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.
A 50-year-old man developed severe chest pain and collapsed to the floor. The pain was sudden in onset, was burning in quality, and was located in the center of his chest. Emergency medical services arrived a few minutes later and found the patient diaphoretic and cyanotic, with an initial blood pressure of 74/54 mm Hg and a heart rate of 125 beats per minute. He was rushed to the hospital.
His medical history was unremarkable. He smoked one pack of cigarettes per day for 20 years. His father died of a “heart attack” at age 52.
In the emergency department he underwent echocardiography with a portable handheld unit, which showed a pericardial effusion and cardiac tamponade. He was sent for emergency computed tomography of the chest, which revealed an aneurysm of the aortic root and acute type A (Stanford classification) aortic dissection with hemopericardium.
He underwent emergency cardiac surgery. At the time of surgery, he was in cardiogenic shock from aortic dissection complicated by severe aortic regurgitation and cardiac tamponade with hemopericardium. The aortic valve was trileaflet. A 27-mm St. Jude composite valve graft root replacement was performed.
The patient did well and was discharged home 7 days after surgery. Pathologic study of the aorta revealed cystic medial degeneration. He did not have any features of Marfan syndrome or Loeys-Dietz syndrome. His three children underwent evaluation, and each had a normal physical examination and echocardiographic test results.
A HIGH INDEX OF SUSPICION IS CRITICAL
Acute aortic dissection is the most common aortic catastrophe, with an incidence estimated at 5 to 30 per 1 million people per year, amounting to nearly 10,000 cases per year in the United States.1–4
The diagnosis of acute aortic dissection has many potential pitfalls.2,3 Aortic dissection may mimic other more common conditions, such as coronary ischemia, pleurisy, heart failure, stroke, and acute abdominal illness. Because acute aortic dissection may be rapidly fatal, one must maintain a high index of suspicion.2,3 Prompt diagnosis and emergency treatment are critical.
WHAT CAUSES AORTIC DISSECTION?
One hypothesis is that acute aortic dissection is caused by a primary tear in the aortic intima, with blood from the aortic lumen penetrating into the diseased media leading to dissection and creating a true and false lumen.2 Another is that rupture of the vasa vasorum leads to hemorrhage in the aortic wall with subsequent intimal disruption, creating the intimal tear and aortic dissection.
Once a dissection starts, pulsatile flow of blood within the aortic wall causes it to extend. The dissection flap may be localized, but it often spirals the entire length of the aorta. Distention of the false lumen with blood may cause the intimal flap to compress the true lumen and potentially lead to malperfusion syndromes.
CLASSIFIED ACCORDING TO LOCATION
It is important to recognize the location of the dissection, as the prognosis and treatment depend on whether the ascending aorta is involved.2,3 For classification purposes, the ascending aorta is the portion proximal to the brachiocephalic artery, while the descending aorta is the portion distal to the left subclavian artery.3
The DeBakey classification defines a type I aortic dissection as one that begins in the ascending aorta and extends at least to the aortic arch or beyond. Type II dissections involve the ascending aorta only, while type III dissections begin in the descending aorta, most often just distal to the left subclavian artery.
The Stanford classification scheme divides dissections into type A and type B. Type A dissections involve the ascending aorta, while type B dissections do not involve the ascending aorta.
Which classification scheme is used is not important. However, identifying patients with dissection of the ascending aorta (DeBakey type I or type II or Stanford type A) is critical, as emergency cardiac surgery is recommended for this type of dissection.2,3 For the purposes of this paper, the Stanford classification scheme will be used.
Dissection that involves the ascending aorta most commonly occurs in people ages 50 to 60, whereas acute dissection of the descending aorta typically occurs in people 10 years older.1,2
An acute aortic dissection is one that has occurred within 2 weeks of symptom onset. A chronic dissection is one that occurred more than 2 weeks after symptoms began.
