Abdominal Aorta Aneurysm

Abdominal aortic aneurysm (AAA) is ballooning and enlargement of the lower part of the aorta in the abdomen region. The aorta is the main artery (blood vessel) of the body that begins in the heart and supplies blood to rest of the body through its multiple branches. Distension of the aorta and aneurysm can happen in its course through the chest (thoracic aorta aneurysm) or the abdomen (abdominal aorta aneurysm).

Abdominal aorta aneurysm

Causes

 The walls of the aorta, like other blood vessels, is made up of endothelial cells (lining cell of the blood vessels), elastic tissue and muscles. An aneurysm develops when the walls of the artery becomes weak and bulges out.

The exact cause for abdominal aorta aneurysm is not known. The predisposing factors include:

  • Smoking
  • Elderly age
  • Male gender (AAA is most often seen in men over the age of 60 years)
  • Genetic predisposition (having family history of AAA increases the risk)
  • Congenital defects causing weakness of blood vessels (such as Marfan’s syndrome)
  • High blood pressure
  • Atherosclerosis (thickening of the arteries and deposition of fat and plaque that blocks the blood flow)
  • High cholesterol levels

atherosclerosisSymptoms

Aneurysms can develop and progress gradually over many years without causing any symptoms. It may be incidentally discovered when an abdomen scan is done or while getting a medical examination of the abdomen for some other problems. Sometimes the physician may feel a pulsating enlargement in the abdomen when examining the patient’s tummy.

AAA can cause symptoms when it distends rapidly, ruptures into the abdomen or there is blood leak within the walls of the aorta (called as aortic dissection).

A ruptured aneurysm is a medical emergency. The symptoms of rupture or dissection can include:

  • Pain in the back or abdomen, which can spread to the groin, legs or buttocks. The pain may be sudden, severe, persistent and not relieved by change in position or pain killers
  • Cold clammy skin
  • Dizziness
  • Nausea and vomiting
  • Losing consciousness
  • Rapid heart rate
  • Shock
  • Death in short duration

Diagnosis

Many cases of AAA do not cause symptoms and are incidentally detected when undergoing imaging tests (scans) such as Ultrasound scan, CT scan, MRI scan or angiogram of the abdominal region.

Your doctor may sometimes diagnose AAA during physical examination with findings such as:

  • Mass (lump) in the abdomen
  • Pulsating bulge or strong pulse around your navel

If you are having any symptoms suggestive of AAA, your doctor may order tests such as Ultrasound scan, CT scan or MRI scan to make the diagnosis.

Treatment

  • When an aneurysm is small and there are no symptoms, your doctor will discuss with you about the risks of bleeding is higher or lower than the risk of undergoing surgery. You may be advised to undergo periodic (every six months) monitoring ultrasound tests to check the size of the aneurysm.
  • When surgery is not needed or possible, or if you decide not to have it, your doctor may advise certain medical measures such as smoking cessation, cholesterol reduction, and blood pressure control.

If the risk of bleeding is high, you may be recommended to undergo surgery. If there is bleeding from an aortic aneurysm inside your body, you will require emergency surgery. The aim of the surgery is to replace the weakened portion of the blood vessel with a piece of synthetic tubing.

There are two types of surgery:

  • Open surgical repair: A big incision is made on the abdominal wall to access the aorta. The diseased part of the aorta is then replaced with a graft made of synthetic-material which acts as a substitute blood vessel.
  • Endovascular repair: In this procedure, no cut is made on the abdominal wall. A small incision is made in the groin through which the stent-graft is inserted upward through the arteries into the diseased part of the aorta, and the graft is opened and left there. The stent-graft reinforces the weakened portion of the aorta and prevent the risk of rupture. The recovery is faster in this type of treatment as the abdominal wall is not cut.

Prevention

Some of the measures that can help in preventing getting an aneurysm or reduce the risk of aneurysm growing bigger or rupturing include:

  • Quitting smoking
  • Eating heart-healthy diet
  • Exercising and maintaining ideal body weight
  • Keeping blood pressure and sugars under control (if you have hypertension or diabetes)
  • Reducing/managing stress

Complications

  •  Rupture of aneurysm: The risk of rupture depends on the size of the aneurysm. Small aneurysms (< 4 cm) have much less risk compared to large aneurysms (>6 cm).  The annual risk of rupture based on the size is as follows:
    • < 4 cm: < 0.5 %
    • 4.0 – 4.9 cm: 0.5 – 5 %
    • 5.0 – 5.9 cm: 3 – 15%
    • 6.0 – 6.9 cm: 10 – 20 %
    • 7.0 -7.9 cm: 20 – 40%
    • ≥8.0 cm: 30 – 50%
  • Inflammation of aneurysm – Can cause pain in the abdomen
  • Aorto-enteric fistula – Abnormal conection formed between aorta and the bowel
  • Aorto-venous fistula – Abnormal connection between the aorta and a vein.
  • Thromboembolism- Blood clots can be formed in the aorta and block the blood flow to the legs.

Next Steps

 If you are detected with an abdominal aortic aneurysm during any scans, consult a vascular surgeon for further evaluation and treatment planning. 

Red Flags 

If you have abdominal aorta aneurysm, be alert to symptoms of rupture such as pain in the abdomen or back, rapid heart beat, cold extremities and faintness. Seek immediate medical attention when you experience such symptoms.

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References

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  • NHS choices. Abdominal aortic aneurysm. Accessed at http://www.nhs.uk/conditions/Repairofabdominalaneurysm/Pages/Introduction.aspx on 17 June 2016
  • Cleveland Clinic. Abdominal Aortic Aneurysm. Accessed at http://my.clevelandclinic.org/services/heart/disorders/aortic-aneurysm/Abdominal-Aortic-Aneurysm on 16 June 2016
  • Stanford Healthcare. Abdominal Aortic Aneurysm. Accessed at https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/abdominal-aortic-aneurysm.html on 16 June 2016.
  • Medline Plus. Abdominal aortic aneurysm. Accessed at https://www.nlm.nih.gov/medlineplus/ency/article/000162.htm on 17 June 2016.

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