281.1 🎓 醫孞生版

281.1.0.1 📌 䞀頁重點

281.1.0.1.1 Anatomy + Basics
281.1.0.1.1.1 Aorta Sections
  • Ascending aorta: from aortic valve to brachiocephalic artery
  • Aortic arch: brachiocephalic to L subclavian
  • Descending thoracic: L subclavian to diaphragm
  • Abdominal: diaphragm to bifurcation
281.1.0.1.1.2 Layers
  • Intima (endothelium)
  • Media (elastic fibers + smooth muscle — strength)
  • Adventitia (collagen, vasa vasorum)
281.1.0.1.2 Aneurysms
281.1.0.1.2.1 Thoracic Aortic Aneurysm (TAA)
  • Localization:
    • Ascending (60%)
    • Arch (10%)
    • Descending (30%)
  • Etiology:
    • Atherosclerotic (esp descending) — most common
    • Cystic medial degeneration (Marfan, Loeys-Dietz, vEDS, bicuspid AV)
    • Inflammatory (Takayasu, GCA, IgG4)
    • Mycotic / infectious (Salmonella, Staph)
    • Traumatic (deceleration → aortic isthmus)
  • Asymptomatic until complications
  • Symptoms when large/dissecting: chest/back pain, dyspnea, hoarseness (RLN compression), Horner, dysphagia, hemoptysis
281.1.0.1.2.2 Abdominal Aortic Aneurysm (AAA)
  • Definition: aortic diameter > 3 cm (or > 1.5× normal)
  • Most common location: infrarenal
  • Etiology: atherosclerotic + degenerative (most), genetic (familial), inflammatory, mycotic
  • Risk factors: smoking (#1, 4-7x), age, male, FHx, HTN, atherosclerosis
  • Often asymptomatic until rupture
  • Triad of ruptured AAA: hypotension + back pain + pulsatile abdominal mass (50% have all three)
281.1.0.1.2.3 Screening
  • AAA: One-time US screening for men 65-75 with smoking history (USPSTF Class B)
  • Women with risk factors: individualized
  • First-degree relatives of AAA patients: screen
  • TAA: imaging screening for Marfan, Loeys-Dietz, vEDS, BAV; family history; coarctation
281.1.0.1.2.4 Workup
  • Ultrasound for AAA (cheap, no radiation, screening)
  • CTA: gold standard for TAA + AAA, surgical planning
  • MRA: alternative if CKD or younger
  • Echocardiogram (TTE/TEE): aortic root, ascending aorta
281.1.0.1.2.5 Treatment
  • Medical:
    • Smoking cessation (slows growth)
    • BP control < 130/80 (ACEi/ARB, β-blocker; β-blocker historically used, less clear benefit)
    • Statin
    • Avoid heavy lifting
    • Treat connective tissue disorder (losartan in Marfan)
  • Surveillance:
    • AAA 3-4 cm: every 2-3 years
    • AAA 4-5 cm: every 12 months
    • AAA 5-5.4 cm: every 6 months
    • AAA > 5.5 cm: surgical consult
281.1.0.1.2.6 Surgical Indications
  • AAA:
    • Diameter ≥ 5.5 cm ♂, ≥ 5.0 cm ♀
    • Rapid growth ≥ 0.5 cm/year
    • Symptomatic (pain)
    • Rupture (emergency)
  • TAA (Ascending):
    • ≥ 5.5 cm (general)
    • ≥ 5.0 cm with Marfan, BAV
    • ≥ 4.5 cm with FHx of dissection at smaller size
    • ≥ 4.0 cm for Loeys-Dietz, vEDS
    • Rapid growth ≥ 0.5 cm/year
    • Coexisting AV disease requiring surgery
  • TAA (Descending):
    • ≥ 5.5-6.0 cm
    • Symptomatic
    • TEVAR often first-line
281.1.0.1.2.7 Repair Options
  • Open surgery: gold standard for ascending TAA, complex anatomy
  • EVAR (endovascular AAA repair): less invasive, ↑ early survival, ↓ early morbidity (but ↑ re-intervention long-term — EVAR-1, OVER)
  • TEVAR (thoracic EVAR): for descending TAA, type B dissection
  • Branched / fenestrated grafts: for visceral artery involvement
281.1.0.1.3 Acute Aortic Syndromes (AAS)
281.1.0.1.3.1 Spectrum
  • Aortic dissection (most common)
  • Intramural hematoma (IMH) — variant
  • Penetrating atherosclerotic ulcer (PAU) — variant
  • Ruptured / contained leak aneurysm
281.1.0.1.3.2 Aortic Dissection

Mechanism: - Intimal tear → blood enters media → propagates → creates true + false lumen - Compromise of branch vessels → end-organ ischemia - Risk: HTN (most), Marfan, BAV, pregnancy, cocaine, trauma, vasculitis

Classification — Stanford: - Type A: involves ascending aorta (60%) - Type B: confined to descending aorta (40%)

Classification — DeBakey: - I: ascending + descending - II: ascending only - III: descending only

Clinical Presentation: - Sudden severe tearing chest pain radiating to back - BP differential between arms > 20 mmHg - New murmur of aortic regurgitation (Type A) - Neurologic deficits (carotid involvement) - Limb ischemia (subclavian, iliac) - Cardiac tamponade (rupture into pericardium — Type A) - Hemothorax (rupture) - Renal/mesenteric ischemia - Spinal cord ischemia

Workup: - CT angiography (gold standard, fastest) - TEE (excellent for Type A, requires sedation) - MRA (more time, less practical acute) - D-dimer (high NPV, useful for low-risk rule-out) - AAS detection risk score (ADD-RS): 3 features (high-risk conditions, pain features, exam findings); score 0-3, ≥ 1 suggests AAS

Treatment:

Type A: - EMERGENCY SURGERY (50% 30-day mortality untreated) - Replace ascending aorta ± valve sparing or AVR + root replacement - Bentall procedure if root involvement - Hybrid approach (frozen elephant trunk) for arch + descending involvement

Type B: - Uncomplicated: medical management - β-blocker FIRST (esmolol, then labetalol) - SBP < 120, HR < 60 within 10-30 min - Pain control - Avoid vasodilator alone (reflex tachy worsens dissection) - Complicated: - Ongoing pain - Malperfusion (renal, mesenteric, limb, spinal cord) - Rupture / impending rupture - Aneurysmal dilation - TEVAR preferred (INSTEAD-XL, ADSORB trials)

281.1.0.1.3.3 Intramural Hematoma (IMH)
  • Hemorrhage in aortic media without intimal flap
  • Type A: treat like dissection (surgery)
  • Type B: medical first, monitor for progression
281.1.0.1.3.4 Penetrating Atherosclerotic Ulcer (PAU)
  • Atherosclerotic plaque ulcerates into media
  • Older patients, descending aorta
  • May lead to IMH → dissection
  • TEVAR if symptomatic or growing
281.1.0.1.4 Inflammatory + Infectious Aortic Disease
281.1.0.1.4.1 Takayasu Arteritis
  • Large vessel vasculitis
  • Young Asian women
  • Aorta + main branches (subclavian, carotid, renal)
  • “Pulseless disease”
  • Treatment: glucocorticoids, methotrexate, biologics
  • See Ch295 for vasculitis
281.1.0.1.4.2 Giant Cell Arteritis (GCA)
  • Large vessel vasculitis in elderly
  • Cranial branches → vision loss
  • Thoracic aorta also affected (TAA risk)
  • ESR / CRP high
  • Temporal artery biopsy
  • Treatment: high-dose steroids; tocilizumab
281.1.0.1.4.3 Mycotic Aneurysm
  • Infectious (usually Salmonella, Staph aureus, less Strep)
  • Saccular shape, rapid growth
  • Treatment: long-term IV abx + emergent surgical / endovascular repair
281.1.0.1.5 Genetic Aortopathies
281.1.0.1.5.1 Marfan Syndrome
  • AD, FBN1 mutation → fibrillin-1 abnormal → TGF-β signaling dysregulated
  • Skeletal: tall, arachnodactyly, pectus, scoliosis, joint laxity
  • Cardiovascular: aortic root dilation + dissection, MV prolapse
  • Ocular: ectopia lentis (upward), myopia
  • Diagnosis: Ghent criteria
  • Treatment:
    • Losartan + β-blocker (slows aortic growth — COMPARE, MEND, AIMS)
    • Aortic surgery at root ≥ 5.0 cm (some 4.5 cm if family hx)
    • Avoid contact sports + isometric exercise
281.1.0.1.5.2 Loeys-Dietz Syndrome
  • TGFBR1/2, SMAD3, TGFB2/3 mutations
  • Aggressive aortopathy with dissection at smaller sizes (≥ 4.0 cm threshold)
  • Cleft palate, hypertelorism, arterial tortuosity
  • Bifid uvula characteristic
  • Higher dissection risk than Marfan
281.1.0.1.5.3 Vascular Ehlers-Danlos (vEDS)
  • COL3A1 mutation (type III collagen)
  • Spontaneous arterial rupture, bowel rupture, uterine rupture
  • Translucent skin, easy bruising
  • Avoid catheterization / surgery if possible
  • Celiprolol (β-blocker) — BBEST trial reduced events
281.1.0.1.5.4 Bicuspid Aortic Valve (BAV)
  • 1-2% population
  • Often familial
  • Associated with aortic root + ascending aneurysm + coarctation
  • Screening of first-degree relatives
  • Aortic surgery threshold ≥ 5.0 cm (some 4.5)
281.1.0.1.5.5 Turner Syndrome
  • Aortic coarctation, BAV, root dilation
  • Screen with echo + MRI/CTA
  • Aortic surgery thresholds individualized (often smaller — surface area indexed)

281.1.0.2 🩺 床邊速查

  • AAA screening: 65-75 男性吞菞者䞀次 USUSPSTF Class B
  • AAA repair: ♂ ≥ 5.5 cm, ♀ ≥ 5.0 cm, growth ≥ 0.5 cm/yr
  • TAA repair: ≥ 5.5 cm普通≥ 5.0 cmMarfan, BAV≥ 4.0-4.5 cmLoeys-Dietz
  • Type A dissection: EMERGENCY surgery
  • Type B dissection: medical firstesmolol → nicardipine, SBP < 120, HR < 60complicated → TEVAR
  • D-dimer + ADD-RS: 甚斌䜎颚險 AAS rule-out