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(Stroke. 2009;40:e505.)
© 2009 American Heart Association, Inc.

Letters to the Editor

Bubble Study in Patients With Massive Right-to-Left Shunt and Recurrent Stroke

Talip Asil, MD Nikolai Steffenhagen, MD

Department of Clinical Neurosciences, University of Calgary, Calgery, Alberta, Canada

Muhammed Ibrahim, MD

Department of Neurology, University of Alberta, Edmonton, Alberta, Canada

Andrew Demchuk, MD, FRCPC

Department of Clinical Neurosciences, University of Calgary, Calgery, Alberta, Canada

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We thank Serena and colleagues for their important contribution with this prospective, multicenter, observational study analyzing the risk of recurrent stroke with the presence of right-to-left shunt (RLS).¹ In this study, the presence and magnitude of RLS through a patent foramen ovale (PFO) were not associated with stroke recurrence in patients with a first cryptogenic stroke. The transcranial Doppler procedure used in this study was an agitated saline solution injected 3 times during normal breathing and 3 times during Valsalva maneuver. Patients were divided into 5 groups and analyzed on the basis of the maximum number of microbubble signals (MBS) in the middle cerebral artery in any single frame. The article did not address the differences in MBS based on the type of procedure if it was done at rest or with Valsalva maneuver. In addition, no separate analysis was done to define whether RLS at rest or with Valsalva maneuver is a predictor of stroke recurrence. MBS counts are typically higher with Valsalva maneuver than at rest, but MBS counts at rest may be more clinically important.

De Castro et al² reported that cumulative risk of cerebrovascular event recurrence at 3 years was higher (12.5%) in high-risk PFO defined as a mobile septum and RLS at rest than in low-risk PFO defined as RLS only with Valsalva maneuver (event rate of 4.3%). It is also known that patients with a shunt during quiet breathing have an increased exposure time for paradoxical embolism and should in theory . . . [Full Text of this Article]

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