The evolving role of echocardiography in the assessment of patent foramen ovale in patients with left-side thromboembolism

Patent foramen ovale (PFO) is the most common congenital cardiac abnormality found approximately in 25% of the adult population The pathophysiological role of paradoxical embolization through the PFO in ischemic stroke is well established. "Self-expanding double disk" and, more recently, suture-based "deviceless" systems are used for PFO closure in the setting of secondary prevention after ischemic stroke likely related to paradoxical embolization. Ultrasound plays a significant role in PFO assessment, indication to treatment, intra-procedural guidance, and follow-up for those undergoing PFO closure. Three different techniques are frequently used for these purposes: transesophageal echocardiography, transthoracic echocardiogram, and transcranial Doppler. In this review, advantages and limits of these techniques are discussed in detail to improve our skills in detection and treatment of this important condition by using ultrasound.