The aorta

The aorta and aortic dissection

The aorta is the large blood vessel that exits the heart and delivers blood to the body. It is composed of layers of muscle that need to be strong enough to withstand the pressure generated by the beating heart. In some people, a tear can occur in one of the layers of the aortic wall, and blood can track between the wall muscles.

This is called an aortic dissection and is potentially life-threatening. The type of dissection and treatment is dependent upon where in the aorta the dissection occurs. Type A dissections are located in the ascending aorta which runs from the heart to the aortic arch where blood vessels that supply the brain and arms exit. Type B dissections are located in the descending aorta.

The majority of aortic dissections occur as a long-term consequence of poorly controlled high blood pressure. Other associated conditions include:

• Marfan's syndrome


• trauma


• pregnancy


• a late post-operative complication of open heart surgery
  
  

The pain from aortic dissection occurs suddenly and often is described as intense stabbing or ripping. It may be constant, or the pain may be pleuritic (worse with a deep breath) Often it radiates to the back. The pain of dissection is often confused with the pain of heart attack, esophagitis, or pericarditis.

Diagnosis is based upon history, review of the risk factors, physical examination, and clinical suspicion. Physical examination may reveal loss or delay of pulses in the wrist or leg when comparing one side to the other. A new heart murmur may be detected if the dissection involves the aortic valve, where the aorta leaves the heart. If blood vessels exiting the aorta are involved in the area of dissection, the organs that they supply may be at risk. Stroke and paralysis can be seen in dissection. Blood supply can be lost to kidneys and bowel, and to arms and legs.

The diagnosis of aortic dissection is confirmed by imaging, most commonly by CT angiography of the aorta.

Type A dissections of the ascending aorta are treated by surgery in which the damaged piece of aorta is removed and replaced with an artificial graft. Sometimes the aortic valve needs to be repaired or replaced if it is damaged.

Type B dissections are initially treated by medications to control blood pressure and maintain it in a normal range. Beta blockers and calcium channel blocker medications are commonly used. If medical therapy fails, surgery may be necessary.

If the dissection tears completely through all three layers of the aortic wall, then the aorta ruptures. This is a catastrophe, and more than 50% of affected patients die before reaching a hospital. The overall mortality of aortic rupture is greater than 80%.

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