Stent Grafts (AAA EVAR or Other Arterial Placement / Locations)

1. Normal

a. Aortic sac diameter is smaller or remains stable compared to prior exam

b. No endoleak is detected

c. No limb dysfunction

d. No focal velocity increases along the segments evaluated

e. Velocities are typically dampened (lower) in the stent graft segments

f. Doppler velocity waveforms in the outflow (untreated) iliac vessels are normally bi-to-triphasic

g. No dilation of the iliac vessels along their course

h. Renal arteries are patent

2. Abnormal

a. An increase in sac diameter ≥5 mm (0.50 cm) on the postoperative and/or serial exams in considered a significant increase in size.

b. Endoleak: flow outside the graft within the residual sac

c. 50-74% diameter reduction: velocities double (ratio X 2) across contiguous arterial segments. in areas of disease

d. 75-99% diameter reduction: velocities quadruple  (ratio X 4) across contiguous arterial segments in areas of disease

e. Occlusion identified when there is no flow with spectral Doppler interrogation f. Renal artery occlusion

Endoleak Classification

Type I: Leak from the proximal or distal fixation of endovascular stent graft

Type II: Flow in an aortic branch vessel that reverses and feeds back into the sac.  These vessels can be lumbar, inferior mesenteric or accessory renal arteries for example

Type III: Leak arising from junctions between graft modular components or from fabric tear within the stent grafts.

Type IV: Transgraft flow / porosity of the stent graft fabric

Note: Type II is most common; Type III and IV are the least common