continued expansion of aortic necks after endovascular repair of abdominal aortic aneurysms evt investigators endovascular technologies inc background longitudinal studies have revealed that the aortic segment proximal to an infrarenal abdominal aortic aneurysm aaa is at risk for continued enlargement after a standard aneurysm repair similarly preliminary reports have shown expansion of one or both aortic necks after endovascular repair although some investigators have suggested that this may be a transient effect continued dilatation at the endograft attachment site could effect the overall device stabilitymethods as part of a multiinstitutional trial of endovascular grafting for the treatment of aaa 59 patients were successfully implanted with straight endografts between february 1993 and january 1995 a morphometric analysis of aortic neck size was undertaken with serial review of computed tomography scans available through april 1997 the neck sizes at both graft attachment sites were measured with investigators blinded to patient identity and date of scan changes in minor diameter were defined annual interval expansion rates were calculated and the data were correlated with endoleak device migration aneurysm size change endograft diameter attachment system fractures and initial preimplant neck sizeresults significant aortic neck enlargement particularly at the level of the distal neck was observed for at least 24 months after aaa repair the annual interval dilation rates of the proximal aortic neck were 07 21 mmyear p 023 and 09 19 p 008 mmyear during the first and second years respectively enlargement of the distal neck during the observation period was more marked with corresponding annual expansion rates of 17 29 mmyear p 001 and 19 25 p 001 mmyear in 5 patients 14 the minor diameter of the distal neck was at least 6 mm larger than the preimplant diameter of the graft migration of the distal attachment system was observed in 3 of these 5 patients expansion rates did not have a statistically significant correlation with initial neck size endograft dimensions aneurysm size change presence of endoleak or attachment system fractureconclusions aortic neck enlargement was observed for at least 2 years after endovascular grafting close patient followup remains mandatory in lieu of the potential risk of late failure as a result of continued aortic expansion the relative contribution of device design to this phenomenon will need to be defined