Patent Foramen Ovale

Incidence: 25–30% at autopsy.

Atrial septal aneurysm (a deformity of the septum that results in deviation of the septum more than 15 mm into either atrium) is associated with at least 50% of PFOs and is considered an additional risk factor for stroke.

Unclear if a PFO increases the risk of stroke or cognitive dysfunction in the periop period.

R-to-L shunting of blood leading to profound hypoxemia

Paradoxical embolization of air, blood clot, or tissue fragments, potentially resulting in stroke

The foramen ovale directs oxygenated blood returning from the placenta and into the right atrium across the intra-atrial septum to the left ventricle.

As right-sided pressures decrease after birth, the foramen ovale flap is pressed against the septum secundum.

This results in the fusion of the ovale flap to the septum secundum; irreversible closure of the ovale occurs in 75% of pts.

Diagnosed by:

• Right heart cath, with the ability to cross a guide wire across the atrial septum.

• TEE is considered the “gold standard” imaging technique, using a contrast agent (bubble study) and provocative technique (Valsalva maneuver).

• TCD is less invasive than TEE with similar sensitivity but reduced specificity.

• TTE: Sensitivity 50% of TEE, with similar specificity.

See also Atrial Septal Defect .

Unknown what, if any, risk factors predispose to patent foramen ovale

A higher incidence of PFO was found in pts who suffer migraine with aura; unclear whether this represents coexistence or a causal relationship between the two entities.