What is an Aortic Dissection?
An aortic dissection is a partial tear of the aorta, the largest artery in the body.
The leading cause of death in patients with an aortic dissection is not the initial tear, but the progressive dissection that results in rupture. When the lining of the aorta tears, blood can push through the tear, separating (dissecting) the middle layer of the wall from the still intact outer layer. As a result, a new, false channel forms in the wall of the aorta. The tear in the aorta allows blood (and the pressure of the blood flow) to penetrate the arterial wall and over time, this continuous flow can cause the aorta to rupture--a condition that most do not survive.
An aortic dissection should be on the differential diagnosis of all patients presenting with chest pain. Chest pain is caused by the dissection interrupting blood flow to the coronary arteries, resulting in myocardial ischemia.
The Signs and Symptoms of an Aortic Dissection
The most common presenting symptom of an aortic dissection is the sudden onset of severe chest pain. The pain of an aortic dissection can be different from the pain of an acute myocardial infarction (heart attack) by its sudden onset and maximal severity at rest and seems to move around. An aortic dissection may also cause back or abdominal pain that is sudden in onset, severe or ripping/tearing and the patient may have numbness, weakness, tingling, pallor in an arm or leg, loss of sensation or localized pain. Altered mental status may also be reported. Pain in the neck or jaw indicates that the dissection involves the aortic arch.
The symptoms of an aortic dissection may include:
- Sudden onset of chest pain,
- Limb pain, numbness or weakness,
- Shortness of breath,
- Neck or jaw pain,
- Back pain
An aortic dissection may decrease or stop the blood flow to many different parts of the body, and this may result in numbness or a tingling sensation in the legs. The symptoms of an aortic dissection may include decreased ability to move an arm, leg or other part of the body. Neurologic deficits can be a presenting sign of an aortic dissection. In about two-thirds of people with aortic dissection, pulses in the arms or legs are diminished or absent.
Some people describe a pulsating bulge as a symptom of an aortic dissection. Progression of an aortic dissection has been attributed to the pulsatile nature of blood flow.
Testing for an Aortic Dissection
The key to diagnosing an aortic dissection is to confirm that it is in fact a dissection and not a heart attack. A small percentage (5-10%) are Type B dissections (dissections of the descending aorta). Aortic dissection should be presumed in patients wtih symptoms and signs of an acute myocardial infarction.
The gold standard for diagnosing an aortic dissection is a CT scan. Emergency physicians may use a CT angiogram (CTA) to exclude thoracic aortic dissection.
There are no blood tests or EKG findings that diangose an aortic dissection. However, D-dimer blood levels are higher in patients with acute thoracic aortic dissection compared with levels in patients wtih acute myocardial infarction (heart attack).
One of the most important elements in diagnosing aortic dissections is the history provided by the patient. Only 40% of patients are asked the basic questions about their pain, namely, P, Q, R, S and T: Position, Quality, Radiation, Severity and Timing of the pain. Timing includes the rate of onset, duration and the frequency of pain. The clinician should also ask about the migration of the pain, aggravating or alleviating factors and associated symptoms.
Types of Aortic Dissection
A dissection to the ascending aorta is classified as a Type A dissection, and a dissection to the descending aorta is known as a Type B dissection.
Treatment for an Aortic Dissection
Type A dissections require surgery. Surgery involves opening the chest and surgically removing the dissected aorta. A synthetic graft is sewn in its place for blood to flow freely to the rest of the arterial system. Medications that reduce heart rate and blood pressure are also recommended for the treatment of an aortic dissection.
Without treatment, about 80% of people who have an aortic dissection die within the first two weeks. With treatment, about 70% who have a dissection of the first part of the aorta survive to leave the hospital. The survival rate increases dramatically the sooner the person is treated for an aortic dissection.
Have Questions about an Aortic Dissection?
If you have any questions, don't hesitate to call John Fisher at 518-265-9131. I look forward to speaking with you.