleeding site should be performed first, followed by vascular control and primary arteriography. Sometimes a retroperitoneal incision may be required for obtaining external iliac artery exposure in large PSA. If the primary repair cannot be successfully achieved, a vein graft should be used to reconstruct the arterial system.

Ultrasound compression visualizes the neck of the PSA and applies pressure until the neck is occluded. If a PSA is present, care should be taken to avoid compressing the femoral artery while performing compression. When the neck is less than 2 cm, PSA is treated successfully with ultrasound. Technical failures with this method have been estimated up to 10% to 30%. If this occurs, alternative treatment should be sought.

Ultrasound thrombin injection is also a minimally invasive procedure that can be performed at the bedside under local anesthesia. To qualify for this treatment modality, the PSA should typically have a long neck that is narrow and easily seen on ultrasound. A spinal needle (22 gauges) is inserted into the sac, and under continuous visualization, thrombin is injected into the sac. The needle is visualized during the entire procedure to avoid accidental thrombin injection into the arterial system. Approximately 100 to 500 U/ml of thrombin is injected into the sac at about 0.1mL increments until thrombosis is achieved. A technical failure between 5% and 10% has been reported using this method, providing neck anatomy is adequate.

Another minimally invasive treatment is endovascular treatment, which could entail coil embolization or covered stent deployment. Complications include treatment failure and PSA formation since the contralateral groin is often used to gain access. 

Complications with any treatment mentioned above include thrombosis of both the venous and arterial systems. Embolization into the distal arterial tree can occur in 2% to 4% of cases; hence, a thorough pulse examination should be carried out prior to and after the procedure. If distal embolization is suspected, a Fogarty catheter should be passed proximally and distally. Once the flow has been restored, the nurse should be asked to palpate the pulses in the feet.

If the patient has a true aneurysm, then repair is not recommended. The aneurysm should be resected, and a prosthetic graft should be inserted.

Differential Diagnosis

The differential diagnoses for femoral artery pseudoaneurysm include the following:

• Constipation
• Diverticulitis
• Ectopic testis
• Femoral artery aneurysm
• Gastroenteritis
• Inguinal lymph node
• Lipoma
• Osteoarthritis
• Psoas abscess
• Psoas bursa
• Saphena varix

Prognosis

The prognosis for most patients with treatment is good. However, without treatment, the pseudoaneurysm can continue to expand, and there is also a risk of rupture. True aneurysms have the potential to induce limb ischemia. In patients who have an invasive procedure at the groin, often there is marked bleeding in the groin, which may take months to resolve. Because the blood is in the connective tissue, inserting a drain is futile. It is important to understand that most patients who undergo a percutaneous procedure for heart disease also have other co-morbidities. Thus, most of these patients need close monitoring.

Complications

The complications that can manifest with femoral artery pseudoaneurysm are as follows:

• Embolization
• Ischemia and gangrene of the leg
• Blue toe syndrome
• Rupture
• Venous compression