A medical emergency resulting from a tear in the aortic wall intima, which causes blood flow into a new false channel composed of the inner and outer layers of the media. May propagate in an antegrade or retrograde direction, or both.
Typically presents in men older than 50, with sudden onset of severe ripping or tearing substernal or interscapular pain.
May present with syncope, heart/renal failure, or mesenteric or limb ischaemia; O2/ALS protocol and haemodynamic support should be instituted without delay when the condition is suspected.
Diagnostic modalities include CT scan, MRI, or trans-thoracic/trans-oesophageal echocardiography.
Involvement of the ascending aorta and/or arch warrants urgent surgical repair. Dissections of the descending aorta are managed medically with beta blockade; surgery in this group is reserved for those with end-organ malperfusion, persistent pain, or rupture.
Lifelong surveillance is needed with regular imaging to detect aneurysmal degeneration of the remaining aorta, which may later require surgery.
Aortic dissection describes the condition when a separation has occurred in aortic wall intima, causing blood flow into a new false channel composed of the inner and outer layers of the media. Dissection most commonly occurs with a discrete intimal tear, but can occur without one. An aortic dissection is considered acute if the process is less than 14 days old. 
Professor and Chairman
Department of Cardiothoracic and Vascular Surgery
The University of Texas Medical School at Houston
HJS declares that he has no competing interests.
Professor Hazim J. Safi would like to gratefully acknowledge Dr Jeffrey Wu and Dr Eric E. Roselli, previous contributors to this monograph. JW and EER declare that they have no competing interests.
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