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Thoracic aortic dissection occurs when an intimal tear allows redirection of blood flow from the aorta (true lumen) through the intimal defect into the media of the aortic wall (false lumen). A dissection plane that separates the intima from the overlying adventitia forms within the media. The acute form of aortic dissection is often rapidly lethal, whereas those surviving the initial event go on to develop a chronic dissection with more protean manifestations. The purpose of this chapter is to review the etiology and pathogenesis of aortic dissection, examine current diagnostic algorithms, and provide detailed descriptions of contemporary surgical techniques for treatment. Additional information regarding follow-up and the subsequent management of these patients is presented to provide a comprehensive understanding of a clinical entity that has challenged physicians and surgeons for centuries.
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Sennertus is credited with the first description of the dissection process, but the earliest detailed descriptions of the clinical entity appeared in the seventeenth and eighteenth centuries, during which time Maunoir named the process aortic "dissection." Laennec defined the propensity of the chronically dissected aorta to become aneurysmal. Aortic dissection was exclusively a postmortem diagnosis until the first part of the twentieth century, but in 1935 Gurin attempted surgical intervention with the first aortic fenestration procedure to treat malperfusion syndrome.1 In 1949, Abbott and Paulin advanced surgical treatment by theoretically preventing aortic rupture by wrapping the aorta with cellophane. Other attempts at surgical treatment over the years met with limited clinical success, although certain concepts regarding surgical management are still in use today.2 With the advent of cardiopulmonary bypass, DeBakey and Cooley forever altered the natural history of aortic dissection by successfully performing primary surgical repair using techniques not remarkably different from contemporary procedures.3 Investigators such as Wheat made substantial contributions by defining physiologically based medical management algorithms to complement surgical correction.4 There is still considerable controversy regarding surgical versus medical treatment of certain forms of acute thoracic aortic dissection.
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The classification systems used for aortic dissection are based on the location and extent of dissection. The particular type is then subclassified based on the timing of dissection. Acute dissection has traditionally been used to describe presentation within the first 2 weeks, whereas the term chronic is reserved for those patients presenting at more than 2 months after the initial event. The more recently added subacute designation is sometimes used to describe the period between 2 weeks and 2 months.
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Two classification systems are most frequently used in clinical practice: the DeBakey and the Stanford systems (Fig. 50-1). The DeBakey system differentiates patients based on the location and extent of aortic dissection.5 The advantage of this system is that four different groups of patients with different forms of aortic dissection emerge. This structure provides the greatest opportunity for subsequent comparative research. In contrast, the Stanford system proposed by Daily et al. is a functional classification system.6 All dissections ...