The diagnosis and treatment of paradoxical embolism: a systematic review

One in five adults has patent foramen ovale (PFO), which is typically without symptoms. Because of the low pressure in both atria and the anatomical position of the septum secundum, there is no left-to-right shunting and little right-to-left shunting in the general condition; however, when the right atrial pressure increases, this slit-like flap separates and allows right-to-left shunting. According to the Johnson criteria, simultaneous occurrences of arterial emboli, such as those caused by cerebrovascular accident or pulmonary embolism, demonstrate the presence of paradoxical embolism through a PFO. When a patient presents with multivascular arterial embolism, the clinician should perform a contrast transthoracic echo, a transesophageal (TEE), a real-time three-dimensional TEE, and even an intracardiac echocardiography (ICE) in order to differentiate between PFO, flat atrial septal defect (ASD) and hybrid defects. The randomized trials that have assessed therapeutic interventions for paradoxical embolism have not produced any clear guidelines as to how best to treat this condition. The classic treatment is surgical embolectomy with exploration of the right chambers and the pulmonary arteries under full cardiopulmonary bypass. Patients with a history of ≥1 paradoxical embolism may be indicated for device PFO closure.