Aortic Dissection

Aortic dissection is a life-threatening condition, which is in certain aspects similar to classic rupture of aortic aneurysm.

Causes

Aortic dissection may occur in long-lasting untreated hypertension that overloads the aortic wall and it is also related to some rare genetic disorders causing decreased strength of arterial walls – for example Marfan syndrome or Ehlers-Danlos syndrome. Cases of acute aortic dissection have been also reported after injuries, for example after car accidents.

Mechanism

The aortic dissection typically occurs in its thoracic (chest) part. When the aortic wall is unable to withstand the local blood pressure, the aorta may dilate and in some point, the inner part of the wall may rupture. However, in aortic dissection, the rupture does not affect the whole width of arterial wall and the blood flows into the arterial wall forming a new arterial lumen. Through the arterial wall, the blood may flow either back towards the heart, or follow the aorta into its abdominal part. This new arterial lumen may in its end lead back into the aortic lumen, or open into abdominal cavity, which causes rapid and usually fatal internal hemorrhage. 

Symptoms

Aortic dissection typically manifests with acute chest pain that may mimic angina pectoris or heart attack. However, the pain commonly moves to the back and frequently towards the abdomen. Hypertension is usually present. When the aortic dissection causes a total rupture of any part of the aortic wall, the condition manifests with severe internal bleeding with symptoms of hypovolemic circulatory shock (low blood pressure, pallor, rapid pulse and rapid breathing, disorders of consciousness). When the aortic dissection opens into pericardial sac, it causes acute heart tamponade, which also manifests with sudden circulatory shock.

 

Severe complications occur when the newly formed aortic cavity closes or significantly narrows any artery that branches from the aorta. This situation disrupts blood supply to tissue or organs supplied by such artery. It is a situation that can be described as acute arterial closure. The possible consequences include acute heart attack (closed coronary artery), ischemic stroke (closed carotid artery), upper limb ischemia (closed subclavian artery), acute liver failure (closed renal artery), acute ischemia of various parts of the gastrointestinal tract (mesenteric arteries, hepatic artery, etc.) and acute ischemia of the lower extremity (iliac artery).

Aortic dissection
The picture shows the dissection - the blood gets directly through a hole wall right into the aorta's wall, where it creates a new cavity.

 

Diagnosis

Aortic dissection is very dangerous as it may cause rapid deterioration and it is not easy to state the right diagnosis in time. When we have suspicion of the condition from patient’s clinical signs, it is advisable to perform CT angiography of the chest and abdominal aorta that can confirm the presence of two lumens and affection of other arteries branching from aorta.

Treatment

The therapy of acute dissection with internal bleeding should be surgical and aim to stop the hemorrhage. However, the majority of patients die before any effective surgery is possible. Certain types of aortic dissection without acute hemorrhage or arterial closure may be treated conservatively (bed rest, antihypertensives, monitoring vital functions) or by cardiosurgical approach.