Abstract WMP56: Utility of Bubble Test with Cervical Internal Carotid Artery Triplex Ultrasound in Detection of Right-to-left Shunts
BACKGROUND: Transcranial Doppler (TCD) ultrasound with bubble test is a dependable method to detect cardiac right-to-left shunts (RLS). In patients with insufficient temporal bone windows, cervical internal carotid artery (ICA) recording can be used as an alternative method for detection of RLS. However, bubble tests performed via insonation of cervical ICA have issues with probe fixation, signal differentiation and breathing/swallowing artifacts. To overcome these problems, we developed a new technique for bubble test with cervical ICA and compared its utility with traditional middle cerebral artery (MCA) TCD studies.
METHODS: MCA and ICA recordings were compared in 156 bubble studies obtained from 78 patients. ICA bubble study was performed by hand-held 1-3 MHz phase-arrayed sector transducer and triplex ultrasound technology. RLS volume was graded according to the International Consensus Criteria (ICC) [grade-0: no micro bubble (MB), grade-1: 1-20 MB, grade-2: >20 MB or shower, and grade-3: curtaining].
RESULTS: In 133 studies there was concordance of MCA and ICA studies. In 11 patients ICC grade was higher with MCA monitoring, while in 12 patients, ICA method showed higher RLS grade. Overall MB number was higher in ICA than MCA (33 vs. 20 MB). Bubble test with triplex ICA was reliable (Cronbach’s alpha: 0.87) and well correlated (weighted quadratic kappa: 0.874) with traditional MCA method. There was no signal loss during Valsalva’s maneuver with ICA recording, where triplex technique provided timely relocation of the signal with real-time color imaging.
CONCLUSION: The bubble test performed with triplex ICA recording is a sensitive and specific alternative of traditional bubble studies performed by MCA recording. This method is feasible not only in patients with poor ultrasonic bone windows but also for all cases evaluated for RLS presence and grading.
- © 2012 by American Heart Association, Inc.