abdominal aortic aneurysm

File:Abdominal Aortic Aneurysm Location.png

The vast majority of aneurysms are asymptomatic. However, as the abdominal aorta expands and/or ruptures, the aneurysm may become painful and lead to pulsating sensations in the abdomen or pain in the chest, lower back, legs, or scrotum.{{cite book|last=Fauci|first=Anthony|title=Harrison's Principles of Internal Medicine|publisher=McGraw-Hill Professional|date=2008-03-06|edition=17|chapter=242|isbn=978-0-07-146633-2}}

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 heartbeat may also be felt. The bleeding can lead to a hypovolemic shock with low blood pressure and a fast heart rate, which may cause fainting. 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.{{cite journal |vauthors=Brown LC, Powell JT | title = Risk Factors for Aneurysm Rupture in Patients Kept Under Ultrasound Surveillance | journal = Annals of Surgery | volume = 230 | issue = 3 | pages = 289–96; discussion 296–7 | date = September 1999 | pmid = 10493476 | pmc = 1420874 | doi = 10.1097/00000658-199909000-00002 }} 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.Treska V. et al.:Aneuryzma břišní aorty, Prague, 1999, {{ISBN|80-7169-724-9}} Flank ecchymosis (appearance of a bruise) is a sign of retroperitoneal bleeding and is also called Grey Turner's sign.{{cite book |last=Goldman |first=Lee |title=Goldman's Cecil Medicine |publisher=Elsevier Saunders |location=Philadelphia, PA |date=25 July 2011 |edition=24th |pages=837 |isbn=978-1-4377-2788-3}}

The exact causes of the degenerative process remain unclear. There are, however, some hypotheses and well-defined risk factors.{{cite journal |vauthors=Keisler B, Carter C |title=Abdominal aortic aneurysm |journal=Am Fam Physician |volume=91 |issue=8 |pages=538–543 |date=April 2015 |pmid=25884861}}

• Tobacco smoking: More than 90% of people who develop an AAA have smoked at some point in their lives.{{cite journal |vauthors=Greenhalgh RM, Powell JT |title=Endovascular repair of abdominal aortic aneurysm |journal=N. Engl. J. Med. |volume=358 |issue=5 |pages=494–501 |date=January 2008 |pmid=18234753 |doi=10.1056/NEJMct0707524}}
• Alcohol and hypertension: The inflammation caused by prolonged use of alcohol and hypertensive effects from abdominal edema which leads to hemorrhoids, esophageal varices, and other conditions, is also considered a long-term cause of AAA.{{Citation needed|date=June 2022}}
• Genetic influences: The influence of genetic factors is high. AAA is four to six times more common in male siblings of known patients, with a risk of 20–30%.{{cite journal |vauthors=Baird PA, Sadovnick AD, Yee IM, Cole CW, Cole L |title=Sibling risks of abdominal aortic aneurysm |journal=Lancet |volume=346 |issue=8975 |pages=601–604 |date=September 1995 |pmid=7651004 |s2cid=27523622 |doi=10.1016/S0140-6736(95)91436-6}} The high familial prevalence rate is most notable in male individuals.{{cite journal |author=Clifton MA |title=Familial abdominal aortic aneurysms |journal=Br J Surg |volume=64 |issue=11 |pages=765–766 |date=November 1977 |pmid=588966 |s2cid=40560333 |doi=10.1002/bjs.1800641102}} There are many hypotheses about the exact genetic disorder that could cause a higher incidence of AAA among male members of the affected families. Some have presumed that the influence of alpha 1-antitrypsin deficiency could be crucial, while other experimental works favor the hypothesis of X-linked mutation, which would explain the lower incidence in heterozygous females. Other hypotheses of genetic causes have also been formulated. Connective tissue disorders, such as Marfan syndrome and Ehlers-Danlos syndrome, have also been strongly associated with AAA. Both relapsing polychondritis and pseudoxanthoma elasticum may cause abdominal aortic aneurysm.{{cite book |last1=Rapini |first1=Ronald P. |last2=Bolognia |first2=Jean L. |last3=Jorizzo |first3=Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis, MO |year=2007 |isbn=978-1-4160-2999-1}}
• Atherosclerosis: The AAA was long considered to be caused by atherosclerosis because the walls of the AAA frequently carry an atherosclerotic burden. However, this hypothesis cannot explain the initial defect and the development of occlusion, which is observed in the process. Another hypothesis is that plaque buildup can cause a feed-forward dysfunction in the signaling among neurons that regulate pressure in the aorta. This feed-forward process leads to an over-pressuring condition that ruptures the aorta.{{cite journal |last1=Conley |first1=Buford R. |last2=Doux |first2=John D. |last3=Lee |first3=Patrick Y. |last4=Bazar |first4=Kimberly A. |last5=Daniel |first5=Stephanie M. |last6=Yun |first6=Anthony J. |title=Integrating the theories of Darwin and Bernoulli: Maladaptive baroreceptor network dysfunction may explain the pathogenesis of aortic aneurysms |url=https://www.sciencedirect.com/science/article/pii/S0306987705001507 |journal=Medical Hypotheses |volume=65 |issue=2 |pages=266–272 |date=1 January 2005 |issn=0306-9877 |pmid=15922098 |doi=10.1016/j.mehy.2005.03.006}}
• Other causes of the development of AAA include: infection, trauma, arteritis, and cystic medial necrosis.

File:Aortadiagramgray.png with yellow lines depicting the most common infrarenal location of the AAA]]

File:Aortic Aneurism 76F 3D SR Nevit Dilmen.stl

The most striking histopathological changes of the aneurysmatic aorta are seen in the tunica media and intima layers. These changes include the accumulation of lipids in foam cells, extracellular free cholesterol crystals, calcifications, thrombosis, and ulcerations and ruptures of the layers. Adventitial inflammatory infiltrate is present.

However, the degradation of the tunica media by means of a proteolytic process seems to be the basic pathophysiologic mechanism of AAA development. Some researchers report increased expression and activity of matrix metalloproteinases in individuals with AAA. This leads to the elimination of elastin from the media, rendering the aortic wall more susceptible to the influence of blood pressure. Other reports have suggested the serine protease granzyme B may contribute to aortic aneurysm rupture through the cleavage of decorin, leading to disrupted collagen organization and reduced tensile strength of the adventitia.{{cite journal |vauthors=Chamberlain CM, Ang LS, Boivin WA, Cooper DM, Williams SJ, Zhao H, Hendel A, Folkesson M, Swedenborg J, Allard MF, McManus BM, Granville DJ | title = Perforin-independent extracellular granzyme B activity contributes to abdominal aortic aneurysm | journal = Am. J. Pathol. | volume = 176 | issue = 2 | pages = 1038–49 | year = 2010 | pmid = 20035050 | pmc = 2808106 | doi = 10.2353/ajpath.2010.090700 }}{{cite journal |vauthors=Ang LS, Boivin WA, Williams SJ, Zhao H, Abraham T, Carmine-Simmen K, McManus BM, Bleackley RC, Granville DJ | title = Serpina3n attenuates granzyme B-mediated decorin cleavage and rupture in a murine model of aortic aneurysm | journal = Cell Death Dis | volume = 2 | issue = 9| pages = e209 | year = 2011 | pmid = 21900960 | pmc = 3186906 | doi = 10.1038/cddis.2011.88 }} There is also a reduced amount of vasa vasorum in the abdominal aorta (compared to the thoracic aorta); consequently, the tunica media must rely mostly on diffusion for nutrition, which makes it more susceptible to damage.{{cite journal |vauthors=MacSweeney ST, Powell JT, Greenhalgh RM | title = Pathogenesis of abdominal aortic aneurysm | journal = Br J Surg | volume = 81 | issue = 7 | pages = 935–41 | year = 1994 | pmid = 7922083 | s2cid = 21272785 | doi = 10.1002/bjs.1800810704}}

Hemodynamics affect the development of AAA, which has a predilection for the infrarenal aorta. The histological structure and mechanical characteristics of the infrarenal aorta differ from those of the thoracic aorta. The diameter decreases from the root to the aortic bifurcation, and the wall of the infrarenal aorta also contains a lesser proportion of elastin. The mechanical tension in the abdominal aortic wall is therefore higher than in the thoracic aortic wall. The elasticity and distensibility also decline with age, which can result in gradual dilatation of the segment. Higher intraluminal pressure in patients with arterial hypertension markedly contributes to the progression of the pathological process. Suitable hemodynamic conditions may be linked to specific intraluminal thrombus (ILT) patterns along the aortic lumen, which in turn may affect AAA's development.{{cite journal |vauthors=Biasetti J, Hussain F, Gasser TC | title = Blood flow and coherent vortices in the normal and aneurysmatic aortas: a fluid dynamical approach to intra-luminal thrombus formation | journal = J R Soc Interface | volume = 8 | issue = 63 | pages = 1449–61 | year = 2011 | pmid = 21471188 | pmc = 3163425 | doi = 10.1098/rsif.2011.0041 }}

An abdominal aortic aneurysm is usually diagnosed by physical exam, abdominal ultrasound, or CT scan. Plain abdominal radiographs may show the outline of an aneurysm when its walls are calcified. However, the outline will be visible by X-ray in less than half of all aneurysms. Ultrasonography is used to screen for aneurysms and to determine their size if present. Additionally, free peritoneal fluid can be detected. It is non-invasive and sensitive, but the presence of bowel gas or obesity may limit its usefulness.{{cite journal |vauthors=Lu F, Lin Y, Zhou J, Chen Z, Liu Y, Zhong M, Wang L |title=Obesity and the obesity paradox in abdominal aortic aneurysm |journal=Front Endocrinol (Lausanne) |volume=15 |issue= |pages=1410369 |date=2024 |pmid=39055063 |pmc=11269098 |doi=10.3389/fendo.2024.1410369 |doi-access=free |url=}} CT scan has nearly 100% sensitivity for an aneurysm and is also useful in preoperative planning, detailing the anatomy and possibility for endovascular repair. In the case of suspected rupture, it can also reliably detect retroperitoneal fluid. Alternative less often used methods for visualization of an aneurysm include MRI and angiography.{{cite journal |vauthors=Green DB, Palumbo MC, Lau C |title=Imaging of Thoracoabdominal Aortic Aneurysms |journal=J Thorac Imaging |volume=33 |issue=6 |pages=358–365 |date=November 2018 |pmid=29979239 |doi=10.1097/RTI.0000000000000341 |url=}}

An aneurysm ruptures if the mechanical stress (tension per area) exceeds the local wall strength; consequently, peak wall stress (PWS),{{cite journal |vauthors=Fillinger MF, Marra SP, Raghavan ML, Kennedy FE |title=Prediction of rupture risk in abdominal aortic aneurysm during observation: wall stress versus diameter |journal=Journal of Vascular Surgery |volume=37 |issue=4 |pages=724–732 |date=April 2003 |pmid=12663969 |doi=10.1067/mva.2003.213 |doi-access=free}} mean wall stress (MWS),{{cite journal |last1=Chung |first1=Timothy K. |last2=Gueldner |first2=Pete H. |last3=Kickliter |first3=Trevor M. |last4=Liang |first4=Nathan L. |last5=Vorp |first5=David A. |date=November 2022 |title=An Objective and Repeatable Sac Isolation Technique for Comparing Biomechanical Metrics in Abdominal Aortic Aneurysms |journal=Bioengineering |volume=9 |issue=11 |pages=601 |doi=10.3390/bioengineering9110601 |pmid=36354512 |pmc=9687639 |issn=2306-5354|doi-access=free}} and peak wall rupture risk (PWRR){{cite journal |vauthors=Gasser TC, Auer M, Labruto F, Swedenborg J, Roy J |title=Biomechanical rupture risk assessment of abdominal aortic aneurysms: model complexity versus predictability of finite element simulations |journal=Eur J Vasc Endovasc Surg |volume=40 |issue=2 |pages=176–185 |year=2010 |pmid=20447844 |doi=10.1016/j.ejvs.2010.04.003 |doi-access=free}} are more reliable parameters than diameter to assess AAA rupture risk. Medical software allows computing these rupture risk indices from standard clinical CT data and provides a patient-specific AAA rupture risk diagnosis.{{cite web |title=VASCOPS |url=http://www.vascops.com/en/vascops-A4clinics.html |url-status=live |access-date=15 January 2011 |archive-url=https://web.archive.org/web/20110717185318/http://www.vascops.com/en/vascops-A4clinics.html |archive-date=17 July 2011}}{{cite journal |last1=Canchi |first1=Tejas |last2=Patnaik |first2=Sourav S. |last3=Nguyen |first3=Hong N. |last4=Ng |first4=E.Y.K. |last5=Narayanan |first5=Sriram |last6=Muluk |first6=Satish C. |last7=De Oliveira |first7=Victor |last8=Finol |first8=Ender A. |title=A Comparative Study of Biomechanical and Geometrical Attributes of Abdominal Aortic Aneurysms in the Asian and Caucasian Populations |journal=Journal of Biomechanical Engineering |volume=142 |issue=6 |date=1 June 2020 |issn=1528-8951 |pmid=31633169 |s2cid=204813645 |pmc=10782868 |doi=10.1115/1.4045268}}{{cite journal |last1=Rengarajan |first1=Balaji |last2=Patnaik |first2=Sourav S. |last3=Finol |first3=Ender A. |title=A Predictive Analysis of Wall Stress in Abdominal Aortic Aneurysms Using a Neural Network Model |journal=Journal of Biomechanical Engineering |volume=143 |issue=12 |date=1 December 2021 |issn=1528-8951 |pmid=34318314 |pmc=8420793 |doi=10.1115/1.4051905}} This type of biomechanical approach has been shown to accurately predict the location of AAA rupture.{{cite journal |vauthors=Doyle BJ, McGloughlin TM, Miller K, Powell JT, Norman PE |title=Regions of high wall stress can predict the future location of rupture in abdominal aortic aneurysm |journal=Cardiovasc Intervent Radiol |volume=37 |issue=3 |pages=815–818 |year=2014 |pmid=24554200 |s2cid=35797072 |doi=10.1007/s00270-014-0864-7}}

File:Ultrasonographic measurement of aortic diameter at the navel.svg|Aortic measurement on abdominal ultrasonography in the axial plane between the outer margins of the aortic wall{{cite web|url=https://emedicine.medscape.com/article/1977715-overview#a3|title=Bedside Ultrasonography Evaluation of Abdominal Aortic Aneurysm - Technique|author=Timothy Jang|date=2017-08-28|website=Medscape|url-status=live|archive-url=https://web.archive.org/web/20180125015641/https://emedicine.medscape.com/article/1977715-overview#a3|archive-date=2018-01-25}}

File:Ultrasonography of abdominal aortic aneurysm in sagittal plane, annotated.jpg|Ultrasonography in the sagittal plane, showing axial plane measure (dashed red line), as well as maximal diameter (dotted yellow line), which is preferred

File:RupturedAAA.png|A ruptured AAA with an open arrow marking the aneurysm and the closed arrow marking the free blood in the abdomen

File:Sagital aaa.JPG|Sagittal CT image of an AAA

File:AAA rupture risk.png|Biomechanical AAA rupture risk prediction

File:Contrast-enhanced CT scan demonstrating abdominal aortic aneurysm.jpg|An axial contrast-enhanced CT scan demonstrating an abdominal aortic aneurysm of 4.8 by 3.8 cm

File:RupturedAAAXray.png|The faint outline of the calcified wall of an AAA as seen on a plain X-ray

File:Abdominal aortic aneurysm.JPG|Abdominal aortic aneurysms (3.4 cm)

File:AneursymCTMark.png|An aortic aneurysm as seen on CT with a small area of remaining blood flow

File:UOTW 35 - Ultrasound of the Week 1.webm|Ultrasound showing a previously repaired AAA that is leaking with flow around the graft{{cite web|title=UOTW #35 - Ultrasound of the Week|url=https://www.ultrasoundoftheweek.com/uotw-35/|website=Ultrasound of the Week|access-date=27 May 2017|date=27 January 2015|url-status=live|archive-url=https://web.archive.org/web/20170509114214/https://www.ultrasoundoftheweek.com/uotw-35/|archive-date=9 May 2017}}

File:Ultrasonography of abdominal aortic aneurysm with mural thrombus.jpg|Ultrasonography of an aneurysm with a mural thrombus

Abdominal aortic aneurysms are commonly divided according to their size and symptomatology. An aneurysm is usually defined as an outer aortic diameter over 3 cm (normal diameter of the aorta is around 2 cm), or more than 50% of normal diameter.{{cite journal |last=Kent |first=K. Craig |title=Abdominal Aortic Aneurysms |journal=The New England Journal of Medicine |date=27 November 2014 |volume=371 |issue=22 |pages=2101–2108 |doi=10.1056/NEJMcp1401430 |pmid=25427112}} If the outer diameter exceeds 5.5 cm, the aneurysm is considered to be large. Ruptured AAA should be suspected in any person older than 60 who experiences collapse, unexplained low blood pressure, or sudden-onset back or abdominal pain. Abdominal pain, shock, and a pulsatile mass are only present in a minority of cases.{{citation needed|date=June 2022}} Although an unstable person with a known aneurysm may undergo surgery without further imaging, the diagnosis will usually be confirmed using CT or ultrasound scanning.{{citation needed|date=October 2021}}

The suprarenal aorta normally measures about 0.5 cm larger than the infrarenal aorta.{{cite web|url=https://www.uptodate.com/contents/clinical-features-and-diagnosis-of-abdominal-aortic-aneurysm|title=Clinical features and diagnosis of abdominal aortic aneurysm|author=Jeffrey Jim, Robert W Thompson|website=UpToDate|date=2018-03-05|url-status=live|archive-url=https://web.archive.org/web/20180330212246/https://www.uptodate.com/contents/clinical-features-and-diagnosis-of-abdominal-aortic-aneurysm|archive-date=2018-03-30}}

Aortic aneurysm rupture may be mistaken for the pain of kidney stones, or muscle related back pain.

In terms of prevention, the following are effective measures to reduce the risk of developing a AAA:{{cn|date=September 2024}}

• Smoking cessation
• Treatment of hypertension

The U.S. Preventive Services Task Force (USPSTF) recommends a single screening abdominal ultrasound for abdominal aortic aneurysm in males aged 65 to 75 years who have a history of smoking.{{cite journal |last1=US Preventive Services Task |first1=Force. |last2=Owens |first2=DK |last3=Davidson |first3=KW |last4=Krist |first4=AH |last5=Barry |first5=MJ |last6=Cabana |first6=M |last7=Caughey |first7=AB |last8=Doubeni |first8=CA |last9=Epling JW |first9=Jr |last10=Kubik |first10=M |last11=Landefeld |first11=CS |last12=Mangione |first12=CM |last13=Pbert |first13=L |last14=Silverstein |first14=M |last15=Simon |first15=MA |last16=Tseng |first16=CW |last17=Wong |first17=JB |title=Screening for Abdominal Aortic Aneurysm: US Preventive Services Task Force Recommendation Statement. |journal=JAMA |date=10 December 2019 |volume=322 |issue=22 |pages=2211–2218 |doi=10.1001/jama.2019.18928 |pmid=31821437|doi-access=free }} Among this group who does not smoke, screening may be selective. It is unclear if screening is useful in women who have smoked and the USPSTF recommends against screening in women who have never smoked.{{cite journal|last1=Ali|first1=MU|last2=Fitzpatrick-Lewis|first2=D|last3=Miller|first3=J|last4=Warren|first4=R|last5=Kenny|first5=M|last6=Sherifali|first6=D|last7=Raina|first7=P|title=Screening for abdominal aortic aneurysm in asymptomatic adults.|journal=Journal of Vascular Surgery|date=December 2016|volume=64|issue=6|pages=1855–1868|doi=10.1016/j.jvs.2016.05.101|pmid=27871502|doi-access=free}}

In the United Kingdom, the NHS AAA Screening Programme invites men in England for screening during the year they turn 65. Men over 65 can contact the programme to arrange to be screened.{{cite web|url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/617871/AAA_draft_short_form_decision_aid.pdf|title=NHS Abdominal Aortic Aneurysm Screening Programme}}

In Sweden one time screening is recommended in all males over 65 years of age. This has been found to decrease the risk of death from AAA by 42% with a number needed to screen just over 200. In those with a close relative diagnosed with an aortic aneurysm, Swedish guidelines recommend an ultrasound at around 60 years of age.{{cite web|url=https://alfresco.vgregion.se/alfresco/service/vgr/storage/node/content/6861/Aortascreening%20av%20n%C3%A4ra%20sl%C3%A4kting.pdf?a=false&guest=true|title=Aortascreening av nära släkting (Aortic screening of close relative)|website=Västra Götaland Regional Council|access-date=2019-01-03|archive-date=2019-01-04|archive-url=https://web.archive.org/web/20190104124416/https://alfresco.vgregion.se/alfresco/service/vgr/storage/node/content/6861/Aortascreening%20av%20n%C3%A4ra%20sl%C3%A4kting.pdf?a=false&guest=true|url-status=dead}}

Australia has no guideline on screening.{{cite journal|last1=Robinson|first1=Domenic|last2=Mees|first2=Barend|last3=Verhagen|first3=Hence|last4=Chuen|first4=Jason|date=June 2013|title=Aortic aneurysms – screening, surveillance and referral.|url=|journal=Australian Family Physician|volume=42|issue=6|pages=364–9|pmid=23781541}}

Repeat ultrasounds should be carried out in those who have an aortic size greater than 3.0 cm. In those whose aorta is between 3.0 and 3.9 cm this should be every three years, if between 4.0 and 4.4 cm every two years, and if between 4.5 and 5.4 cm every year.{{cite journal |vauthors=Bown MJ, Sweeting MJ, Brown LC, Powell JT, Thompson SG | title = Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis | journal = JAMA | volume = 309 | issue = 8 | pages = 806–13 | date = February 2013 | pmid = 23443444 | doi = 10.1001/jama.2013.950 | doi-access = | url = http://jama.jamanetwork.com/data/Journals/JAMA/926459/joc130012_806_813.pdf }}

The treatment options for asymptomatic AAA are conservative management, surveillance with a view to eventual repair, and immediate repair. Two modes of repair are available for an AAA: open aneurysm repair, and endovascular aneurysm repair (EVAR). An intervention is often recommended if the aneurysm grows more than 1 cm per year or it is bigger than 5.5 cm.{{cite journal |last1=Ulug |first1=Pinar |last2=Powell |first2=Janet T |last3=Martinez |first3=Melissa Ashley-Marie |last4=Ballard |first4=David J |last5=Filardo |first5=Giovanni |title=Surgery for small asymptomatic abdominal aortic aneurysms |journal=Cochrane Database of Systematic Reviews |date=1 July 2020 |volume=2020 |issue=7 |pages=CD001835 |doi=10.1002/14651858.CD001835.pub5 |pmid=32609382 |pmc=7389114 }} Repair is also indicated for symptomatic aneurysms. Ten years after open AAA repair, the overall survival rate was 59%.{{cite journal |last1=Timmers |first1=Tim K. |last2=van Herwaarden |first2=Joost A. |last3=de Borst |first3=Gert-Jan |last4=Moll |first4=Frans L. |last5=Leenen |first5=Luke P. H. |title=Long-Term Survival and Quality of Life After Open Abdominal Aortic Aneurysm Repair |journal=World Journal of Surgery |date=December 2013 |volume=37 |issue=12 |pages=2957–2964 |doi=10.1007/s00268-013-2206-3 |pmid=24132818 |s2cid=9019195}} Mycotic abdominal aorta aneurysm (MAAA) is a rare and life-threatening condition. Because of its rarity, there is a lack of adequately powered studies and consensus on its treatment and follow-up. A management protocol on the management of mycotic abdominal aortic aneurysm was recently published in the Annals of Vascular Surgery by Premnath et al.{{cite journal |last1=Premnath |first1=Sivaram |last2=Zaver |first2=Vasudev |last3=Hostalery |first3=Aurelien |last4=Rowlands |first4=Timothy |last5=Quarmby |first5=John |last6=Singh |first6=Sanjay |date=2021-07-01 |title=Mycotic Abdominal Aortic Aneurysms – A Tertiary Centre Experience and Formulation of a Management Protocol |url=https://www.annalsofvascularsurgery.com/article/S0890-5096(21)00079-0/abstract |journal=Annals of Vascular Surgery |volume=74 |pages=246–257 |doi=10.1016/j.avsg.2020.12.025 |issn=0890-5096 |pmid=33508457|s2cid=231760989}}

Conservative management is indicated in people where repair carries a high mortality risk and in patients where repair is unlikely to improve life expectancy. The mainstay of the conservative treatment is smoking cessation.{{citation needed|date=October 2021}}

Surveillance is indicated in small asymptomatic aneurysms (less than 5.5 cm) where the risk of repair exceeds the risk of rupture. As an AAA grows in diameter, the risk of rupture increases. Surveillance until an aneurysm has reached a diameter of 5.5 cm has not been shown to have a higher risk as compared to early intervention.{{cite journal |vauthors=Powell JT, Brown LC, Forbes JF, Fowkes FG, Greenhalgh RM, Ruckley CV, Thompson SG | title = Final 12-year follow-up of surgery versus surveillance in the UK Small Aneurysm Trial | journal = Br J Surg | volume = 94 | issue = 6 | pages = 702–8 | date = Jun 2007 | pmid = 17514693 | doi = 10.1002/bjs.5778 | s2cid = 25392801 | doi-access = free }}{{cite journal | vauthors = Lederle FA, Wilson SE, Johnson GR, Reinke DB, Littooy FN, Acher CW, Ballard DJ, Messina LM, Gordon IL, Chute EP, Krupski WC, Busuttil SJ, Barone GW, Sparks S, Graham LM, Rapp JH, Makaroun MS, Moneta GL, Cambria RA, Makhoul RG, Eton D, Ansel HJ, Freischlag JA, Bandyk D | title = Immediate repair compared with surveillance of small abdominal aortic aneurysms | journal = N Engl J Med | volume = 346 | issue = 19 | pages = 1437–44 | date = May 2002 | pmid = 12000813 | doi = 10.1056/NEJMoa012573 | doi-access = free }}

No medical therapy is effective at decreasing the growth rate or rupture rate of asymptomatic AAAs. Blood pressure and lipids should, however, be treated per usual.{{cite journal |last1=Hirsch |first1=Alan T. |last2=Haskal |first2=Ziv J. |last3=Hertzer |first3=Norman R. |last4=Bakal |first4=Curtis W. |last5=Creager |first5=Mark A. |last6=Halperin |first6=Jonathan L. |last7=Hiratzka |first7=Loren F. |last8=Murphy |first8=William R.C. |last9=Olin |first9=Jeffrey W. |last10=Puschett |first10=Jules B. |last11=Rosenfield |first11=Kenneth A. |last12=Sacks |first12=David |last13=Stanley |first13=James C. |last14=Taylor |first14=Lloyd M. |last15=White |first15=Christopher J. |last16=White |first16=John |last17=White |first17=Rodney A. |last18=Antman |first18=Elliott M. |last19=Smith |first19=Sidney C. |last20=Adams |first20=Cynthia D. |last21=Anderson |first21=Jeffrey L. |last22=Faxon |first22=David P. |last23=Fuster |first23=Valentin |last24=Gibbons |first24=Raymond J. |last25=Halperin |first25=Jonathan L. |last26=Hiratzka |first26=Loren F. |last27=Hunt |first27=Sharon A. |last28=Jacobs |first28=Alice K. |last29=Nishimura |first29=Rick |last30=Ornato |first30=Joseph P. |last31=Page |first31=Richard L. |last32=Riegel |first32=Barbara |title=ACC/AHA Guidelines for the Management of Patients with Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic) |journal=Journal of Vascular and Interventional Radiology |date=September 2006 |volume=17 |issue=9 |pages=1383–1398 |doi=10.1097/01.RVI.0000240426.53079.46 |pmid=16990459 |doi-access=free }}

The threshold for repair varies slightly from individual to individual, depending on the balance of risks and benefits when considering repair versus ongoing surveillance. The size of an individual's native aorta may influence this, along with the presence of comorbidities that increase operative risk or decrease life expectancy. Evidence, however, does not usually support repair if the size is less than 5.5 cm.

{{Main|Open aortic surgery}}

Open repair is indicated in young patients as an elective procedure, or in growing or large, symptomatic or ruptured aneurysms. The aorta must be clamped during the repair, denying blood to the abdominal organs and sections of the spinal cord; this can cause a range of complications. As it is essential to perform the critical part of the operation quickly, the incision is typically made large enough to facilitate the fastest repair. Recovery after open AAA surgery takes significant time. The minimums are a few days in intensive care, a week total in the hospital, and a few months before full recovery.{{citation needed|date=September 2021}}

File:Endovasc.jpg

{{Main|Endovascular aneurysm repair}}

Endovascular repair first became practical in the 1990s and although it is now an established alternative to open repair, its role is yet to be clearly defined. It is generally indicated in older, high-risk patients or patients unfit for open repair. However, endovascular repair is feasible for only a portion of AAAs, depending on the morphology of the aneurysm. The main advantages over open repair are that there is less peri-operative mortality, less time in intensive care, less time in hospital overall, and an earlier return to normal activity. Disadvantages of endovascular repair include a requirement for more frequent ongoing hospital reviews and a higher chance of further required procedures. According to the latest studies, the EVAR procedure does not offer any benefit for overall survival or health-related quality of life compared to open surgery, although aneurysm-related mortality is lower.{{cite journal | author = Rutherford RB | title = Randomized EVAR trials and advent of level I evidence: a paradigm shift in the management of large abdominal aortic aneurysms? | journal = Semin Vasc Surg | volume = 19 | issue = 2 | pages = 69–74 | date = Jun 2006 | pmid = 16782510 | doi = 10.1053/j.semvascsurg.2006.03.001 }}{{cite journal |vauthors=Lederle FA, Kane RL, MacDonald R, Wilt TJ | title = Systematic review: repair of unruptured abdominal aortic aneurysm | journal = Annals of Internal Medicine | volume = 146 | issue = 10 | pages = 735–41 | year = 2007 | pmid = 17502634 | doi = 10.7326/0003-4819-146-10-200705150-00007 | s2cid = 20273503 | doi-access = }}{{cite journal | author = Evar Trial Participants | title = Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial | journal = Lancet | volume = 365 | issue = 9478 | pages = 2179–86 | year = 2005 | pmid = 15978925 | doi = 10.1016/S0140-6736(05)66627-5 | s2cid = 54288202 }}{{cite journal | vauthors = Blankensteijn JD, de Jong SE, Prinssen M, van der Ham AC, Buth J, van Sterkenburg SM, Verhagen HJ, Buskens E, Grobbee DE | title = Two-year outcomes after conventional or endovascular repair of abdominal aortic aneurysms | journal = N Engl J Med | volume = 352 | issue = 23 | pages = 2398–405 | date = Jun 2005 | pmid = 15944424 | doi = 10.1056/NEJMoa051255 | hdl = 1874/14151 | hdl-access = free }} In patients unfit for open repair, EVAR plus conservative management was associated with no benefit, more complications, subsequent procedures and higher costs compared to conservative management alone.{{cite journal | author = Evar Trial Participants | title = Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR trial 2): randomised controlled trial | journal = Lancet | volume = 365 | issue = 9478 | pages = 2187–92 | year = 2005 | pmid = 15978926 | doi = 10.1016/S0140-6736(05)66628-7 | s2cid = 26174408 }} Endovascular treatment for paraanastomotic aneurysms after aortobiiliac reconstruction is also a possibility.{{cite journal |vauthors=Amato AC, Kahlberg AK, Bertoglio LB, Melissano GM, Chiesa RC |title=Endovascular treatment of a triple paraanastomotic aneurysm after aortobiiliac reconstruction |journal=Jornal Vascular Brasileiro|volume=7 |issue=3 |pages=1–3 |year=2008 |doi=10.1590/S1677-54492008000300016 |doi-access=free }} A 2017 Cochrane review found tentative evidence of no difference in outcomes between endovascular and open repair of ruptured AAA in the first month.{{cite journal |last1=Badger |first1=Stephen |last2=Forster |first2=Rachel |last3=Blair |first3=Paul H |last4=Ellis |first4=Peter |last5=Kee |first5=Frank |last6=Harkin |first6=Denis W |title=Endovascular treatment for ruptured abdominal aortic aneurysm |journal=Cochrane Database of Systematic Reviews |date=26 May 2017 |volume=2017 |issue=6 |pages=CD005261 |doi=10.1002/14651858.CD005261.pub4 |pmid=28548204 |pmc=6481849 }}

In those with aortic rupture of the AAA, treatment is immediate surgical repair. There appear to be benefits to allowing permissive hypotension and limiting the use of intravenous fluids during transport to the operating room.{{cite journal |last1=Hamilton |first1=H |last2=Constantinou |first2=J |last3=Ivancev |first3=K |title=The role of permissive hypotension in the management of ruptured abdominal aortic aneurysms |journal=The Journal of Cardiovascular Surgery |date=April 2014 |volume=55 |issue=2 |pages=151–159 |pmid=24670823 |url=https://www.minervamedica.it/en/journals/cardiovascular-surgery/article.php?cod=R37Y2014N02A0151 }}

Although the current standard of determining rupture risk is based on maximum diameter, it is known that smaller AAAs that fall below this threshold (diameter<5.5 cm) may also rupture, and larger AAAs (diameter>5.5 cm) may remain stable.{{cite journal |vauthors=Darling RC, Messina CR, Brewster DC, Ottinger LW | title = Autopsy study of unoperated abdominal aortic aneurysms. The case for early resection | journal = Circulation | volume = 56 | issue = 3 Suppl | pages = II161–4 | date = September 1977 | pmid = 884821 }}{{cite journal |vauthors=Nicholls SC, Gardner JB, Meissner MH, Johansen HK | title = Rupture in small abdominal aortic aneurysms | journal = Journal of Vascular Surgery | volume = 28 | issue = 5 | pages = 884–8 | date = November 1998 | pmid = 9808857 | doi = 10.1016/S0741-5214(98)70065-5 | doi-access = free }} In one report, it was shown that 10–24% of ruptured AAAs were less than 5 cm in diameter. It has also been reported that of 473 non-repaired AAAs examined from autopsy reports, there were 118 cases of rupture, 13% of which were less than 5 cm in diameter. This study also showed that 60% of the AAAs greater than 5 cm (including 54% of those AAAs between 7.1 and 10 cm) never experienced rupture.{{cite journal | author = Vorp DA | title = Biomechanics of abdominal aortic aneurysm | journal = Journal of Biomechanics | volume = 40 | issue = 9 | pages = 1887–902 | year = 2007 | pmid = 17254589 | pmc = 2692528 | doi = 10.1016/j.jbiomech.2006.09.003 }} Vorp et al. later deduced from the findings of Darling et al. that if the maximum diameter criterion were followed for the 473 subjects, only 7% (34/473) of cases would have died from rupture before surgical intervention as the diameter was less than 5 cm, with 25% (116/473) of cases possibly undergoing unnecessary surgery since these AAAs may never have ruptured.

Alternative methods of rupture assessment have been recently reported. The majority of these approaches involve the numerical analysis of AAAs using the common engineering technique of the finite element method (FEM) to determine the wall stress distributions. Recent reports have shown that these stress distributions have been shown to correlate to the overall geometry of the AAA rather than solely to the maximum diameter.{{cite journal |vauthors=Vorp DA, Raghavan ML, Webster MW | title = Mechanical wall stress in abdominal aortic aneurysm: influence of diameter and asymmetry | journal = Journal of Vascular Surgery | volume = 27 | issue = 4 | pages = 632–9 | date = April 1998 | pmid = 9576075 | doi = 10.1016/S0741-5214(98)70227-7 | doi-access = free }}{{cite journal |vauthors=Sacks MS, Vorp DA, Raghavan ML, Federle MP, Webster MW | title = In vivo three-dimensional surface geometry of abdominal aortic aneurysms | journal = Annals of Biomedical Engineering | volume = 27 | issue = 4 | pages = 469–79 | year = 1999 | pmid = 10468231 | doi = 10.1114/1.202 | s2cid = 21394944 }}{{cite journal |vauthors=Doyle BJ, Callanan A, Burke PE, Grace PA, Walsh MT, Vorp DA, McGloughlin TM | title = Vessel Asymmetry as an Additional Diagnostic Tool in the Assessment of Abdominal Aortic Aneurysms | journal = Journal of Vascular Surgery | volume = 49 | issue = 2 | pages = 443–54 | date = February 2009 | pmid = 19028061 | pmc = 2666821 | doi = 10.1016/j.jvs.2008.08.064 }} It is also known that wall stress alone does not completely govern failure as an AAA will usually rupture when the wall stress exceeds the wall strength. In light of this, rupture assessment may be more accurate if the patient-specific wall stress is coupled together with patient-specific wall strength. A noninvasive method of determining patient-dependent wall strength was recently reported,{{cite journal |vauthors=Vande Geest JP, Wang DH, Wisniewski SR, Makaroun MS, Vorp DA | title = Towards A Noninvasive Method for Determination of Patient-Specific Wall Strength Distribution in Abdominal Aortic Aneurysms | journal = Annals of Biomedical Engineering | volume = 34 | issue = 7 | pages = 1098–1106 | year = 2006 | pmid = 16786395 | doi = 10.1007/s10439-006-9132-6 | s2cid = 25411800 }} with more traditional approaches to strength determination via tensile testing performed by other researchers in the field.{{cite journal |vauthors=Raghavan ML, Kratzberg J, Castro de Tolosa EM, Hanaoka MM, Walker P, da Silva ES | title = Regional distribution of wall thickness and failure properties of human abdominal aortic aneurysm | journal = Journal of Biomechanics | volume = 39 | issue = 16 | pages = 3010–6 | year = 2006 | pmid = 16337949 | doi = 10.1016/j.jbiomech.2005.10.021 }}{{cite journal |vauthors=Raghavan ML, Webster MW, Vorp DA | title = Ex vivo biomechanical behavior of abdominal aortic aneurysm: assessment using a new mathematical model | journal = Annals of Biomedical Engineering | volume = 24 | issue = 5 | pages = 573–82 | year = 1996 | pmid = 8886238 | doi = 10.1007/BF02684226 | s2cid = 21970395 }}{{cite journal |vauthors=Thubrikar MJ, Labrosse M, Robicsek F, Al-Soudi J, Fowler B | title = Mechanical properties of abdominal aortic aneurysm wall | journal = Journal of Medical Engineering & Technology | volume = 25 | issue = 4 | pages = 133–42 | year = 2001 | pmid = 11601439 | doi = 10.1080/03091900110057806 | s2cid = 218868284 }} Some of the more recently proposed AAA rupture-risk assessment methods include: AAA wall stress;{{cite journal |vauthors=Fillinger MF, Raghavan ML, Marra SP, Cronenwett JL, Kennedy FE | title = In vivo analysis of mechanical wall stress and abdominal aortic aneurysm rupture risk | journal = Journal of Vascular Surgery | volume = 36 | issue = 3 | pages = 589–97 | date = September 2002 | pmid = 12218986 | doi = 10.1067/mva.2002.125478 | doi-access = free }}{{cite journal |vauthors=Venkatasubramaniam AK, Fagan MJ, Mehta T, Mylankal KJ, Ray B, Kuhan G, Chetter IC, McCollum PT | title = A comparative study of aortic wall stress using finite element analysis for ruptured and non-ruptured abdominal aortic aneurysms | journal = European Journal of Vascular and Endovascular Surgery | volume = 28 | issue = 2 | pages = 168–76 | date = August 2004 | pmid = 15234698 | doi = 10.1016/j.ejvs.2004.03.029 | doi-access = free }} AAA expansion rate;{{cite journal |vauthors=Hirose Y, Takamiya M | title = Growth curve of ruptured aortic aneurysm | journal = The Journal of Cardiovascular Surgery | volume = 39 | issue = 1 | pages = 9–13 | date = February 1998 | pmid = 9537528 }} degree of asymmetry; presence of intraluminal thrombus (ILT);{{cite journal |vauthors=Wang DH, Makaroun MS, Webster MW, Vorp DA | title = Effect of intraluminal thrombus on wall stress in patient-specific models of abdominal aortic aneurysm | journal = Journal of Vascular Surgery | volume = 36 | issue = 3 | pages = 598–604 | date = September 2002 | pmid = 12218961 | doi = 10.1067/mva.2002.126087 | doi-access = free }} a rupture potential index (RPI);{{cite journal |vauthors=Vorp DA, Vande Geest JP | title = Biomechanical determinants of abdominal aortic aneurysm rupture | journal = Arteriosclerosis, Thrombosis, and Vascular Biology | volume = 25 | issue = 8 | pages = 1558–66 | date = August 2005 | pmid = 16055757 | doi = 10.1161/01.ATV.0000174129.77391.55 | s2cid = 23649698 | doi-access = }}{{cite journal |vauthors=Vande Geest JP, Di Martino ES, Bohra A, Makaroun MS, Vorp DA | title = A biomechanics-based rupture potential index for abdominal aortic aneurysm risk assessment | journal = Annals of the New York Academy of Sciences | volume = 1085 | pages = 11–21 | year = 2006 | pmid = 17182918 | doi = 10.1196/annals.1383.046 | issue=1| bibcode = 2006NYASA1085...11V | s2cid = 40000934 }} a finite element analysis rupture index (FEARI);{{cite journal |last1=Doyle |first1=Barry J. |last2=Callanan |first2=Anthony |last3=Walsh |first3=Michael T. |last4=Grace |first4=Pierce A. |last5=McGloughlin |first5=Timothy M. |title=A Finite Element Analysis Rupture Index (FEARI) as an Additional Tool for Abdominal Aortic Aneurysm Rupture Prediction |journal=Vascular Disease Prevention |date=11 July 2009 |volume=6 |issue=1 |pages=114–121 |doi=10.2174/1567270001006010114 |hdl=10344/184 |doi-access=free |hdl-access=free }} biomechanical factors coupled with computer analysis;{{cite journal |vauthors=Kleinstreuer C, Li Z | title = Analysis and computer program for rupture-risk prediction of abdominal aortic aneurysms | journal = BioMedical Engineering OnLine | volume = 5 | page = 19 | year = 2006 | pmid = 16529648 | pmc = 1421417 | doi = 10.1186/1475-925X-5-19 | issue=1 | doi-access = free }} growth of ILT;{{cite journal |vauthors=Stenbaek J, Kalin B, Swedenborg J | title = Growth of thrombus may be a better predictor of rupture than diameter in patients with abdominal aortic aneurysms | journal = European Journal of Vascular and Endovascular Surgery | volume = 20 | issue = 5 | pages = 466–9 | date = November 2000 | pmid = 11112467 | doi = 10.1053/ejvs.2000.1217 | doi-access = free }} geometrical parameters of the AAA;{{cite journal |vauthors=Giannoglou G, Giannakoulas G, Soulis J, Chatzizisis Y, Perdikides T, Melas N, Parcharidis G, Louridas G | s2cid = 22127197 | title = Predicting the risk of rupture of abdominal aortic aneurysms by utilizing various geometrical parameters: revisiting the diameter criterion | journal = Angiology | volume = 57 | issue = 4 | pages = 487–94 | year = 2006 | pmid = 17022385 | doi = 10.1177/0003319706290741 }} and also a method of determining AAA growth and rupture based on mathematical models.{{cite journal |vauthors=Watton PN, Hill NA, Heil M | title = A mathematical model for the growth of the abdominal aortic aneurysm | journal = Biomechanics and Modeling in Mechanobiology | volume = 3 | issue = 2 | pages = 98–113 | date = November 2004 | pmid = 15452732 | doi = 10.1007/s10237-004-0052-9 | s2cid = 10539114 }}{{cite journal |vauthors=Volokh KY, Vorp DA | title = A model of growth and rupture of abdominal aortic aneurysm | journal = Journal of Biomechanics | volume = 41 | issue = 5 | pages = 1015–21 | year = 2008 | pmid = 18255074 | doi = 10.1016/j.jbiomech.2007.12.014 }}

The postoperative mortality for an already ruptured AAA has slowly decreased over several decades but remains higher than 40%.{{cite journal |vauthors=Bown MJ, Sutton AJ, Bell PR, Sayers RD | title = A meta-analysis of 50 years of ruptured abdominal aortic aneurysm repair | journal = The British Journal of Surgery | volume = 89 | issue = 6 | pages = 714–30 | date = June 2002 | pmid = 12027981 | doi = 10.1046/j.1365-2168.2002.02122.x | s2cid = 30298923 | doi-access = free }} However, if the AAA is surgically repaired before rupture, the postoperative mortality rate is substantially lower, approximately 1-6%.{{cite journal |vauthors=Greenhalgh RM, Brown LC, Kwong GP, Powell JT, Thompson SG | title = Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial | journal = Lancet | volume = 364 | issue = 9437 | pages = 843–8 | year = 2004 | pmid = 15351191 | doi = 10.1016/S0140-6736(04)16979-1 | s2cid = 26394236 }}

The occurrence of AAA varies by ethnicity. In the United Kingdom, the rate of AAA in Caucasian men older than 65 years is about 4.7%, while in Asian men it is 0.45%.{{cite journal |vauthors=Salem MK, Rayt HS, Hussey G, Rafelt S, Nelson CP, Sayers RD, Naylor AR, Nasim A | title = Should Asian men be included in abdominal aortic aneurysm screening programmes? | journal = Eur J Vasc Endovasc Surg | volume = 38 | issue = 6 | pages = 748–9 | date = December 2009 | pmid = 19666232 | doi = 10.1016/j.ejvs.2009.07.012 | doi-access = free | hdl = 2381/7912 | hdl-access = free }} It is also less common in individuals of African, and Hispanic heritage. They occur four times more often in men than in women.

There are at least 13,000 deaths yearly in the U.S. secondary to AAA rupture. The peak number of new cases per year among males is around 70 years of age, and the percentage of males affected over 60 years is 2–6%. The frequency is much higher in smokers than in non-smokers (8:1), and the risk decreases slowly after smoking cessation.{{cite journal |vauthors=Wilmink TB, Quick CR, Day NE | title = The association between cigarette smoking and abdominal aortic aneurysms | journal = J Vasc Surg | volume = 30 | issue = 6 | pages = 1099–105 | date = Dec 1999 | pmid = 10587395 | doi = 10.1016/S0741-5214(99)70049-2 | doi-access = free }} In the U.S., the incidence of AAA is 2–4% in the adult population.{{eMedicine|med|3443|Abdominal Aortic Aneurysm}}

Rupture of the AAA occurs in 1–3% of men aged 65 or more, for whom the mortality rate is 70–95%.{{cite journal |vauthors=Lindholt JS, Juul S, Fasting H, Henneberg EW | title = Screening for abdominal aortic aneurysms: single centre randomised controlled trial | journal = BMJ | volume = 330 | issue = 7494 | page = 750 | date = Apr 2005 | pmid = 15757960 | pmc = 555873 | doi = 10.1136/bmj.38369.620162.82 }}

The first historical records about AAA are from Ancient Rome in the 2nd century AD, when Greek surgeon Antyllus tried to treat the AAA with proximal and distal ligature, central incision and removal of thrombotic material from the aneurysm.

However, attempts to treat the AAA surgically were unsuccessful until 1923. In that year, Rudolph Matas (who also proposed the concept of endoaneurysmorrhaphy), performed the first successful aortic ligation on a human.{{cite journal |vauthors=Livesay JJ, Messner GN, Vaughn WK | title = Milestones in Treatment of Aortic Aneurysm: Denton A. Cooley, MD, and the Texas Heart Institute | journal = Tex Heart Inst J | volume = 32 | issue = 2 | pages = 130–4 | year = 2005 | pmid = 16107099 | pmc = 1163455 }} Other methods that were successful in treating the AAA included wrapping the aorta with polyethene cellophane, which induced fibrosis and restricted the growth of the aneurysm. Endovascular aneurysm repair was first performed in the late 1980s and has been widely adopted in the subsequent decades. Endovascular repair was first used for treating a ruptured aneurysm in Nottingham in 1994.{{cite journal |vauthors=Yusuf SW, Whitaker SC, Chuter TA, Wenham PW, Hopkinson BR | title = Emergency endovascular repair of leaking aortic aneurysm | journal = Lancet | volume = 344 | issue = 8937 | page = 1645 | date = December 1994 | pmid = 7984027 | doi = 10.1016/S0140-6736(94)90443-X | s2cid = 45648419 }}

Theoretical physicist Albert Einstein underwent an operation for an abdominal aortic aneurysm in 1949 that was performed by Rudolph Nissen, who wrapped the aorta with polyethylene cellophane. Einstein's aneurysm ruptured on April 13, 1955. He declined surgery, saying, "I want to go when I want. It is tasteless to prolong life artificially. I have done my share, it is time to go. I will do it elegantly." He died five days later at age 76.{{cite news |last1=Lowenfels |first1=Albert B. |title=Famous Patients, Famous Operations, Part 3 |url=https://www.medscape.com/viewarticle/436253 |work=Medscape |date=14 June 2002 }}

Actress Lucille Ball died on April 26, 1989, from an abdominal aortic aneurysm. At the time of her death, she was in Cedars-Sinai Medical Center recovering from emergency surgery performed just six days earlier because of a dissecting aortic aneurysm near her heart. Ball was at increased risk as she had been a heavy smoker for decades.{{cite news|last=Ball|first=Lucille|title=Ball dies of ruptured aorta|url=https://www.latimes.com/archives/la-xpm-1989-04-27-mn-1618-story.html|newspaper=Los Angeles Times|access-date=May 12, 2013|date=April 27, 1989}}

Musician Conway Twitty died in June 1993 from an abdominal aortic aneurysm at the age of 59, two months before the release of what would be his final studio album, Final Touches.{{citation needed|date=October 2021}}

Actor George C. Scott died in 1999, aged 71, from a ruptured abdominal aortic aneurysm.{{citation needed|date=October 2021}}

In 2001, former presidential candidate Bob Dole underwent surgery for an abdominal aortic aneurysm in which a team led by vascular surgeon Kenneth Ouriel inserted a stent graft:{{cite news| title = Bob Dole has surgery to treat aneurysm| publisher = USA Today via Associated Press| date = 2001-06-27| url = https://www.usatoday.com/news/nation/june01/2001-06-27-dole.htm| access-date = 2009-09-22| url-status = live| archive-url = https://web.archive.org/web/20090507190454/http://www.usatoday.com/news/nation/june01/2001-06-27-dole.htm| archive-date = 2009-05-07}}

{{cquote|Ouriel said that the team inserted a Y-shaped tube through an incision in Dole's leg and placed it inside the weakened portion of the aorta. The aneurysm will eventually contract around the stent, which will remain in place for the rest of Dole's life.}}

— Associated Press

Actor Robert Jacks, who played Leatherface in Texas Chainsaw Massacre: The Next Generation, died from an abdominal aneurysm on August 8, 2001, one day shy of his 42nd birthday. When Jacks was a child, his father died from the same cause.

Actor Tommy Ford died of abdominal aneurysm in October 2016 at 52 years old.{{cite news |last=Mele |first=Christopher |title=Thomas Mikal Ford, Known for His Role in '90s Sitcom 'Martin,' Dies at 52 |url=https://www.nytimes.com/2016/10/13/arts/television/thomas-mikal-ford-costar-of-martin-dies.html |access-date=8 March 2019 |work=The New York Times |date=12 October 2016}}

Gary Gygax, co-creator of Dungeons & Dragons, died from an abdominal aortic aneurysm in 2008, at the age of 69.

Harvey Korman died on May 29, 2008, aged 81, at UCLA Medical Center as the result of complications from a ruptured abdominal aortic aneurysm he had suffered four months earlier. He is interred at Santa Monica's Woodlawn Cemetery.

There have been many calls for alternative approaches to rupture risk assessment over the past number of years, with many believing that a biomechanics-based approach may be more suitable than the current diameter approach. Numerical modeling is a valuable tool to researchers allowing approximate wall stresses to be calculated, thus revealing the rupture potential of a particular aneurysm. Experimental models are required to validate these numerical results and provide further insight into the biomechanical behavior of the AAA. In vivo, AAAs exhibit a varying range of material strengths{{cite journal |vauthors=Raghavan ML, Kratzberg J, Castro de Tolosa EM, Hanaoka MM, Walker P, da Silva ES | title = Regional distribution of wall thickness and failure properties of human abdominal aortic aneurysm | journal = J. Biomech | volume = 39 | issue = 16 | pages = 3010–3016 | year = 2006 | pmid = 16337949 | doi = 10.1016/j.jbiomech.2005.10.021 }} from localised weak hypoxic regions{{cite journal |vauthors=Vorp DA, Lee PC, Wang DH, Makaroun MS, Nemoto EM, Ogawa S, Webster MW | title = Association of intraluminal thrombus in abdominal aortic aneurysm with local hypoxia and wall weakening | journal = Journal of Vascular Surgery | volume = 34 | issue = 2 | pages = 291–299 | year = 2001 | pmid = 11496282 | doi = 10.1067/mva.2001.114813 | doi-access = free }} to much stronger regions and areas of calcifications.{{cite journal |vauthors=Speelman L, Bohra A, Bosboom EM, Schurink GW, van de Vosse FN, Makaorun MS, Vorp DA | title = Effects of wall calcifications in patient-specific wall stress analyses of abdominal aortic aneurysms | journal = Journal of Biomechanical Engineering | volume = 129 | issue = 1 | pages = 105–109 | year = 2007 | pmid = 17227104 | doi = 10.1115/1.2401189 }}

Finding ways to predict future AAA growth is seen as a research priority.{{cite journal |last1=Lee |first1=Regent |last2=Jones |first2=Amy |last3=Cassimjee |first3=Ismail |last4=Handa |first4=Ashok |last5=Oxford Abdominal Aortic Aneurysm |first5=Study. |title=International opinion on priorities in research for small abdominal aortic aneurysms and the potential path for research to impact clinical management |journal=International Journal of Cardiology |date=October 2017 |volume=245 |pages=253–255 |doi=10.1016/j.ijcard.2017.06.058 |pmid=28874296 |url=https://ora.ox.ac.uk/objects/uuid:c8773f49-d2a4-44f2-9957-510d39b9d476 }}

Another related line of research is utilizing mathematical decision modeling (e.g., Markov decision processes) to determine improved treatment policies. Initial results suggest that a more dynamic policy could provide benefits, although such claims have not been clinically verified.{{cite book |last1=Mattila |first1=Robert |last2=Siika |first2=Antti |last3=Roy |first3=Joy |last4=Wahlberg |first4=Bo |title=2016 IEEE Conference on Control Applications (CCA) |chapter=A Markov decision process model to guide treatment of abdominal aortic aneurysms |date=2016 |pages=436–441 |doi=10.1109/CCA.2016.7587869 |arxiv=1611.02177 |isbn=978-1-5090-0755-4 |s2cid=5632830 |chapter-url=https://ieeexplore.ieee.org/document/7587869}}{{cite journal |last1=Grant |first1=Stuart |last2=Sperrin |first2=Matthew |last3=Carlson |first3=Eric |last4=Chinai |first4=Natasha |last5=Ntais |first5=Dionysios |last6=Hamilton |first6=Matthew |last7=Dunn |first7=Graham |last8=Bunchan |first8=Iain |last9=Davies |first9=Linda |last10=McCollum |first10=Charles |title=Calculating when elective abdominal aortic aneurysm repair improves survival for individual patients: development of the Aneurysm Repair Decision Aid and economic evaluation |journal=Health Technology Assessment |date=2015 |volume=19 |issue=32 |pages=1–154 |doi=10.3310/hta19320 |pmid=25924187 |pmc=4781543 |url=https://www.journalslibrary.nihr.ac.uk/hta/hta19320/#/abstract}} A study recently showed that aneurysms can be accurately predicted as to whether they are stable (lacking repair or intervention), requiring repair, or at risk of rupture from scans years prior to any event based on a machine-learning based classification tool.{{cite journal |last1=Chung |first1=Timothy K. |last2=Gueldner |first2=Pete H. |last3=Aloziem |first3=Okechukwu U. |last4=Liang |first4=Nathan L. |last5=Vorp |first5=David A. |date=9 February 2024 |title=An artificial intelligence based abdominal aortic aneurysm prognosis classifier to predict patient outcomes |journal=Scientific Reports |volume=14 |issue=1 |pages=3390 |doi=10.1038/s41598-024-53459-5 |pmid=38336915 |issn=2045-2322|pmc=10858046 |bibcode=2024NatSR..14.3390C}}

Experimental models can now be manufactured using a novel technique involving the injection-moulding lost-wax manufacturing process to create patient-specific anatomically correct AAA replicas.{{cite journal |last1=Doyle |first1=B. J. |last2=Morris |first2=L. G. |last3=Callanan |first3=A. |last4=Kelly |first4=P. |last5=Vorp |first5=D. A. |last6=McGloughlin |first6=T. M. |title=3D Reconstruction and Manufacture of Real Abdominal Aortic Aneurysms: From CT Scan to Silicone Model |journal=Journal of Biomechanical Engineering |date=1 June 2008 |volume=130 |issue=3 |pages=034501 |doi=10.1115/1.2907765 |pmid=18532870 }} Work has also focused on developing more realistic material analogues to those in vivo, and recently a novel range of silicone-rubbers was created allowing the varying material properties of the AAA to be more accurately represented.{{cite journal |last1=Doyle |first1=Barry J. |last2=Corbett |first2=Timothy J. |last3=Cloonan |first3=Aidan J. |last4=O'Donnell |first4=Michael R. |last5=Walsh |first5=Michael T. |last6=Vorp |first6=David A. |last7=McGloughlin |first7=Timothy M. |title=Experimental modelling of aortic aneurysms: Novel applications of silicone rubbers |journal=Medical Engineering & Physics |date=October 2009 |volume=31 |issue=8 |pages=1002–1012 |doi=10.1016/j.medengphy.2009.06.002 |pmid=19595622 |pmc=2757445 }} These rubber models can also be used in a variety of experimental situations, from stress analysis using the photoelastic method{{cite journal |last1=Doyle |first1=Barry J. |last2=Corbett |first2=Timothy J. |last3=Callanan |first3=Anthony |last4=Walsh |first4=Michael T. |last5=Vorp |first5=David A. |last6=McGloughlin |first6=Timothy M. |title=An Experimental and Numerical Comparison of the Rupture Locations of an Abdominal Aortic Aneurysm |journal=Journal of Endovascular Therapy |date=June 2009 |volume=16 |issue=3 |pages=322–335 |doi=10.1583/09-2697.1 |pmid=19642790 |pmc=2795364}} New endovascular devices are being developed that are able to treat more complex and tortuous anatomies.{{cite journal |last1=Albertini |first1=JN |last2=Perdikides |first2=T |last3=Soong |first3=CV |last4=Hinchliffe |first4=RJ |last5=Trojanowska |first5=M |last6=Yusuf |first6=SW |title=Endovascular repair of abdominal aortic aneurysms in patients with severe angulation of the proximal neck using a flexible stent-graft: European Multicenter Experience. |journal=The Journal of Cardiovascular Surgery |date=June 2006 |volume=47 |issue=3 |pages=245–250 |id={{ProQuest|224419745}} |pmid=16760860 |url=https://www.minervamedica.it/en/journals/cardiovascular-surgery/article.php?cod=R37Y2006N03A0245}}

An animal study showed that removing a single protein prevents early damage in blood vessels from triggering a later-stage, frequently lethal complication. By eliminating the gene for a signaling protein called cyclophilin A (CypA) from a strain of mice, researchers were able to provide complete protection against abdominal aortic aneurysm.{{cite magazine |title=Study establishes major new treatment target in diseased arteries |date=May 10, 2009 |magazine=U.S. News & World Report |url=http://www.physorg.com/news161183060.html |url-status=live |archive-url=https://web.archive.org/web/20110606091215/http://www.physorg.com/news161183060.html |archive-date=June 6, 2011 }}

Other recent research identified Granzyme B (GZMB) (a protein-degrading enzyme) to be a potential target in the treatment of abdominal aortic aneurysms. Elimination of this enzyme in mice models both slowed the progression of aneurysms and improved survival.{{cite journal |vauthors=Chamberlain CM, Ang LS, Boivin WA, Cooper DM, Williams SJ, Zhao H, Hendel A, Folkesson M, Swedenborg J, Allard MF, McManus BM, Granville DJ | title = Perforin-Independent Extracellular Granzyme B Activity Contributes to Abdominal Aortic Aneurysm | journal = The American Journal of Pathology | volume = 176 | issue = 2 | pages = 1038–1049 | year = 2010 | pmid = 20035050 | pmc = 2808106 | doi = 10.2353/ajpath.2010.090700 }}{{cite web |title=Discovery points way for new treatment for aneurysms |date=January 27, 2010 |publisher=University of British Columbia |url=http://www.hli.ubc.ca/news_events/news.php?user=events&index=1&count=1&date=20100101 |url-status=dead |archive-url=https://web.archive.org/web/20100219124709/http://www.hli.ubc.ca/news_events/news.php?user=events&index=1&count=1&date=20100101 |archive-date=February 19, 2010 }}

The mechanisms that lead to AAA development are still not completely understood at a cellular and molecular level. To better understand the pathophysiology of AAA, it is often necessary to use experimental animal models. It is often questioned how well these models translate to human disease. Even though no animal model exactly represents the human condition, all the existing ones focus on one different pathophysiological aspect of the disease. Combining the results from different animal models with clinical research can provide a better overview of the AAA pathophysiology. The most common animal models are rodents (mice and rats), although, for certain studies, such as testing preclinical devices or surgical procedures, large animal models (pig, sheep) are more frequently used. The rodent models of AAA can be classified according to different aspects. There are dissecting models vs non-dissecting models and genetically determined models vs chemically induced models. The most commonly used models are the angiotensin-II infusion into ApoE knockout mice (dissecting model, chemically induced), the calcium chloride model (non-dissecting, chemically induced), and the elastase model (non-dissecting, chemically induced model).{{cite journal|last1=Sénémaud|first1=Jean|last2=Caligiuri|first2=Giuseppina|last3=Etienne|first3=Harry|last4=Delbosc|first4=Sandrine|last5=Michel|first5=Jean-Baptiste|last6=Coscas|first6=Raphaël|date=March 2017|title=Translational Relevance and Recent Advances of Animal Models of Abdominal Aortic Aneurysm|journal=Arteriosclerosis, Thrombosis, and Vascular Biology |volume=37|issue=3|pages=401–410|pmid=28062500|issn=1079-5642|doi=10.1161/ATVBAHA.116.308534|doi-access=free}}{{cite journal|last1=Daugherty|first1=Alan|last2=Cassis|first2=Lisa A.|date=2004-03-01|title=Mouse Models of Abdominal Aortic Aneurysms|journal=Arteriosclerosis, Thrombosis, and Vascular Biology|volume=24|issue=3|pages=429–434|doi=10.1161/01.ATV.0000118013.72016.ea|pmid=14739119|s2cid=28971998|doi-access=}} A recent study has shown that β-Aminopropionitrile plus elastase application to abdominal aorta causes more severe aneurysm in mice as compared to elastase alone.{{cite journal|last1=Berman|first1=Alycia G.|last2=Romary|first2=Daniel J.|last3=Kerr|first3=Katherine E.|last4=Gorazd|first4=Natalyn E.|last5=Wigand|first5=Morgan M.|last6=Patnaik|first6=Sourav S.|last7=Finol|first7=Ender A.|last8=Cox|first8=Abigail D.|last9=Goergen|first9=Craig J.|date=2022-01-07|title=Experimental aortic aneurysm severity and growth depend on topical elastase concentration and lysyl oxidase inhibition|journal=Scientific Reports|volume=12|issue=1|pages=99|doi=10.1038/s41598-021-04089-8|issn=2045-2322|pmc=8742076|pmid=34997075|bibcode=2022NatSR..12...99B }}

{{Reflist}}

{{Medical resources

| DiseasesDB = 792

| ICD10 = {{ICD10|I|71|3|i|70}}, {{ICD10|I|71|4|i|70}}

| ICD9 = {{ICD9|441.3}}, {{ICD9|441.4}}

| ICDO =

| OMIM = 100070

| MedlinePlus = 000162

| eMedicineSubj = med

| eMedicineTopic = 3443

| eMedicine_mult = {{eMedicine2|emerg|27}} {{eMedicine2|radio|1}}

| MeshID = D017544

}}

{{Commons category}}

• [https://vascular.cochrane.org/welcome Cochrane Peripheral Vascular Diseases Review Group]

{{Vascular diseases}}

Category:Diseases of the aorta

Category:Vascular surgery

Category:Deaths from abdominal aortic aneurysm

Category:Wikipedia medicine articles ready to translate

Category:Men's health

Category:Medical triads

Category:Wikipedia emergency medicine articles ready to translate

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