Related Subjects:
|Congenital Acyanotic Heart Disease
|Congenital Cyanotic Heart Disease
|Cardiac Embryology
|Cyanosis - Central and Peripheral
|Down's syndrome (Trisomy 21)
|Tetralogy of Fallot
|Patent Foramen Ovale (PFO)
🫀 Introduction
- Patent Foramen Ovale (PFO): An embryological flap-valve between LA ↔ RA that normally closes after birth, but persists in ~25% of adults.
- In utero it is essential for fetal circulation, but persistence allows potential right → left shunting in later life.
- Shunting is usually silent but may become clinically relevant during raised RA pressure (e.g. Valsalva manoeuvre, coughing, straining).
⚖️ Aetiology & Pathophysiology
- Not inherently pathological - most with a PFO never have problems.
- 🧠 Paradoxical embolism: A clot from a DVT bypasses the pulmonary filter via PFO → enters systemic arterial circulation → possible stroke.
- Mechanism: RA pressure > LA pressure (e.g. straining) opens the flap → transient R→L shunt.
- Bubble contrast echo can visualise shunting (≥50 bubbles = significant).
🧠 DVT/PFO/Stroke Hypothesis
- PFOs are found more often in cryptogenic stroke patients than in the general population.
- But ⚠️ association ≠ causation - could be a marker for another risk (e.g. paroxysmal AF).
- Always exclude other causes (especially AF with prolonged monitoring) before attributing stroke to a PFO.
✅ Arguments for Closure
- Younger patient (<55), no other stroke risk factors.
- Multiple embolic strokes in different vascular territories.
- Large or aneurysmal PFO, significant bubble study shunt.
- No evidence of PAF after prolonged monitoring (≥7 days Holter).
- No other indication for anticoagulation.
❌ Arguments against Closure
- Older age (>55) - PFO less likely to be causal.
- Small, non-aneurysmal PFO.
- Clear alternative risk (AF, thrombophilia needing anticoagulation, OCP/HRT-related DVT risk).
🩺 Clinical Clues
- Stroke/TIA preceded by Valsalva (lifting, coughing, straining).
- Multiterritory embolic stroke pattern.
- History of DVT/PE, or procoagulant state.
📊 Trial Evidence (2017)
| Study | Findings | Risks |
|---|
| Søndergaard et al. (NEJM) | PFO closure ↓ recurrent stroke (1.4% vs 5.4%). | ↑ AF (6.6%), device complications. |
| Mas et al. (CLOSE trial) | Zero strokes with closure vs 14 in antiplatelet only. | ↑ AF, procedural complications. |
| Saver et al. (REDUCE trial) | Lower stroke recurrence with closure (0.58 vs 1.07/100 pt-yrs). | ↑ VTE in closure group. |
💬 Key Teaching Point
PFO closure reduces but does not eliminate stroke risk.
Absolute risk reduction is small (<1% per year).
Trade-off: fewer strokes vs ↑ AF and device risks.
Decision = shared discussion, weighing uncertainty, patient values, and stroke pattern.
