Pilot Study of a Prototype Endoscopic Doppler Ultrasound (DOP-US) Device in Measuring Changes in Variceal Blood Flow After Band Ligation

Abstract

Background: Endoscopic band ligation (EBL) is commonly used to treat acute esophageal variceal hemorrhage (EVH). However, there is no objective marker of adequacy of EBL and, in some cases, recurrent varices or EVH may be secondary to ineffective or incomplete EBL. The utility of DOP-US in assessing persistent blood flow (BF) in arteries after endoscopic therapy for acute peptic ulcer bleeding has been well-documented. Data on DOP-US for varices are limited. Aims: To assess the utility of the VTI Flowmeter, a prototype DOP-US device, in examining esophageal varices. The Flowmeter provides both an audible Doppler signal and quantitative values of relative BF velocity and signal intensity based on vessel size and reflectance from blood cells. The second aim was to determine whether quantitative changes in variceal BF occur after EBL. Methods: Pts presenting to our institution with suspected EVH or for elective follow-up EBL were recruited for the study. A total of 5 Flowmeter studies in 4 pts were conducted in this pilot study. During initial EGD, variceal BF was measured 5 cm above the GE junction by placing the DOP-US probe in direct contact with the varix at an oblique angle. The angle was varied until the most consistent audible Doppler signal was obtained. After BF measurement, EBL was performed by standard technique. Repeat DOP-US exam was then performed. BF measurements following EBL were made by placing the probe 1 cm above the variceal band. If no signal was detected, the incident angle was varied to ensure that no signal was present. Means of quantitative DOP-US signals were compared by ANOVA. Results: In 5 studies, a total of 8 columns of Grade I, 8 Grade II, and 4 Grade III varices were examined. The pre-EBL signal intensity of Grade I varices (15.8) was lower than the signal intensity of Grade II (81.4) and Grade III (84.3) varices (p < 0.01). Relative BF velocity pre-EBL did not correlate with vessel size. 70% of examined varices had a positive (+) audible Doppler signal pre-EBL. Only 1 varix had a persistently (+) signal post-EBL. In this varix signal intensity decreased by 33% and relative BF velocity decreased by 23% post-EBL. Conclusions: In our preliminary experience, the Flowmeter is able to detect and quantify blood flow in pts with esophageal varices pre- and post-EBL. Varix size correlated with signal intensity. The absence of a detectable signal in all but 1 varix post-EBL suggests that EBL is highly effective at arresting BF. Additional studies with long term follow-up are needed to determine whether such a device can predict variceal recurrence or rebleeding in pts with a persistently (+) Doppler signal post-EBL.