- Pathophysiology
- Failed fusion of septum primum and septum secundum.
- Present in ~25% of adults.
- Clinical Significance
- Paradoxical Embolism: DVT bypasses lungs via R → L shunt (during Valsalva) causing Cryptogenic Stroke.
- Diagnosis
- TEE with Bubble Study: Agitated saline crosses to LA during Valsalva.
- Treatment
- Antiplatelets/Anticoagulants.
- PFO Closure reserved for recurrent cryptogenic strokes.