Clinical History
A 61-year man was transferred to the emergency department in a state of coma. He was found unconscious after having multiple epileptic seizures. Clinical examination showed left eye mydriasis, left lower limb ischemia and decreased urine output. His Glasgow Coma Score at admission was 4.
Imaging Findings
The patient was immediately brought into the computed tomography(CT) scanner for a head scan, followed by computed tomography aortography(CTA), due to the brain findings.
Contrast-enhanced images showed diffuse brain edema and absense of flow in the intracranial parts of both internal carotids (Fig 1). There was no sign of intracranial haemorrhage.
CTA revealed a Stanford A aortic dissection, starting from the aortic root and extending to the aortic bifurcation (Fig 2). Both common carotid arteries, the innominate artery, the celiac artery and the superior mesenteric artery were involved in the dissection (Figs 3). The left renal artery was thrombosed, resulting in an extended infarction covering the upper half of the left kidney. The left common iliac artery was also completely thrombosed (fig 4).
Discussion
Acute aortic dissection is one of the most life threatening medical emergencies, associated with high mortality and morbidity rates.
Dissection is characterized by separation of the aortic wall layers; blood enters the space between intima and media and propagates quickly, expanding the dissection into other arteries.
In most cases, one or more tears in the intimal layer allows communication between the two layers. In other cases, there is an intramural hematoma, often originating from the vasa vasorum, that ruptures into the intima-media space[1].
Classification of aortic dissection is based on anatomic location of the dissection and the time from onset of symptoms. The more popular Stanford classification distinguishes dissections between type A and type B. Type A dissections involve the ascending aorta, while a type B dissection involves the descending aorta, distal to the left subclavian artery. When it comes to the time from the onset of symptoms, the first 14 days (acute phase) are the most critical for the prognosis[2].
Patients typically present with sudden onset of tearing chest and/or back pain, often with radiating and migrating nature, depending on which arteries are involved in the dissection[3, 4]. Symptoms may mimic common diseases, such as myocardial infarction, pulmonary embolism or stroke. In some cases, typical clinical findings can even be absent. Therefore, the diagnosis of acute aortic dissection requires a high index of suspicion.
Risk factors include age above 65 years, male sex, smoking, systemic hypertension, biscupid aortic valve, connective tissue disorders and pregnancy[5].
CTA is the indicated imaging technique for the diagnosis of aortic dissection because:
a) it provides accurate information about the dissection type, its origin and its extent
b) it helps distinguishing the true from the false lumen and
c) allows the complete evaluation of the aorta and its branches, as well as the condition of any ischemic organs, if present[6].
Type A dissections require urgent surgical intervention, in which the area with the intimal tear is usually resected and replaced with a Dacron graft.
Type B dissections are treated either medically or surgically, depending on the severity of the complications, such as organ ischemia, internal bleeding and uncontrollable arterial pressure[7].
In our case, the patient underwent the Bentall procedure. The initial tear was located at the aortic root, at the level of Valsalva sinuses. Unfortunately, he died a few hours after being connected to the extracorporeal unit, due to irreparable brain damage.
Written informed patient consent for publication has been obtained.
Differential Diagnosis List
Acute Aortic Dissection
Stroke
Peripheral Arterial Embolism
