Transorbital Doppler with carotid siphon monitoring detects right-to-left shunt effectively

AbstractBackgroundTranstemporal Doppler (TTD) with middle cerebral artery (MCA) is widely used for right-to-left shunt (RLS) detection. However, an alternative method for patients without suitable temporal bone windows should be established. The present study prospectively evaluated the effectiveness of transorbital Doppler (TOD) with carotid siphon (CS) monitoring in detecting RLS.MethodsA total of 357 subjects with sufficient temporal bone windows underwent simultaneous TTD with MCA and TOD with CS. After injection of microbubbles, the numbers of artificial high-intensity signals were recorded at rest and after Valsalva maneuver.ResultsTOD with CS detected RLS in 146 patients. Sensitivity was 97.1%, specificity 95%, positive predictive value 92.5%, and negative predictive value 98.1%. The total positive rates for RLS detection by CS (40.9%) and MCA (37.8%) monitoring were comparable without significant difference, but TOD with CS detected significantly more grade 2 and 3 RLS than TTD with MCA (p = 0.001...