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Patent Foramen Ovale (PFO): Diagnosis, Stroke Risk, and Closure Treatment

What Is a Patent Foramen Ovale?

A patent foramen ovale (PFO) is a persistent opening between the right and left atria that normally exists during fetal development.

Before birth, the foramen ovale allows blood to bypass the fetal lungs.

After birth, changes in cardiac pressures usually cause this communication to close functionally.

However, the opening remains patent in approximately 25% of adults.

Most people with PFO never experience symptoms or complications.

The presence of PFO does not automatically indicate heart disease or a need for closure.

What Is the Difference Between PFO and ASD?

PFO and atrial septal defect (ASD) are different conditions.

PFO results from incomplete fusion of two layers of the atrial septum, leaving a flap-like communication.

ASD represents a true deficiency of atrial septal tissue.

ASD may cause significant left-to-right shunting and enlargement of the right heart chambers.

PFO usually does not cause substantial continuous shunting or cardiac chamber enlargement.

Its main clinical significance relates to the possibility of blood clots crossing from the venous to the arterial circulation under certain conditions.

What Are the Symptoms of PFO?

Most individuals with PFO are asymptomatic.

PFO is often discovered incidentally during echocardiography.

It may be associated with:

  • Ischemic stroke of undetermined cause
  • Paradoxical embolism
  • Decompression illness in certain divers
  • Rarely, platypnea-orthodeoxia syndrome

An association between PFO and migraine, particularly migraine with aura, has been reported.

However, PFO is not considered the cause of every migraine.

Can PFO Cause Stroke?

One of the most important potential complications of PFO is paradoxical embolism.

Normally, a blood clot originating in the venous circulation travels to the right side of the heart and then to the lungs.

In certain circumstances, transiently increased right atrial pressure may allow a clot to cross through a PFO into the left atrium.

The clot may then enter the systemic circulation and obstruct a cerebral artery, causing ischemic stroke.

However:

  • PFO is common in the general population.
  • Most individuals with PFO never experience a stroke.
  • Finding a PFO after a stroke does not prove that the PFO caused the stroke.

Careful assessment of causality is essential.

What Is Cryptogenic Stroke?

Cryptogenic stroke is an ischemic stroke for which no definite cause is identified despite appropriate investigation.

In younger and middle-aged patients, PFO may be considered as a potential mechanism after other causes have been excluded.

However, not every patient with cryptogenic stroke and PFO is an appropriate candidate for closure.

Brain imaging, vascular disease, atrial fibrillation, and other potential causes must be evaluated.

How Is PFO Diagnosed?

1. Transthoracic Echocardiography

Standard echocardiography provides an initial assessment of cardiac structure.

PFO may not always be directly visible on routine imaging.

2. Contrast Echocardiography (Bubble Study)

Agitated saline is injected into a peripheral vein to detect right-to-left shunting.

Normally, microbubbles remain on the right side of the heart.

If a right-to-left communication is present, bubbles may appear in the left heart chambers.

The Valsalva maneuver may increase the likelihood of detecting a PFO-related shunt.

3. Transesophageal Echocardiography (TEE)

TEE provides detailed imaging of the interatrial septum.

It is particularly valuable before transcatheter closure.

It evaluates:

  • PFO tunnel length
  • Septal anatomy
  • Atrial septal aneurysm
  • Associated atrial septal defects
  • Adjacent cardiac structures

4. Transcranial Doppler

Contrast-enhanced transcranial Doppler can detect right-to-left shunting.

However, it does not independently establish that the shunt originates from a PFO.

When Should a PFO Be Closed?

Routine PFO closure is not recommended for everyone with a PFO.

Closure is primarily considered in carefully selected patients with PFO-associated ischemic stroke.

Important considerations include:

  • Particularly age 18–60 years
  • Imaging-confirmed ischemic stroke
  • No alternative stroke mechanism identified after appropriate investigation
  • A clinically plausible causal relationship between the PFO and the stroke

Patients older than 60 years may require individualized assessment, although evidence is more limited in this age group.

Which Factors Influence the Decision to Close a PFO?

1. Large Right-to-Left Shunt

A substantial shunt detected on contrast echocardiography may increase the likelihood that the PFO is clinically relevant.

2. Atrial Septal Aneurysm

Excessive mobility of the atrial septum may be associated with a greater likelihood of PFO-related stroke in selected patients.

3. Stroke Characteristics

Brain imaging findings suggesting an embolic mechanism are important.

4. Alternative Causes of Stroke

Potential causes such as:

  • Atrial fibrillation
  • Carotid or intracranial arterial disease
  • Small vessel disease
  • Other cardiac embolic sources

must be evaluated.

Prolonged cardiac rhythm monitoring may be appropriate in selected patients.

5. RoPE and PASCAL Assessment

The RoPE score and PASCAL classification may help estimate the likelihood that a PFO contributed to an ischemic stroke.

They should not be used as the sole basis for closure decisions.

How Is Transcatheter PFO Closure Performed?

PFO closure is generally performed without open-heart surgery.

The procedure is usually carried out through the femoral vein.

Procedure Steps

  1. A catheter is advanced from the femoral vein into the heart.
  2. The PFO is assessed under echocardiographic and fluoroscopic guidance.
  3. An appropriately sized closure device is selected.
  4. The device is positioned across the interatrial septum.
  5. Device stability and positioning are checked.
  6. The device is released after satisfactory placement is confirmed.

Over time, the device becomes covered by the patient's own tissue.

How Long Does PFO Closure Take?

Procedure duration varies depending on anatomy and the imaging technique used.

After uncomplicated closure, patients are usually observed for a short period, and many can be discharged the following day.

What Are the Risks of PFO Closure?

Transcatheter PFO closure is generally safe in appropriately selected patients.

Potential complications include:

  • Bleeding at the vascular access site
  • Vascular complications
  • New-onset or transient atrial fibrillation
  • Device-related thrombus
  • Residual right-to-left shunting
  • Device displacement
  • Rarely, cardiac injury or other serious complications

The possibility of atrial fibrillation after closure is an important consideration when discussing treatment options.

Are Medications Required After PFO Closure?

Antiplatelet medication is commonly prescribed for a period after closure to reduce the risk of device-related thrombosis.

The regimen and duration depend on the device, clinical circumstances, and treatment protocol.

Patients with previous stroke also require individualized long-term antithrombotic management.

Is Follow-Up Necessary After PFO Closure?

Yes.

Follow-up evaluates:

  • Device position
  • Residual shunting
  • Cardiac rhythm
  • Possible device-related complications

Contrast echocardiography may be used when necessary to assess persistent right-to-left shunting.

Does PFO Closure Completely Prevent Stroke?

No.

In appropriately selected patients with PFO-associated stroke, closure may reduce recurrent ischemic stroke risk compared with medical therapy alone.

However, it does not eliminate all causes of stroke.

Assessment and treatment of hypertension, diabetes, dyslipidemia, atrial fibrillation, and other vascular risk factors remain important.

Should PFO Be Closed to Treat Migraine?

Although PFO is associated with migraine, particularly migraine with aura, routine PFO closure solely for migraine treatment is not recommended.

Some patients report improvement in migraine symptoms after closure, but this cannot be reliably predicted.

Should an Incidentally Discovered PFO Be Closed?

Routine closure is not recommended for an incidentally discovered PFO in patients without stroke or another relevant clinical indication.

Most individuals require no specific treatment.

When Should You Consult a Cardiologist?

Patients with ischemic stroke of undetermined cause and a detected PFO should undergo coordinated evaluation by cardiology and neurology specialists.

Sudden speech difficulty, facial drooping, weakness of an arm or leg, vision loss, or other stroke symptoms require immediate emergency medical attention.

Assoc. Prof. Sezen Bağlan Uzunget, MD
Cardiologist

This content is provided for general educational purposes. PFO closure decisions should be individualized according to stroke mechanism, PFO anatomy, and patient-specific risks.