GENERAL CONSIDERATIONS AND HISTORY
Aortic dissection is not a new disease process. While accounts prior to its initial reporting have been retrospectively identified, aortic dissection was first described by Maunoir in 1802, as blood “dissecting throughout the circumference of the aorta.”1 The inception of the concept, however, is often attributed to Laennec, much due to his fame throughout Europe garnered by inventing the stethoscope, as he coined the term “Aneurysme dissequant”—i.e., dissecting aneurysm—in 1819.1–3 It would not be until 150 years after being originally described that the first major milestone in the treatment of aortic dissection would be achieved by Michael DeBakey and his team, who described the surgical treatment of dissecting aneurysms.4 The superiority of medical therapy for aortic dissection in patients who were not rapidly deteriorating was established by Wheat et al. in 1965.5 Medical therapy soon became the standard of care for patients with Type B Aortic Dissections. The modern era of treatment for aortic dissection began in 1999 when two landmark papers published in the New England Journal of Medicine described the use, safety, and feasibility of thoracic endovascular aortic repair (TEVAR), along with other endovascular techniques, in acute, subacute, and chronic aortic dissections.6,7 The history of aortic dissection has been defined by major treatment advances separated by long periods of time. However, with the recent surge in new technology and techniques, it is clear that the current era is one where treatment paradigms for aortic dissection are rapidly changing and will continue to do so.
Anatomy and Classification
Under normal circumstances, the lumen of the aorta is beset by the three concentric layers of the aortic wall: the intima, the innermost layer, the media, and the outer adventitia. Dissection occurs when a false lumen, that is blood flow between the intimal and adventitial layers, is formed, giving the aorta a “double barrel” appearance (Figure 26-1). This usually occurs via a tear in the intima followed by shearing of the aortic wall layers for a variable distance. An alternative etiologic mechanism that has been postulated is the rupture of vasa vasorum causing an intramural hematoma, which subsequently ruptures into the aortic true lumen.8
Computed tomographic (CT) images from a patient with an acute type B aortic dissection. (A) Note the false lumen (arrow) and true lumen (triangle). (B) The dissection flap (arrow) extends along the length of the aorta.
Multiple anatomic classification systems have been developed to streamline communication between providers. The most common are the DeBakey and the Stanford Classifications (Table 26-1). The Society for Vascular Surgery (SVS) and the Society of Thoracic Surgeons (STS) have recently updated their reporting standards for aortic dissection with a new classification scheme.9...