Patent foramen ovales: quick facts

NEJM article2005:353:22:2361-2372 Etiologic role in stroke questioned due to a) prevalence of PFO b) gradient for right to left shunting must exist (normally exists only in early systole, with prolonged Vasalva, or pulmonary hypertension c) usual lack of evidence of peripheral venous embolic source d) evidence that the yearly risk of stroke in patients with PFO may be as low as 0.1 %. How to pick the bad PFO's from the beningn ones? Factors include a large separation of > 4 mm between the primum and secondum septa; increased right to left shunting; shunting at rest; increased septal mobility; and presence of ASA. Also risk factors for venous thromboembolism are important including trauma, recent surgery, oral contraceptive use and hypercoagulable states. Atrial septal aneurysm (ASA) prevalence at autopsy is about 1 %. 50-90 % have associated PFO (association does not work in reverse, only about 7 % of patients with PFO have ASA). Detection of thrombus in situ is helpful but rarely found. ASA is associated with prominent Eustachian valves or Chiari networks, membranes that facilitate right to left shunts, by directing flow from the IVC to fossa ovalis, and presence of tachyarrythmias predisposing to thromboembolism. Diagnosis TTE v. TEE-- TTE diagnoses about 25 % of PFO's but less than 10 % of ones without signs or symptoms. Contrast TEE diagnoses 57 % of patients with cryptogenic stroke. Treatment-- ASA v. anticoagulation-- risk of recurrence is low among patients <>10-155 mm. PFO + ASA has increased stroke recurrence (3.8 v. 1 %). Officially, use anticoagulation as its beneficial if there is recurrent stroke, systemic thrombosis or (blogger thought-- elevated d-dimer). Role of ASA (risk) is not certain if PFO not also present.

Suspect PFO if one sees an M shaped notch on inferior leads on EKG.