• En

Aneurysm

Dr. Suvansh Raj NirulaMBBS

November 25, 2020

November 27, 2020

Aneurysm
Aneurysm

An aneurysm is a localised abnormal ballooning (dilatation) of a blood vessel that has become weak at one or more points.

Arteries are blood vessels that take blood from the heart to the rest of the body. An arterial aneurysm can happen anywhere in the body but it is more commonly seen in the stomach (abdominal aorta), pelvic region (iliac artery), thighs (femoral artery) and legs (popliteal artery). A cerebral aneurysm (a bulge in the artery in the brain) can prove lethal if not detected in time.

There are two classifications of aneurysms:

  • True aneurysms: A true arterial aneurysm involves all the three layers of the artery. These three layers are the tunica intima (innermost layer), tunica media (intermediate or middle layer) and tunica adventitia (outermost layer). The ballooning of the arterial wall can be symmetrical (called a fusiform aneurysm) or localised blow out (saccular aneurysm).
    True aneurysms are commonly located at the abdominal aorta, iliac artery, femoral artery and the popliteal artery.
  • False aneurysms/pseudoaneurysms: A pseudoaneurysm does not affect the vessel wall. It is basically a collection of blood that is held in place around the vessel by the wall of a connective tissue.
    A pseudoaneurysm might be observed after a trauma or due to the leakage of blood encapsulated by the surrounding connective tissue. It may also occur after certain procedures like an angiogram (test to detect blockages in an artery) or angioplasty (to open the blockage by pushing the cholesterol plaque outwards).
    A false aneurysm usually progresses to form a blood-filled cavity that can ultimately rupture or lead to thrombosis (formation of a blood clot in a blood vessel). The patient usually presents with a painful pulsatile mass—the skin over it may appear red.

Read on to know about aneurysms, where in the body they can occur, their symptoms, causes, diagnosis and treatment:

Types of aneurysms

Apart from their classifications as true (fusiform and saccular) and false aneurysms, aneurysms can also have different signs and complications based on where they occur in the body. These are the different sites where an aneurysm might occur:

  • Cerebral aneurysms; for example, berry aneurysm
  • Aortic aneurysms: Thoracic aortic aneurysm and abdominal aortic aneurysm
  • Popliteal artery aneurysms: The popliteal artery is a branch of the femoral artery
  • Femoral aneurysms: Aneurysms that are observed in the femoral artery in the thighs

Cerebral aneurysms

Studies suggest that 2-3% of all adults have an unruptured and uncomplicated intracranial (inside the skull) aneurysm. This number has increased in recent times due to a rise in detection, thanks to technology such as magnetic resonance imaging scans (MRI scans) and computed tomography scans (CT scans).

Saccular aneurysms are the most common type of cerebral aneurysms. They are called berry aneurysms as they tend to be berry-shaped. These aneurysms are situated at the point where the cerebral artery leaves the circle of Willis (circular artery) at the base of the brain.

Cerebral aneurysms can be further classified as:

  • Congenital saccular cerebral aneurysm: The ballooning of an artery that is smaller than 2.5 mm, located at the division of the arteries at the circle of Willis/circular artery.
  • Arteriosclerotic fusiform cerebral aneurysm: This is seen in patients suffering from severe arteriosclerosis (when blood vessels become thick and stiff resulting in restricted blood flow). Usually, these patients also suffer from hypertension (high blood pressure). The arteries in the circle of Willis are most commonly affected.
  • Mycotic cerebral aneurysm: This is a rare type of cerebral aneurysm that is caused by septic destruction of the layers of the cerebral arteries, including the elastic and muscular layers of arteries.
  • Giant aneurysms: These usually have a diameter larger than 2.5 mm.

Aortic aneurysms

An aortic aneurysm is defined as an unusual bulge in the wall of the aorta (a very important blood vessel that is responsible for carrying blood from the heart to the rest of the body).

There are three major types of aortic aneurysms:

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

Popliteal aneurysms

They are aneurysms that are situated in the popliteal artery. The popliteal artery is a branch of the femoral artery. Popliteal artery aneurysms comprise 60-70% of all peripheral arterial aneurysms. Most patients with popliteal artery aneurysms also suffer from aortic aneurysms. Popliteal arterial aneurysms are usually bilateral (located on both sides of the body). Popliteal arterial aneurysms usually present with thrombosis (formation of a blood clot in the artery) or embolism (transport and lodging of blood clots in the blood vessels of the body).

Femoral arterial aneurysms
Femoral artery aneurysms are the second most common cause of peripheral arterial aneurysms. The femoral artery is a major blood vessel that supplies the thigh and the leg of the body. Patients can present with local pressure symptoms such as pain. A femoral artery aneurysm can also become complicated and cause thrombosis and embolism to distal regions of the body. On examination, the doctor might notice a pulsating or throbbing in the groin region.

Visceral artery aneurysms
Visceral artery aneurysms are aneurysms that are situated in the arteries supplying the internal organs (viscera) of the body. These may include the following:

  • Hepatic artery aneurysms: These are the most common kind of visceral artery aneurysms. They usually occur due to degeneration of the hepatic artery. Another cause is a traumatic injury to the hepatic artery.
  • Splenic artery aneurysms: Situated in the splenic artery that is responsible for supplying blood to the spleen.
  • Renal artery aneurysms: They are very rare and patients usually have no symptoms. Sometimes, a patient might present with pain, blood in the urine (haematuria), hypertension (increased blood pressure), thrombosis or embolism.

Aneurysm symptoms

The symptoms of an aneurysm could also vary depending on where it is located:

Symptoms of cerebral aneurysm

A cerebral aneurysm usually presents as a subarachnoid haemorrhage; that is, bleeding between the brain and the covering of the brain (subarachnoid space). The bleeding occurs due to a rupture of the cerebral aneurysm. Patients who present with a subarachnoid haemorrhage usually belong to the age group of 50-60 years. (Read more: Brain haemorrhage and stroke)

Symptoms of abdominal aortic aneurysm 

Most patients with abdominal aortic aneurysms have no symptoms. These aneurysms are usually discovered incidentally on clinical examinations or on radiological scans like ultrasound, CT scan or MRI scan. Having said that, some patients may present with the following symptoms:

  • Pain: The pain may be present in the back, abdomen or groin region. It occurs 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 the event that the aneurysm ruptures, the patient may present with low blood pressure, loss of consciousness and severe abdominal pain. 
  • Sometimes, on examination, bruising on the abdominal flanks may be observed (Grey-Turners sign).

Symptoms of thoracic aortic aneurysm

Physical examination of the patient is extremely important to successfully diagnose aortic aneurysms. Most unruptured aortic aneurysms are asymptomatic. A large number of aortic aneurysms are discovered on investigations such as chest X-ray, CT scan or echocardiogram (Echo). The symptoms, when they do appear, may include:

  • Compression effects or local mass effects:
    • Compression of the trachea (windpipe) causing cough, dyspnoea (shortness of breath) and wheezing
    • Compression of the recurrent laryngeal nerve (a branch of the vagus nerve) causing hoarseness of voice
    • Compression of the oesophagus (food pipe)
    • Distended neck veins due to compression of superior vena cava
    • Back pain due to compression of the spine
  • Chest pain
  • Abdominal pain
  • Difficulty in swallowing
  • 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.

Symptoms of iliac, femoral and popliteal aneurysms

These are mostly asymptomatic, but some patients may present signs such as:

  • Back pain
  • Groin pain
  • Leg pain
  • Palpable, pulsatile mass at the back of the knee
  • Paresthesia or the feeling of pins and needles usually in the hands and feet but it can also occur in the arms and legs
  • Swelling in the calf
  • Blood clots as a result of aneurysms may cause further symptoms like paresis (muscle weakness), pallor (pale skin) and poikilothermia (unable to maintain body temperature)
  • Blue toe syndrome
  • Acral cyanosis
  • Bleeding

Aneurysm causes

Some of the causes of aneurysms are:

  • Atherosclerosis: It is an accumulation of fat and cholesterol in the arterial walls that can ultimately reduce the blood flow. This arterial buildup can rupture and result in a blood clot. (Read more: How to improve blood flow)
  • Vasculitis: Inflammation of blood vessels or vasculitis could occur because of Kawasaki disease, polyarteritis nodosa (inflammation in small- and medium-sized arteries), temporal arteritis (giant cell arteritis), Buerger’s disease (inflammation of small- and medium-sized arteries in the hands and feet, and sometimes in the veins of the hands and feet too) and Behcet’s disease, among other health conditions. 
  • Infections: Bacteria or fungi may invade the wall of the blood vessel. Sometimes they spread from distant regions such as in infective endocarditis (often caused by a bacterial infection that may enter the blood and spread to the lining or valves of the heart). Syphilis, which is caused by the bacteria Treponema pallidum, could also lead to an aneurysm.
  • Traumatic injuries: Blunt trauma or injury due to penetration
  • Congenital aneurysms: Some aneurysms, for example, berry aneurysm (occurs at the point where the cerebral artery leaves the circle of Willis/circular artery at the brain base) can be congenital or present since birth.
  • Drug use: Use of drugs like cocaine can cause a cerebral aneurysm or aortic aneurysms at the peripheral regions of the body.

Risk factors of aneurysms

The following factors can increase your risk of developing an aneurysm:

  • Aortic aneurysms are usually seen in patients with a high degree of atherosclerosis
  • Cerebral aneurysms are associated with the following conditions: 
    • Polycystic kidney disease, an inherited disease that results in the formation of cysts in the kidney 
    • Connective tissue diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis and scleroderma
    • Coarctation of the aorta: It is defined as the narrowing of the aorta (a major blood vessel that carries blood from the heart to the rest of the body) 
    • Vascular anomalies such as anomalies in blood vessels 
    • Malformation of arteries
    • Fibromuscular dysplasia: A condition that involves the narrowing of blood vessels (stenosis) and the formation of aneurysms.

Aneurysm diagnosis

Most aneurysms do not present with symptoms, so discovery is often by chance. However, if your doctor suspects something or if you are at high risk of an aneurysm, your doctor may order some tests. Depending on the location of the aneurysm, it may be diagnosed in the following ways:

Thoracic aortic aneurysms diagnosis 

Thoracic aortic aneurysms are diagnosed based on clinical examination, and radiological and routine biochemical investigations. The biochemical investigations to be performed are as follows:

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 an assessment for fitness of surgery in patients with thoracic aortic disease.

Abdominal aortic aneurysms diagnosis 

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 an inflammatory cause is suspected, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) tests are also performed.

An ECG (Electrocardiogram) is also performed to rule out any cardiac complication.

Radiological investigations are required to make a definitive diagnosis of an abdominal Aortic aneurysm. The following investigations are typically done:

  • 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 ultrasound and is the most appropriate investigation in patients suspected of suffering from an 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.

Aneurysm treatment and management

Some of the medical interventions may vary depending on the location of the aneurysm:

The management of thoracic aortic aneurysms

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

The surgical technique that is commonly used is called thoracic endovascular aortic repair or 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.

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

Abdominal aortic aneurysms management

  • Patients with an abdominal aortic aneurysm that is over 5.5cm in diameter need surgery 
  • Patients with an abdominal aortic aneurysm that is expanding at the rate of more than 1 cm/year need surgery
  • Patients with symptomatic abdominal aortic aneurysms need surgery 
  • Complicated abdominal aortic aneurysm such as aortic rupture requires surgery

The types of surgery performed for this condition are:

  • Surgical (open) repair: This surgery 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.
    An endovascular repair has better short term result 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 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: 

  • Annual ultrasound is the aneurysm is 3-4.4cm
  • Ultrasound scan every three month if it is 4.5-5.4cm


cross
Ask your health query now and get connected with a doctor within 10 minutes!