Endotension in an experimental aneurysm model

Purpose: The purpose of this study was to design an experimental model of endotension and to investigate whether attachment site failure without endoleak results in higher aneurysm sac pressure (ASP). Methods: Infrarenal aortic aneurysms were created in canines with an elliptical knitted polyester patch. Pressure transducers were inserted into the aneurysm. Group I (n = 4) underwent endovascular stent graft exclusion of the aneurysm. An attachment site failure was formed in group II (n = 5) before aneurysm exclusion. ASP measurements were obtained for 3 weeks, and the ratio of mean ASP to mean systemic blood pressure (ASP/BP) was calculated. Before explant, norepinephrine was administered and ASPs were recorded at varying systemic pressures. Stent graft cuff exclusion of the attachment site failure was performed in group II. Results. Intraoperative arteriography and duplex ultrasonagraphy did not reveal an endoleak in either group. ASP/BP in group I was 0.39 +/- 0.02 compared with 1.01 +/- 0.02 in group II (P <.001). Mean systemic pressure varied from 55 to 177 mm Hg after norepinephrine administration. Within this interval, ASP/BP was 0.51 +/- 0.10 in group I compared with 0.91 +/- 0.10 in group II (P <.001). ASP/BP before cuff deployment in group II was 0.98 +/- 0.08 compared with 0.46 +/- 0.04 after cuff deployment (P <.001). Conclusion: Systemic pressure is transmitted to the aneurysm sac through an attachment site failure, despite no endoleak, resulting in endotension. Cuff exclusion of the attachment site failure decreases ASP. ASP may help determine the need for future intervention after endovascular aneurysm repair.