288.1 🎓 醫學生版

288.1.0.1 📌 一頁重點

288.1.0.1.1 Atrial Septal Defect (ASD)

288.1.0.1.1.1 Types (Anatomic Locations)

1. Ostium secundum (70%): middle of septum (foramen ovale region) — most common; closes via percutaneous device
2. Ostium primum (15-20%): low septum near AV valves (partial AVSD); requires surgical repair; associated with mitral cleft
3. Sinus venosus (5-10%): near SVC or IVC entry; often with anomalous pulmonary venous return; surgical
4. Coronary sinus (< 1%): unroofed coronary sinus; rare

288.1.0.1.1.2 Pathophysiology

• L→R shunt at atrial level (LA → RA via defect)
• Volume overload of RA + RV → RA/RV dilation
• ↑ pulmonary blood flow → eventual pulmonary HTN (slower than VSD/PDA)
• AF common in adults (LA + RA dilation)
• Eisenmenger uncommon (only ~ 10% of unrepaired large ASD)

288.1.0.1.1.3 Clinical Presentation

• Asymptomatic through childhood and young adulthood
• 3rd-4th decade onset of symptoms: dyspnea, fatigue, palpitations
• AF common adult presentation
• Paradoxical embolism / stroke
• Recurrent pulmonary infections

288.1.0.1.1.4 Examination

• Fixed split S2 (classic — S2 doesn’t vary with respiration)
• Soft systolic ejection murmur at L upper sternal border (relative pulmonic stenosis from ↑ flow)
• Mid-diastolic rumble at L lower sternal border (relative tricuspid stenosis from ↑ flow)
• RV heave
• Loud P2 if PH

288.1.0.1.1.5 ECG

• Right axis deviation
• Incomplete RBBB (typical secundum)
• Left axis deviation + first-degree AV block (ostium primum)
• RAE, RVH (advanced)
• AF (adults)

288.1.0.1.1.6 CXR

• Cardiomegaly (RA + RV)
• Increased pulmonary vasculature (shunt vascularity)
• “Snowman” sign (TAPVR — total anomalous pulmonary venous return)

288.1.0.1.1.7 Echo

• Defect visualization (2D + color Doppler)
• Bubble study (agitated saline): RA bubbles → LA (R→L flow with Valsalva release)
• Pulmonary HTN assessment
• RV function

288.1.0.1.1.8 TEE

• Definitive for ASD type, size, surrounding structures
• Critical for percutaneous closure planning

288.1.0.1.1.9 Treatment

Closure Indications - Hemodynamically significant ASD: RA/RV dilation, Qp:Qs > 1.5:1 - Paradoxical embolism (cryptogenic stroke) - Exercise intolerance - Pulmonary HTN (early/moderate, not Eisenmenger) - AF - Decompensated HF (controversial)

Closure Contraindications - Eisenmenger syndrome (PVR > SVR, R→L shunt) — absolute - Severe pulmonary HTN with reactive vasculature debatable

Methods - Percutaneous device closure (Amplatzer septal occluder) — first-line for ostium secundum - Surgical closure for ostium primum, sinus venosus, coronary sinus, or complex anatomy - AC + DAPT for 6 months post-percutaneous

288.1.0.1.2 Ventricular Septal Defect (VSD)

288.1.0.1.2.1 Types

1. Perimembranous (80%): most common; in membranous septum
2. Muscular (5-20%): in muscular septum; often multiple
3. Inlet (5%): AV canal type (AVSD)
4. Outlet (subaortic, supracristal, 5%): high; AR risk
5. Doubly committed subarterial (Asian populations)

288.1.0.1.2.2 Pathophysiology

• L→R shunt at ventricular level (LV → RV via defect)
• Magnitude depends on defect size + PVR
• Small (restrictive): high gradient, small shunt → minimal hemodynamic consequence
• Moderate-large: significant shunt → LV volume overload → HF, PH
• Most VSDs close spontaneously in childhood (75% by 10 yo, especially small muscular)
• Adult unrepaired large VSD → Eisenmenger common

288.1.0.1.2.3 Clinical Presentation

• Small VSD: asymptomatic (Roger’s murmur)
• Moderate-large: HF symptoms, exercise intolerance
• Adult unrepaired: Eisenmenger (cyanosis, polycythemia)

288.1.0.1.2.4 Examination

• Holosystolic harsh murmur at L lower sternal border (3rd-4th ICS)
• Thrill (large defect)
• Loud P2 if PH
• S3, signs of HF

288.1.0.1.2.5 ECG

• Small VSD: normal
• Large: LAE, LVH, biventricular hypertrophy with PH

288.1.0.1.2.6 Echo

• Defect visualization, size, location
• Doppler gradient
• LV/LA size, function
• PH assessment
• Aortic regurgitation (associated with subaortic VSD)

288.1.0.1.2.7 Treatment

Closure Indications - Symptomatic with significant shunt (Qp:Qs > 1.5) - LV volume overload - Aortic regurgitation (subaortic VSD) - Prior IE - Pulmonary HTN (early, before Eisenmenger)

Closure Methods - Surgical patch (gold standard) for perimembranous, inlet, outlet - Transcatheter device closure for muscular VSD or post-MI VSD (now expanding indication)

Post-MI VSD - Mechanical complication (Ch273) - Acute, devastating - Emergent surgical or transcatheter repair - IABP, ECMO bridge

288.1.0.1.3 Patent Ductus Arteriosus (PDA)

288.1.0.1.3.1 Embryology

• Fetal: ductus connects pulmonary artery to descending aorta (bypasses fetal lungs)
• Closes within days postnatal (functional) → fibroses (anatomic, weeks-months)
• Failure to close: PDA
• Prematurity, hypoxia, prostaglandins (E2) keep open

288.1.0.1.3.2 Pathophysiology

• L→R shunt at level of great arteries (aorta → pulmonary)
• Continuous “machine” murmur
• Variable severity: small to massive
• Untreated → Eisenmenger
• Eisenmenger: reversed shunt → cyanosis of lower body only (R→L below ductus)

288.1.0.1.3.3 Clinical Presentation

• Small PDA: asymptomatic
• Moderate-large: HF, exercise intolerance
• Eisenmenger: cyanosis + clubbing of lower extremities; pink upper body

288.1.0.1.3.4 Examination

• Continuous “machinery” murmur at L upper chest, beneath L clavicle
• Wide pulse pressure, bounding pulses
• Eisenmenger PDA: differential cyanosis (cyanotic + clubbed feet, normal arms)

288.1.0.1.3.5 ECG

• Normal (small)
• LV/LA enlargement (large)
• RV hypertrophy if PH

288.1.0.1.3.6 Echo

• Direct visualization, color Doppler from PA into descending aorta

288.1.0.1.3.7 Treatment

Closure Indications - Hemodynamically significant - Prior IE - LV volume overload, PH

Closure Methods - Percutaneous coil / device — first-line for most - Surgical ligation for very large or complex

Pharmacologic Closure (Neonates) - Indomethacin or ibuprofen in premature infants - Definitive in many cases

288.1.0.1.4 Patent Foramen Ovale (PFO)

288.1.0.1.4.1 Background

• 25-30% of adults have PFO (vs ASD = pathologic defect)
• Usually clinically silent
• Small R→L shunt possible during Valsalva

288.1.0.1.4.2 Clinical Significance

• Cryptogenic stroke in young: paradoxical embolism via PFO
• Migraine with aura (debated)
• Decompression sickness in divers
• Platypnea-orthodeoxia syndrome

288.1.0.1.4.3 Diagnosis

• Bubble study (agitated saline) during Valsalva release
• TEE definitive (anatomy, size, atrial septal aneurysm)

288.1.0.1.4.4 PFO Closure for Cryptogenic Stroke

Key Trials: - CLOSURE I (2012) — neg (Starflex device) - PC trial (2013) — neg (Amplatzer) - RESPECT (2013, extended 2017) — PFO closure reduces recurrent stroke - CLOSE (2017) — PFO closure + antiplatelet > antiplatelet alone (especially if atrial septal aneurysm or large shunt) - DEFENSE-PFO (2018) — Korean — confirmed benefit - RESPECT extended (2017) — long-term benefit

Patient Selection (2024 ACC/AHA) - Age < 60 (selected 60-65) - Cryptogenic stroke (CRYPTOGENIC, not from other source) - PFO with paradoxical embolism mechanism (RoPE score) - ASA or NOAC alone vs PFO closure

Procedure: Percutaneous device, ASA + clopidogrel post-procedure

288.1.0.1.5 Atrioventricular Septal Defect (AVSD / Endocardial Cushion)

• AKA “AV canal defect”
• Failure of endocardial cushion fusion → ostium primum ASD + inlet VSD + common AV valve
• Down syndrome strongly associated (40-50% of T21 with CHD)
• Partial AVSD (ostium primum + cleft MV) vs complete AVSD (large VSD + common AV valve)
• Treatment: surgical repair in infancy
• Adult issues: MR (residual mitral cleft), arrhythmia, HF

288.1.0.1.6 Anomalous Pulmonary Venous Return

• Total Anomalous Pulmonary Venous Return (TAPVR): all 4 pulmonary veins to systemic
  • Supracardiac (most common): to L vertical vein → innominate
  • Cardiac: to coronary sinus or RA
  • Infradiaphragmatic: to portal vein
  • Mixed
• Partial Anomalous Pulmonary Venous Return (PAPVR):
  • One or more PV → systemic
  • Right upper PV to SVC common (often with sinus venosus ASD)
  • “Scimitar syndrome” = right PV to IVC + R lung hypoplasia + dextroposition
• Treatment: surgical re-routing in infancy/childhood

288.1.0.2 🩺 床邊速查

• ASD: secundum most common; fixed split S2; percutaneous closure for secundum
• VSD: perimembranous most common; holosystolic at LLSB; surgical repair preferred
• PDA: continuous “machinery” murmur; percutaneous coil
• PFO closure: cryptogenic stroke < 60 yo (CLOSE, RESPECT, DEFENSE-PFO)
• Eisenmenger: absolute contraindication to shunt closure

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