Abstract 233: Endotension: Net Flow through an Endoleak Determines its Visibility

Abstract

OBJECTIVES Unexplained aneurysm growth despite multimodality imaging following EVAR is often attributed to endotension. We tested a hypothesis that endotension may be from a type 1a endoleak (EL) pressurizing the aneurysm sac without net forward flow, not visualized on standard angiographic imaging. METHODS A patient-specific aortic aneurysm phantom was constructed of polyvinyl alcohol using 3D molding techniques. A bifurcated stent graft was implanted and the phantom connected to a hemodynamic simulator for testing. Type 1a ELs were created using 7 Fr catheters. Three scenarios were studied: complete exclusion (no EL); inflow with no sac outflow; and inflow with sac outflow. DSA imaging was performed at 48kvP at 5fps followed by delayed imaging (1 frame/min) over 30 minutes. RESULTS With no EL, the systemic MAP (sMAP) averaged 113mmHg and Aneurysm Sac MAP (asMAP) averaged 101mmHg. (Table 1) With EL without outflow, the sMAP averaged 116mmHg and asMAP averaged 120mmHg. EL flow was bidirectional with no net forward flow. With EL with aneurysm sac outflow, the sMAP averaged 119mmHg, asMAP averaged 105.5mmHg and net EL flow was +21cc/min across the EL channel. With DSA imaging, the EL with no outflow was noted after >9 min of delayed imaging. CONCLUSIONS Our model demonstrated a Type Ia EL in the absence of aneurysm sac outflow resulting in full pressurization of the aneurysm sac with biphasic (zero net) flow. This EL was not visible on standard contrast DSA until >9 min. This model may serve as a first step in explaining both the mystery of endotension and in vivo aneurysm sac growth with no detectable ELs using current standard imaging modalities.