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 PFO as isolated findings receive no treatment. When PFO is associated with an otherwise unexplained neurologic event, no consensus for treatment exists

Medical Therapy

aspirin therapy alone in low risk patients
addition of warfarin (INR 2-3)in high risk individuals

Surgical Care

Indications for surgical closure of PFO

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 long-term anticoagulation and its risks

Percutaneous closure of PFO during cardiac catheterization is an emerging therapeutic option.

External Links

References

emedicine.Medscape.com

Authors: