Glossary of Thoracic Aortic Conditions

Specialists at the Massachusetts General Hospital Thoracic Aortic Center are dedicated to making sure patients fully understand their conditions and treatment options.

Acute aortic syndrome: The sudden onset of a life-threatening problem with the aorta, such a tear through the wall (aortic rupture) or a tear of the inner lining of the aorta (aortic dissection)

Aneurysm: A significant dilation (enlargement) of the aorta

Aneurysm, abdominal aortic (AAA): Significant enlargement of the part of the aorta within the abdomen

Aneurysm, aortic root: Significant enlargement of the part of the aorta where the aortic valve sits and where the aorta meets the heart

Aneurysm, thoracic aortic (TAA): Significant enlargement of the part of the aorta within the chest (thorax)

Aneurysm, ascending thoracic aortic: Significant enlargement of the part of the aorta that leads from the heart up the front of the chest

Aneurysm, descending thoracic aortic: Significant enlargement of the part of the aorta that runs from the neck down the back

Aneurysm, thoracoabdominal: Significant enlargement of the part of the aorta within the chest (thorax) that extends into the abdomen as well

Antegrade cerebral perfusion: Pumping oxygen-rich blood into the carotid arteries (which supply blood to the brain) to protect the brain during open heart surgery

Aorta: The largest artery in the body; it receives blood from the heart and distributes it to branch arteries throughout the body

Aorta, abdominal: The segment of the aorta located below the diaphragm; it gives off arterial branches that supply blood to the intestines, liver, kidneys and legs

Aorta, ascending thoracic: The first segment of the aorta, which begins just above the aortic valve and rises in the front part of the chest

Aorta, descending thoracic: The segment of the aorta that runs from the neck and down the to the level of the diaphragm

Aorta, thoracic: The part of the aorta that leads from the heart up the front of the chest

Aorta, thoracoabdominal: The part of the aorta within the chest (thorax) that extends into the abdomen as well

Aortic arch: The segment of the aorta in the upper chest that runs under the neck and connects the ascending with the descending aorta; it gives off branch arteries that supply blood to the arms and head

Aortic arch repair: Open heart surgery to replace and enlarged portion of the aortic arch using an artificial fabric tube graft that has branches coming off it

Aortic dissection: A life-threatening condition in which there is a tear in the inner lining of the aorta that allows blood to penetrate the artery wall, followed by splitting of the aortic wall into two layers with the blood within the wall creating a "false lumen"

Aortic dissection, type A: An aortic dissection that involves the ascending portion of the aorta. Other terms include type I, type II, and “proximal” aortic dissection

Aortic dissection, type B: An aortic dissection that involves the descending portion of the aorta but spares the ascending aorta. Other terms include type III and “distal” aortic dissection

Aortic Insufficiency: Inappropriate leaking of the aortic valve, which allows blood that has been ejected from the heart into the aorta to leak backwards into the heart

Aortic regurgitation: Aortic regurgitation is a leak in the aortic valve

Aortic root: This refers to the bulging portion at the base of the ascending aorta. This segment provides structural support for the aortic valve. The left and right coronary arteries also originate from this segment

Aortic stenosis: Aortic stenosis is a narrowing of the aorta

Aortic valve: A valve that separates the heart from the aorta. It opens when the heart pumps blood out into the aorta, but then closes so that blood does not leak back into the heart when the heart relaxes

Aortic valve-preserving aneurysm repair: An operation to replace an enlarged aortic root, while preserving a normally functioning aortic valve and sewing it into an artificial fabric tube-graft

Atherosclerosis: A disease of the arteries in which there is a thickening of the walls due to inflammation and a build up cholesterol

Bicuspid aortic valve: The normal aortic valve has three cusps or leaflets. In the case of a bicuspid aortic valve, the valve is formed with only two leaflets rather than three. Often this results in a narrowed or a leaky aortic valve

Common iliac arteries: The large arteries that arise at the end of the abdominal aorta and head into the groin and toward the legs

Composite aortic root replacement: When the aorta root needs to be replaced and the aortic valve is badly diseased or cannot be spared, in this operation we replace both the enlarged segment of the aorta and the aortic valve in one operation using a fabric tube graft with an artificial valve sewn onto one end

Contrast angiography: A more traditional and invasive procedure, which is now performed only in selected cases, such as the pre-operative evaluation of patients with unusually complex aortic anatomy

CT angiogram (CTA): A CT scan (see below) using a IV contrast dye to light up the blood within the aorta and other arteries. For patients with complex aortic anatomy, this can create a 3-dimensional CT scan image of the entire aorta, which can then be viewed from all angles.

CT scan: CT (computed tomography) scans use extremely fast processing of x-ray beams to produce images of the body that look like slices. CT images of the aorta are very clear.

Cystic medial degeneration or necrosis: A common precursor of aortic dissection and aneurysms, due to breakdown of elastic fibers and loss of smooth muscle cells in the aortic wall

Dilatation: A medical term for enlargement of an anatomic structure

Echocardiogram: Ultrasound images of the heart beating

Familial thoracic aortic aneurysm syndrome: A genetic condition in which two or more members of a family have abnormal enlargement of the thoracic aorta

Graft: Artificial material used to replace aortic aneurysms

Hypertension: Abnormally high blood pressure

Hypothermic circulatory arrest: When, during cardiac surgery, the body temperature is lowered significantly and the heart-lung bypass machine is turned off for a brief period to allow the surgeon to operate on complex portions of the aortic anatomy

Intramural hematoma of the aorta: A variant of the more classic aortic dissection. This involves bleeding within the aortic wall but without evidence of a tear in the lining of the aorta. The risk factors and symptoms of this condition are very much the same as for classic aortic dissection, but its appearance on imaging studies is quite different and subtler.

Marfan syndrome: A congenital (genetic) connective tissue disorder in which aortic root aneurysms commonly form and are associated with a high risk of aortic dissection

Media: The middle layer of the aorta

Medial degeneration: A common precursor of aortic dissection and aneurysms, due to breakdown of elastic fibers and loss of smooth muscle cells in the aortic wall

MRI: MRI (magnetic resonance imaging) uses magnetic fields but no radiation. It produces images of the aorta from different angles, although the images are not always as sharp as those produced by CT scanning. MRI is often used as an alternative to CT scanning when patients have kidney failure or an allergy to the IV contrast material needed for CT scanning.

MRA: MRA (magnetic resonance angiography) is a fancier type of MRI that uses a special non-toxic contrast agent called gadolinium, which is safe for the kidneys. MRA is used when we need to examine the branch vessels that come off the aorta, and MRA can also produce 3-dimensional images of the aorta.

Penetrating atherosclerotic ulcer: A small hole in the inner layer of the aortic wall that begins with an atherosclerotic plaque (cholesterol buildup) on the inner wall of the aorta in which an ulcer (small hole) develops and lets a small amount of blood inside the wall

Pseudoaneurysm of the aorta: A collection of blood bulging out from the aorta that looks similar to an aneurysm, but is instead of a bulging out of the actual wall of the artery it represents a contained collection of blood that has leaked out of the aorta

Stent-graft: An artificial fabric covered tube used to repair an aortic aneurysm. However, instead of using open surgery, doctors insert stent-grafts using a minimally invasive technique through an artery in your groin

Stent-graft repair: A minimally invasive approach for descending and thoracoabdominal aneurysm repair, in which a tube is inserted via a groin artery and advanced to the site of the aortic aneurysm

Thoracic aortic aneurysm: An aneurysm of the ascending, arch, or descending portion of the aorta

Thoracoabdominal aortic aneurysm: An aneurysm of that involves the descending portion of the aorta and extends below the diaphragm to involve a variable length of the abdominal aorta as well

Transsection of the aorta: When patients have been in motor vehicle accidents, the aorta is often injured. This produced a full thickness tear of the aortic wall, which may lead to a contained rupture. This is distinct from aortic dissection.

Transesophageal echocardiography (TEE): Transesophageal echocardiography (TEE) is a special type of ultrasound that uses sound waves to images the aorta. However, instead of sending sound waves into the body from the surface of the skin, this procedure sends the sound waves from a thin plastic tube inserted into the patient’s esophagus. This is especially effective because the esophagus lies right next to the aorta, so the ultrasound images of the aorta are typically very clear.

Tricuspid aortic valve: The normal aortic valve has three cusps that meet in the middle to close the valve, as opposed to a bicuspid aortic valve (an abnormality from birth in which the valve has only two leaflets