Evolution of type II endoleaks based on different ultrasound-identified patterns

Objective: The objective of this study was to delineate the specific types of waveforms that exist in type II endoleaks (T2ELs) and their effect on aneurysm sac size. Methods: Patients who underwent an endovascular aneurysm repair and were diagnosed with a T2EL were included in the study. The flow velocity characteristics of the T2ELs were evaluated in detail with duplex ultrasound. Four different flow patterns were identified: high resistance, low flow; low resistance, low flow; low resistance, high flow; and to-fro flow. The type and number of vessels involved, time at detection, evolution, and need for treatment were recorded. The aneurysm sac diameter was monitored with duplex ultrasound. A computed tomography scan was always performed at baseline within 1 month of the procedure and repeated only when symptoms developed or there were changes in the ultrasound examination findings, such as sac enlargement. Results: Of 382 patients who underwent endovascular aneurysm repair in our institution, 56 (14.65%) were found to have a T2EL. There were 52 male and four female patients with a mean age of 74 years (61-86 years). The T2EL was diagnosed within the first month in 32 patients; 9 patients were diagnosed at 3 months, 5 patients at 6 months, 3 patients at 9 months, and 7 patients at 1 year or later. There were 43 patients who had a T2EL involving one vessel; two vessels were involved in 11 patients and three vessels were involved in two patients. During follow-up, several changes were observed for the different types of T2EL. High-resistance, low-flow endoleak was detected in 14 patients; of those, 13 were occluded and 1 converted to high flow. Low-resistance, low-flow endoleak was detected in seven patients; of those, 5 were occluded, 1 remained stable, and 1 converted to high flow with sac enlargement requiring treatment. Low-resistance, high-flow endoleak was found in 13 patients; of those, 8 were occluded, 3 remained stable, and 2 had sac enlargement requiring treatment; 1 patient presented with rupture. Finally, to-fro flow was identified in the majority of the patients (22); of those, 14 occluded, 3 remained stable, and 5 had sac enlargement requiring treatment; 2 patients presented with rupture. No deaths due to T2EL were encountered. Conclusions: Most of the T2ELs resulted in spontaneous occlusion and were not associated with sac enlargement. A low-resistance, high-flow or to-fro flow T2EL has higher chances of sac enlargement, rupture, and requiring reintervention.