A model to demonstrate that endotension is a nonvisualized type I endoleak

Area of Science:

• Vascular Surgery
• Medical Imaging
• Biomedical Engineering

Background:

• Endovascular aneurysm repair (EVAR) is a common treatment for aortic aneurysms.
• Unexplained aneurysm sac growth post-EVAR is often attributed to endotension.
• Current imaging modalities may fail to detect certain types of endoleaks causing endotension.

Purpose of the Study:

• To investigate the hypothesis that type Ia endoleaks, without net forward flow, can cause endotension.
• To determine if standard angiographic imaging can visualize such endoleaks.
• To explore the role of delayed imaging in detecting these subtle endoleaks.

Main Methods:

• A patient-specific aortic aneurysm phantom was created using polyvinyl alcohol.
• A bifurcated stent graft was implanted, and the phantom was connected to a hemodynamic simulator.
• Type Ia endoleaks were simulated, and imaging was performed using digital subtraction angiography with standard and delayed protocols.

Main Results:

• A type Ia endoleak without sac outflow resulted in sac pressure exceeding systemic pressure (120 mm Hg vs 116 mm Hg).
• This specific endoleak scenario exhibited bidirectional flow with no net forward flow.
• Standard digital subtraction angiography failed to visualize the endoleak; it was only detected after >9 minutes of delayed imaging.

Conclusions:

• Undetected type Ia endoleaks, characterized by pressurization without net flow, can cause endotension.
• Limitations in current iodinated contrast imaging modalities hinder the detection of these specific endoleaks.
• Delayed imaging protocols may be crucial for identifying endoleaks contributing to endotension post-EVAR.