Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 12-09: Abdominal Aortic Aneurysm + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Most aortic aneurysms are asymptomatic until rupture, which is catastrophic Aneurysms measuring 5 cm are palpable in 80% of patients; the usual threshold for treatment is 5.5 cm Back or abdominal pain with aneurysmal tenderness may precede rupture Excruciating abdominal pain that radiates to the back Hypotension +++ General Considerations ++ The aorta of a healthy young man measures approximately 2 cm An aneurysm is considered present when the aortic diameter exceeds 3 cm Aneurysms rarely cause rupture until diameter exceeds 5 cm 90% of abdominal atherosclerotic aneurysms originate below the renal arteries Aortic bifurcation is usually involved Common iliac arteries are often involved +++ Demographics ++ Found in 2% of men over age 55 Male to female ratio is 4:1 + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Most asymptomatic aneurysms are discovered on ultrasound or CT imaging as part of a screening program or during the evaluation of unrelated abdominal symptoms Symptomatic aneurysms Mild to severe midabdominal pain due to aneurysmal expansion often radiates to lower back Pain may be constant or intermittent, exacerbated by even gentle pressure on aneurysm sack, and may also accompany inflammatory aneurysms Inflammatory aneurysms have an inflammatory peel, similar to the inflammation seen with retroperitoneal fibrosis, surrounds the aneurysm and encases adjacent retroperitoneal structures, such as the duodenum and, occasionally, the ureters Ruptured aneurysms Severe pain Hypotension Free rupture into the peritoneal cavity is lethal Most aneurysms have a thick layer of thrombus lining the aneurysmal sac Embolization to lower extremities is rarely seen +++ Differential Diagnosis ++ Perforated viscus, eg, peptic ulcer, appendix, gallbladder, diverticulitis Pancreatitis or pancreatic pseudocyst Urinary calculi Pyelonephritis Gastritis Intestinal ischemia Bowel obstruction Musculoskeletal pain Sudden death due to other causes, eg, ventricular fibrillation, myocardial infarction, pulmonary embolism + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Hematocrit will be normal, since there has been no opportunity for hemodilution Patients with aneurysms may also have the cardiopulmonary diseases of elderly male smokers, which include Coronary artery disease Carotid disease Kidney impairment Emphysema Preoperative testing may indicate the presence of these comorbid conditions +++ Imaging Studies ++ Abdominal ultrasonography Diagnostic study of choice for initial screening Useful in screening 65- to 75-year-old men, but not women, who have a history of smoking Repeated screening does not appear to be needed Abdominal or back radiographs: curvilinear calcifications outlining portions of aneurysm wall may be seen in approximately 75% of patients CT scans Provide a more reliable assessment of aneurysm diameter Should be done when the aneurysm nears the diameter threshold (5.5 cm) for treatment Contrast-enhanced CT scans Show the arteries above and below the aneurysm Visualization of this vasculature is essential for planning repair + Treatment Download Section PDF Listen +++ +++ Emergency Repair ++ If the bleeding is confined to the retroperitoneum, blood loss may be arrested long enough for the patient to undergo urgent operation Endovascular repair is available for ruptured aneurysm repair in most major vascular centers, with the results offering some improvement over open repair for these critically ill patients +++ Elective Repair ++ Generally indicated for aortic aneurysms ≥ 5.5 cm in diameter or aneurysms that have undergone rapid expansion (> .5 cm in 6 months) +++ Surgery ++ Not indicated when inflammatory aneurysm is present unless retroperitoneal structures, such as the ureter, are compressed or there is pain upon palpation of the aneurysm Interestingly, the inflammation that encases an inflammatory aneurysm recedes after either endovascular or open surgical aneurysmal repair Open surgical aneurysm repair Graft is sutured to the non-dilated vessels above and below the aneurysm This involves an abdominal incision, extensive dissection, and interruption of aortic blood flow Mortality rate is low (2–5%) when the procedure is performed in good risk patients in experienced centers Older, sicker patients may not tolerate cardiopulmonary stresses of the surgery +++ Endovascular Repair ++ Stent-graft is used to line the aorta and exclude the aneurysm Anatomic requirements to securely achieve aneurysm exclusion vary according to performance characteristics of the specific stent-graft device Stent must be able to seal securely against the wall of the aorta above and below the aneurysm, thereby excluding blood from flowing into the aneurysm sac Long-term survival is equivalent between the two techniques Patients who undergo endovascular repair require more repeat interventions and need to be monitored postoperatively since there is a 10–15% incidence of continued aneurysm growth post endovascular repair + Outcome Download Section PDF Listen +++ +++ Follow-Up ++ Once an aneurysm is identified, routine follow-up with ultrasound determines size and growth rate The frequency of imaging depends on aneurysm size ranging from every 2 years for small (< 4 cm aneurysms) to every 6 months for aneurysms at or approaching 5 cm At approximately 5 cm, a CT angiography with contrast should be done to more accurately size the aneurysm and define the anatomy +++ Complications ++ Myocardial infarction Routine infrarenal aneurysms Respiratory complications are similar to those seen in most major abdominal surgery Gastrointestinal hemorrhage suggests the possibility of graft enteric fistula, most commonly between the aorta and the distal duodenum +++ Prognosis ++ Open elective surgical resection Mortality rate is 1–5% Of those who survive surgery, about 60% are alive at 5 years Myocardial infarction is leading cause of death Endovascular aneurysm repair May be less definitive than open surgical repair In high-risk patients, endovascular approach reduces perioperative morbidity and mortality Prognosis depends on how successfully aneurysm has been excluded from the circulation Mortality rate for endovascular therapy is 0.5–2% Mortality rates among patients with large aneurysms 12% annual risk of rupture in aneurysms ≥ 6 cm in diameter 25% annual risk of rupture in aneurysms ≥ 7 cm diameter The long-term survival (5 years or more) after open and endovascular repairs is equivalent +++ When to Refer ++ Any patient with a 4.5 cm aortic aneurysm or larger should be referred for imaging and assessment by a vascular specialist Urgent referrals should be made if the patient complains of pain and gentle palpation of the aneurysm confirms that it is the source, regardless of aneurysm size +++ When to Admit ++ Aneurysm is tender to palpation Signs of aortic rupture + References Download Section PDF Listen +++ + +Brahmbhatt R et al. Improved trends in patient survival and decreased major complications after emergency ruptured abdominal aortic aneurysm repair. J Vasc Surg. 2016 Jan;63(1):39–47. [PubMed: 26506941] + +Chaikof EL et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg. 2018 Jan;67(1):2–77. [PubMed: 29268916] + +Kent KC. Clinical practice. Abdominal aortic aneurysms. N Engl J Med. 2014 Nov 27;371(22):2101–8. [PubMed: 25427112] + +Lederle FA et al; OVER Veterans Affairs Cooperative Study Group. Open versus endovascular repair of abdominal aortic aneurysm. N Engl J Med. 2019 May 30;380(22):2126–35. [PubMed: 31141634]