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Mechanistic Deep Dive
Shunt Hemodynamics
- Qp:Qs = pulmonary flow / systemic flow
- Qp:Qs > 1.5 = significant shunt
- Calculated from O2 step-up at cath
- Determines closure benefit
Pulmonary Vascular Reactivity
- Pre-Eisenmenger: reactive (lowered with NO, prostaglandin)
- Post-Eisenmenger: fixed remodeling
- Closure futile or harmful in fixed disease
- Vasoreactivity testing during cath (small role in CHD)
Recent Trials & Updates
CLOSE (2017) â Cryptogenic Stroke + PFO
- N = 663 cryptogenic stroke < 60 yo with PFO + atrial septal aneurysm or large shunt
- PFO closure + antiplatelet vs antiplatelet alone
- â recurrent stroke (HR 0.03)
- Class I for cryptogenic stroke with PFO
RESPECT (2017 extended)
- 10-year follow-up confirms benefit
DEFENSE-PFO (2018)
- Korean trial
- PFO closure for high-risk PFO (large shunt or ASA)
- Reduced stroke
REDUCE (2017)
- PFO closure + antiplatelet vs antiplatelet alone
- â stroke
2024 Updates
- AHA/ACC: closure Class I in selected
- Considering closure age > 60 in select (REDUCE-2 ongoing)
- LAA closure for AF in patients post PFO closure being studied
High-Yield Specialist Points
RoPE Score
- Risk of Paradoxical Embolism
- 10 points: age, vascular RF, PFO features
- Higher RoPE = higher likelihood PFO is causative
- Validates patient selection
ASD Closure Techniques
- Amplatzer Septal Occluder (most common)
- Helex (now retired in some markets)
- GORE Cardioform Septal Occluder
- DAPT 6 months post-closure
Sinus Venosus ASD
- Anomalous pulmonary venous return common (RUPV to SVC)
- Surgical baffle repair
- Warden procedure: redirect SVC
Coronary Sinus ASD
- Unroofed CS â RA to LA via coronary sinus
- Surgical
- Persistent L SVC association
VSD with Aortic Regurgitation
- Subaortic VSD (supracristal): aortic cusp prolapse into VSD â AR
- Surgical repair to prevent progressive AR
Acquired (Post-Surgical) Shunts
- Patent surgical patch with residual shunt
- Re-operation or transcatheter repair
- Endocarditis risk
Future Therapies
- Biodegradable devices for atrial closure
- Personalized device sizing with 3D CT / 4D MRI
- AI-guided procedural planning
Pearls
- ASD secundum most common; fixed split S2; percutaneous device closure
- VSD perimembranous most common; holosystolic LLSB; surgical patch
- PDA continuous âmachineryâ; percutaneous coil first-line
- PFO closure: CLOSE, RESPECT, DEFENSE-PFO for cryptogenic stroke < 60 yo
- Eisenmenger = absolute contraindication to shunt closure
- AVSD strongly associated with Down syndrome
- Differential cyanosis in Eisenmenger PDA (cyanotic feet, pink arms)