Acute aortic dissection and its variants. Toward a common diagnostic and therapeutic approach.

Acute dissection of the aorta is an uncommon yet potentially catastrophic clinical event that mandates prompt recognition and expeditious treatment. Diagnosis begins with a high clinical index of suspicion in a patient presenting with chest pain and one or more predisposing risk factors, most notably, hypertension or an inherited disorder of connective tissue. Verification can be rapidly achieved with a high degree of accuracy using one of several noninvasive imaging techniques and, when necessary, contrast angiography. Involvement of the ascending aorta (type A) requires surgical intervention, whereas clinically stable dissection limited to the descending thoracic aorta (type B) can in general be treated medically. Negative inotropic andantihypertensive medical therapy is provided to all patients. Hospital and long-term survival has improved substantially over the past 40 years, yet there remains ample room for continued progress. For centers with an active interest in the evaluation and management of acute dissection, hospital mortality rates have been lowered to 15% to 25%.1 2 3 Five-year actuarial survival rates range between 50% and 70%,2 4 5 with a 7% to 20% incidence of late reoperation, usually for aneurysmal enlargement or redissection.2 6 7 There has long been some debate over the pathogenesis of aortic dissection. In the majority of cases, the initiating event is a tear in the intima of the aorta through which blood surges into the middle to outer third of the media.8 9 10 Intimal disease, such as that associated with atherosclerosis, is not a prerequisite, although underlying medial disease due to both elastic fiber and smooth muscle cell degeneration is the rule.11 12 13 Intimal tears are most commonly located a few centimeters above the aortic valve, along the right anterolateral aspect of the aorta, where hydrodynamic and torsional forces are greatest.9 The second most …