Color Duplex Ultrasound Characteristics: Can we Predict Aortic Aneurysm Expansion following Endovascular Repair?

Abstract

Introduction The goal of aortic endovascular repair (EVAR) is to successfully exclude the aneurysm. Color duplex ultrasonography (CDU) is effective in the identification of endoleak and assessment of abdominal aortic aneurysm (AAA) morphology after EVAR. In a subset of patients with subtle endoleak, there is a characteristic appearance that predicts significant endoleak leading to AAA expansion. These endoleaks are difficult to detect by computed tomography (CT), and CDU and may represent the phenomenon known as endotension when endoleak is not identified. Methods All patients with several EVAR devices were prospectively followed with CDU for evaluation of endoleak at intervals during a 4-year period. All CDU exams were performed using Philips 5000, 3000, and IU22 systems according to protocol. Assessment of the AAA sac with spectral and color Doppler was used to identify endoleak. The B-mode echogenicity of the AAA sac was characterized for echogenicity and sac symmetry. The patients were followed with CT scan and/or angiography for confirmation of endoleaks. Results There were 12 patients with subtle Type II endoleaks and a characteristic texture by CDU identified from 1 month to 16 months after intervention. The endoleaks had low velocities within the sac ranging from 10 to 50 cm/sec with a bidirectional spectral Doppler waveform. An asymmetrical AAA sac with a “spongy” multiechogenic texture was a finding in all 12 patients. The endoleaks were difficult to detect by both CDU and CT scan because of the low velocities despite AAA sac enlargement in all patients. The average AAA sac enlargement was 4.4 mm. CT scan and/or angiography failed to detect endoleak in 6 of 12 patients positive by CDU for endoleak with AAA sac expansion. Conclusion CDU after EVAR can effectively detect the presence of endoleak and assess the B-mode characteristics of the AAA sac. Important clues such as low flow, sac expansion, sac asymmetry, and a “spongy” B-mode appearance are consistent with subtle endoleak that may lead to AAA expansion. When undetected, this type of endoleak may be misdiagnosed as endotension.