285.1 🎓 醫學生版

285.1.0.1 📌 一頁重點

285.1.0.1.1 Aortic Stenosis (AS)

285.1.0.1.1.1 Etiology

• Calcific (degenerative): most common in elderly; same RF as atherosclerosis (age, smoking, lipid, HTN, DM, CKD); calcium deposition on cusps
• Bicuspid aortic valve (BAV): 1-2% population; presents in 50s-60s; family history; associated with aortopathy + coarctation
• Rheumatic: post-strep, often with concomitant MS; declining in developed world
• Congenital: unicuspid (severe early), quadricuspid (rare)
• Subvalvular: HOCM, subaortic membrane
• Supravalvular: Williams syndrome

285.1.0.1.1.2 Pathophysiology

• Reduced valve area → LV outflow obstruction → pressure overload
• LV hypertrophy (concentric → eccentric over time)
• Diastolic dysfunction early; systolic late
• Subendocardial ischemia even without CAD (↑ wall stress + ↑ O2 demand)
• Pulmonary HTN from chronic LV failure

285.1.0.1.1.3 Symptoms (SAD)

• Syncope (exertional, vasodepressor reflex; LVOT obstruction with reduced preload)
• Angina (50% have concomitant CAD; ↑ O2 demand from LVH)
• Dyspnea (HF, pulmonary congestion)

285.1.0.1.1.4 Natural History

• Asymptomatic phase: years to decades
• Onset of symptoms → mortality rises dramatically:
  • Dyspnea: 2 years
  • Syncope: 3 years
  • Angina: 5 years
• Severe AS asymptomatic: progress to symptoms ~ 10-20%/year

285.1.0.1.1.5 Examination

• Crescendo-decrescendo systolic murmur at R 2nd ICS, radiates to carotids
• Late peak = more severe AS
• S2 paradoxically split (LV ejection prolonged); A2 soft/absent in severe
• Parvus et tardus pulse (delayed, low-amplitude carotid)
• S4 gallop (LV hypertrophy)
• Sustained apical impulse (LVH)

285.1.0.1.1.6 Echocardiography (Quantification)

Parameter	Mild	Moderate	Severe
Peak velocity (m/s)	2.5-2.9	3.0-3.9	≥ 4.0
Mean gradient (mmHg)	< 20	20-39	≥ 40
AVA (cm²)	> 1.5	1.0-1.5	≤ 1.0
AVA indexed (cm²/m²)	> 0.85	0.60-0.85	≤ 0.60

285.1.0.1.1.7 Stages (2020 ACC/AHA)

• A: At risk (BAV, AV sclerosis)
• B: Progressive (mild/moderate)
• C: Asymptomatic severe (C1 normal LV; C2 LV dysfunction)
• D: Symptomatic severe
  • D1: High-gradient
  • D2: Low-flow, low-gradient with reduced EF
  • D3: Low-flow, low-gradient with preserved EF (paradoxical low-flow)

285.1.0.1.1.8 Low-Flow, Low-Gradient AS

• AVA ≤ 1.0 cm² + mean gradient < 40 + EF < 50%
• Dobutamine stress echo to distinguish:
  • True severe AS: increases gradient, area stays low
  • Pseudosevere: AVA increases with flow recovery
  • No contractile reserve: high mortality, may benefit from TAVR

285.1.0.1.1.9 Investigations

• Echo (definitive)
• CT for TAVR planning (annulus sizing, valve calcium score, vascular access)
• Cardiac cath: assess CAD (60% of severe AS have CAD)
• BNP for severity assessment
• 6MWT, exercise stress test (asymptomatic severe, controlled environment)

285.1.0.1.1.10 Treatment

Medical - No drug therapy delays progression - Statin trials neg (SEAS, ASTRONOMER, SALTIRE) - Treat CV risk factors - Symptomatic relief: diuretics (cautiously) - AVOID nitrates, ACEi/ARB cautious (afterload reduction may cause hypotension)

SAVR (Surgical AVR) - Indications: - Symptomatic severe AS (Class I) - Asymptomatic severe AS + LV dysfunction (EF < 50%) - Asymptomatic severe AS undergoing other cardiac surgery - Very severe AS (peak velocity ≥ 5 m/s) — Class IIa - Abnormal stress test in asymptomatic severe — Class IIa - Mechanical valve: lifelong anticoagulation; younger (< 50-60) - Bioprosthetic valve: no AC needed long-term; older or AC contraindication - Ross procedure: pulmonic autograft to aortic position + pulmonic homograft (young patients, growing role)

TAVR (Transcatheter AVR) - Initially for high surgical risk; now expanded to all risk levels (≥ 65 yo) - PARTNER trials (1, 2, 3): inoperable → high risk → intermediate → low risk - CoreValve / Evolut trials (Extreme Risk, High Risk, SURTAVI, Low Risk) - Femoral access most common; alternative: transapical, transaortic, transcaval, axillary - Balloon-expandable (SAPIEN) vs self-expanding (CoreValve) - Patient selection: heart team, frailty assessment, life expectancy > 1 year - Anticoagulation: ASA + clopidogrel 1-3 mo (recent: SAPIEN study suggests ASA alone may suffice)

285.1.0.1.1.11 Acute Severe AS (Critical AS)

• Hemodynamic instability
• Balloon valvuloplasty bridge
• Emergent TAVR/SAVR

285.1.0.1.1.12 Asymptomatic Severe AS — 2024 Updates

• EARLY-TAVR (2024): early TAVR for asymptomatic severe AS improved outcomes
• 2024 ACC/AHA Focused Update: Class IIa for early intervention in asymptomatic severe AS
• Watchful waiting + close surveillance still acceptable in low-risk asymptomatic

285.1.0.1.2 Aortic Regurgitation (AR)

285.1.0.1.2.1 Etiology

Chronic AR - Aortic root dilation (BAV, Marfan, idiopathic, HTN, syphilis, ankylosing spondylitis) - Cuspal disease: BAV, calcific, rheumatic, IE healed, congenital - Connective tissue: Marfan, Loeys-Dietz, vEDS

Acute AR - Aortic dissection (Type A) - Endocarditis - Trauma - Iatrogenic (post-PCI/TAVR)

285.1.0.1.2.2 Pathophysiology

Chronic AR - Volume overload → LV dilation + hypertrophy (eccentric) - Increased SV → systolic HTN, wide pulse pressure - Slow progressive LV dysfunction - Asymptomatic for years, then HF symptoms

Acute AR - Sudden ↑ in LV volume without compensatory dilation - Rapidly elevated LVEDP → pulmonary edema, shock - MEDICAL EMERGENCY

285.1.0.1.2.3 Symptoms

• Chronic: dyspnea on exertion, fatigue, palpitations, pounding pulse
• Acute: severe dyspnea, pulmonary edema, shock

285.1.0.1.2.4 Examination (Classic)

• Diastolic decrescendo murmur at L sternal border (3rd-4th ICS), better with patient sitting forward, breath held in expiration
• Wide pulse pressure (e.g., 160/40)
• Bounding pulses (water hammer / Corrigan)
• Pulsus bisferiens (double-peaked)
• Austin Flint murmur (diastolic rumble at apex from severe AR jet impinging on anterior MV leaflet)
• Various eponyms (high-yield):
  • de Musset: head bobbing
  • Müller: uvula pulsation
  • Quincke: nail bed pulsation
  • Traube: pistol shot femoral
  • Duroziez: to-and-fro femoral murmur with stethoscope
  • Hill: BP gap (leg > arm by > 20)
  • Becker: visible retinal artery pulsation

285.1.0.1.2.5 Echocardiography

• Severity grading: vena contracta width, regurgitant volume, regurgitant fraction, EROA
• Severe AR:
  • Vena contracta > 6 mm
  • Regurgitant volume > 60 mL/beat
  • Regurgitant fraction > 50%
  • EROA > 0.30 cm²
• LV end-systolic dimension (LVESD) — key for surgical timing
• LV ejection fraction
• Aortic root dimensions

285.1.0.1.2.6 Cardiac MRI

• Best for accurate regurgitant fraction
• LV volumes
• Aortic root assessment
• Useful when echo equivocal

285.1.0.1.2.7 Treatment

Chronic AR — Medical - Vasodilators (ACEi, dihydropyridine CCB) — Class IIa for symptomatic patients not candidates for surgery - Long-term mortality benefit unclear - Treat HTN

Chronic AR — Surgical Indications - Symptoms (NYHA II-IV) — Class I - Asymptomatic with: - LV systolic dysfunction (EF < 55%) — Class I - LVESD > 50 mm or > 25 mm/m² BSA indexed — Class I - LVEDD > 65 mm — Class IIa (some guidelines) - Other cardiac surgery indication - AVR + aortic root replacement if root > 5.0 cm (BAV/Marfan) or > 5.5 cm (other)

Acute Severe AR — EMERGENCY - IV diuretics, inotropes - AVOID beta-blockers (rely on tachycardia to maintain CO) - IABP contraindicated - Emergent surgery

TAVR for AR - Off-label for native AR (limited use due to lack of calcium for anchor) - Dedicated AR devices (JenaValve, Trilogy) — emerging

285.1.0.2 🩺 床邊速查

• AS severity: peak vel ≥ 4 m/s + mean gradient ≥ 40 + AVA ≤ 1.0 = severe
• AS symptoms (SAD): syncope, angina, dyspnea → urgent AVR
• TAVR ≥ 65 yo all risk levels (2024); SAVR for younger / BAV / complex anatomy
• Chronic AR surgical timing: symptoms OR EF < 55% OR LVESD > 50 mm
• Acute severe AR: emergency surgery; AVOID β-blocker, AVOID IABP
• EARLY-TAVR 2024: asymptomatic severe AS → early TAVR Class IIa

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