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- With each heartbeat blood is ejected into the aorta exerting multiple mechanical forces on it: pressure, radial and longitudinal stress, tension. Just as diseases of the aorta can affect the heart, diseases of the heart can affect the aorta. Cardiac patients often suffer from both and this makes their clinical care more complex.
- The aorta ascends in the anterior mediastinum, curves backward into the aortic arch from which emanate the great vessels of the head and the upper extremities, descends into the posterior mediastinum and beyond the diaphragm continues into the abdomen providing blood to the spinal cord, gut, kidneys, ultimately dividing to deliver blood to the lower extremities. Diseases that interfere with the delivery of blood to the tissues (eg, aortic dissections, atherosclerosis, and emboli) place patients at great risk for organ ischemia. Other disease conditions (eg, aneurysms) weaken the wall of the aorta and often result in aortic rupture and sudden death. Many patients with aortic disease present emergently in the setting of acute aortic dissection, contained aneurysmal rupture, or following blunt or penetrating traumatic aortic injury. Others, with long-standing aortic aneurysms, present for elective surgery for repair of progressive dilatation of the thoracic aorta. Irrespective of the nature of their thoracic aorta disease these patients are often quite unstable and their prognosis can be disappointing. Consequently, cardiac surgeons and their anesthesia colleagues are called upon to exert great skill to manage these "high-risk" patients.
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Patients with ascending thoracic aortic aneurysms present either acutely or electively (Figure 9–1). Crushing chest pain often heralds acute presentations. Suffice it to say these patients may never undergo surgery as they bleed and/or tamponade to death. However, sometimes ruptures are contained such that patients do not exsanguinate or tamponade. In these cases, the patient will present emergently for repair following diagnosis in the ER. Acute, contained ascending aortic aneurysm ruptures require immediate surgical correction. Radiographic (MRI, CT) and ultrasound techniques are routinely employed to make the diagnosis of a thoracic aortic aneurysm. Rapid accumulation of blood in the pericardium results in a tamponade physiology necessitating emergency surgical treatment.
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Nonemergent presentations occur when patients develop aneurismal dilatations over time and become symptomatic from anatomic compression of the trachea, the main bronchi, or the esophagus by the expanding aneurysm. At times, an ascending aneurysm widens the aortic root making the aortic valve leaflets no longer competent leading to severe aortic insufficiency (AI). These patients often present with the symptoms of aortic regurgitation. Echocardiography will readily demonstrate dilatation of the aortic root and aortic valvular incompetence. Often a widened mediastinum on routine x-ray examination may herald the presence of an ascending thoracic aneurysm. Chronic aneurismal dilatations are regularly followed with surgical repair suggested either when the patient becomes symptomatic or when the aneurysm becomes greater ...