The aorta is the largest artery and distributes oxygen-rich blood from the heart to every part of the body. Therefore any disturbance in the aorta has an effect on blood circulation throughout the body sometimes with serious and life-threatening consequences. There are many different types of diseases that can affect the aorta and one of these conditions is known as an aortic dissection. It closely resembles a heart attack in the symptoms, may appear similar to a stroke and can be deadly within minutes.
What is an aortic dissection?
An aortic dissection is a condition where there is a tear in the inner lining of the aorta. Blood can the enter and full the space between the inner layer and middle layer of the aortic wall. As the blood forms a channel within the wall of aorta there is a possibility that the wall can rupture. Blood will the spill out of the aorta and death can occur within minutes. Although a rupture is not common, an aortic dissection should always be considered as a medical emergency.
Overall aortic dissections are uncommon in the United States. It affects about 1 in 10,000 people who are hospitalized and in many instances it is only discovered during an autopsy. Aortic dissections are about two to three times more common in males than females. It is mainly seen in the 50 to 65 year age group although patients with Marfan syndrome may experience it earlier in life, during the forties. Surgery is often needed but medication alone may be sufficient to manage some types of aortic dissections.
Causes of Aortic Dissection
The aorta has to handle blood at a very high pressure as the heart pushes out oxygen-rich blood into the aorta. Furthermore the aorta has to ensure that the pressure is maintained to some degree in order for the blood to be propelled to different parts of the body. It has to be elastic but strong. The high pressure also makes it prone to injury but the aorta wall is designed to compensate to some degree. However, it is not entirely immune from mechanical trauma and is also one of the most likely blood vessels to rupture.
When a tear forms in the inner lining (intima) blood can then enter and create a channel in the wall between the intima and middle layer (media). Sometimes the tear can even extend deeper thereby allowing for a blood channel to form deeper within the aortic wall. Dissections do not usually run the full course of the aorta. It typically stops where branches arise from the aorta or where there are atherosclerotic plaques in the aortic wall. Most dissections occur in the ascending aorta.
Types of Dissections
There are two classifications for aortic dissections. The first is the DeBakey classification and the different types are as follows:
- Type I – tear occurs in the ascending aorta but also involves the descending aorta.
- Type II – tear only in the ascending aorta.
- Type III – tear only in the descending aorta.
The second system is known as the Stanford classification and the types are as follows:
- Type A – tear in the ascending aorta.
- Type B – tear in the descending aorta.
Aortic dissections are more likely to occur in certain conditions. In these conditions the force that the aortic wall has to deal with is greater than normal or where the wall of the aorta is injured or weakened in some way.
- Poorly controlled hypertension (high blood pressure)
- Atherosclerosis – fatty hardened plaques
- Aneurysm – abnormal bulging of the aorta
- Birth defects of the aorta and congenital diseases including aortic coarctation, valve defects and Marfan syndrome.
- Iatrogenic – coronary artery bypass surgery, heart valve replacement, cardiac catheterization.
- Chest trauma usually related to deceleration as with car accident injuries.
- Cocaine use.
- Pregnancy where there are underlying defects.
Signs and Symptoms
The signs and symptoms of aortic dissection usually start up suddenly and closely resemble a heart attack. The condition can progress rapidly and complications can quickly arise, many of which are fatal. The signs and symptoms of aortic dissection include:
- Severe chest pain that radiates to the back. It can extend to the neck and down to the lower back. The pain is described as tearing in nature. Sometimes the pain may start in the back (thoracic region). Up to 10% of cases are painless.
- Loss of consciousness which can occur suddenly. It may be preceded by lightheadedness or dizziness.
- Difficulty breathing usually with a sensation of being short of breath.
- Rapid an weak pulse in one arm when compared to the pulse on the other arm.
- Stroke-like symptoms including slurred speech, visual disturbances, paralysis and muscle weakness on one side of the body may be seen in about 20% of cases.
- Anxiety similar to the feeling of impending doom as is seen in heart attacks.
- Nausea, vomiting, paleness and excessive sweating may also arise similar to a heart attack.
- Abdominal pain if the dissection involves the abdominal aorta as well.
- Flank pain or kidney pain when the renal artery (to the kidney) is affected.
- Fever (sometimes).
Treatment of Aortic Dissection
Both medication and surgery are required in the treatment of aortic dissection. The treatment may vary depending on whether the dissection involves the ascending aorta (type A) or descending aorta (type B). Medication involves the used of drugs such as beta blockers and nitroprusside to lower heart rate and reduce blood pressure. Usually these drugs are administered in the short term until the patient can be stabilized for surgery. It also helps prevent the worsening of the dissection. Painkillers may also be administered at times.
Type A dissections require surgery while type B can sometimes be managed with medication alone. Surgery involves removal of the aorta where the dissection has occurred with a synthetic tube used to reconstruct the affected part of the aorta. Stenting may be a consideration for certain complicated cases of type B dissections. If necessary the aortic valve may also be replaced. Sometimes coronary artery bypass surgery is also done if the coronary arteries are affected.