Cardiovascular · Topic 39 of 48

Aortic Aneurysm

Cardiovascular · aortic aneurysm

Aortic Aneurysm

An aorta 3 cm or wider. Screen male ever-smokers at 65–75, repair at 5.5 cm (men) or 5.0 cm (women), and treat pain plus hypotension as rupture.

Key numbers

AAA: aorta 3.0 cm or wider≥ 3.0 cm

Screen men 65–75 who ever smokedMen 65–75, ever smoked

Repair: men 5.5, women 5.0 cmM ≥ 5.5 · F ≥ 5.0 cm

Permissive hypotension: MAP no higher than 70–80MAP ≤ 70–80 mmHg

01 · What it isAAA: aorta 3.0 cm or wider

An abdominal aortic aneurysm is an abdominal aortic diameter of 3.0 cm or more, usually infrarenal and fusiform; most are asymptomatic and found incidentally on examination or imaging.

02 · Defined byRepair: men 5.5, women 5.0 cm

Elective repair is recommended for an AAA ≥ 5.5 cm in men or ≥ 5.0 cm in women, and for any aneurysm causing symptoms attributable to it.

03 · Look forRupture triad: pain, hypotension, pulsatile mass

The classic rupture triad is sudden severe abdominal or back pain, hypotension and a pulsatile abdominal mass; the mass is often not palpable, so pain plus shock in an older patient is enough to act.

Causes & risk factors

Why it happens

Smoking is the strongest risk factorSmoking is the strongest AAA risk factor; others are male sex (3 times more common), older age (peak 70–80), hypertension, a first-degree relative with AAA, and inherited connective tissue disorders.

Diagnosis & monitoring

Work-up

Ultrasound surveillance interval by sizeAAA surveillance: 3.0–3.9 cm every 3 years; 4.0–4.9 cm (men) or 4.0–4.4 cm (women) yearly; ≥ 5.0 cm (men) or ≥ 4.5 cm (women) every 6 months.

Rapid growth: repair regardless of sizeGrowth of more than 0.5 cm in 6 months, chronic pain attributable to the aneurysm, or thromboembolic complications are indications for repair whatever the diameter.

EVAR needs lifelong imaging for endoleakEndovascular repair (EVAR) has lower early morbidity and mortality than open repair but requires lifelong surveillance — imaging at 1, 6 and 12 months, then yearly — for endoleak, migration and graft thrombosis.

Ascending thoracic aneurysm: repair at 5.5 cmFor a sporadic aortic root or ascending aortic aneurysm, surgery is recommended at a diameter ≥ 5.5 cm, with rapid growth, or with symptoms; Marfan syndrome lowers the root threshold to ≥ 5.0 cm.

Ruptured AAA: about half die in hospitalMost patients with a ruptured AAA die before reaching care, and about 50% of those who reach the hospital alive still die; untreated, mortality approaches 100%.

Do right now

In this order

First moves

Rupture triad: pain, hypotension, pulsatile mass

→

Suspected rupture: emergency open repair or EVAR

→

Permissive hypotension: MAP no higher than 70–80MAP ≤ 70–80 mmHg

Why each step

Rupture triad: pain, hypotension, pulsatile massThe classic rupture triad is sudden severe abdominal or back pain, hypotension and a pulsatile abdominal mass; the mass is often not palpable, so pain plus shock in an older patient is enough to act.

Suspected rupture: emergency open repair or EVARA ruptured AAA needs immediate open repair or endovascular stent grafting (mortality is similar) — call vascular surgery at once; bedside ultrasound confirms the aneurysm faster than CT in the unstable patient.

Permissive hypotension: MAP no higher than 70–80Resuscitate ruptured AAA with blood products but do not raise the mean arterial pressure above 70–80 mmHg (permissive hypotension) — a higher pressure increases bleeding before the aorta is controlled.

Management

Orders

Stop smoking, control BP, give a statinMedical management of a small AAA is risk-factor control: smoking cessation, blood pressure control, and a moderate- or high-intensity statin when there is aortic atherosclerosis.

Red flags & don'ts

Avoid harm

MI is the leading early postoperative death complicationMyocardial infarction is the leading cause of early death after AAA repair because coronary disease is common; other complications include graft infection, pseudoaneurysm, graft occlusion and erectile dysfunction.

The rules

Know these

Screen men 65–75 who ever smoked must knowUSPSTF: one-time abdominal ultrasound screening for men aged 65–75 who have ever smoked (≥ 100 cigarettes in a lifetime).

Who else to screen, and who notUSPSTF: selectively offer screening to men 65–75 who never smoked; do not screen women who never smoked and have no family history. ACC/AHA also screens anyone ≥ 65 with a first-degree relative with AAA.

More detail

Reference

Show 6 reference facts

Annual rupture risk rises with diameter: about 0% under 4 cm, 0.5–5% at 4–4.9 cm, 3–15% at 5–5.9 cm, 10–20% at 6–6.9 cm, and 20–40% at 7–7.9 cm.

Endoleak is persistent flow into the sac after EVAR: type I (attachment-site) and type III (graft defect) leaks need prompt repair; type II (back-bleeding branch) leaks are often watched unless the sac grows.

Mural thrombus can embolize to the kidneys, bowel or legs, causing sudden unilateral limb pain, pallor and pulse loss (acute limb ischemia); large aneurysms rarely cause DIC.

Mycotic (infected) aneurysms are most often caused by Staphylococcus aureus, then Salmonella; obtain blood cultures and treat with targeted antibiotics followed by excision.

Palpation is unreliable: many AAAs are not palpable because of depth or obesity, and a palpable pulsatile mass is often a small aneurysm — confirm and size with ultrasound or CT.

After TEVAR for a descending thoracic aneurysm, image with CT at 1 and 12 months, then yearly if stable; TEVAR is preferred over open repair when anatomy allows and there is no heritable aortopathy.

Pearl

Older smoker with abdominal or back pain and hypotension: a ruptured AAA until proven otherwise — call vascular surgery, do not chase a normal blood pressure.

Sources · Merck Manual Professional — Abdominal Aortic Aneurysms (AAA) · ACC — 2022 ACC/AHA Aortic Disease Guideline Key Perspectives (Part 2 of 2) · USPSTF — Abdominal Aortic Aneurysm: Screening (2019) · Pathogenesis, Diagnosis, and Clinical Management of Aortic Aneurysms: Current Status and Future Perspectives. 2026 review (PMC13339180) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).