Aortic dissection: Prompt diagnosis and emergency treatment are critical
ABSTRACTDiagnosing aortic dissection requires a high index of suspicion, as it may mimic other more common conditions that cause chest pain. Prompt diagnosis is key, as it requires emergency evaluation and treatment for optimal chances of survival. This paper reviews key clinical features as well as laboratory and imaging tests.
KEY POINTS
- Aortic surgery is the treatment of choice for dissection of the ascending aorta, whereas dissection of the descending aorta is initially managed medically.
- Look for an underlying genetic predisposition to aortic disease and, in many instances, screen first-degree relatives for aortic disease.
- Long-term management requires serial imaging of the aorta, blood pressure control, and, for many, future aortic procedures.
- Measuring the D-dimer levels may help in decision-making for appropriate imaging in patients presenting with chest pain, as an elevated level raises the suspicion of dissection. However, more study of this and other biomarkers is needed.
- Advances in molecular genetics and the biology of the aortic wall promise to improve the diagnosis and prognosis of aortic disease.
DISEASES AND CONDITIONS ASSOCIATED WITH AORTIC DISSECTION
Hypertension and disorders leading to disruption of the normal structure and function of the aortic wall. About 75% of patients with acute aortic dissection have underlying hypertension.1–3
Cystic medial degeneration is a common pathologic feature in many cases of aortic dissection.
Cocaine use and intense weight-lifting increase the shear stresses on the aorta.2,3
Inflammatory aortic diseases such as giant cell arteritis.
Pregnancy can be complicated by aortic dissection, usually in the setting of an underlying aortopathy.5
Iatrogenic aortic dissection accounts for about 4% of cases, as a result of cardiac surgery, catheterization, stenting, or use of an intra-aortic balloon pump.1
Aortic aneurysm. Patients with thoracic aortic aneurysm are at higher risk of aortic dissection, and the larger the aortic diameter, the higher the risk.2,3,6 In the International Registry of Acute Aortic Dissection (IRAD), the average size of the aorta was about 5.3 cm at the time of acute dissection. Importantly, about 40% of acute dissections of the ascending aorta occur in patients with ascending aortic diameters less than 5.0 cm.7,8
Thus, many factors are associated with acute dissection, and specific reasons leading to an individual’s susceptibility to sudden dissection are poorly understood.
CLINICAL FEATURES OF ACUTE AORTIC DISSECTION
Because the symptoms of acute dissection may mimic other, more common conditions, one of the most important factors in the diagnosis of aortic dissection is a high clinical suspicion.1–3
What is the pretest risk of disease?
Recently, the American College of Cardiology (ACC) and the American Heart Association (AHA) released joint guidelines on thoracic aortic disease.3 These guidelines provide an approach to patients who have complaints that may represent acute thoracic aortic dissection, the intent being to establish a pretest risk of disease to be used to guide decision-making.3
The focused evaluation includes specific questions about underlying conditions, symptoms, and findings on examination that may greatly increase the likelihood of acute dissection. These include:
- High-risk conditions and historical features associated with aortic dissection, such as Marfan syndrome and other genetic disorders (Table 2), bicuspid aortic valve, family history of thoracic aortic aneurysm or dissection, known thoracic aortic aneurysm, and recent aortic manipulation
- Pain in the chest, back, or abdomen with high-risk features (eg, abrupt onset, severe intensity, or a ripping or tearing quality)
- High-risk findings on examination (eg, pulse deficits, new aortic regurgitation, hypotension, shock, or systolic blood pressure differences).
Using this information, expedited aortic imaging and treatment algorithms have been devised to improve the diagnosis.3
Using the IRAD database of more than 2,500 acute dissections, the diagnostic algorithm proposed in the ACC/AHA guidelines was shown to be highly sensitive (about 95%) for detecting acute aortic dissection.4 In addition, using this score may expedite evaluation by classifying certain patients as being at high risk of acute dissection.3,4
Important to recognize is that almost two-thirds of patients who suffered dissection in this large database did not have one of the “high-risk conditions” associated with dissection.4 Additionally, the specificity of the ACC/AHA algorithm is unknown, and further testing is necessary.4
Acute onset of severe pain
More than 90% of acute dissections present with acute pain in the chest or the back, or both.1–3 The pain is usually severe, of sudden onset, and often described as sharp or, occasionally, tearing, ripping, or stabbing. The pain usually differs from that of coronary ischemia, being most severe at its onset as opposed to the less intense, crescendo-like pain of angina or myocardial infarction. The pain may migrate as the dissection progresses along the length of the aorta or to branch vessels. It may abate, leading to a false sense of security in the patient and the physician.3 “Painless” dissection occurs in a minority, usually in those with syncope, neurologic symptoms, or heart failure.1–3
The patient with acute dissection may be anxious and may feel a sense of doom.
Acute heart failure, related to severe aortic regurgitation, may be a predominant symptom in dissection of the ascending aorta.
Syncope may occur as a result of aortic rupture, hemopericardium with cardiac tamponade, or acute neurologic complications.
Vascular insufficiency may occur in any branch vessel, leading to clinical syndromes that include acute myocardial infarction, stroke, paraplegia, paraparesis, mesenteric ischemia, and limb ischemia.
