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Aortic aneurysm- Thoracic aneurysm, etiology, patho, management

The aorta is the artery in human body. It conduct blood to various parts of the body from left ventricle. Aorta can be divided into three parts:

  • The first part moves upwards towards the head. It is called the ascending aorta.
  • The middle part is curved. It is called the aortic arch.
  • The last part moves downwards, toward the feet. It is called the descending aorta.

MEANING

An aneurysm is an abnormal widening or ballooning of a portion of an artery due to weakness in the wall of the blood vessel.

DEFINITION

It refers to a pathological dilatation of the aortic lumen involving one or more several segments

CLASSIFICATION

According to the layers affected

  • True aneurysm : it involves all three layers of the vessel wall
  • Pseudoaneurysm : The intimal and medial layers are disrupted and the dilatation is lined by adventitia only and sometimes by perivascular clot.

According to the gross appearance

  • Fusiform aneurysm : It affects the entire circumference of a segment of the vessel, resulting in a diffusely dilated lesion.
  • Saccular aneurysm : It involves only a portion of the circumference, resulting in an outpouching of the vessel wall.

According to location

  • Thoracic aneurysm.
  • Abdominal aneurysm.

 

RISK FACTORS

  • Genetic predisposition
  • Smoking (or other type tobacco use)
  • Hypertension

ETIOLOGY

  1. Congenital: Primary connective tissue disorders (Marfan’s syndrome, Ehlers-Danlos syndrome)
  2. Mechanical (hemodynamic): Post-stenotic and arteriovenous fistula
  3. Traumatic (pseudo aneurysms): Penetrating arterial injuries, blunt arterial injuries, pseudoaneurysms
  4. Inflammatory (noninfectious): Associated with arteritis (Takayasu’s disease, giant cell arteritis, systemic lupus erythematosus, Behçet’s syndrome, Kawasaki’s disease) and periarterial inflammation (ie, pancreatitis)
  5. Infectious (mycotic): Bacterial(syphilis), fungal, spirochetal infections
  6. Anastomotic (postarteriotomy) and graft aneurysms: Infection, arterial wall failure, suture failure, graft failure

 

PATHOPHYSIOLOGY

All aneurysms involve a damaged media layer of the vessel. This may be caused by congenital weakness, trauma, or disease. After an aneurysm develops, it tends to enlarge and may lead to haemorrage.

 

THORACIC ANEURYSM

CLINICAL FEATURES

Aneurysms develop slowly over many years. Most patients have no symptoms until the aneurysm begins to leak or expand. Chest or back pain may indicate sudden widening or leakage of the aneurysm.

Symptoms often begin suddenly when:

  • The aneurysm grows quickly
  • The aneurysm tears open (called a rupture)
  • Blood leaks along the wall of the aorta (aortic dissection).

If the aneurysm presses on nearby structures, the following symptoms may occur:

  • Hoarseness
  • Swallowing problems
  • High-pitched breathing (stridor)
  • Swelling in the neck

Other symptoms may include:

  • Chest or back pain
  • Clammy skin
  • Nausea and vomiting
  • Rapid heart rate
  • Low blood pressure

INVESTIGATIONS

  • Physical examination is often normal, unless a rupture or leak has occurred.
  • Most thoracic aortic aneurysms are detected by tests performed for other reasons, usually a chest x-ray, echocardiogram, or a chest CT scan.
  • Chest CT scan shows the size of the aorta and the exact location of the aneurysm.
  • Aortogram (a special set of x-ray images made when dye is injected into the aorta) can identify the aneurysm and any branches of the aorta that may be involved.

MANAGEMENT

The treatment depends on the location of the aneurysm.

For patients with aneurysms of the ascending aorta or aortic arch:

  • Surgery to replace the aorta is recommended if an aneurysm is larger than 5 – 6 centimeters. The aorta is replaced with a plastic or fabric graft. This is major surgery that requires a heart-lung machine.

 

For patients with aneurysms of the descending thoracic aorta:

  • Majory surgery is done to replace the aorta with a fabric graft if the aneurysm is larger than 6 centimeters.Endovascular stenting is a less invasive option. ( A stent is a tiny metal or plastic tube that is used to hold an artery open. Stents can be placed into the body without cutting the chest. All patients with descending thoracic aneurysms are not candidates for stenting.)

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