Aortic aneurysm

There are two major types of aortic aneurysms. A patient may present with any of the following:

• Thoracic aortic aneurysm: Present in that part of the aorta that traverses through the chest cavity.
• Abdominal aortic aneurysm: Present in that part of the aorta that traverses through the abdomen.

Some individuals may have a combination of both thoracic and abdominal aortic aneurysm.

Symptoms may vary, based on the type of aortic aneurysm

Thoracic aortic aneurysm 

Physical examination of the patient is extremely important to successfully diagnose aortic aneurysms.

• Most unruptured aortic aneurysms are asymptomatic. A large fraction of aortic aneurysms are discovered on investigations such as chest X-rays, computed tomography scans (CT scans) or echocardiogram
  • Compression effects or local mass effects include:
  • Compression of trachea causing cough, dyspnoea (shortness of breath) and wheezing.
  • Compression of the recurrent laryngeal nerve causing hoarseness of voice.
  • Compression of the oesophagus (food pipe)
• Distended neck veins due to compression of superior vena cava
• Chest pain
• Abdominal pain
• Difficulty swallowing 
• Back pain due to compression of spine
• Murmurs or additional heart sounds due to a valvular dysfunction called aortic regurgitation. The type of added heart sound heard in this case is a diastolic murmur.

Abdominal aortic aneurysm

• Most patients with abdominal aortic aneurysms have no symptoms. They are usually discovered incidentally on clinical examinations or on radiological scans like ultrasound, computed tomography (CT) scans or magnetic resonance imaging (MRI) scans.
• Pain: Back pain, abdomen pain or groin pain may occur due to the pressure exerted by the aneurysm on surrounding structures.
• Abdominal swelling: A pulsatile (beating or throbbing) swelling may be observed on the patient’s abdomen.
• Weight loss
• In case of rupture of the aneurysm, the patient may present with low blood pressure, loss of consciousness and severe abdominal pain. 
• Sometimes, on examination a bruising on the abdominal flanks may be observed (Grey-Turners sign) 

Aortic aneurysms may arise due to a single factor or may be caused by a combination of factors.

The risk factors are as follows:

• Smoking is the single most important risk factor that is associated with the development of aortic aneurysms.
• High blood pressure
• High blood cholesterol levels
• Atherosclerosis: It is defined as the accumulation of fat and cholesterol inside the arterial walls which hinders the flow of blood.
• Connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome are inherited diseases and risk factors for aortic aneurysm, aortic dissection and problems with the aortic valve. Hence, it is important to ask a patient regarding any family history of genetically inherited diseases.
• Being male: Studies suggest that males are more likely to suffer from aortic disease as compared to females
• Advanced age: The chances of suffering an aortic aneurysm increase with age
• Lung diseases such as chronic obstructive pulmonary disease (COPD) 
• Trauma and injuries increase the likelihood of developing aortic diseases
• Infections such as tuberculosis, HIV (Human immunodeficiency virus) and brucellosis. 
• Inflammatory diseases like Takayasu arteritis and Behçet's disease

Depending on the type of aortic aneurysm, diagnosis may involve the following:

Thoracic aortic aneurysm

Thoracic aortic aneurysms are diagnosed based on clinical examination, radiological and routine biochemical investigations. 

The biochemical investigations to be performed are as follows: 

• Complete blood count (CBC)
• Coagulation screening to detect any bleeding disorders
• Kidney function test
• If the doctor is suspecting an inflammatory cause, then ESR (Erythrocyte sedimentation rate) test and CRP (C-Reactive protein) test will also be performed
• Sometimes, depending on the suspected cause relevant tests will be performed for example, HIV or syphilis 

The radiological investigations to be performed are as follows: 

• Chest X-ray: A thoracic aortic aneurysm can be detected on a plain Chest X-ray by identifying the widening of the mediastinum (Space between the two lungs in the chest cavity) with the deviation of the trachea (windpipe). Even if this feature is present, further investigations are needed to make a definite diagnosis. 
• Computed tomography scan (CT scan) with contrast: It is the most appropriate investigation that is usually conducted for diagnosing a thoracic aortic aneurysm. Generates 3D images using an X-ray machine. It makes it possible to determine the level (Section of aorta) and the size of the aneurysm. 
• Transoesophageal echocardiography (TOE): It is beneficial as it helps in identifying any complications associated with Thoracic aortic aneurysms such as aortic insufficiency and aortic dissection. Apart from people suspected of having thoracic aortic disease, it is routinely conducted in patients with genetic disorders like Marfan disease.
• Magnetic resonance imaging (MRI) angiography: Performs the same function as the computed tomography (CT) scan as it shows the anatomical structures well. The only difference is that this modality uses magnetic waves instead of X-rays. 
• Coronary angiography: May be performed in certain cases like assessment for fitness of surgery in patients with thoracic aortic disease.

Abdominal aortic aneurysm

Diagnosis of abdominal aortic aneurysm is usually made by a combination of patient profile, clinical examination, biochemical and radiological investigations. 

Blood tests that are performed are as follows: 

• Complete blood count (CBC)
• Coagulation screening to identify any bleeding disorders
• Liver function test
• Blood matching and arranging blood for transfusion if surgery is planned
• If inflammatory cause is suspected, an Erythrocyte sedimentation rate (ESR) and C - reactive protein (CRP) tests are to be performed. 
• ECG (Electrocardiogram) is also to be performed to rule out any cardiac complication.

Radiological investigations are required to make a definite diagnosis of abdominal aortic aneurysm. The following investigations are to be ordered: 

• Ultrasound scan: It is the initial/first radiological investigation that is performed in patients with suspected abdominal aortic disease. It is convenient, easy to perform and cheap. It can assess the aorta in great detail. 
• Computed tomography scan (CT scan): It is considered superior to an ultrasound and is the most appropriate investigation that is performed in patients suspected of suffering from abdominal aortic aneurysm. It has the advantage of providing more anatomical details. A thin-slice contrast-based CT angiography (Using a dye to identify the disease more accurately) is preferred over a plain CT scan as per universal guidelines. 
• Abdominal X-ray: May be performed to rule out any other causes of severe abdominal pain such as perforation of an ulcer. It rarely shows an abdominal aortic aneurysm.

There are surgical and non-surgical treatment options for both types of aortic aneurysms:

Patients with thoracic aortic aneurysms

Which patients require surgery? 

• Immediate surgery is needed if the patient has a complicated disease like ruptured TAA or aortic dissection
• Surgery to be considered for patients with a symptomatic TAA (Patients who present with clinical features) 
• Also to be considered in certain asymptomatic cases. For example, if aneurysm diameter is >5.5cm or patients with a genetic disorder like Marfan syndrome. 

The surgical technique that is commonly used is called an Endovascular repair. It is also known as endovascular stenting. It is a minimally invasive procedure that involves placing a stent via a blood vessel. Possible complications of this method are stroke (reduction in blood supply to the brain) and acute kidney failure. 

Medical management

For those patients who do not meet the criteria for undergoing surgery, medical treatment is initiated.  This involves the following: 

• Controlling the blood pressure with the help of drugs like beta blockers. 
• Patients to stop smoking
• Treatment of the underlying cause for example, infection
• Treatment of other risk factors like high cholesterol or high lipid levels with the help of lipid lowering drugs (statins).
• Regular monitoring of the thoracic aortic aneurysm with the help of CT or MRI every six months 

Patients with abdominal aortic aneurysm

Which patients require surgery? 

• Patients with abdominal aortic aneurysm of size >5.5cm in diameter 
• Patients with abdominal aortic aneurysm that is expanding at the rate of >1cm/year
• Patients with symptomatic abdominal aortic aneurysms 
• Complicated abdominal aortic aneurysm such as aortic rupture

Types of surgeries that are routinely performed are: 

• Surgical (open) repair: It is common traditional surgery that involves clamping of the abdominal aorta and placing a graft to replace the aneurysmal portion of the blood vessel. The graft is considered to be highly effective for a long duration of time. 
• Endovascular repair: A stent with a graft is inserted through the femoral artery (an artery in the thigh), which realigns the aneurysm and diverts the flow of blood through the graft. 

Endovascular repair has better short term results as it reduces the hospital stay and 30 day perioperative and postoperative mortality. But, studies suggest that it has a higher rate of rupture of the aneurysm. In terms of long term outcomes, both procedures are equally effective. Hence, it is recommended that in young patients a Surgical (Open) repair is to be performed. 

Medical management

Medical treatment is provided to those patients who do not meet the specific criteria for surgical repair. 

• Blood pressure control to be encouraged using drugs like beta-blockers
• Cessation of smoking 
• Drugs that reduce the occurrence of various cardiovascular diseases like Aspirin (Anti-platelet drug) and Statins (lipid-lowering drugs)
• Weight loss
• Exercise

Patients with abdominal aortic aneurysm of size less than 5.5cm are supposed to undergo routine monitoring using Ultrasound scans. The frequency of these scans is as follows: 

• 3-4.4cm: Annual ultrasound
• 4.5-5.4 cm: Ultrasound scan every three months

The outcome, too, depends on the type of aneurysm:

Thoracic aortic aneurysm

The most common cause of death in these patients is rupture of the aneurysm. In case of a rupture, the patient usually dies within six hours. 

In patients undergoing surgery, 30 day perioperative (occurring during or around the time of surgery) mortality is around 5%.

Abdominal aortic aneurysm

Patients who suffer a rupture of the abdominal aortic aneurysm have a mortality of 80%. The risk of rupture depends on the diameter of the aneurysm. Most patients usually die before reaching the hospital. Even after surgical repair of a ruptured abdominal aortic aneurysm, mortality rate stands at 50%. 

70% of patients undergoing open or endovascular repair usually will survive for the next five years after the surgery. 

Patients who don’t undergo surgery and have an abdominal aortic aneurysm of more than 5 cm have an annual survival rate of only 20%.