Acute Aortic Syndrome

The Common Vein Copyright 2008

Ashley Davidoff MD

Definition

Acute aortic syndrome” (AAS) is a complication of atherosclerotic disease of the aorta that is characterized by a classical clinical presentation of sudden acute searing pain in the chest or back,

usually in the older patient

with atherosclerosis

usually in an hypertensive patient.

• Life threatening
  • high risk of aortic rupture and sudden death
    • aortic dissection, – media
    • intramural hematoma, –
    • penetrating atherosclerotic ulcer originates in the intima
  • New Classification
    •  based upon the primary location of the lesion within the aortic wall:
      • aortic dissection involves the aortic media, penetrating aortic ulcer originates within the aortic intima,
      • aortic aneurysm is a disease of all three layers.
  • Intramural hematoma may be seen in any of the three fundamental pathologies.

Pathogenesis

Ulcerated Plaque

Usually Caused by Stretching of the Aortic Wall often as a result of a intramural hematoma

Atherosclerosis Pathogenesis

Ulcerated Plaque

Clinical Presentation

Excruciating chest pain is the hallmark of the disease caused by  acute distension of the aortic wall

Cause is distension of the aortic wall caused either by the acute intramural hematoma or by advancing penetrating ulcer or by the focal dissection

Pathogenesis of Atherosclerosis

Starts out as a fibrofatty  atheromatous plaque – –

The pain  simulates the pain of acute aortic dissection. Hence the same dramatic pain characteristics that occur in dissection apply to acute aortic syndrome, characterized by a sudden acute, severe, shearing or lancinating, pain that reaches maximum intensity at onset.

Similarly though as well, the symptoms may be minimal or absent.

Comparison to Dissection

The clinical features and pathology of the two entities can be quite different.  Whereas dissection is usually in a younger age group, acute aortic syndrome is seen in the older atherosclerotic age group and is more commonly associated with hypertension.

Classic aortic dissection is characterized by the presence  of intimal tear that usually progresses to the media and then rapidly dissects for quite a distance (sometimes the entire aorta) and will usually have a reentrance site.

Intramural hematoma is characterized by the presence of severe atherosclerotic plaque, with acute hemorrhage into the aortic media which may remain as a hematoma in the media or may progress to a dissection.  The dissection though is usually  limited because the atherosclerosis and inflammatory changes and fibrosis present in the wall prevent s an easy route for progression.  The reentrance of the dissection in AAS is usually absent and hence thrombosis of the focal dissection results.

Please see page on Atherosclerosis of the Aorta

Murillo H et al Aortic Dissection and other Acute Aortic Syndromes Radiographics 2021

The cause of AAS is an acute mural hematoma.  This may result from a hematoma into a plaque, into a  penetrating ulcer, or a hematoma in a focal dissection.  The space occupation and sudden distension associated with the disease process by one of these disorders results in the classical pain syndrome.  The disorders are best diagnosed by using a combination of  non-contrast CT combined with a contrast enhancing CT.

The hematoma in the wall may be complicated by a classicial dissection , where the tear in the wall extends along the longitudianl plain.  Aortic rupture can occur as well.

Treatment is based on the size position and nature of the lesion, as well as comorbid conditions, and thus would be either surgical or medical.

The pain is very similar to that of acute aortic dissection in that it is acute, severe, shearing or lancinating, but the clinical features and pathology of dissection is different.  Whereas dissection is usually in a younger age group acute aortic  syndrome is in the older atherosclerotic age group and is more commonly associated with hypertension. Classic aortic dissection is characterized by the presence  of intimal tear that usually progresses to the media and then rapidly dissects for quite a distance (sometimes the entire aorta) and will usually have a reentrance site.  Intramural hematoma is characterized by the presence of severe atherosclerotic plaque, with acute hemorrhage into the aortic media which may remain as a hematoma in the media or may progress to a dissection, but the dissection usually is limited because the atherosclerosis and inflammatory changes and fibrosis in general prevents easy route for progression.  The reentrance of the dissection is usually absent and hence the focal dissection usually thrombosis.

Penetrating Ulcer

48363 descending thoracic aorta fx aortic ulcer fx atherosclerosis atheroma fx penetrating ulcer CTscan Courtesy Ashley Davidoff MD

Penetrating Ulcer Mural Hematoma and Focal Dissection

This combination of images reflects the CTscan of a patient who presented with acute chest pain, and has findings reflecting a focal dissection of an atheromatous aorta. Note in (a) how thick the “intimal” flap is. Note also the mural dissection or hematoma with no flow within it. (b) Other parts of the descending aorta (c) and abdominal aorta (d) show only severe atheromatous disease. Courtesy Ashley Davidoff MD. 19416c code CVS aorta abdomen thorax dissection focal atherosclerosis

Focal Dissection

Penetrating Ulcer with Rupture

17529c01 artery descending thoracic aorta abdominal aorta dx rupture pseudoaneumysm ulcerating plaque mural hematoma ruptured through aortic wall hemorrhage hematoma retroperitoneum CTscan Courtesy Ashley DAvidoff MD Ashley Davidoff MD

Links and References

Murillo H et al Aortic Dissection and other Acute Aortic Syndromes Radiographics 2021

Grist T and Rubin G  from Diseases of the Chest Breast and Heart Chapter 18 Imaging Acute Aortic Syndromes

Acute Aortic Syndrome

Atherosclerosis Pathogenesis

Ulcerated Plaque