Patent foramen ovale
Patent foramen ovale (PFO) is a flap-like opening between the atrial septa primum and secundum at the location of the fossa ovalis that persists after 1 year of age. This inter-atrial communication gives potential for right-to-left shunting in the cardiovascular system. Although most patients with an isolated PFO are asymptomatic, there is increasing evidence being found that PFO is the culprit in paradoxical embolic events and therefore, the relative importance of the anomaly is being re-evaluated.
- History of stroke or TIA of undefined etiology
- 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
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)
- Color flow Doppler imaging: small "flame" of color signal may be seen in middle region of atrial septum
- Contrast echocardiography (Bubble Study): After obtaining optimal visualization of atrial septum on TTE or TEE, a bolus of agitated saline is injected to an antecubital vein. Subsequently, microbubbles appear in the right atrium. The study is positive for PFO if microbubbles appear in left atrium within 3 cardiac cycles of their appearance in the right atrium. Valsalva increases right atrial pressure and facilitates right-to-left shunting if present.
- 2D TEE with contrast provides superior visualization and is therefore preferred for detecting PFO. When clinically indicated, 2D TEE with contrast is strongly recommended if transthoracic echo is negative.
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
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.