72 Outcomes of prophylactic wrapping of the thoracic aorta with a Polyethylene terephthalate (ExoVasc®) mesh: a rat model

Abstract Introduction Aortic dissections are medical emergencies associated with a high mortality. Thoracic aortic aneurysms leading to dissection and/or rupture are characteristic, but not exclusive, to known genetic disorders. While medical therapies may retard the enlargement of aortic aneurysms, prophylactic surgical repair is mandated when the aortic diameter reaches a specific criteria. The newest, less invasive ‘exostenting’ offers a personalised external aortic root support (PEARS). We aimed to assess the possibility of prophylactic exostenting of the rats’ thoracic aorta, the time needed for Exostent incorporation, and the extracellular molecular changes induced. Methods Twentythree, 6-7 weeks old Wistar rats of both genders underwent a left sided thoracotomy for wrapping their thoracic aorta with a sleeve of a length of ∼1 cm of ExoVasc® mesh; these rats were euthanised 8, 12, 16, 20 and 24 weeks postop. Samples of thoracic aorta were harvested, fixed in 10% formalin and embedded in paraffin wax prior to cutting 5μm thick transverse sections. These tissue sections were then stained using the Haematoxylin and Eosin method, the combined van Gieson/Verhoeff method and examined microscopically. The scale, nature and anatomical location of the tissue response to the mesh was assessed for each timepoint post-op and also compared with thoracic aortas harvested from rats of similar age and gender. Results The Exostent incorporates with the aortic adventitia ∼16-20 weeks postop; afterwards no major cellular changes are noticed; however, the foreign body reactions persist throughout. We aim this model to serve as a valid template for further research.