Aortic diseases can range from apparently innocuous atherosclerosis to complex aneurysmal pathology. Regardless of the type of disease, the involvement of aortic pathology in any surgical plan can present a challenge to both surgeons and anesthesiologists. Whereas significant atherosclerosis at critical locations can alter surgical plans, aortic dissections can rupture and are life threatening, require rapid and accurate diagnosis, and need definitive medical and/or surgical management due to their high risk of morbidity and mortality.1,2 A key ingredient in the efficient management of these patients is imaging of the thoracic aorta. The anatomical juxtaposition of the esophagus and aorta makes transesophageal echocardiography (TEE) an attractive imaging tool. It is now recognized as an essential noninvasive diagnostic modality for acute thoracic aortic pathologies, and is a standard part of the echocardiographer's armamentarium in the operating room.3–6 In emergent situations, TEE may be the only imaging modality available. It is therefore important for the echocardiographer to quickly and accurately verify the diagnosis, distinguish true pathology from the many common confounding artifacts, and clearly communicate precise echocardiographic findings of the aorta and related cardiac anatomy to the surgeon to guide intervention. The following text reviews aortic anatomy and pathology and associated echocardiographic features that assist with imaging during aortic surgery.
In order to truly appreciate the invaluable role that TEE plays in the assessment for diseases of the aorta, a detailed understanding of the aorta and surrounding anatomical structures is important. The geometrically complex thoracic aorta can be divided into three segments: ascending thoracic aorta, aortic arch, and descending thoracic aorta (Fig. 16-1). The ascending thoracic aorta originates at the level of the aortic valve annulus. As previously described in Chapter 4, the aortic valve comprises three crescent-shaped leaflets that coapt to form three commissures. Immediately distal to the aortic valve apparatus is a short and dilated aortic segment—the sinus of Valsalva—which is subdivided into the noncoronary, left coronary, and right coronary sinuses. As the nomenclature suggests, the left and right coronary arteries each originate from their respectively named sinus. Distal to the sinus of Valsalva, the aorta slightly narrows, forming the sinotubular junction (STJ). From this point, the ascending aorta crosses beneath the main pulmonary artery, then courses in an anterior, cranial, and rightward direction over the origin of the right pulmonary artery.
Anatomical course of the thoracic aorta. The relationship with the esophagus is particularly important with regard to orientation of the probe and the aorta in each of its thoracic sections: the ascending aorta, aortic arch, and descending aorta. The interposition of the trachea makes portions of the ascending aorta and arch either completely invisible or partially visible.
The ascending aorta terminates and continues as the aortic arch at the origin of ...