The largest artery in the body is the aorta. When under a great amount of pressure, the aorta can bulge, creating an aneurysm (Figure 1); this usually occurs in a weak part of the artery. Aneurysm is derived from the Greek term "aneurysma", which means dilation. An abdominal aortic aneurysm (AAA) is a widening in one part of the abdominal aorta. This paper will cover how an aneurysm is developed and diagnosed, different types of aneurysms, clinical values, stages of aneurysms, what the risk factors are, who is at risk, treatment options, cost, and what will happen if an aneurysm erupts.
A normal aorta measures less than 3 centimeters. Aneurysms are categorized by an increase in diameter of 1. 5 times greater than the normal diameter (Hagen, 2012). According to Sandy Hagen, development is based on a number of things such as, trauma, congenital defects, atherosclerosis, syphilis, mycosis, cystic medial necrosis, inflammation of the media and adventitia, increased pressure, and abnormal volume load, which means a severe aortic regurgitation. Men who are active smokers, have high blood pressure, high cholesterol, and have a family history of AAA are considered at the highest risk for developing an AAA.
30%-60% of patients diagnosed with AAA are asymptomatic. According to the National Library of Medicine, an aneurysm is typically found during a physical examination. The physician may feel a large pulsatile mass in the abdomen, and feel the pulsation of the aorta. To verify findings, an angiogram, computed tomography (CT) or ultrasound may be performed (Figure 2). Aneurysms are classified under two categories: true aneurysm and pseudoaneurysm. A true aneurysm occurs when the aneurysm is lined by all three layers of the aorta (tunica intima, tunica media, tunica adventitia).
The occurrence of this type of aneurysm forms when tensile strength decreases in the wall. Meaning, the strength in the wall of the aorta weakens under tension. A pseudoaneurysm is classified when blood leaks from tunica intima, but is contained by other layers of the aorta or the tissue surrounding the area of interest. There are two ways to describe an aneurysm; saccular and fusiform (Figure 3). A fusiform aneurysm is a transition from normal to abnormal; this type of aneurysm gradually increases in size as the aorta progresses inferior.
Fusiform aneurysms resemble the shape of a football. Saccular aneurysms are aneurysms that suddenly change shapes. The size of these aneurysms are greater than fusiform aneurysms and balloon outward. Saccular aneurysms create a sac which branches off from the aorta. Aneurysms that are smaller than 6 centimeters indicate a slow growth pattern. These are followed up by an ultrasound every 6 months. Studies show if an aneurysm measures less than 6 centimeters, 75% of patients have a 1 year survival rate. 50% of patients with an aneurysm of 6 centimeters have a survival rate of 1 year.
The percentage of survival decreases to 25% with an aneurysm greater than 7 centimeters, and decreases to 1% if an aneurysm measuring less than 5 centimeters ruptures (Hagen, 2012). When an aneurysm ruptures, the mortality rate is 50%. Ruptured aneurysms cause excruciating pain in the abdomen, shock, and an expanding abdominal mass. CT scans are the first imaging modality used when an aneurysm erupts because it obtains the most information in the least amount of time. Rupture causes compression of the common bile duct, renal artery, and kidney.
Compressions of these structures lead to obstructions of these structures. Clinical values will show a drop in hematocrit if an aneurysm has ruptured. A gold standard is the generally accepted standard of care for treatment of a defined condition (Zarins & Harris, 1997). When an abdominal aneurysm requires surgical treatment, elective surgery repair is the gold standard. If surgery is the option for the patient, a long incision in the abdomen is made. The aorta is clamped above the aneurysm to stop blood flow and the aneurysm is incised with a tube connecting the two ends of the aorta on both sides of the aneurysm.
Other treatment options include aortic graft and endovascular stent grafting. An aortic graft (Figure 4) is a flexible graft material that is attached to the remaining aorta. This material is placed endovascular and is anastomosed. Similar to an aortic graft is stent grafting. With stent grafting, a metal structure which resembles an aorta is placed endovascular -inside the vessel- at the level of the iliac bifurcation. A small incision is made into the vessel to guide the catheter inside the vessel.
The stent graft then expands to press against the aorta wall to stop vascular supply to the aneurysm. Both the aortic graft and stent graft method of repair for an aneurysm, but pose a danger for users by causing complications such as hematoma, infection, and degeneration of material. The effectiveness of surgery on an aortic aneurysm created a directly related relationship. For patients who chose surgery, survival percentage increased as survival years increased (Figure 5). If surgery is necessary, cost is an important factor to consider.
According to the National Business Group on Health, an elective surgery is about $25,000, but if an emergency surgery is required, the cost of surgery surges to $50,000 ("Abdominal aortic aneurysm," 2011). The cost of an aortic stent is about $12,000 ("Aortic aneurysm repair," 2014). Abdominal Aortic Aneurysms are dangerous if left undetected. Without proper treatment, rupture can occur increasing the potential of fatality. Men over the age of 60 who have a history of high blood pressure, high cholesterol, are active smokers, and have a history of AAA in the family are recommended receiving a check-up.