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The aorta is the largest artery in the body.
It starts at the top of the heart, rises up (ascending aorta) and passes over the heart in an arch before a portion travels down through the chest to the lower abdomen (descending aorta).
Along the way, it has many branches that supply blood to vital organs as well as your arms and legs. Several disease processes can weaken the wall of the aorta. These weakened areas can tear.
The wall of an artery is made up of three layers. When there is a tear along the wall of the aorta, blood can flow in between the layers of the wall (aortic dissection) resulting in decreased blood flow (ischemia) to vital organs.
If the tear extends through all three layers, blood can leak out of the aorta into surrounding tissues (aortic rupture). Both are life-threatening conditions and usually require an emergency intervention or they can result in death.
When the tear of the aortic wall occurs in the aorta as it moves up through the chest (ascending aorta) or arch, it is known as a Stanford Type A dissection. Tears that occur anywhere in the descending aorta or abdomen are known as Stanford Type B dissections.
What causes an aortic dissection?Toggle accordion item
The exact cause of an aortic dissection is unclear and remains the focus of ongoing research at the Center for Aortic Disease. Common risk factors include:
- Atherosclerosis (the build-up of fatty plaque) causing hardening of the arteries
- Blunt trauma, such as hitting a steering wheel of a car during an accident
- High blood pressure
Other risk factors and conditions linked to aortic dissection include an abnormal (bicuspid) aortic valve, narrowing (coarctation) of the aorta, Marfan syndrome, Ehlers-Danlos syndrome, previous heart surgery or procedures, pregnancy, and inflammation of the aorta.
How is an aortic dissection diagnosed?Toggle accordion item
During a regular exam, your health care provider will take your family history and listen to your heart, lungs, and abdomen using a stethoscope. If there is aortic dissection present, the exam may find:
- A blowing murmur over the area of the tear, a heart murmur, or other abnormal sound
- A difference in blood pressure between the right and left arms, or between arms and legs
- Low blood pressure
- Signs resembling a heart attack
- Signs of shock, but with normal blood pressure.
Aortic dissection is most often diagnosed by using tests such as X-ray, aortic angiography, MRI, CT scan with contrast, Doppler ultrasonography, or an echocardiogram.
Why does this make people sick?Toggle accordion item
An aortic dissection occurs when a tear develops in the inner wall of the aorta. This will create two channels: one in which blood continues to travel, and another in which blood stays still between the layers. When the channel with non-travelling blood gets bigger, it can push on other branches of aorta. This can narrow the other branches and reduce blood flow through them. This can cause rapid heart rate, anxiety and feeling of doom, fainting, dizziness, clammy skin, nausea, and vomiting. It may also cause failure of the organs that have reduced blood flow.
In most cases, symptoms may begin suddenly and include severe chest pain that may feel like a heart attack. It may be felt below the chest bone, then moves under shoulder blade or back. It can be described as sharp, stabbing, tearing or ripping.
How are aortic dissections treated?Toggle accordion item
An aortic dissection is a life-threatening condition and needs treatment right away. When the tear or dissection is anywhere in the part of the aorta that goes upward from the heart (ascending aorta), it usually requires surgery. Dissection that occurs in the other part of the aorta (descending aorta) can often be managed with medicines for the short-term but will eventually require surgery, usually about half of all cases.
Medications: Patients with uncomplicated dissection confined to the descending aorta can be treated with medical therapy. Drugs that lower blood pressure may be prescribed and may be given intravenously. Beta blockers are the drug of choice.
Surgery: Surgery is required for almost all ascending aortic dissections. Surgery is also performed for complicated descending aortic dissections, like dissections with high blood pressure that does not respond to medications, dissections that reduce blood flow to vital organs or limbs, and dissections that are about to leak (rupture).
- Open Surgery: A cardiovascular surgeon will perform this surgery under general anesthesia by making an incision along the center or side of the chest, or in the abdomen. The surgeon will then use clamps to stop the blood flow temporarily in the aorta above and below the dissection. This may require use of a heart-lung bypass machine. The section of the aorta where the dissection starts is replaced with an artificial graft (a durable fabric tube). The graft is sewn in place with fine stitches and the incision is closed. Patients are monitored in the intensive care unit (ICU) after surgery and will usually require a hospital stay of at least 7-14 days.
- Endovascular treatment: A vascular surgeon will perform this under general anesthesia by making an incision in the groin, followed by inserting and deploying a fabric-covered metal or plastic tube (a stent graft) at the top of the dissection. This stent graft will provide a new pathway for blood flow at the site of the dissection. It also prevents further expansion of the dissection and usually keeps the aorta from rupturing. Patients are closely monitored after surgery and usually have shorter hospital stays than with an open repair. This technique requires continued monitoring with CT scans every 6-12 months following discharge from the hospital to look for problems with the stent graft. However, not everyone is a candidate for endovascular treatment.
What is the long-term outcome for patients with aortic dissections?Toggle accordion item
The outcome is often good if the aortic dissection is medically managed and monitored, or repaired with surgery to prevent an aortic rupture. Those who survive will need life-long, aggressive treatment of high blood pressure. They will need regular CT scans to monitor the aorta.