Does Valsalva's Maneuver Precipitate Paradoxical Brain Embolism in Healthy Individuals?

To the Editor.  —In a review of 144 young adults with nonhemorrhagic cerebral infarcts, Adams and co-workers¹ suggested a direct relationship between right-to-left shunts demonstrated on contrast echocardiography and paradoxical brain embolism in six patients without any other evidence of cardiac or systemic disease. According to the authors' opinion, Valsalva's maneuver could be the predisposing factor for such events. We think this is a very questionable statement.Paradoxical brain embolism usually occurs in the setting of acute cor pulmonale caused by massive pulmonary embolism or in patients with cyanotic congenital heart disease.² Such conditions were not present in the patients described by Adams et al.¹ It is also possible that right-to-left shunts occur in healthy individuals through a patent foramen ovale with Valsalva's maneuver,³ but this phenomenon should not be expected to cause paradoxical brain embolism in the absence of another concomitant factor that favors deep venous thrombosis.