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Abdominal aortic repair is a major surgical procedure done to treat an aortic aneurysm. Elective surgery on an abdominal aortic aneurysm is indicated when an aneurysm is four or five cm or larger. Usually, the aneurysm is resected, and the aorta is replaced with a tube graft. Alternatively, an endograft may be placed, the femoral artery is accessed, and the graft is placed across the aorta under fluoroscopic guidance. This activity reviews the indication, contraindication, technique, and complications of both methods and the role of the healthcare team. Objectives: Outline the different approaches for treating abdominal aortic aneurysms. Review the complications of the different treatment approaches for abdominal aortic aneurysms. Summarize the indications for treating an abdominal aortic aneurysm. Describe the importance of improving care coordination amongst the interdisciplinary team to improve outcomes for patients affected by an abdominal aortic aneurysm. Access free multiple choice questions on this topic.

An abdominal aortic aneurysm (AAA) is defined as a permanent dilation of the abdominal aorta, with a diameter greater than 3 cm or a diameter greater than 50% of the aortic diameter at the level of the diaphragm. If left untreated, progressive vessel wall degeneration leads to dilation and thinning of the vessel. Eventually, these changes can result in the rupture of the AAA. AAA prevalence and incidence rates have decreased over the last 20 years, both in developed and in developing countries. This decrease has been attributed partially to the decline in smoking. Prevalence is negligible before the age of 55 to 60 years, and after that, the prevalence increases with age. AAA prevalence is up to fourfold more in men (between 1.3% and 12.5%) than women (between 0.0% and 5.2%).[1] The risk of rupture increases with the size of the aneurysm: the 5-year risk for aneurysms less than 5 cm is 1% to 2%, whereas it is 20% to 40% for aneurysms greater than 5 cm in diameter. Abdominal aortic aneurysm represents about 1% of deaths in males over the age of 65 and is the tenth leading cause of death in men 65 years of age or older. The mortality rate of ruptured abdominal aortic aneurysm is over 80%.[2] Early diagnosis and treatment, therefore, is very important before its rupture. To this day, treatment for AAA relies on two different surgical methods: Endovascular placement of an aortic stent graft (EVAR) and open surgical repair of AAA (OSR). Open surgical repair is a major operation involving the excision of dilated area and placement of a sutured woven graft. The surgery may be performed electively or under emergent situations. Unlike OSR, the EVAR is meant to seal the sac from the inside of the aneurysm, while the aneurysm wall is left untouched. The paradigm is therefore changed from replacing the aneurysm to excluding it from the systemic circulation.[3][4]

To this day, treatment for AAA relies on two different surgical methods: Endovascular placement of an aortic stent graft (EVAR) and open surgical repair of AAA (OSR). Open surgical repair is a major operation involving the excision of dilated area and placement of a sutured woven graft. The surgery may be performed electively or under emergent situations. Unlike OSR, the EVAR is meant to seal the sac from the inside of the aneurysm, while the aneurysm wall is left untouched. The paradigm is therefore changed from replacing the aneurysm to excluding it from the systemic circulation.[3][4] A serial noninvasive follow-up of small aneurysms (less than 5 cm) is an alternative to surgery. Ultrasonography is the recommended modality for surveillance; it should be performed every three years for aneurysms 3 to 3.9 cm in diameter, or annually for aneurysms 4.0 to 4.9 cm. There is no specific medication or other therapy that can be recommended to reduce the rate of aneurysm growth. Moreover, beta-adrenergic blockers and renin-angiotensin inhibitors, have not proven effective in reducing the rate of aneurysm growth. Lifestyle changes, such as exercise, also have not demonstrated a reduction in the aneurysmal growth rate. However, smoking cessation leads to a reduction in aneurysmal growth rate, as well as the risk of aneurysm rupture. Abdominal aortic aneurysm patients’ have a significant risk for future cardiovascular events that should be addressed. Recommendation of a healthy lifestyle (including exercise and a healthy diet) and blood pressure control, statins, and antiplatelet therapy, should be considered in all patients with abdominal aortic aneurysms.[3]

Postoperative mortality of OSR for AAAs has decreased over the years. While the mortality rate is highly variable among studies, it is considered to be less than 50%. Furthermore, EVAR has a lower short-term mortality rate than OSR. The complication rate following OSR varies among studies. Post-operative complications are pulmonary (42%), cardiac (18%), renal (17%), ischaemic colitis (9%), and wound complications (7%). Postoperative end-organ ischemia, including postoperative colonic ischemia, acute lower limb ischemia, or spinal ischemia, are infrequent but serious complications. Therefore patients should be closely monitored for these conditions. EVAR carries similar risk as OSR but with a lower incident rate. Unique complications of EVAR are graft migration and endoleaks.[3] Migration, a condition in which due to loss of fixation, the graft moves from the original location. Hooks and barbs assist aortic attachment, increasing the friction to prevent migration from occurring. An endoleak is a condition in which the graft fails to exclude blood from entering the aneurysmal sac. Endoleaks can subdivide into; type I endoleak- due to improper fixation or sealing between the proximal graft and the blood vessel at the proximal or distal zone of the stent. Type II endoleak-blood flow from patent collateral arteries (lumbar or inferior mesenteric arteries), to the aneurysmal sac. Type III endoleak-separation of stent-graft components with possible overlapping of stent material allowing leakage. Type IV and V endoleak- type IV endoleak-blood flow through the pores of the stent-graft. Type V endoleak is blood flow into the aneurysmal sac from an unknown source. In the past, EVAR associated with access site complications such as dissection, perforation, hematoma, and fistula. But with technical advancement, these complications are less frequent.[6][5] From a didactical point of view, it might be important to classify common postoperative complications as immediate, early, and late; OSR immediate complication: hemorrhage and myocardial infarction. OSR early complication: hemorrhage, ileus, ischemic colitis, myocardial infarction, pneumonia, renal failure, wound infection. OSR late complication: incisional hernia EVAR immediate complication: aneurysm rupture with conversion to open, stent misplacement, myocardial infarction EVAR early complication: contrast nephropathy, endoleaks

OSR early complication: hemorrhage, ileus, ischemic colitis, myocardial infarction, pneumonia, renal failure, wound infection. OSR late complication: incisional hernia EVAR immediate complication: aneurysm rupture with conversion to open, stent misplacement, myocardial infarction EVAR early complication: contrast nephropathy, endoleaks EVAR late complication: endoleaks, stent migration

Unruptured abdominal aortic aneurysms are detected more than ever before primarily because of more frequent use of accessible imaging tools and asymptomatic patient screening. The majority of patients with an abdominal aortic aneurysm are asymptomatic or present with nonspecific symptoms. Screening of asymptomatic patients has shown reduced mortality. Hence, educating first primary care physicians on the criteria for screening and followup for an abdominal aortic aneurysm is highly important. Screening Recommendation: All men above age 65 years should be screened with ultrasound, at least once in a lifetime.[3] Women above age 50 with a first-degree family member with a history of AAA should be considered for AAA screening in 10 years intervals.[3] Men or women with a peripheral aortic aneurysm should be considered for AAA screening, every 5 to 10 years.[3] Referral to a vascular surgeon at the time of initial diagnosis of aortic aneurysm, of any diameter is recommended. Furthermore, abdominal aortic aneurysm patients’ significant risk for another cardiovascular event. Hence, lifestyle changes, smoking cessation, and referral for cardiologists can improve patients' outcomes.[3] The biggest risk of abdominal aortic aneurysm is the risk of rupture. However, less than half of the patient presents with the classical triad of hypotension, pulsatile mass, and abdominal and back pain. Moreover, it has been shown that more than 30% of ruptured AAA are misdiagnosed.[3] Therefore, education of first responders including the nurse practitioner, primary care physicians, physician assistants, and emergency department physicians can facilitate diagnosis in the emergency scenario. Establishing a protocol for urgent management has also shown to improve outcomes.[5] The mortality rate of emergency surgical intervention following rupture is ten-fold higher than the mortality of patients undergoing planned intervention under specialist vascular surgeons. Hence it is important to educate patients regarding the importance of elective surgery. Moreover, once the decision for repair has been made, a multidisciplinary approach involving a cardiologist and pulmonologist should be utilized for risk stratification and medical optimization before repair to reduce negative outcomes.[3][5]