How Common Is Right-to-Left Shunting on Echocardiography?

Increasingly, clinicians are ordering saline contrast echocardiograms (“bubble studies”) to identify right-to-left shunting in patients with adverse cerebrovascular events or migraine. Thus, knowing the background prevalence of shunting is important.

Researchers in Milwaukee performed saline contrast echocardiography, using a rigorous protocol, in 104 healthy volunteers (age range, 18–55). Fully 71% of participants had evidence of right-to-left shunting; findings were consistent with patent foramen ovale (PFO) in 38%, pulmonary arteriovenous malformation in 28%, and both in 5%. Most shunts were small-to-moderate in size. About 40% of patients had histories of headaches consistent with migraine; the prevalence of shunting was the same in pati…