Patent foramen ovale

Background

• Flap-like opening between the atrial septa primum and secundum
• Occurs at fossa ovalis
• Persists beyond 1 year of age
• Inter-atrial communication allows right-to-left cardiac shunting
• Most patients with isolated PFO are asymptomatic
  • But there is increasing evidence that PFO is the culprit in paradoxical embolic events

Clinical Features

• Stroke or TIA of undefined etiology
  • Consider in young, healthy patients without risk factors for stroke
• Migraine or migraine-like symptoms
• Neurologic decompression sickness (seen in scuba divers)
• Acute myocardial infarction
• Systemic embolism, such as renal infarction
• Fat embolism
• Paradoxical embolism caused by right atrial tumors that increase right atrial pressure
• Left-sided valve disease in carcinoid syndrome

Differential Diagnosis

Missile embolism types

• Intrapericardial foreign body
• Systemic venous embolism
• Right heart and pulmonary artery embolism
• Pulmonary vein embolism
• Left heart embolism
• Coronary artery embolism
• Paradoxical embolus (due to patent foramen ovale)

Evaluation

• Color flow Doppler imaging
  • Small "flame" of color signal may be seen in middle region of atrial septum
• Contrast echocardiography (Bubble Study)
  • Bolus of agitated saline injected to antecubital vein
  • Microbubbles appear in right atrium
    • Study positive for PFO if microbubbles appear in left atrium within 3 cardiac cycles of their appearance in right atrium
  • Valsalva increases right atrial pressure and facilitates right-to-left shunting if present
• 2D TEE with contrast provides superior visualization and is preferred
  • Obtain 2E TEE with constrast if suspicion is high and TTE is negative

Management

• Most patients with incidental or isolated PFO receive no treatment
• Treatment more common when PFO associated with unexplained neurologic event, but no consensus for treatment exists

Medical Therapy

• Aspirin therapy alone in low risk patients
• Warfarin with ASA (INR 2-3) in high-risk individuals

Surgical Closure

• Indications:
  • PFO more than 25 mm in size
  • Inadequate rim of tissue around defect
  • Percutaneous device failure
• Advantages of surgical closure
  • Permanent closure of defect
  • Prevents future paradoxical emboli
  • No need for long-term anticoagulation
• Percutaneous closure
  • Emergency therapeutic option

See Also

• Congenital Heart Disease
• Missile embolism

References

emedicine.Medscape.com