Abstract WP238: Utility of the Bubble Test With Cervical Triplex Ultrasound in Diagnosis of Patent Foramen Ovale in Patients With Inadequate Transtemporal Sonic Window

Abstract

Introduction: Transcranial Doppler (TCD) detection of microbubble signals in the middle cerebral artery (MCA) after agitated saline injection, known as the bubble test, is a dependable method to detect right-to-left shunts (RLS) such as patent foramen ovale (PFO). In patients with inadequate temporal bone windows, cervical internal carotid or vertebral arteries (ICA and VA) are suggested to be alternatives of MCA. However, utility of the bubble test with cervical arteries has never been documented in this population. Methods: Using contrast transesophageal echocardiography (cTEE) as gold standard, the sensitivity (Se) and specificity (Sp) of unilateral hand-held cervical triplex ultrasound bubble test technique was computed and compared with other available TCD methods. RLS volume was graded per the International Consensus Criteria (ICC). Results: Of 796 patients who underwent the bubble test in 3 years, 41 (5.3%) patients had no adequate temporal bone windows for MCA insonation. cTEE was available for 184 patients. Se and Sp of cervical bubble test was excellent in patients without adequate bone windows (n=36, Se: 88% (57-98) and Sp: 91% (71-99) for ICA; n=33, Se: 85% (55-98) and Sp: 90% (68-98) for VA), and was to comparable to those with adequate bone windows (n=78, Se: 93% (95%CI: 82-99) and Sp: 79% (61-91) for ICA; n=48, Se: 92% (74-99) and Sp: 91% (72-99) for VA). Diagnostic yield is comparable to standard bubble test with bilateral MCA Doppler monitoring (n=56, Se: 74% (55-88) and Sp: 56% (35-76) for spectral Doppler and M-mode). Of note, unilateral hand-held transcranial Doppler (n=26, Se: 93% (66-99) and Sp: 58% (28-85) for spectral Doppler: Se: 93% (66-99) and Sp: 50% (21-79) for M-mode) and color-coded (n=125, Se: 88% (78-94) and Sp: 64% (48-78) for color-coded MCA) techniques are also acceptable and apparently more practical methods for RLS detection. Conclusions: Hand-held cervical artery bubble test has high Se/Sp enough for routine use for PFO screening. Yield is good in the setting of impermeable transtemporal bone windows.