Diagnosis

History

One of the most important elements in diagnosing aortic dissections is the history provided by a patient. Physicians will want to know--among many other things--when the pain started, how long it has lasted, how severe the pain is, and what the pain feels like. A physician will ask about risk factors whenever he or she is concerned about any disease, and aortic dissections are no different. To determine what studies are necessary, physicians rely on their clinical suspicion based upon a patient's complaints and whether or not the patient has any associated risk factors.

Symptoms and Signs:

Aortic dissections are most commonly described as a sudden, severe, knifelike "tearing pain through the back". However, dissections do not always present in this manner. It may instead cause limb pain or weakness, fainting episodes, or even pain in the groin.

The following symptoms have been associated with aortic dissections:

When a patient has these complaints, a physician will first rule out emergencies such as an aortic dissection or heart attack. Aortic dissections and heart attacks are not the most common causes of the symptoms listed above, however they are some of the most worrisome causes.

Physical Exam:

As in the diagnosis of any disease, the physical exam is extremely important to a physician. So what are physicians looking for? If a physician is concerned about a dissection, a physician will immediately evaluate the patient's blood pressure. During an aortic dissection, blood pressure may increase or decrease. If it is high, it may be the result of the stress placed on your body by the dissection. Any pain can cause an increase in blood pressure. If blood pressure is low, it may be an ominous sign--it could be that the dissection is involving the sac surrounding the heart or that the aorta has torn. In addition, a physician will measure the blood pressure on both the right and left arms. If there is a significant difference (greater than 20 mmHg) between the two arms, it is not a sure sign the patient has a dissection, but it does increase the concern for a dissection.

As part of a complete physical exam, a physician will listen to a patient's heart and lungs. A new heart murmur could signify that the dissection has involved the aortic valve, or it could signify an entirely different process occurring. Listening to the lungs may help a physician determine whether or not the pain is being caused by something wrong with the lungs. In addition, the physician will examine the patient's abdomen, as many abdominal diseases may present with similar symptoms.

Key Points

  • Aortic Dissections classically cause a "sharp, tearing" pain through the back, but my present with other vague complaints.
  • They may cause an increase or decrease in blood pressure.

Differential Diagnosis:

Based upon the symptoms that a patient presents with, the physician will consider several other possibilities.  These other diagnoses may be occurring instead of an aortic dissection, or more drastically some may occur at the same time as an aortic dissection.

Studies and Tests

After listening to a patient's complaints, reviewing any risk factors, and interpreting any physical signs, if a physician is still concerned about an aortic dissection several tests will be performed to confirm the diagnosis.

Chest X-Ray

The first test most physicians will request will be a chest x-ray. A chest x-ray cannot rule in or out a dissection. However, a chest x-ray can show signs that will increase a physician's suspicion for a dissection. Patients may hear physicians refer to a "widened mediastinum", meaning that the central part of a chest x-ray, which contains some of the major vessels, appears wider than normal. In rare instances, an outline of the false lumen may be visible on x-ray.

CT Scan

If a patient looks fairly well and does not appear to be in any immediate danger, after a chest x-ray a physician may then order a CT scan of the chest. A CT scan is an excellent test for diagnosing dissections; it is possible to see the two lumens (true and false) created by an aortic dissection on a CT.

Transesophageal Echocardiogram (TEE)

Unfortunately, CT scans take some time to be performed, and often immediate intervention is required in patients with an aortic dissection. If a physician feels that immediate action may be warranted, he will likely first order a transesophageal echocardiogram: an ultrasound image taken through the esophagus. TEEs are excellent, accurate tests that, while uncomfortable for the patient, are absolutely necessary in emergencies.

What about other imaging tests?

Other tests that are less often used to diagnose an aortic dissection include aortography and MRI. Aortography involves the injection of dye directly into the aorta. The dye is highlighted on a series of x-rays. However, it is an invasive test and accurate, non-invasive tests like the CT scan and TEE are available. MRI is an excellent and very detailed test that can diagnose an aortic dissection. However, MRI tests are more expensive and take much longer than a CT scan or TEE. Because most dissections are accurately and efficiently diagnosed with CT scans or TEEs, these more elaborate tests are usually unnecessary.

What about other tests like blood tests?

At the moment, there are no blood tests or EKG findings that diagnose an aortic dissection, but it is important for a physician to look for other diseases or complications. These tests will be used to make sure other diseases are not occurring. Blood tests will be performed to check for enzymes (troponins, creatine kinase) released by the heart if it suffers damage. In addition, an electrocardiogram (EKG) will also be taken. As an example, these tests can help a physician determine if the patient is instead (or concurrently) having a heart attack.

What complications will a physician worry about?:

Dissections may cause other problems if they extend to involve other vessels. These conditions will need to be treated as well.

Key Points

  • Although non-specific, the first test is usually an X-ray.
  • This will be followed by a CT if the patient is stable, or a TEE if an emergent diagnosis is required.
  • There are no blood tests that diagnose dissections, but other tests are needed to rule out other problems.