Acute Aortic Disease.. - Index of

68 Raghupathy and Eagle
the incidence of aortic dissection is quite rare, with an estimated range of 5 to
30 cases per million persons per year (1). As such, clinical observations pertaining
to acute aortic conditions, although valuable, are often limited by the naturally
smaller sample sizes found in single-center case series. In contrast, much of our
current and expanding body of knowledge derives from our experience with the
International Registry of Aortic Dissection (IRAD). Since its inception in 1996,
this ongoing, worldwide multi-institution research collaboration among specialized
aortic referral centers has collected important clinical data on over 1350
consecutive patients to gain insight into the clinical presentation, management,
and outcomes of acute aortic conditions.
This chapter is designed to equip the triaging clinician with the essential
information required to develop a practical and efficient diagnostic approach to
the patient with an acute aortic condition. Speed in appropriately suspecting and
confirming the diagnosis is a recurring theme echoed throughout this discussion,
as severe, often catastrophic complications tend to develop quickly. From the time
of symptom onset, mortality in untreated (or undiagnosed) acute dissection rises
rapidly with each passing hour, approaching 50% in the first 24 hours (6,7). Early
mortality is usually the result of a ruptured aorta, manifesting clinically as cardiac
tamponade or frank exsanguination. Serious morbidity, including multisystem
organ failure, may result from occlusion of the aortic branches, with resultant
malperfusion to vital organs such as brain, kidney, spinal cord, and limbs.
Therefore, the importance of prompt action and maintaining a high index of
suspicion to minimize diagnostic delays cannot be overemphasized.
PREDISPOSING FACTORS
The initial approach to evaluating the patient suspected of having an acute aortic
condition begins with recognizing the constellation of high-risk conditions that are
associated with the disease. A summary of such predisposing conditions is listed in
Table 1. Hypertension exists in up to 72% of patients and is by far the most common
feature. Advanced age is another common characteristic, with a mean age of dissection
occurring in the seventh decade of life (1,8). Among younger patients
(age 70 years old. Contrary to previous reports from case studies, our
experience with IRAD suggests that pregnancy is only rarely associated with acute
dissection, unless it co-exists with the Marfan’s syndrome and an aortic root diameter
>40 mm (1,10). Prior cardiovascular intervention, including surgical or catheter
instrumentation of the aorta, is an important feature found in 4% to 5% of
patients with Type A or Type B dissection. An even greater association is seen in
patients presenting with Type A dissection, where a history of recent or prior
cardiac surgery is present in approximately one of every six patients (11,12).