Patent Foramen Ovale (PFO) — What Is It?
A patent foramen ovale (PFO) is a small flap-like opening in the wall between the heart's upper chambers (atria) that failed to close after birth — present in approximately 25% of the general population. In most people, it causes no problems. However, in patients who have suffered a cryptogenic stroke (stroke with no identified cause), a PFO allows blood clots from the venous system to cross directly from the right to left heart and travel to the brain — a process called paradoxical embolism.
Who Should Have PFO Closure?
The 2025 ACC/AHA/SCAI guidelines recommend PFO closure (Class IIa) for patients with:
- Cryptogenic ischemic stroke AND age under 60
- High-risk PFO features: large shunt on bubble study, atrial septal aneurysm (ASA), or both
- Adequate workup excluding other stroke causes (AF, large vessel atherosclerosis, lacunar infarct)
- Neurology team evaluation confirming PFO as most likely stroke mechanism
Atrial Septal Defect (ASD) — Larger Holes
An atrial septal defect (ASD) is a larger, true hole in the atrial septum (rather than a flap) that causes a significant left-to-right shunt. The excess blood flow into the right heart causes RV volume overload, right heart enlargement, and over time, arrhythmias and pulmonary hypertension. Ostium secundum ASDs (the most common type) are closed percutaneously when the Qp:Qs ratio exceeds 1.5:1 or when right heart enlargement is present.
The Closure Procedure
Both PFO and ASD closure are performed under general anesthesia or conscious sedation with TEE or intracardiac echocardiography (ICE) guidance. A catheter is advanced from the femoral vein to the right heart, and a closure device (typically Amplatzer or Gore CARDIOFORM for PFO; Amplatzer Septal Occluder for ASD) is deployed across the defect to seal it. Most patients go home the same day or the following morning.
Key Clinical Trial Evidence
Frequently Asked Questions
Do I need blood thinners after PFO closure?
After PFO closure, patients typically take aspirin plus clopidogrel for 1–6 months, then aspirin alone long-term. Anticoagulation is generally not required unless there is another indication (like atrial fibrillation).
How do I know if my stroke was caused by my PFO?
This is the most important question in PFO management and requires a careful workup. Neurological evaluation, cardiac monitoring for AF, brain MRI, and echocardiography with bubble study are all part of the standard evaluation. The presence of a high-risk PFO (large shunt, ASA) and absence of alternative stroke causes supports PFO as the mechanism.
What is the difference between a PFO and an ASD?
A PFO is a small flap that was present before birth and didn't seal after birth — it is not a true defect in the tissue but rather a tunnel. An ASD is a true hole in the septum that allows continuous left-to-right blood flow and causes right heart volume overload over time.