CardiologyTier 1Disease (DEADMAN)

Thoracic aortic aneurysm

Description

Permanent dilatation >50% of expected normal diameter for age, sex and body size
Normal ascending aorta ~3.0-3.5 cm; descending ~2.5-3.0 cm
Indexed measures matter more than absolute in small/tall patients: aortic size index, or cross-sectional area (cm2) / height (m) >10

By segment - different diseases

Segment	Typical driver
Root / ascending (~60%)	Medial degeneration - connective tissue disease, bicuspid valve, familial TAAD, ageing
Arch (~10%)	Extension of ascending or descending
Descending (~35%)	Atherosclerosis, hypertension
Thoraco-abdominal	Crawford I-V classification

Aneurysm = all three layers; pseudoaneurysm = contained rupture, adventitia/haematoma only
Fusiform (commonest) vs saccular (higher rupture risk at any size)

Incidence ~5-10 per 100,000/yr; prevalence rising with imaging
M>F ~2-4:1, but women rupture at smaller diameters and have worse outcomes
Mean age at presentation ~65 (<50 suggests a genetic aortopathy)
~20% have a family history of thoracic aortic disease
Bicuspid aortic valve in 1-2% of the population; up to 50% develop aortopathy
~95% are asymptomatic at detection - found incidentally

Final common pathway: medial degeneration

Loss of smooth muscle cells, elastic fibre fragmentation, proteoglycan accumulation ("cystic medial necrosis")
-> dec tensile strength -> dilatation -> Laplace: wall stress = (P x r)/2h -> self-accelerating

Causes

Degenerative / hypertensive (commonest overall)
Bicuspid aortic valve aortopathy - intrinsic medial abnormality + flow-related shear; dilates independently of valve function; does not regress after AVR
Genetic
- Marfan (FBN1) - inc TGF-beta signalling
- Loeys-Dietz (TGFBR1/2, SMAD3, TGFB2/3) - arterial tortuosity, hypertelorism, bifid uvula; dissects at small diameters
- Vascular EDS (COL3A1) - arterial rupture without much dilatation
- Familial TAAD - ACTA2 (commonest), MYH11 (+ PDA), MYLK, PRKG1
- Turner syndrome - index to BSA; coarctation and bicuspid valve
Inflammatory aortitis - giant cell arteritis (late thoracic aneurysm - a reason for long-term follow-up), Takayasu, IgG4, Behcet, rheumatoid, ankylosing spondylitis
Infective (mycotic) - Salmonella, Staph, syphilis (saccular ascending aneurysm, tree-bark intima, linear calcification)
Trauma/deceleration - pseudoaneurysm at the isthmus
Chronic dissection with false lumen degeneration

Clinical

Usually silent
Compression: hoarseness (left recurrent laryngeal - Ortner), dysphagia, stridor, SVC obstruction, Horner
Aortic regurgitation from annular dilatation - early diastolic murmur, wide pulse pressure
Pain = expansion, impending rupture or dissection - new or changed pain is an emergency
Haemoptysis/haematemesis = aorto-bronchial or aorto-oesophageal fistula (ominous)

Imaging

CT angiography - gold standard; ECG-gated for the root/ascending
- Measure perpendicular to the centreline, outer-to-outer wall, in a reproducible plane. Non-gated CT overestimates the ascending aorta
MR angiography - no radiation; preferred for serial surveillance in young patients
TTE - root and proximal ascending only; used for annual surveillance in Marfan/bicuspid
CXR - widened mediastinum, abnormal contour (insensitive)

Diagnostic work-up

Whole-aorta imaging at diagnosis - disease is often multi-segment
Screening for concomitant AAA (~20-25%) and peripheral aneurysms
BP, lipids, smoking status
Genetic testing if: age <60, syndromic features, family history, bicuspid valve with aortopathy
First-degree relatives: screening imaging (Class I)
Inflammatory markers, syphilis serology, blood cultures if mycotic suspected

A. Medical - slow growth, prevent dissection

Strict BP control - target <130/80 (lower if tolerated)
Beta blocker - reduces dP/dt; standard in Marfan, widely used in others
ARB (losartan) - Marfan; combination with beta blocker may be superior to either alone
Statin, smoking cessation (smoking accelerates growth)
Avoid fluoroquinolones
Activity: avoid heavy isometric/resistance training, competitive/collision sport, stimulants; moderate aerobic exercise encouraged

B. Surveillance

Size	Interval
<4.5 cm, stable	12 months
4.5-5.0 cm	6-12 months
>5.0 cm or growing	6 months or less
Genetic aortopathy	At least annually, whichever size

C. Surgical thresholds - ascending / root

Sporadic or bicuspid: >=5.5 cm (>=5.0 cm at an experienced multidisciplinary aortic centre)
Marfan: >=5.0 cm; consider 4.5 cm with family history of dissection, rapid growth, severe AR or planned pregnancy
Loeys-Dietz: ~4.2-4.5 cm (dissects smallest)
Turner syndrome: aortic size index >=2.5 cm/m2
Rapid growth = an indication irrespective of size:
- >=0.5 cm in 1 yr, or >=0.3 cm/yr over 2 consecutive years (sporadic)
- >=0.3 cm in 1 yr (heritable aortopathy or bicuspid valve)
>=4.5 cm if undergoing aortic valve surgery for another reason - replace the aorta at the same time
Indexed alternative: cross-sectional area (cm2) / height (m) >10, or aortic size index

D. Surgical thresholds - descending / thoraco-abdominal

>=6.0 cm (retained in ESVS 2026); >=5.5 cm in connective tissue disease or with high-risk features
Symptomatic, rapidly expanding, saccular, or mycotic -> repair regardless of size

E. Procedure choice

Root/ascending: open repair
- Valve-sparing root replacement (David) if the valve is normal - avoids anticoagulation
- Bentall (composite valve graft) if the valve is diseased
- Arch: hemi-arch, total arch, or frozen elephant trunk; deep hypothermic circulatory arrest +/- cerebral perfusion
Descending: TEVAR preferred where anatomy allows - lower early mortality and paraplegia rate than open
- Open repair preferred in connective tissue disease - graft does not seal into diseased aorta
- Complications: endoleak, spinal cord ischaemia (CSF drainage, permissive hypertension, staged repair), stroke, retrograde type A dissection
Thoraco-abdominal: open or branched/fenestrated endovascular in specialist centres

F. Pregnancy

Bicuspid aortic valve, coarctation, Turner syndrome
Abdominal aortic aneurysm (~20-25%) and peripheral aneurysms - image the whole arterial tree
Giant cell arteritis - late thoracic aneurysm
Polycystic kidney disease
Chronic obstructive pulmonary disease (shared smoking aetiology)
Family history - screen all first-degree relatives
Cocaine/amphetamine use, anabolic steroids, heavy weightlifting

Growth rate: ascending ~0.1 cm/yr; descending ~0.3 cm/yr; faster if larger, bicuspid, or genetic
"Hinge point" - risk of dissection/rupture rises steeply at ~6.0 cm ascending, ~7.0 cm descending
- -> thresholds are set below the hinge point
Annual risk of rupture/dissection/death:
- <5.0 cm: ~4%/yr
- 5.0-5.9 cm: ~7%/yr
- >=6.0 cm: ~14%/yr
*Most dissections occur in aortas below the surgical threshold* - size is a population-level, not individual, predictor
- -> family history, genotype, growth rate and indexed size supplement the diameter

Complications

Dissection, rupture (mortality >90% if free rupture), acute AR, tamponade
Compression - recurrent laryngeal nerve, bronchus, oesophagus, SVC
Thromboembolism from mural thrombus
Aorto-bronchial / aorto-oesophageal fistula
Post-repair: paraplegia, endoleak, stroke, renal failure, re-intervention, graft infection
Lifelong imaging surveillance is mandatory after repair - the rest of the aorta remains diseased

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