Detection of Right-to-Left Shunt With Transcranial Doppler Is Affected by Body-Positioning

To the Editor:We read with great interest the recent study by Caputi et al regarding the postural dependency of right-to-left shunt (RLS) detection using contrast-enhanced transcranial Doppler (TCD).1 After using TCD to detect the bubble-load in 2 different body positions (recumbent and standing) in consecutive RLS-positive patients (confirmed by transthoracic echocardiogram), the authors concluded that the amount of bubbles detected was dependent on body position, with 42% of the study population exhibiting almost a 3-fold increase in the yield of microbubbles in the standing compared to the supine position.1Our group has previously investigated whether body-positioning may affect the sensitivity of TCD in detecting and grading RLS in patients with ischemic stroke …