17 year old male was brought to the UMH ER after a syncopal episode. He experienced syncope while leaning over to tie his shoes. His parents witnessed the episode and reported that he slid to the floor and grunted slightly, but denied an outright fall.

Dilation and dissection of ascending aorta

Hemopericardium which resulted in tamponade

Aortic dissections usually begin with a tear in the intima. The tear can result from a weakened part in the wall (from medial necrosis) or an increase in shear stress. Blood then moves through the tear into the media and separates the intima from the adventitia and the tear can expand either proximally or distally. The incidence of aortic dissections ranges from 5-30/1,000,000 and more commonly effect older males. The most common predisposing factor is hypertension, but other conditions like cocaine abuse, heavy lifting, vasculitis, or collagen disorders can be present in younger patients.
There are two main classification systems for aortic dissections. The DeBakey system is based on the origin of the tear. Type I involves the ascending aorta and the arch, Type II is confined to the ascending aorta, and Type III starting in descending aorta distal to left subclavian and extends either proximally or distally. The Stanford (Daily) system classifies dissections involving the ascending aorta as Type A and all others are Type B. About 60% of dissections are Type A and roughly 40% are Type B.
Type A dissections require emergency surgery to resect the tear and replace the involved area with a graft. The valve may need to be replaced if the dissection involves the aortic root or the leaflets prolapse. Type B dissections are usually medically managed with strict blood pressure control, but may require surgery or stenting for complications.

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Wong, D., Lemaire, S., et al. Managing Dissections of the Thoracic Aorta. Am Surg. 2008 May; 74(5): 364–380.

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http://emedicine.medscape.com/article/756835-overview#a1

Multidetector CT of Aortic Dissection: A Pictorial Review. RadioGraphics March 2010 vol. 30 no. 2 445-460.

http://radiographics.rsna.org/content/30/2/445/F29.expansion.html

UpToDate, Clinical manifestations and diagnosis of aortic dissection