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Dissecting Aortic Aneurysm
1
Why is the term dissecting aortic aneurysm really incorrect?
The correct term should be dissecting aortic hematoma because the lesion is not an aneurysm. Blood passes into the media, creating a hematoma that separates the intima from the media or adventitia. It is unclear whether the inciting event is the intimal tear or blood from the media tearing through the intima. Hence, an intimal tear is not a prerequisite because 5%–13% of patients do not have one.
2
When should the diagnosis be entertained?
Suspicion is the most important factor because no one feature is common to patients presenting with aortic dissections. In any patient who presents with severe knifelike, ripping chest and back pain, the diagnosis of aortic dissection should be considered. Other symptoms include syncope and neurologic symptoms.
3
After the diagnosis is entertained, how should the patient be managed?
Two-thirds of patients are hypertensive, so blood pressure (BP) must be controlled to a systolic BP of <100 mm Hg. Pain must also be managed to reduce catecholamine surge. The other diagnosis to be strongly considered is acute myocardial infarction (MI). An electrocardiogram often rules out MI, but some aortic dissections tear off a coronary artery; thus, both acute infarction and aortic dissection occur concurrently (this patient group has a higher mortality).
4
What is the most significant diagnostic clue on physical examination?
A new aortic valvular diastolic murmur, indicating aortic valvular regurgitation caused by distortion of the valve structure by the mural hematoma. In addition, the dissecting hematoma can encircle the lumen or actually cleave the takeoff of the subclavian or femoral vessels, resulting in the loss of pulses or systolic variation between arms. Neurologic findings, including paraplegia and hemiplegia, may also be present because of similar flap occlusion of the great vessels.
5
Which chest radiograph findings are helpful in diagnosis?
Widened mediastinum and loss of aortic knob silhouette—a hematoma surrounding the aorta makes the aortic outline blurry—are helpful findings. In 15%–25% of patients, a left-sided pleural effusion is present.
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