About aortic dissection

What is aortic dissection?

Introduction to aortic dissection

The aorta is the large blood vessel that leads from the heart and carries blood to the rest of the body. It originates at the aortic valve at the outlet of the left ventricle of the heart and ascends within the chest to an arch where blood vessels branch off to supply blood flow to the arms and head. The aorta then begins to descend through the chest and into the abdomen where it splits into two iliac arteries that provide blood flow to the legs. Along its descent, more small arteries branch out to supply blood to the stomach, intestine, colon, kidneys, and the spinal cord. As well, at its origin at the aortic valve, coronary arteries branch from the aorta to supply the heart muscle with blood.

The aorta has a thick wall with three layers of muscle that allow the blood vessel to withstand the high pressure that is generated when the heart pumps blood to the body. The three layers are the tunica intima, tunica media, and the tunic adventitia. The intima is the inside layer that is in contact with the blood, the media is in the middle, and the adventitia is the outermost layer.

In an aortic dissection, a small tear occurs in the tunica intima (the inside layer of the aortic wall in contact with blood). Blood can enter this tear and cause the intima layer to strip away from the media layer, in effect dividing the muscle layers of the aortic wall and forming a false channel, or lumen. This channel may be short or may extend the full length of the aorta. Another tear more distal (further along the course of the aorta than the initial tear) in the intima layer can let blood re-enter the true lumen of the aorta.

In some cases, the dissection will cross all three layers of the aortic wall and cause immediate rupture and almost certain death. In most other cases, the blood is contained between the wall layers, usually causing pain felt in the back or flanks.

While there have been different historic classifications of aortic dissection, the Stanford classification is now most commonly used.

  • Type A dissections involve the ascending aorta and arch.
  • Type B involves the descending aorta.

A patient can have a type A dissection, type B dissection, or a combination of both.

Some patients may experience an aortic dissection without pain and it may be found incidentally on imaging studies performed for other purposes.

What are the symptoms for aortic dissection?

Aortic dissection symptoms may be similar to those of other heart problems, such as a heart attack. Typical signs and symptoms include:

  • Sudden severe chest or upper back pain, often described as a tearing, ripping or shearing sensation, that radiates to the neck or down the back
  • Sudden severe abdominal pain
  • Loss of consciousness
  • Shortness of breath
  • Sudden difficulty speaking, loss of vision, Weakness or paralysis of one side of your body, similar to those of a stroke
  • Weak pulse in one arm or thigh compared with the other
  • Leg pain
  • Difficulty walking
  • Leg paralysis

When to see a doctor

If you have signs or symptoms such as severe Chest pain, Fainting, sudden onset of Shortness of breath or symptoms of a stroke, call 911 or emergency medical assistance. These signs and symptoms don't always indicate a serious problem, but it's best to get checked quickly. Early detection and treatment may help save your life.

What are the causes for aortic dissection?

An aortic dissection occurs in a weakened area of the aortic wall. Chronic high blood pressure may stress the aortic tissue, making it more susceptible to tearing. You can also be born with a condition associated with a weakened and enlarged aorta, such as Marfan syndrome, bicuspid aortic valve or other rarer conditions associated with weakening of the walls of the blood vessels. Rarely, aortic dissections are caused by traumatic injury to the chest area, such as during motor vehicle accidents.

Aortic dissections are divided into two groups, depending on which part of the aorta is affected:

  • Type A. This more common and dangerous type involves a tear in the part of the aorta where it exits the heart or a tear in the upper aorta (ascending aorta), which may extend into the abdomen.
  • Type B. This involves a tear in the lower aorta only (descending aorta), which may also extend into the abdomen.

What are the treatments for aortic dissection?

The ABCs of resuscitation are always a priority.

In the emergency department, intravenous lines will be placed, monitors for heart rate and rhythm will be attached, and supplemental oxygen provided. Treatment and diagnostic testing usually occur at the same time until the final diagnosis is established and definitive treatment is required.

The initial medications used for treatment of an aortic dissection are directed at lowering the blood pressure to prevent further tearing or damage to the aorta. Beta blocker medications (for example, esmolol [Brevibloc], labetalol [Normodyne, Trandate], metoprolol [Lopressor, Toprol XL]) decrease the adrenaline action on the heart and blood vessels. Nitroglycerin dilates blood vessels to decrease blood pressure. These medications cannot be used if the patient is in shock with low blood pressure because of the aortic dissection. Specific medication combinations will depend upon the patient's needs.

Ultimately, type A aortic dissections of the ascending aorta require surgery as the treatment of choice. The area of the aorta that is damaged is replaced with an artificial graft. If the aortic valve has been damaged, it too may need replacement or repair.

Medical management (nonsurgical) is usually preferred for type B dissection of the descending aorta, but again, each patient needs to be assessed individually as to the specific treatment suggested. Medications are prescribed to aggressively control high blood pressure to prevent further dissection and aortic injury

What are the risk factors for aortic dissection?

Risk factors for aortic dissection include:

  • Uncontrolled high blood pressure (hypertension)
  • Hardening of the arteries (atherosclerosis)
  • Weakened and bulging artery (pre-existing aortic aneurysm)
  • An aortic valve defect (bicuspid aortic valve)
  • A narrowing of the aorta at birth (aortic coarctation)

Certain genetic diseases increase the risk of having an aortic dissection, including:

  • Turner's syndrome. High blood pressure, heart problems and a number of other health conditions may result from this disorder.
  • Marfan syndrome. This is a condition in which connective tissue, which supports various structures in the body, is weak. People with this disorder often have a family history of aneurysms of the aorta and other blood vessels or family history of aortic dissections.
  • Other connective tissue disorders. This includes Ehlers-Danlos syndrome, a group of connective tissue disorders characterized by skin that bruises or tears easily, loose joints and fragile blood vessels and Loeys-Dietz syndrome, with twisted arteries, especially in the neck.
  • Inflammatory or infectious conditions. These may include giant cell arteritis, which is an inflammation of the arteries, and syphilis, a sexually transmitted infection.

Other potential risk factors include:

  • Sex. Men have about double the incidence of aortic dissection.
  • Age. The incidence of aortic dissection peaks in the 60s and 80s.
  • Cocaine use. This drug may be a risk factor for aortic dissection because it temporarily raises blood pressure.
  • Pregnancy. Infrequently, aortic dissections occur in otherwise healthy women during pregnancy.
  • High-intensity weightlifting. This and other strenuous resistance training may increase the risk of aortic dissection by increasing blood pressure during the activity.

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