SONOWORLD : Spontaneous aortic dissection

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Vascular » Aortoiliac

Spontaneous aortic dissection

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Author(s) :

Chaitali Shah, FRCR

Pamela T. Johnson, MD

Presentation A 67year-old woman presented with excruciating, non-radiating pain in the peri-umbilical region. She also complained of back pain which started at about the same time as the abdominal pain. An abdominal ultrasound was performed.

Caption: Transverse aortic scan.

Description: A bright linear reflector is seen within the lumen of the aorta.

Caption: Sagittal sonogram of the aorta.

Description: The bright echogenic linear reflector is depicted well in this scan.

Caption: Sagittal view of the aorta.

Description: Sagittal scan showing the linear echogenic reflector within the lumen of the aorta. The aorta is mildly ectatic.

Caption: Sagittal color Doppler view.

Description: Color Doppler scan showing flow of blood on either side of the reflector, suggestive of an aortic dissection with the echogenic line representing intimal flap.

Differential Diagnosis Acute aortic dissection, foreign body such as retained piece of catheter in the lumen [if the patient gives relevant history].

Final Diagnosis Acute focal spontaneous infrarenal aortic dissection.

Discussion Spontaneous abdominal aortic dissection is a rare entity and may pose a diagnostic challenge. This condition should be suspected in mainly elderly patients with acute but non specific vague abdominal pain. Patients may present with inguinal or pelvic pain if the iliacs or femorals are involved. A review of English literature by Mozes, et al found that the majority of the patients with spontaneous dissection were men in their sixth decade who were hypertensive. Seventy-five percent of them were symptomatic and over half of these aneurysms were in the infrarenal location. Extension into the femoral or iliacs was also quite common. A small percentage of patients may present with rupture of the aorta which is a dreaded complication. Secondary dissection may occur following blunt trauma, in systemic diseases such as Marfan’s or Ehler-Danlos or may be iatrogenic -secondary to angiographic catheterization.

The dissection may or may not be associated with an aneurysm of the aorta. A sudden tear in the intima is the initiating factor and causes blood to track between the intima and media resulting in the double barrel aorta. Ultrasound with duplex Doppler is not the definitive modality of choice, but may be initially performed as the patient symptoms are often vague. If visualization is adequate, the sonogram may depict the intimal flap as an echogenic area within the aortic lumen and color Doppler demonstrates flow in the true and false lumen, if the false lumen is patent. Extension into the iliac or femoral vessels can also be demonstrated. Compromise of blood supply to these branches may also be due to secondary compression by the blood filled false channel.

Spiral CT angiography is the modality of choice for aortic dissections and is fast replacing conventional angiography. MR angiography can be performed in hemodynamically stable patients. Patients with focal dissections of the aorta may simply be followed up and this can be performed with ultrasound. In patients requiring treatment, open surgery or endovascular repair may be offered. In the latter form of treatment, intravascular ultrasound may be used to better delineate the aortoiliac anatomy for stent placement.

Case References 1. Mozes G, et al. Spontaneous dissection of the infrarenal abdominal aorta. Semin Vasc Surg. 2002 Jun; 15(2): 128-36.
2. Stierli P, et al. Differential diagnosis of groin pain: isolated, symptomatic dissection of the infrarenal aorta and iliac arteries. Chirurg. 2001 Aug; 72(8): 940-4.
3. Carreno JA, et al. Spontaneous acute abdominal aortic dissection. Ann Vasc Surg. 1998 Jul; 12(4): 373-8.
4. Gorog DA, et al. Treatment of iatrogenic aortic dissection by percutaneous stent placement. J Invasive Cardiol. 2003 Feb; 15(2): 84-5.
5. Kibria SM, et al. Spontaneous dissection of the abdominal aorta. J R Coll Surg Edinb. 2000 Dec; 45(6): 408-10.
6. VanMaele RG, et al. Limited acute dissections of the abdominal aorta. Report of five cases. J Cardiovasc Surg (Torino). 1992 May-Jun; 33(3): 298-304.

Follow Up A MRI scan in this patient confirmed the diagnosis of infrarenal aortic dissection. This patient was managed medically and followed up with serial ultrasounds. A year late, the patient is stable and has no ischemic symptoms.