EVAR stent graft: Ultrasound characteristics
Myra Calumpong, Joao Carreira, Steven Rogers, Vascular Studies Unit, University of South Manchester NHS Trust, Manchester
Aims
Management of Abdominal Aortic Aneurysms via Endovascular Aneurysm Repair (EVAR) has become common practice. EVAR choice is partly governed by specific stent graft features that lend themselves to best treatment for that aneurysm. Multiple stent graft types exist within post EVAR ultrasound (US) surveillance. This poster identifies the various stent models that are frequently being used by vascular surgeons today and highlights common pitfalls that US practitioners must be aware of to avoid misdiagnosis.
Methods
Device images have been obtained with permission from EVAR manufacturers including Vascutek, Trivascular Endologix, Medtronic, Lombard and Cook Medical. Selection of US images were obtained with the purpose of demonstrating common pitfalls and highlight the potential risks of misdiagnosis as a result of common EVAR device characteristics.
Results
Different stent graft device characteristics can be visualised on 2D US. Endobags in Nellix devices can be mistaken for thrombus/dissection. Altura with a unique bilateral “D” shape stent design lacks a single neck which can be perceived as a dissection. Ovation stent graft consists of sealing rings and therefore type Ia endoleak misdiagnosis from pooled blood at the two polymer rings can occur. Anaconda devices have a saddle shape configuration designed for aneurysm with highly angulated necks and are commonly misdiagnosed as a kinked/fractured stent graft. Conventional devices include Cook which uses anchoring barbs and Endurant with endoanchors. Both are visualised as echogenic walled structures poses low risk of misdiagnosis despite little evidence on endoanchors until the ANCHOR trial is complete.
Conclusion
The multitude of stent grafts adopted in EVAR surgery has increased the occurrence of new stent types within EVAR surveillance. Communication between the surgical team and surveillance team is ever more important. A good understanding of the device characteristics by US practitioners is essential to prevent misdiagnosis.