Abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA or triple A) is a localized enlargement of the abdominal aorta such that the diameter is greater than 3 cm or more than 50% larger than normal. They usually cause no symptoms, except during rupture. Occasionally, abdominal, back, or leg pain may occur. Large aneurysms can sometimes be felt by pushing on the abdomen. Rupture may result in pain in the abdomen or back, low blood pressure, or loss of consciousness, and often results in death.Aortic measurement on abdominal ultrasonography in the axial plane between the outer margins of the aortic wall.Ultrasonography in the sagittal plane, showing axial plane measure (dashed red line), as well as maximal diameter (dotted yellow line) which is preferred.A ruptured AAA with an open arrow marking the aneurysm and the closed arrow marking the free blood in the abdomenSagittal CT image of an AAABiomechanical AAA rupture risk predictionAn axial contrast-enhanced CT scan demonstrating an abdominal aortic aneurysm of 4.8 by 3.8 cmThe faint outline of the calcified wall of an AAA as seen on plain X-rayAbdominal aortic aneurysms (3.4 cm)An aortic aneurysm as seen on CT with a small area of remaining blood flowUltrasound showing a previously repaired AAA that is leaking with flow around the graftUltrasonography of an aneurysm with a mural thrombus. Abdominal aortic aneurysm (AAA or triple A) is a localized enlargement of the abdominal aorta such that the diameter is greater than 3 cm or more than 50% larger than normal. They usually cause no symptoms, except during rupture. Occasionally, abdominal, back, or leg pain may occur. Large aneurysms can sometimes be felt by pushing on the abdomen. Rupture may result in pain in the abdomen or back, low blood pressure, or loss of consciousness, and often results in death. AAAs occur most commonly in those over 50 years old, in men, and among those with a family history. Additional risk factors include smoking, high blood pressure, and other heart or blood vessel diseases. Genetic conditions with an increased risk include Marfan syndrome and Ehlers-Danlos syndrome. AAAs are the most common form of aortic aneurysm. About 85% occur below the kidneys with the rest either at the level of or above the kidneys. In the United States, screening with abdominal ultrasound is recommended for males between 65 and 75 years of age with a history of smoking. In the United Kingdom and Sweden, screening all men over 65 is recommended. Once an aneurysm is found, further ultrasounds are typically done on a regular basis. Not smoking is the single best way to prevent the disease. Other methods of prevention include treating high blood pressure, treating high blood cholesterol, and not being overweight. Surgery is usually recommended when the diameter of an AAA grows to >5.5 cm in males and >5.0 cm in females. Other reasons for repair include the presence of symptoms and a rapid increase in size, defined as more than one centimeter per year. Repair may be either by open surgery or endovascular aneurysm repair (EVAR). As compared to open surgery, EVAR has a lower risk of death in the short term and a shorter hospital stay, but may not always be an option. There does not appear to be a difference in longer term outcomes between the two. Repeat procedures are more common with EVAR. AAAs affect 2-8% of males over the age of 65. Rates among women are one-fourth as high. In those with an aneurysm less than 5.5 cm, the risk of rupture in the next year is below 1%. Among those with an aneurysm between 5.5 and 7 cm, the risk is about 10%, while for those with an aneurysm greater than 7 cm the risk is about 33%. Mortality if ruptured is 85% to 90%. During 2013, aortic aneurysms resulted in 168,200 deaths, up from 100,000 in 1990. In the United States AAAs resulted in between 10,000 and 18,000 deaths in 2009. The vast majority of aneurysms are asymptomatic. However, as abdominal aortic aneurysms expand, they may become painful and lead to pulsating sensations in the abdomen or pain in the chest, lower back, or scrotum. The risk of rupture is high in a symptomatic aneurysm, which is therefore considered an indication for surgery. The complications include rupture, peripheral embolization, acute aortic occlusion, and aortocaval (between the aorta and inferior vena cava) or aortoduodenal (between the aorta and the duodenum) fistulae. On physical examination, a palpable and pulsatile abdominal mass can be noted. Bruits can be present in case of renal or visceral arterial stenosis. The signs and symptoms of a ruptured AAA may include severe pain in the lower back, flank, abdomen or groin. A mass that pulses with the heart beat may also be felt. The bleeding can lead to a hypovolemic shock with low blood pressure and a fast heart rate. This may lead to brief passing out. The mortality of AAA rupture is as high as 90 percent. 65 to 75 percent of patients die before they arrive at the hospital and up to 90 percent die before they reach the operating room. The bleeding can be retroperitoneal or into the abdominal cavity. Rupture can also create a connection between the aorta and intestine or inferior vena cava. Flank ecchymosis (appearance of a bruise) is a sign of retroperitoneal bleeding, and is also called Grey Turner's sign. Aortic aneurysm rupture may be mistaken for the pain of kidney stones, or muscle related back pain. The exact causes of the degenerative process remain unclear. There are, however, some hypotheses and well-defined risk factors.