Duplex ultrasound factors predicting persistent type II endoleak and increasing AAA sac diameter after EVAR

While the significance of type II endoleaks (T2ELs) on the long-term outcome of endovascular abdominal aneurysm repair (EVAR) to repair abdominal aortic aneurysms (AAAs) is debatable, duplex ultrasonography (DU) parameters have been suggested to be predictive of their closure or persistence. The purpose of this study was to determine which, if any, of these variables was associated with persistent T2EL or increased AAA sac diameter.

Between 1998 and 2009, 278 patients underwent EVAR and post-operative DU surveillance during long-term follow-up (1-11 years) in our accredited non-invasive vascular laboratory by one of three experienced technologists. DU measured intra-sac flow velocity (IFV), spectral doppler waveform (SDW) patterns, post-EVAR sac diameter, and number of T2ELs.

T2ELs developed in 14% (38/278) of patients post-EVAR. Fourteen patients had T2ELs that resolved, and sac diameter decreased or remained the same: the average IFV was 42 cm/second; SDW patterns were monophasic in five, biphasic in seven and bidirectional in two; and multiple T2ELs were not present (0%) in any patient. Twelve patients had T2ELs that persisted, but sac diameter decreased or remained the same: the average IFV was 47 cm/second; SDW patterns were monophasic in one, biphasic in five, bidirectional in five, and undetermined in one; and multiple T2ELs were found in 17% (2) of patients. Twelve patients had T2ELs that persisted and were associated with increased sac diameter: the average IFV was 43 cm/second, SDW patterns were monophasic in one, biphasic in two, and bidirectional in nine; and multiple T2ELs were identified in 75% (9) of patients. None of the 38 patients with T2ELs treated with selective surgical or endovascular intervention for enlarging sac diameters (11/12) experienced a ruptured aneurysm.

Contrary to previous smaller reports of T2ELs and DU surveillance, parameters such as IFV did not correlate with increased post-EVAR sac diameter. The presence of multiple T2ELs and bidirectional SDW may be the strongest factors predictive of increased sac diameter.