There is a wide variety of aneurysm types, including:
- Aortic aneurysm
- Thoracoabdominal aortic aneurysm
- Aortic dissection
- Traumatic aortic transection (aortic rupture)
- Intramural hematoma
- Penetrating aortic ulcer
- Aortic coarctation
- Coarctation aneurysm
- Embolizing (shaggy) aorta
- Aorto-enteric fistula
- Aorto-bronchial fistula
- Inflammatory aortic disease (arortitis)
- Giant cell arteritis
- Takayasu’s arteritis
- Aortic infection
An aortic aneurysm is a dilation of the aorta to approximately twice its normal size. This usually represents an underlying weakness in the wall of the aorta at that location. An aneurysm may cause discomfort and there may be no symptoms in most patients. Of great concern is the risk of rupture, which causes severe pain, massive internal hemorrhage and may result in sudden death.
Thoracoabdominal aortic aneurysms
Thoracoabdominal aortic aneurysms are classified by Crawford criteria:
- Type I aneurysms involve most or the entire descending thoracic aorta and may extend to upper abdominal aorta.
- Type II aneurysms involve most or the entire descending thoracic aorta and extend into infra-renal aorta. These are the most challenging type to treat.
- Type III aneurysms involve the lower half or less of the descending thoracic aorta and varying portion of the abdominal aorta.
- Type IV aneurysms involve most or the entire abdominal aorta.
Aortic dissection is a tear in the wall of the aorta that causes blood to flow between the medial layers of the wall of the aorta and force the layers apart. An intimomedial flap divides the two lumen of the aorta: the true lumen represents the original aortic lumen, while the false lumen is an artificially created space. It is thinner than normal aortic wall and therefore prone to early rupture.
Aortic dissection is a medical emergency. If the dissection tears through all three layers of the aorta, massive and rapid blood loss occurs.
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Traumatic aortic transection (aortic rupture)
Aortic transection (aortic rupture) is the near-complete tear through all the layers of the aorta due to trauma such as motor vehicle collisions or falls. Traumatic aortic transection is the second most-common cause of death secondary to motor vehicle accidents. Patients who survive to the emergency department usually have partial-thickness tears of the aortic wall with pseudoaneurysm formation.
Intramural hematoma of the aorta is a relatively new entity: It may occur as a primary event in hypertensive patients in whom there is a ruptured small vessel supplying the aorta (vasavasorum) into the media or may be caused by a penetrating aortic ulcer. It represents a hematoma within the layers of the aorta, and it can be the precursor to aortic dissection.
Intramural hematoma may also develop as a result of blunt chest trauma with aortic wall injury. Intramural hematoma may be associated with pain or asymptomatic.
Penetrating aortic ulcer
Penetrating aortic ulcer is an atherosclerotic plaque, which penetrates through the intima and into the aortic media. It may precipitate atrue dissection or may rupture into the adventitia to form a pseudoaneurysm.
The typical patient with penetrating atheromatous aortic ulcer is elderly and has hypertension, hyperlipidemia, atherosclerosis, and back or chest pain. Classic aortic dissection and symptomatic thoracic aortic aneurysms are among possibilities in the differential diagnosis.
The penetrating aortic ulcer is frequently accompanied with intramural hematoma. Disease progresses from intimal plaque ulceration to media hematoma formation to adventitial saccular pseudoaneurysm formation and finally ruptures if there is penetration of all three layers.
The penetrating aortic ulcer may be associated with pain or asymptomatic.
Coarctation of the aorta is a narrowing of the aorta between the upper body branches and the lower body branches. It’s typically in an isolated location just after the “arch” of the aorta. The blockage can increase blood pressure in your arms and head; yet reduce pressure in your legs. Abnormalities of the aortic valve (usually bicuspid; see Aortic Stenosis and Insufficiency section) may also be present. At times, the narrowing of the aorta is so severe that there’s essentially no connection between the upper and lower portions of the aorta (“Interrupted aortic arch”).
Coarctation of the aorta is generally present at birth (congenital). Coarctation of the aorta may range from mild to severe, and may not be detected until adulthood, depending on how narrowed the aorta is.
Coarctation of the aorta often occurs along with other heart defects. While treatment for coarctation of the aorta is usually successful, it's a condition that requires careful follow-up through infancy and throughout adulthood.
There are three types of aortic coarctation:
- Preductal coarctation: The narrowing is proximal to the ductusarteriosus. If severe, blood flow to the aorta distal to the narrowing (supplying lower body) is dependent on a patent ductusarteriosus, and hence its closure can be life threatening. Preductal coarctation results when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart, leading to hypoplastic development of the aorta. This is the type seen in approximately 5% of infants with Turner Syndrome.
- Ductal coarctation: The narrowing occurs at the insertion of the ductusarteriosus. This kind usually appears when the ductusarteriosus closes.
- Postductal coarctation: The narrowing is distal to the insertion of the ductusarteriosus. Even with an open ductusarteriosus blood flow to the lower body can be impaired. This type is most common in adults. It is associated with notching of the ribs (because of collateral circulation), hypertension in the upper extremities, and weak pulses in the lower extremities. Postductal coarctation is most likely the result of the extension of a muscular artery (ductusarteriosus) into an elastic artery (aorta) during fetal life, where the contraction and fibrosis of the ductusarteriosus upon birth subsequently narrows the aortic lumen.
A previously repaired aortic coarctation may become aneurysmal in the follow-up. This is usually due to abnormal aortic tissue surrounding the previous repair. Most affected patients are asymptomatic and have previous operations in infancy and childhood. The coarctation aneurysm has a significant rupture risk especially if it is asymmetric and or saccular in form.
Embolizing (shaggy) aorta
A shaggy aorta is usually very diseased and calcified aorta. The atheroma or the thrombus in the aortic wall may embolize to the brain (causing stroke), to the visceral arteries (causing abdominal pain due to intestinal ischemia), to the renal arteries (causing flank pain and hematuria), or the extremities (causing painful spots in arms and legs). In case of recurrent embolization, an endovascular or surgical procedure may be necessary to obviate/reduce the risk of further embolization of aortic plaque.
Aorto-enteric fistula is a connection between the aorta and the intestinal tract (usually the esophagus or small bowl). Symptoms are abdominal pain, vomiting blood and/or passing dark blood from rectum. The patients usually have either an advanced cancer or a previous operation. This pathology requires prompt diagnosis and treatment.
Aorto-bronchial fistula is a connection between the aorta and the respiratory tract (the lung or trachea). Symptoms are chest pain, and/or vomiting blood. The patients usually have either an advanced cancer or a previous operation. This pathology requires prompt diagnosis and treatment.
Inflammatory aortic disease (Aortitis)
This rather rare entity entails inflammatory changes in the aortic wall that causes necrosis and destruction of structural elements of the vessel wall.
Giant cell arteritis
This is a generalized vasculitis that affects the medium and large vessels of the body mostly the aortic arch and the extra-cranial carotid arteries. It affects almost exclusively elderly Caucasians. It is frequently associated with jaw pain, headache, visual disturbances and scalp tenderness.Corticosterioids is the mainstay of therapy with operations only reserved for rare complications.
Similar to the giant cell arteritis, Takayasu’s arteritis is associated with granuloma formation in the media of the vessels. Fever, malaise and weight loss is similarly prevalent in this disease. It affects the aorta, the pulmonary artery and its major branches.Corticosterioids is the mainstay of therapy with operations indicated for up to 30% of patients to prevent ischemic complications.
- Mycotic aneurysm: Mycotic aneurysms develop usually from septic emboli from the heart. Infective endocarditis of the heart valves may embolize to the vasavasorum or the wall of the aorta causing mycoting aneurysm. Alternatively, the aortic wall may be directly inoculated with bacteria causing arteritis with aneurysm formation. In any instance, aortic rupture is common, and prompt treatment is key. Extraanatomic revascularization and long-term antibiotic coverage are mainstay of treatment.
- Graft/stentgraft infection: In patients with previous open or endovascular aortic procedures, the aortic graft or stent grafts are at risk for infection. This may be related to bacterial contamination form the index procedure or due to bacterial inoculation due to persistent bacteria in the blood stream (bacteremia and sepsis).Promptextra-anatomic revascularization and long-term antibiotic coverage are mainstay of treatment.