Common carotid artery duplex for the bubble test to detect right-to-left shunt.
We prospectively compared the bubble test with agitated saline for right-to-left shunt using transcranial Doppler (TCD) of the right middle cerebral artery and second harmonic imaging duplex of the right common carotid artery (CCA) in 100 consecutive patients. Microembolic signals (MES) were counted offline. MES were classified into 6 classes: absent (class 0), 1-10 MES (class 1), 11-20 MES (class 2), 21-30 MES (class 3), 31-50 MES (class 4) and >50 MES or "curtain effect" (class 5). For TCD, classes 2-5 combined (i.e., "large" shunts), the sensitivity of duplex with the Valsalva maneuver was 95.3%, the specificity was 100%, the positive predictive 100%, the negative predictive value 96.6% and accuracy 98.0%. Second harmonic imaging duplex of the CCA may substitute TCD for the bubble test when an adequate cranial bone window is not available. This technique may also greatly increase the number of facilities where the bubble test can be carried out. However, tests with few or no MES need to be confirmed by TCD or transesophageal echocardiography.
Censori
Bruno
B
USC Neurologia, Ospedali Riuniti di Bergamo, Bergamo, Italy. irosnec@live.it
Partziguian
Tania
T
Poloni
Marco
M
D017536:Carotid Artery, Common / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D054092:Foramen Ovale, Patent / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
D003287:Contrast Media