Aortic dissection refers to disruption of the medial layer of the aorta due to blood, leading to separation of the layers resulting in a true lumen and false lumen.
This most commonly results from an intimal tear allowing blood to enter the intima-media space. As this false lumen fills with blood, it may propagate proximally or distally. This results in either rupture through the adventitia or re-entry to the true lumen via a second intimal tear.
Classification is anatomical with two systems most commonly used, Stanford and DeBakey.
The risk factors for aortic dissection may be divided into congenital and acquired factors.
The aorta is composed of three well-defined layers:
Aortic dissection most commonly occurs when an intimal tear allows blood to enter the intima-media space. This leads to the formation of a false lumen. Blood may propagate proximally or distally to the intimal tear.
The pathophysiology of aortic dissection remains poorly understood. Cystic medial degeneration, atherosclerotic ulceration and intramural haematoma have all been implicated. A number of congenital and acquired factors are associated with an increased incidence of aortic dissection.
Aortic dissection may present acutely with severe chest pain or the initial dissection may be entirely asymptomatic.
Clinical features may also reflect the development of acute complications of aortic dissection such as cardiac tamponade and aortic regurgitation.
A combination of clinical acumen, bedside and laboratory investigations, and imaging may be used to diagnose an acute dissection.
Management of aortic dissection depends on the timing of the presentation and the anatomical location.
In acute Stanford A aortic dissection emergency surgery is indicated in suitable patients. It carries a mortality of 50% in the first 48 hours in those not undergoing surgical intervention. Despite advances in acute medical and surgical management preoperative mortality remains 10-25 %.
Endovascular repair has been used but is not yet validated in the management of acute type A aortic dissection.
In patients with uncomplicated Stanford B dissections, medical management remains the treatment of choice. This involves blood pressure management and appropriate analgesia.
The role of endovascular techniques is still evolving. Thoracic endovascular aortic repair (TEVAR) may be used in patients with Stanford B dissections with suitable anatomy.
Emergency or urgent surgery may also be indicated in Stanford type B dissections with:
Further Reading: Aortic dissection is a complex condition and its management involves a wealth of nuance. For further information see the '2014 European Soceity of Cardiology (ESC) Guidelines on the diagnosis and treatment of aortic diseases'.
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