Aortic aneurysm
Encyclopedia
An aortic aneurysm is a general term for any swelling (dilation or aneurysm
) of the aorta
to greater than 1.5 times normal, usually representing an underlying weakness in the wall of the aorta at that location. While the stretched vessel may occasionally cause discomfort, a greater concern is the risk of rupture, which causes severe pain; massive internal hemorrhage; and, without prompt treatment, death occurs rapidly.
and back pain
may develop. Compression of nerve roots may cause leg pain or numbness. Untreated, aneurysms tend to become progressively larger, although the rate of enlargement is unpredictable for any individual. Rarely, clotted blood which lines most aortic aneurysms can break off and result in an embolus
. They may be found on physical examination. Medical imaging is necessary to confirm the diagnosis. Signs may include: anxiety or feeling of stress; nausea and vomiting; clammy skin; rapid heart rate.
In patients presenting with aneurysm of the arch of the aorta, a common sign is a hoarse voice as the left recurrent laryngeal nerve
(a branch of the vagus nerve) is stretched. This is due to the recurrent laryngeal nerve winding around the arch of the aorta.
, the principal load-bearing protein present in the wall of the aorta, is reduced in the abdominal aorta as compared to the thoracic aorta (nearer the heart). Another is that the abdominal aorta does not possess vasa vasorum
, hindering repair. Most are true aneurysms that involve all three layers (tunica intima
, tunica media
and tunica adventitia), and are generally asymptomatic before rupture.
An AAA may remain asymptomatic indefinitely. There is a large risk of rupture once the size has reached 5 cm (2 in), though some AAAs may swell to over 15 cm (6 in) in diameter before rupturing. Before rupture, an AAA may present as a large, pulsatile mass above the umbilicus
. A bruit
may be heard from the turbulent flow in a severe atherosclerotic aneurysm or if thrombosis
occurs. Unfortunately, however, rupture is usually the first hint of AAA. Once an aneurysm has ruptured, it presents with a classic pain
-hypotension
-mass
triad. The pain is classically reported in the abdomen, back or flank. It is usually acute, severe and constant, and may radiate through the abdomen to the back.
The diagnosis of an abdominal aortic aneurysm can be confirmed at the bedside by the use of ultrasound
. Rupture could be indicated by the presence of free fluid in potential abdominal spaces, such as Morison's pouch
, the splenorenal space (between the spleen and left kidney), subdiaphragmatic spaces(underneath the diaphragm) and peri-vesical spaces. A contrast-enhanced abdominal CT scan
is needed for confirmation.
Only 10–25% of patients survive rupture due to large pre- and post-operative mortality. Annual mortality from ruptured aneurysms in the United States
is about 15,000. Most are due to abdominal aneurysms
, with thoracic and thoracoabdominal aneurysms making up 1% to 4% of the total. Another important complication of AAA is formation of a thrombus
in the aneurysm. The prevalence of AAAs increases with age, with an average age of 65–70 at the time of diagnosis. AAAs have been attributed to atherosclerosis
, though other factors are involved in their formation.
, Vascular Ehlers-Danlos or similar connective tissue disorders, and other co-morbidities are all important factors in the overall treatment.
A rapidly expanding aneurysm should under normal circumstances be operated on as soon as feasible, since it has a greater chance of rupture. Slowly expanding aortic aneurysms may be followed by routine diagnostic testing (i.e.: CT scan or ultrasound
imaging).
For abdominal aneurysms, the current treatment guidelines for abdominal aortic aneurysms suggest elective surgical repair when the diameter of the aneurysm is greater than 5 cm (2 in). However, recent data suggest medical management for abdominal aneurysms with a diameter of less than 5.5 cm (2 in).
) patch tube. Once the tube is sewn into the proximal and distal portions of the aorta, the aneurysmal sac is closed around the artificial tube. Instead of sewing, the tube ends, made rigid and expandable by nitinol wireframe, can be much more simply, quickly and effectively ("airtight" seal) inserted into the vascular stumps and there permanently fixed by external ligature (video) http://www.fondazionecarrel.org/ejcts/nd.html
The aorta and possibly also its branching arteries are cross-clamped during open surgery. This can lead to inadequate blood supply to the spinal cord, resulting in neurological deficits. Cerebrospinal fluid drainage (CSFD), when performed in experienced centers, reduce this risk of ischaemic spinal cord injury, as evidenced by randomized trials, by increasing the perfusion pressure to the spinal cord.
In the recent years, the endoluminal treatment of abdominal aortic aneurysms has emerged as a minimally invasive alternative to open surgery repair. The first endoluminal exclusion of an aneurysm took place in Argentina by Dr. Parodi and his colleagues in 1991. The endovascular treatment of aortic aneurysms
involves the placement of an endo-vascular stent
via a percutaneous
technique (usually through the femoral arteries
) into the diseased portion of the aorta. This technique has been reported to have a lower mortality rate compared to open surgical repair, and is now being widely used in individuals with co-morbid conditions that make them high risk patients for open surgery. Some centers also report very promising results for the specific method in patients that do not constitute a high surgical risk group.
There have also been many reports concerning the endovascular treatment of ruptured Abdominal Aortic Aneurysms, which are usually treated with an open surgery repair due to the patient's impaired overall condition. Mid-term results have been quite promising. However, due to the time frame of the emerging, the long term benefit of the EVAR procedure against open surgery has not yet been identified.
In spite aneurysms have been treated by endovascular techniques in virtually all aortic segments, better than open aortic repair results were statistically documented only in uncomplicated, elective descending thoracic and infrarenal aorta. Moreover recent USA Nationwide Inpatient Sample data 2006–2007 review of isolated descending thoracic aorta aneurysm cases showed that only 23% (2,563/11,669) of ideal candidate (uncomplicated, elective descending aortic aneurysms) underwent to TEVAR, the remaining 77% (9,106/11,669) still underwent open surgical repair. Although results were better with TEVAR than with OAR it is clear that still the vast majority of thoracic aortic aneurisms is treated by standard open repair
Other
The endoluminal exclusion of aortic aneurysms has seen a real revolution in the very recent years. It is now possible to treat thoracic aortic aneurysms, abdominal aortic aneurysms and other aneurysms in most of the body's major arteries (such as the iliac and the femoral arteries) using endovascular stents and avoiding big incisions. Still, in most cases the technique is applied in patients at high risk for surgery as more trials are required to fully accept this method as the gold standard for the treatment of aneurysms.
control. This does not treat the aortic aneurysm per se, but control of hypertension
within tight blood pressure parameters may decrease the rate of expansion of the aneurysm.
risks helps reduce the risk on an individual basis. There have been proposals to introduce ultrasound scans as a screening tool for those most at risk: men over the age of 65. The tetracycline antibiotic Doxycycline
is currently being investigated for use as a potential drug in the prevention of aortic aneurysm due to its metalloproteinase
inhibitor and collagen stabilising properties.
Aneurysm
An aneurysm or aneurism is a localized, blood-filled balloon-like bulge in the wall of a blood vessel. Aneurysms can commonly occur in arteries at the base of the brain and an aortic aneurysm occurs in the main artery carrying blood from the left ventricle of the heart...
) of the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
to greater than 1.5 times normal, usually representing an underlying weakness in the wall of the aorta at that location. While the stretched vessel may occasionally cause discomfort, a greater concern is the risk of rupture, which causes severe pain; massive internal hemorrhage; and, without prompt treatment, death occurs rapidly.
Classification
Aortic aneurysms are classified by where on the aorta they occur; aneurysms can appear anywhere.- An aortic root aneurysm, or aneurysm of sinus of ValsalvaAneurysm of sinus of ValsalvaAneurysm of the aortic sinus, also known as the sinus of Valsalva, is comparatively rare. When present, it is usually in either the right or in the noncoronary sinus, rarely in the left Aneurysm of the aortic sinus, also known as the sinus of Valsalva, is comparatively rare. When present, it is...
, appears on the sinuses of Valsalva or aortic root. - Thoracic aortic aneurysmThoracic aortic aneurysmA thoracic aortic aneurysm is an aortic aneurysm that presents primarily in the thorax.It is less common than an abdominal aortic aneurysm. However, a syphilitic aneurysm is more likely to be a thoracic aortic aneurysm than an abdominal aortic aneurysm....
s are found on the thoracic aortaThoracic aortaThe thoracic aorta is contained in the posterior mediastinal cavity.It begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra, at the aortic hiatus in the diaphragm where it...
; these are further classified as ascending, aortic arch, or descending aneurysms depending on the location on the thoracic aorta involved. - Abdominal aortic aneurysmAbdominal aortic aneurysmAbdominal aortic aneurysm is a localized dilatation of the abdominal aorta exceeding the normal diameter by more than 50 percent, and is the most common form of aortic aneurysm...
s, the most common form of aortic aneurysm, are found on the abdominal aortaAbdominal aortaThe abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta .-Path:...
, and thoracoabdominal aortic aneurysms involve both the thoracic and abdominal aorta. There are other classifications that might help treatment.
Signs and symptoms
Most intact aortic aneurysms do not produce symptoms. As they enlarge, symptoms such as abdominal painAbdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
and back pain
Back pain
Back pain is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine.The pain can often be divided into neck pain, upper back pain, lower back pain or tailbone pain...
may develop. Compression of nerve roots may cause leg pain or numbness. Untreated, aneurysms tend to become progressively larger, although the rate of enlargement is unpredictable for any individual. Rarely, clotted blood which lines most aortic aneurysms can break off and result in an embolus
Embolism
In medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
. They may be found on physical examination. Medical imaging is necessary to confirm the diagnosis. Signs may include: anxiety or feeling of stress; nausea and vomiting; clammy skin; rapid heart rate.
In patients presenting with aneurysm of the arch of the aorta, a common sign is a hoarse voice as the left recurrent laryngeal nerve
Recurrent laryngeal nerve
The recurrent laryngeal nerve is a branch of the vagus nerve that supplies motor function and sensation to the larynx . It travels within the endoneurium...
(a branch of the vagus nerve) is stretched. This is due to the recurrent laryngeal nerve winding around the arch of the aorta.
Abdominal aortic aneurysm
Abdominal aortic aneurysms (AAAs) are the most common type of aortic aneurysm. One reason for this is that elastinElastin
Elastin is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of...
, the principal load-bearing protein present in the wall of the aorta, is reduced in the abdominal aorta as compared to the thoracic aorta (nearer the heart). Another is that the abdominal aorta does not possess vasa vasorum
Vasa vasorum
The vasa vasorum is a network of small blood vessels that supply large blood vessels.The vasa vasorum are found in large arteries and veins such as the aorta and its branches....
, hindering repair. Most are true aneurysms that involve all three layers (tunica intima
Tunica intima
The tunica intima is the innermost layer of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina...
, tunica media
Tunica media
The tunica media is the middle layer of an artery or vein.-Artery:It is made up of smooth muscle cells and elastic tissue...
and tunica adventitia), and are generally asymptomatic before rupture.
An AAA may remain asymptomatic indefinitely. There is a large risk of rupture once the size has reached 5 cm (2 in), though some AAAs may swell to over 15 cm (6 in) in diameter before rupturing. Before rupture, an AAA may present as a large, pulsatile mass above the umbilicus
Navel
The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...
. A bruit
Bruit
Bruit is the term for the unusual sound that blood makes when it rushes past an obstruction in an artery when the sound is auscultated with the bell portion of a stethoscope.The term "bruit" simply refers to the sound...
may be heard from the turbulent flow in a severe atherosclerotic aneurysm or if thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
occurs. Unfortunately, however, rupture is usually the first hint of AAA. Once an aneurysm has ruptured, it presents with a classic pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
-hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
-mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
triad. The pain is classically reported in the abdomen, back or flank. It is usually acute, severe and constant, and may radiate through the abdomen to the back.
The diagnosis of an abdominal aortic aneurysm can be confirmed at the bedside by the use of ultrasound
Medical ultrasonography
Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...
. Rupture could be indicated by the presence of free fluid in potential abdominal spaces, such as Morison's pouch
Morison's pouch
The hepatorenal recess or subhepatic recess is the space that separates the liver from the right kidney. As a potential space, the recess is not filled with fluid under normal conditions. However, fluid can collect in this space in circumstances where the abdomen fills with fluid, such as...
, the splenorenal space (between the spleen and left kidney), subdiaphragmatic spaces(underneath the diaphragm) and peri-vesical spaces. A contrast-enhanced abdominal CT scan
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
is needed for confirmation.
Only 10–25% of patients survive rupture due to large pre- and post-operative mortality. Annual mortality from ruptured aneurysms in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
is about 15,000. Most are due to abdominal aneurysms
Abdominal aortic aneurysm
Abdominal aortic aneurysm is a localized dilatation of the abdominal aorta exceeding the normal diameter by more than 50 percent, and is the most common form of aortic aneurysm...
, with thoracic and thoracoabdominal aneurysms making up 1% to 4% of the total. Another important complication of AAA is formation of a thrombus
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
in the aneurysm. The prevalence of AAAs increases with age, with an average age of 65–70 at the time of diagnosis. AAAs have been attributed to atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
, though other factors are involved in their formation.
Risk factors
- CAD
- HypertensionHypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
- HypercholesterolemiaHypercholesterolemiaHypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...
- HyperhomocysteinemiaHyperhomocysteinemiaHyperhomocysteinemia or hyperhomocysteinaemia is a medical condition characterized by an abnormally large level of homocysteine in the blood....
- Elevated C-reactive proteinC-reactive proteinC-reactive protein is a protein found in the blood, the levels of which rise in response to inflammation...
- TobaccoTobaccoTobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
use - Peripheral vascular disease
- Marfan syndromeMarfan syndromeMarfan syndrome is a genetic disorder of the connective tissue. People with Marfan's tend to be unusually tall, with long limbs and long, thin fingers....
- Ehlers-Danlos type IV
Pathophysiology
The physical change in the aortic diameter can occur secondary to trauma, infection, an intrinsic defect in the protein construction of the aortic wall, or due to progressive destruction of aortic proteins by enzymes.Treatment
Surgery is the definite treatment of aortic aneurysm, while medical therapy is typically supportive.Surgery
The definitive treatment for an aortic aneurysm may be surgical or endovascular repair. The determination of surgical intervention is complex and determined on a per-case basis. Risk of aneurysm rupture is weighed against procedural risk. The diameter of the aneurysm, its rate of growth, the presence or absence of Marfan SyndromeMarfan syndrome
Marfan syndrome is a genetic disorder of the connective tissue. People with Marfan's tend to be unusually tall, with long limbs and long, thin fingers....
, Vascular Ehlers-Danlos or similar connective tissue disorders, and other co-morbidities are all important factors in the overall treatment.
A rapidly expanding aneurysm should under normal circumstances be operated on as soon as feasible, since it has a greater chance of rupture. Slowly expanding aortic aneurysms may be followed by routine diagnostic testing (i.e.: CT scan or ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
imaging).
For abdominal aneurysms, the current treatment guidelines for abdominal aortic aneurysms suggest elective surgical repair when the diameter of the aneurysm is greater than 5 cm (2 in). However, recent data suggest medical management for abdominal aneurysms with a diameter of less than 5.5 cm (2 in).
Open
Open surgery typically involves dissection of the dilated portion of the aorta and insertion of a synthetic (Dacron or Gore-TexGore-Tex
Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W. L. Gore and Associates. It was co-invented by Wilbert L. Gore, Rowena Taylor, and Gore's son, Robert W. Gore. Robert Gore was granted on April 27, 1976, for a porous form of polytetrafluoroethylene with a...
) patch tube. Once the tube is sewn into the proximal and distal portions of the aorta, the aneurysmal sac is closed around the artificial tube. Instead of sewing, the tube ends, made rigid and expandable by nitinol wireframe, can be much more simply, quickly and effectively ("airtight" seal) inserted into the vascular stumps and there permanently fixed by external ligature (video) http://www.fondazionecarrel.org/ejcts/nd.html
The aorta and possibly also its branching arteries are cross-clamped during open surgery. This can lead to inadequate blood supply to the spinal cord, resulting in neurological deficits. Cerebrospinal fluid drainage (CSFD), when performed in experienced centers, reduce this risk of ischaemic spinal cord injury, as evidenced by randomized trials, by increasing the perfusion pressure to the spinal cord.
Endovascular
AAAIn the recent years, the endoluminal treatment of abdominal aortic aneurysms has emerged as a minimally invasive alternative to open surgery repair. The first endoluminal exclusion of an aneurysm took place in Argentina by Dr. Parodi and his colleagues in 1991. The endovascular treatment of aortic aneurysms
Endovascular aneurysm repair
EVAR which stands for Endovascular Aneurysm Repair , is a type of Endovascular surgery used to treat an abdominal aortic aneurysm or Thoracic Aortic Aneurysm, the procedure then specifically termed TEVAR...
involves the placement of an endo-vascular stent
Stent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
via a percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
technique (usually through the femoral arteries
Femoral artery
The femoral artery is a general term comprising a few large arteries in the thigh. They begin at the inguinal ligament and end just above the knee at adductor canal or Hunter's canal traversing the extent of the femur bone....
) into the diseased portion of the aorta. This technique has been reported to have a lower mortality rate compared to open surgical repair, and is now being widely used in individuals with co-morbid conditions that make them high risk patients for open surgery. Some centers also report very promising results for the specific method in patients that do not constitute a high surgical risk group.
There have also been many reports concerning the endovascular treatment of ruptured Abdominal Aortic Aneurysms, which are usually treated with an open surgery repair due to the patient's impaired overall condition. Mid-term results have been quite promising. However, due to the time frame of the emerging, the long term benefit of the EVAR procedure against open surgery has not yet been identified.
In spite aneurysms have been treated by endovascular techniques in virtually all aortic segments, better than open aortic repair results were statistically documented only in uncomplicated, elective descending thoracic and infrarenal aorta. Moreover recent USA Nationwide Inpatient Sample data 2006–2007 review of isolated descending thoracic aorta aneurysm cases showed that only 23% (2,563/11,669) of ideal candidate (uncomplicated, elective descending aortic aneurysms) underwent to TEVAR, the remaining 77% (9,106/11,669) still underwent open surgical repair. Although results were better with TEVAR than with OAR it is clear that still the vast majority of thoracic aortic aneurisms is treated by standard open repair
Other
The endoluminal exclusion of aortic aneurysms has seen a real revolution in the very recent years. It is now possible to treat thoracic aortic aneurysms, abdominal aortic aneurysms and other aneurysms in most of the body's major arteries (such as the iliac and the femoral arteries) using endovascular stents and avoiding big incisions. Still, in most cases the technique is applied in patients at high risk for surgery as more trials are required to fully accept this method as the gold standard for the treatment of aneurysms.
Medical therapy
Medical therapy of aortic aneurysms involves strict blood pressureBlood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
control. This does not treat the aortic aneurysm per se, but control of hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
within tight blood pressure parameters may decrease the rate of expansion of the aneurysm.
Prevention
Attention to patient's general blood pressure, smoking and cholesterolCholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
risks helps reduce the risk on an individual basis. There have been proposals to introduce ultrasound scans as a screening tool for those most at risk: men over the age of 65. The tetracycline antibiotic Doxycycline
Doxycycline
Doxycycline INN is a member of the tetracycline antibiotics group, and is commonly used to treat a variety of infections. Doxycycline is a semisynthetic tetracycline invented and clinically developed in the early 1960s by Pfizer Inc. and marketed under the brand name Vibramycin. Vibramycin...
is currently being investigated for use as a potential drug in the prevention of aortic aneurysm due to its metalloproteinase
Metalloproteinase
Metalloproteinases constitute a family of enzymes from the group of proteases, classified by the nature of the most prominent functional group in their active site. These are proteolytic enzymes whose catalytic mechanism involves a metal. Most metalloproteases are zinc-dependent, but some use...
inhibitor and collagen stabilising properties.
External links
- Vascular Medicine — Information for experts and laypersons regarding vascular medicine and related diseases.
- Aortic Aneurysm CT scans MedPix Medical Images