An abdominal aortic aneurysm (also called AAA) is a condition in which the wall of the abdominal aorta is at least 50% larger than normal.
Anatomy of the aorta
- Originates above the left ventricle,
- Runs vertically upwards towards the cervical spine (ascending aorta),
- Then bends downwards (aortic arch) and pulls as a descending aorta over the chest area (descending aorta) to the abdomen (abdominal aorta).
The aorta transports the oxygenated blood pumped from the heart to the rest of the body.
The abdominal aorta begins at the diaphragm and descends to the 4th lumbar vertebra, where it divides into the two large pelvic arteries.
The function of the abdominal artery is to transport oxygen-rich blood to the abdominal organs and pelvis.
The diameter of the aorta is:
Men Women ascending aorta 3.71 cm 3.45 cm descending aorta 2.82 cm 2.54 cm
Source: Kalsch H, Lehmann N, Mohlenkamp S, et al. Kalsch H, Lehmann N, Mohlenkamp S, et al. Body-surface adjusted aortic reference diameters for improved identification of patients with thoracic aortic aneurysms: results from the population-based Heinz Nixdorf Recall study. International journal of cardiology. 2013;163:72–8.
If the aneurysm bursts, it can cause dangerous and fatal bleeding.
The most common aneurysms occur in the abdominal aorta, in the aortic area below the kidneys.
An abdominal aortic aneurysm at this height is also known as an infrarenal aneurysm.
An aneurysm can be classified by:
This swelling can form anywhere, but occurs especially along the arteries:
- In the abdomen,
- In the brain,
- In the chest.
Types of aneurysm by localization
An aneurysm can develop anywhere along the aorta:
- An aneurysm that occurs in the area of the aorta that passes through the abdomen (abdominal aorta) is called an abdominal aortic aneurysm.
- An aneurysm that occurs in the chest area is called a thoracic aortic aneurysm and can involve the aortic root, ascending aorta, aortic arch, or descending aorta.
- An aneurysm that affects the aorta in the area between the abdomen and thorax is called a trans-abdominal aortic aneurysm.
Aneurysms can also develop in other blood vessels:
- The popliteal vessels on the leg: an aneurysm of the femoral artery in the hollow of the knee
- Visceral vessels: an aneurysm of the artery of an internal organ.
Visceral arteries that may have an aneurysm include:
- renal artery of the kidneys,
- Lienal artery of the spleen,
- hepatic artery of the liver,
- pulmonary artery of the lungs (rare),
- Superior mesenteric artery of the stomach and intestines.
Classification of aortic aneurysms
The Stanford classification divides aortic dissection into type A and type B:
- Type A affects the ascending aorta and the aortic arch. The ascending aorta lies behind the aortic arch and the anonymic artery.
- Type B does not affect the ascending aorta. The descending aorta is located behind the left subclavian artery.
- Type I: aorta, aortic arch and descending aorta (30%).
- Type II: only the ascending aorta (20%).
- Type III: descending aorta distal of the left clavicle (50%).
A variant of this disorder is the aneurysm dissecans of the aorta.
A vessel wall is formed by three layers.
- Intima (inner layer of endothelial cells)
- Media (contains smooth muscle fibers)
- Adventitia (outer connective tissue)
Aneurysms can be both real and fake.
The wall of a true aneurysm includes all layers of the wall.
The wall of a false aneurysm (or pseudoaneurysm) involves only the outer layer (tunica adventitia).
An aortic dissection begins with thinning of the inner layer of the artery wall. If the detachment of the innermost layer occurs, blood enters the wall and causes the inner wall to separate from the other.
This leads to aortic wall weakness with a high risk of rupture.
The middle layer of the aorta gives the blood vessel tensile strength and elasticity.
This layer consists of several structural proteins, in particular:
The composition of the wall of the aorta depends on the location:
- In the ascending part there is a lot of elastin,
- In the descending thoracic and abdominal part, there is an increasingly lower elastin content and more collagen. For this reason, an aneurysm in the lower part of the descending aorta is more likely.
In addition, there are more enzymes in this area that break down the structural proteins.
As a result, the wall:
- becomes much weaker,
- It becomes much more rigid.
High blood pressure promotes the dilation of an aneurysm.
Aortic dissection can develop into a dangerous emergency situation.
- Dissection is called acute if it is diagnosed within 14 days of onset.
- If it has existed for some time, it is referred to as chronic dissection.
Causes of abdominal aortic aneurysm
An abdominal aortic aneurysm can be caused by many factors that cause the breakdown of the proteins in the aortic wall that serve to stabilize. The exact cause of this is not known.
Atherosclerosis (deposition of fatty substances and cholesterol) is believed to play an important role in aneurysmal disease.
Risk of atherosclerosis are:
- age (over 60 years),
- Male sex (the disease is four to five times more common in men than in women),
- family history (first-degree relatives such as father or brother),
- heredity, an aneurysm can be hereditary (genetic),
- hyperlipidemia (increased fat levels in the blood),
- hypertension (high arterial blood pressure),
Other diseases that can cause an abdominal aortic aneurysm include:
- Hereditary diseases: connective tissue diseases such as Marfan syndrome, Ehlers-Danlos syndrome, Turner syndrome.
- Marfan syndrome can lead to dilation of the basal aorta or aortic bulb, which is the part that includes the aortic valve and the aortic ring.
- Congenital syndromes (congenital) such as bicuspid aortic valve or coarctation of aortic artery,
- giant cell arteritis (a condition in which the temporal artery and other blood vessels in the head and neck become inflamed, reducing blood flow in the affected areas and leading to persistent headaches and loss of vision),
Aortitis: infection of the aorta caused by pathogenic pathogens such as syphilis, salmonella or staphylococci. These infectious diseases are rare.
Signs and symptoms of aortic aneurysm
Symptoms of this disease can be different depending on its localization.
Normally, the aortic aneurysm grows slowly and causes no symptoms.
Many aneurysms never burst.
Typically, this extension is small and also remains small, although it can also expand over time. In such a case, it causes symptoms.
The rate of growth of an aortic aneurysm is difficult to predict.
Symptoms of thoracic aortic aneurysm
Symptoms may occur:
- If the aneurysm is large and presses on the middle structures in the chest (for example, the reccures laryngeal nerve), swallowing, sound formation (voice) and breathing may be impaired.
- In case of a rupture.
Symptoms of thoracic aneurysm are most significant in the area of the aortic arch.
Symptoms of thoracic aortic aneurysm include:
- Recurrent acute chest pain,
- pain when breathing,
- lowering the voice,
If the aneurysm ruptures, there is a sharp drop in blood pressure.
This circumstance requires immediate medical intervention, as it can lead to death.
Symptoms of abdominal aortic aneurysm
The aneurysm leads to:
- Stomach ache
- chest pain,
- Back pain
- groin pain,
- leg pain,
- pain in the buttocks,
- Pain in the right or left flank.
The intensity of pain can vary from mild to severe and is not movement-dependent.
Some positions, such as sitting and lying down, may be more comfortable than standing upright.
Young people, in particular, are prone to this type of aneurysm.
Symptoms of aortic aneurysm rupture
If the aneurysm ruptures, the blood flow in the lower part of the body is reduced, the consequences are:
- Severe back or chest pain,
- Severely low blood pressure,
- tachycardia (accelerated heartbeat),
- Cold feet,
- Tingling in the legs.
Mortality from aorta rupture is very high: 70 to 90% of patients do not reach the hospital alive.
Abdominal or thoracic aneurysm – surgical intervention
The aorta is the largest blood vessel in the body.
The abnormal dilation of this artery is called an aneurysm and comes not infrequently.
Normally, the deformation affects only a small area of the aorta.
An aneurysm occurs when a segment of the vessel:
- is weakened,
In general, the expansion is small at the beginning, but grows over time.
Aneurysms are dangerous because they can burst and lead to internal bleeding.
Diagnosis of aortic aneurysm
Usually, an aneurysm is accidentally diagnosed during an examination or test for other reasons.
Experts recommend checking men for the following characteristics regarding an abdominal aortic aneurysm:
- smokers aged between 65-75 years,
- At least 60 years of age and with blood relatives (for example, father or brother) who have an aneurysm. These individuals have a higher risk factor for an aneurysm than women or men who don’t smoke.
Examinations for an aortic aneurysm
Tests performed to find out the position, size, and growth rate of an aneurysm include:
1) Echography of the abdomen
Echography is used to determine the size of the aneurysm.
Depending on the size of the dilation, echography may be required:
- Every 6-12 months,
- Every 2 or 3 years.
2) Computed tomography (CT) and magnetic resonance angiography (MR angio), they are performed when a more accurate assessment of echography is required.
This is important when information about the relationship of the aneurysm to the blood vessels of the kidney or other organs is necessary.
The doctor needs this information especially before surgery.
3) Echocardiogram, which is an ultrasound examination performed to evaluate the heart.
A transthoracic (TTE) or transesophageal echocardiogram (TEE) is used to diagnose a thoracic aortic aneurysm.
4) Angiogram. An angiogram shows:
- size of the aneurysm,
- presence of aortic dissection or coagulated blood,
- Other changes in blood vessels.
Treatment of aortic aneurysm
Abdominal aortic aneurysm can be a disease that adversely affects the patient’s health. It is usually treated by surgery.
Therapy of this pathology depends on three factors:
- State of health of the patient.
When to operate?
If the swelling on the artery is small, the doctor can regularly check the patient.
If an aneurysm is observed with increasing size, the wall of the artery may burst.
The best treatment option is vascular surgery.
Surgical intervention for aortic aneurysm
The operation consists of inserting a prosthesis (tube) inside the aorta and at the level of the aneurysm, through which the blood can flow without risk of rupture.
In surgical treatment, prostheses made of synthetic material, for example, Dacron, are used.
In this method, the prosthesis is fixed in the healthy area above and below by means of a stent (a supporting metal mesh).
The stent can be:
- Extended by balloon.
The aortic walls are no longer affected by blood pressure, which prevents the aneurysm from dilating.
- It is less invasive than open thoracic surgery and causes less blood loss.
- The healing times are short, a longer stay in the intensive care unit is not necessary.
The indications for intervention in the aneurysm of the (thoracic) ascending aorta are:
Without changes to the heart and vessels 5.5mm With bicuspid aortic valve 50mm With Marfan syndrome 45mm
Types of surgery for aortic aneurysm
Treatment provides for surgical intervention:
- On the open thorax
- Endoscopic – without abdominal or thoracic incision
In classical surgery, the surgeon proceeds as follows:
- It opens the chest and/or abdomen,
- It replaces part of the aorta,
- He sutures the artery.
With the endoprosthesis you need support points, a small tube inside a catheter must rest on two healthy parts of the aorta:
- “Proximal collar”
- “Distal collar”.
The procedure with the endoprosthesis does not replace the traditional operation.
Since there is no suture that fixes the prosthesis, this method is not stable and a second procedure may be required in 15-20% of patients.
Requirements for endovascular intervention
- upstream and downstream of the aneurysm must be intact parts,
- blood vessels suitable for catheter passage,
- No excessive calcifications and angles.
Only 30-50% of patients meet these conditions.
Advantages and disadvantages of endovascular surgery
- Inpatient stay is short,
- Local anesthesia.
- Radiation exposure
- Necessary controls,
- 1 % rupture in 3 years,
- 6-9% second intervention.
Description of the procedure
Endovascular surgery for aortic aneurysm
Source: Society for Vascular Surgery
This operation can be performed under anesthesia:
In case of an aneurysm on the aortic arch, the incisions are made:
- In the bar,
- On the neck.
In abdominal aortic aneurysm and descending chest aneurysm, the surgeon makes two small incisions in the right and left groin.
- From here, a thin tube (catheter) is inserted and advanced into the area of the aneurysm.
- An angiography is performed to visualize the arteries inside the body.
- An expandable graft or stent (tissue-coated metal structure) is placed through the catheter in the aorta.
- If the stent is in the correct position, the surgeon expands it.
- In this way, he presses against the healthy part of the aorta to prevent him from moving.
- At the end of the procedure, the blood flows through the stent and can no longer enter the aneurysmal bulge.
This procedure is suitable for surgery below the renal arteries.
In other cases, there are grafts with openings that allow the graft to bend and align with the arteries that originate from the aorta.
The procedure for an aortic aneurysm takes 1.5-2.5 hours.
Traditional or open surgery for aortic aneurysm
The operation on the ascending aorta and the aortic arch is performed with extracorporeal blood circulation, with the descending aorta and the abdominal aorta this is not always performed.
The operation is performed under general anesthesia.
Operation of an aneurysm of the ascending aorta and the aortic arch
- The surgeon makes a vertical incision on the thorax and splits the sternum into two parts.
- From here, he reaches the aorta and replaces the deformed part with an artificial prosthesis.
- During the operation of the aortic arch aneurysm, it is necessary to reimplant the blood-carrying arteries:
- To the upper limbs,
- To the brain.
Operation of an aneurysm of the descending aorta and abdomen
- The surgeon makes an incision on the left side of the chest, but if the aneurysm extends to the abdominal aorta, the incision continues to the abdomen.
- The aortic section with the aneurysm is completely replaced by a synthetic prosthesis.
- The surgeon must reimplant the arteries originating from the aorta, i.e. all arteries that carry blood:
- To the spinal cord,
- To the kidneys,
- To the digestive organs.
Complications/risks of surgery for an aortic aneurysm
- bleeding or infection,
- heart attack (rare),
- Paraplegia (paralysis of the lower extremities).
The aorta is a large blood vessel with many branches.
The prosthesis closes the branches, especially the arteries of the medullar circulation such as the anterior spinal artery.
The scientists found that the hypogastric arteries run back with the lumbar arteries and form a huge network.
Therefore, despite the occlusion of the intercostal arteries, compensation may be sufficient.
Today, the risk of spinal cord injury is 2-3%.
Postoperative recovery period after aortic aneurysm surgery
- Usually, inpatient treatment lasts two to three days after surgery.
- It takes a few weeks or months to achieve a full recovery.
- About 98% of patients recover completely.
Traditional or open surgery
- Usually, the patient remains in the hospital for 7-10 days after the procedure.
- Recovery times last a few weeks or months.
- About 95-97% of patients recover completely.
What are the expectations? Prognosis for a patient with aortic aneurysm
If an abdominal aortic aneurysm ruptures, it is an emergency.
Less than 20% of patients survive an aneurysm rupture.
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