title: A model to demonstrate that endotension is a nonvisualized type I endoleak.
abstract: Unexplained aneurysm growth despite multimodality imaging after endovascular aneurysm repair is often attributed to endotension. We tested a hypothesis that endotension may be from a type Ia endoleak pressurizing the aneurysm sac, without net forward flow, not visualized on standard angiographic imaging.
  
  
  
  A patient-specific aortic aneurysm phantom was constructed of polyvinyl alcohol using three-dimensional molding techniques. A bifurcated stent graft was implanted, and the phantom was connected to a hemodynamic simulator for testing. Type Ia endoleaks were created using 7F catheters. Three scenarios were studied: complete exclusion (no endoleak), inflow with no sac outflow, and inflow with sac outflow. Imaging with digital subtraction angiography was performed at 48 kVp at 5 frames/s, followed by delayed imaging at 1 frame/min for 30 minutes.
  
  
  
  With no endoleak, the systemic pressure averaged 113 mm Hg and aneurysm sac pressure averaged 101 mm Hg. With an endoleak present without outflow, the systemic pressure averaged 116 mm Hg, the aneurysm sac pressure averaged 120 mm Hg, and endoleak flow was bidirectional with no net forward flow. With endoleak present with aneurysm sac outflow, the systemic pressure averaged 119 mm Hg, aneurysm sac pressure averaged 105.5 mm Hg, and net endoleak flow into the aneurysm sac was 21 mL/min across the endoleak channel. With digital subtraction imaging, the endoleak with no outflow was noted after >9 minutes of delayed imaging.
  
  
  
  In our model, the creation of a type Ia endoleak in the absence of sac outflow resulted in a mean pressure higher than the systemic mean pressure with zero net flow into the aneurysm sac. Consequently, the endoleak could only be visualized with markedly delayed imaging and not with standard contrast digital subtraction angiography like that used in clinical practice. Our findings suggest that endotension may in fact be the result of undetected endoleaks secondary to the limitations of present iodinated contrast imaging modalities.
authors.affiliation: Department of Vascular Surgery, Danbury Hospital, Danbury, Conn.
authors.forename: Stuart
authors.initials: S
authors.lastname: Blackwood
authors.affiliation: Cardiovascular Engineering Laboratory, Division of Vascular Surgery, University of Rochester, Rochester, NY.
authors.forename: Doran
authors.initials: D
authors.lastname: Mix
authors.affiliation: Cardiovascular Engineering Laboratory, Division of Vascular Surgery, University of Rochester, Rochester, NY.
authors.forename: Ankur
authors.initials: A
authors.lastname: Chandra
authors.affiliation: Department of Vascular Surgery, Danbury Hospital, Danbury, Conn. Electronic address: alan.dietzek@wchn.org.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Dietzek
mesh_terms: D015901:Angiography, Digital Subtraction; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001027:Aortography / Q000379:methods; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects* / Q000295:instrumentation; D057867:Endoleak / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D057510:Endovascular Procedures / Q000009:adverse effects* / Q000295:instrumentation; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D015607:Stents; D013997:Time Factors