What ER Doctors should be looking for!


 

What information should the emergency room team obtain from a patient with chest pain?

Upon arrival in the emergency room, the patient should be asked to clearly describe the pain—its location and severity, and the extent to which it is different from previous pain. While gathering the medical history, the patient should be asked about any known diagnosis of the Marfan syndrome or other form of aortic disease, as well as any knowledge about the status of his or her aorta from previous tests. Many people with the Marfan syndrome are knowledgeable about their medical status. However, emergency department physicians should be able to evaluate individuals with suspected aortic dissection, independent of the Marfan syndrome. The clinical features of aortic dissection are not unique to people with the Marfan syndrome, except that the incidence of dissection in individuals under the age of 45 is markedly increased in people with the Marfan syndrome and other forms of aortic disease.

What part of the physical exam raises the possibility of an aortic dissection?

During the physical examination, it is important to check the blood pressure in both arms and the pulses in both wrists, both legs and both sides of the neck over the carotid arteries. If an aortic dissection is present, a difference in blood pressure can sometimes be found between the arms and the differences in the pulse can be detected.

High blood pressure could indicate a number of factors:

 
  • A predisposing factor to aortic dissection.
     
  • Pain from the dissection
     
  • A partially or completely blocked artery to one or both kidneys.

An abnormally large difference between the top (systolic) blood pressure and the bottom (diastolic) blood pressure, could be due to a leakage of blood back into the heart (aortic regurgitation).

Very low blood pressure can also occur. Many people with the Marfan syndrome are treated with medications to keep their blood pressure at the very bottom of the normal range. It is important to ask patients with a known diagnosis of the Marfan syndrome their normal blood pressure so that, if the emergency providers detect a blood pressure of, for example, 100/60, they are aware that it is the patient's usual blood pressure and not the result of an acute event. This is essential so that doctors do not try to raise the blood pressure, which would be a potential disaster in the setting of a dissection.

What tests are necessary to confirm a diagnosis of an aortic dissection?

Once the possibility of a dissection has been raised, an imaging study of the aorta is needed. A pain that starts at the front of the chest would suggest that the aorta near the heart is involved. In this situation, a standard echocardiogram may be useful. If the pain arises in the back of the chest or in the abdomen, a computed tomographic scan (which is most sensitive when radiographic x-ray contrast is given), transesophogeal echocardiogram, or magnetic resonance imaging study is necessary.

The particular test would depend on which of these tests is most readily available, and most expertly done and interpreted.

If a patient is having severe anterior chest pain, the emergency room physician may first consider a myocardial infarction or an inflammation of the lining around the heart. However, if the electrocardiogram doesn't show an obvious heart attack, and pericardial inflammation is being considered, a test such as an echocardiogram could document that possibility. In that situation, if the aorta is dissected close to the heart, the dissection may appear on the echocardiogram and the correct diagnosis would be achieved without having had to consider it as a first diagnosis.

What are other possible causes of chest pain?

There are many other causes for the type of chest pain associated with an aortic dissection. These include a heart attack (myocardial infarction) and inflammation of the lining around the heart (pericarditis). Problems with the esophagus and the spine also could cause pain in the same general area, although they tend to have different symptoms.

Can an aortic dissection be stabilized?
Dissections that begin away from the heart (Type B or distal dissection) often can be stabilized and may not require immediate surgery. However, a dissection that starts near the heart (Type A or proximal)—in the part of the aorta leading up to the neck—does not tend to stabilize. A dissection in this area is exposed to the full force with which the heart pumps blood on each beat, which extends the tear. Proximal dissections require immediate surgical intervention.

Information gathered from the imaging technology can indicate the likelihood of stabilization. In addition, it is important to see if the aorta in any segment is 5-6 cm or more in diameter, which would indicate elective, if not immediate, surgery. An aorta of 5-6 cm means the aortic wall has been thinned and stretched, and is at a great risk for further enlargement and, potentially, rupture.

How can a dissection be stabilized?

Medication

Upon diagnosis of a dissection, it is important to lower the blood pressure to the bottom end of the normal range, or even a little lower, with medication. In addition, either a beta blocker or verapamil is used to slow the pulse and make the heart beat with less force. These medications can be given intravenously in order to be effective in minutes.

In a dissection that starts away from the heart, if the blood pressure stabilizes, the pain stops, and there's no compromise of blood flow to the kidneys and other vital organs, then the approach is usually based on aggressive use of medications to lower blood pressure to as low as 90-100 mm Hg and to slow the pulse, and careful monitoring to ensure that the aorta doesn't enlarge further.

Surgery

Surgery would be considered if the tear in the descending aorta seems to stabilize, but then grows progressively, or if there is a rapid rate of change in an aorta size not yet considered to be at risk for rupture. Regardless of the cause of an aortic aneurysm, surgery should be considered once the aortic diameter reaches twice normal. On average, this corresponds to 5-6 cm for the thoracic aorta. A lower threshold is recommended for people with the Marfan syndrome with severe aortic regurgitation, family history of aortic dissection or the need for other major surgery.

A patient who is extremely anxious may be aided by some sedation, which may help potentiate the effects of medicine and control blood pressure. However, it is important for patients in this situation to be awake and alert enough to be able to describe the pain and symptoms. If someone has a large dissection that begins near the heart, or the tear is very extensive and they continue to have pain even after the blood pressure has been brought down to a low level, proceeding with surgery as soon as the surgical team is assembled is essential. In the brief time before surgery, medication to control pain can be used without loss of needed diagnostic information.

When is surgery necessary?

Symptomatic ascending aortic dissections or aneurysms, whether acute or chronic, require emergency surgical treatment. Acute descending aortic dissections require admission to intensive care for monitoring and blood pressure control. Those with pain that does not resolve with blood pressure control will need urgent surgery. Those with evidence of organ ischemia (kidneys, bowel, spinal cord) will also require urgent surgery. In patients with chronic descending aortic dissections, pain may indicate impending rupture and, therefore, warrant urgent surgery.

In general, the decision for immediate surgery is based on indicators of especially high risk, such as the presence of a proximal dissection, or continued pain despite blood pressure control.

Other indicators for urgent surgery are:

 

  • Evidence of fluid in the pericardial sac around the heart with a dissection that comes back to the heart, which suggests that the tear is going into the pericardial space.
     
  • Evidence of marked enlargement of the dissected aorta (aneurysm formation).
     
  • Evidence of blood leakage into tissue by contrast CT scan or transesophogeal echocardiogram.
     
  • Evidence that blood flow to one or more vital organs is being compromised.
     
  • Evidence of an intramural hematoma, a localized collection of blood within the aortic wall that can accumulate before the dissection progresses along the length of the aorta. Intramural hematomas indicate an impending dissection, and should be treated in an identical manner.

 



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