Aortic Dissection

A 56-year-old man comes to your office for his yearly executive physical. He mentions that he has had 3 days of epigastric pain with occasional radiation to his mid-back. He denies any vomiting, diarrhea, dark stool, fever, trouble breathing, or other complaints. He tried an antacid with no relief. His past medical history is notable for hypertension and diabetes. He is a smoker but does not abuse drugs.

On physical examination, his vital signs are normal. His lungs are clear and his heart is regular without murmur. He has slight epigastric tenderness but no guarding or mass. There is no rash. Extremities are normal. You have your office phlebotomist draw blood for his yearly lab studies and your tech does an ECG, which is normal. You use your office ultrasound to image his gallbladder and aorta and obtain the following images.

1.    What does the image below show?
2.    What should be your next step in management? (Answers below image)

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Answers
 
1. The ultrasound shows the aorta in cross section and longitudinally. The image on the left shows the circular cross section of aorta just above and to the patient’s left of the vertebral body. Just in front of the back wall of the aorta there is a flap, caused by an aortic dissection. The image on the right is a longitudinal image of the aorta, with the flap also seen.

2. The next step in management should be calling 911 to get the patient to an ED. The image below shows the aortic dissection on CT.

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Discussion

Aortic dissection (AD) classically presents with symptoms of acute chest pain that radiates into the back, however the clinical presentation can vary widely and approximately 40% of cases imitate other more common conditions, such as angina or pericarditis, or present atypically. Pain is typically tearing and unprovoked, but can be exertional or pleuritic. Pain may radiate to areas other than the back, such as the jaw, throat, arms, legs, or abdomen. In some cases, pain is absent. Associated symptoms are not common but may include syncope, vomiting, or neurologic symptoms. Because of these atypical symptoms, many cases of AD are diagnosed late, sometimes too late.

The physical examination is often normal in the presence of AD. Murmurs or pulse deficits are the most common abnormal findings but occur in less than 50% of cases. A difference in systolic blood pressure between arms, though frequently referred to, is neither sensitive nor specific for dissection; the difference is critical, however, in titrating treatment once AD has been diagnosed. See the chart below for other more rare clinical findings and for a list of risk factors, hypertension being the most common.

AD can be visualized using a variety of imaging modalities (see below) but the initial test of choice is almost always CT angiography of the chest. For stable patients with contraindications to contrast, MRI or trans-esophageal echocardiography are viable alternatives for making the diagnosis. See chart below for sensitivity (listed first), specificity (listed next), and other useful information about the various imaging modalities that can be used to diagnose AD.

Treatment of AD usually starts with empiric beta-blockers or other negative chronotropes. These agents should usually be initiated once the diagnosis is suspected, while awaiting confirmation. Titration to a pulse of 50-60 beats/min and a blood pressure of ~100-110 mm Hg in the arm with the higher blood pressure is usually recommended. Definitive therapy for all type A and some type B dissections is operative, either open or by interventional radiology. Time is of the essence as the death rate has been estimated to be about 2% per hour early on, usually from cardiac tamponade.

Excerpt on AORTIC DISSECTION from Emergency Medicine 1-minute Consult pocketbook

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