Iliac fixation length and resistance to in-vivo stent-graft displacement.

PURPOSE Migration of endovascular stent grafts has been related to the security of proximal device fixation to the aortic neck. This study evaluated the importance of iliac fixation in preventing longitudinal in vivo device displacement of a modular, externally supported stent graft. METHODS Experimental ovine infrarenal aneurysms (n = 8) were treated with a fully supported, modular, bifurcated stent graft (AneuRx, Medtronic, Santa Rosa, Calif). Minimum iliac fixation length (1 cm) was used in four animals and iliac extender modules were used to achieve maximum iliac fixation in four animals. Suture anastomosis of bifurcated polyester grafts to the infrarenal aorta served as controls (n = 8). Aortic grafts were displaced in vivo by applying downward traction to a guidewire that was passed over the iliac flow divider and brought out both femoral arteries. The displacement force needed to initiate stent-graft migration was recorded and compared with the force needed to disrupt the sutured anastomosis. RESULTS There was no difference in animal weight (88.8 +/- 2.5 kg vs 87.5 +/- 2.9 kg), aortic neck diameter (12.7 +/- 0.9 mm vs 13.4 +/- 1.1 mm), aortic neck length (23.2 +/- 0.9 mm vs 21.8 +/- 2.4 mm), experimental aneurysm size (24.7 +/- 1.1 mm vs 24.2 +/- 2.0 mm), or iliac artery diameter (9.0 +/- 1.5 mm vs 9.3 +/- 0.5 mm) among the groups. Iliac fixation length was 31.0 +/- 0.3 mm in the maximum iliac fixation group and 11 +/- 0.25 mm in the minimum fixation group (P < .0001). Peak displacement force to initiate migration was 30.2 +/- 5.5 N (range, 25 to 38) in animals with maximum iliac fixation compared with 18.1 +/- 3.7 N (range, 13 to 21) in those with minimum fixation (P = .01). The force needed to disrupt the control surgical anastomosis was 40.6 +/- 7.5 N (range, 31 to 50) (P < .01). CONCLUSIONS Maximizing iliac fixation length increases the longitudinal in vivo force needed to displace a fully supported stent graft by 67%. This suggests that increasing iliac fixation length may reduce the long-term risk of migration in patients undergoing endovascular aneurysm repair.

[1]  Rodney A. White,et al.  Stent graft migration after endovascular aneurysm repair: importance of proximal fixation. , 2003, Journal of vascular surgery.

[2]  N. Fearnot,et al.  Zenith AAA endovascular graft: intermediate-term results of the US multicenter trial. , 2004, Journal of vascular surgery.

[3]  E. Buskens,et al.  Quality of life endovascular and open AAA repair. Results of a randomised trial. , 2004, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[4]  P. Harris,et al.  Factors and Forces Influencing Stent-Graft Migration after Endovascular Aortic Aneurysm Repair , 2002, Journal of endovascular therapy : an official journal of the International Society of Endovascular Specialists.

[5]  J. Semmens,et al.  Evaluation of patient selection guidelines for endoluminal AAA repair with the Zenith Stent-Graft: the Australasian experience. , 2001, Journal of endovascular therapy : an official journal of the International Society of Endovascular Specialists.

[6]  B. Hopkinson,et al.  Stent-Graft Migration after Endovascular Repair of Abdominal Aortic Aneurysm , 2002, Journal of endovascular therapy : an official journal of the International Society of Endovascular Specialists.

[7]  M. Walsh,et al.  A mathematical model to predict the in vivo pulsatile drag forces acting on bifurcated stent grafts used in endovascular treatment of abdominal aortic aneurysms (AAA). , 2004, Journal of biomechanics.

[8]  A. Lumsden,et al.  Detection of isolated hook fractures 36 months after implantation of the Ancure endograft: a cautionary note. , 2001, Journal of vascular surgery.

[9]  T. Chuter,et al.  Stent-Graft Design: The Good, the Bad and the Ugly , 2002, Cardiovascular surgery.

[10]  S. Travis,et al.  Anatomical risk factors for proximal perigraft endoleak and graft migration following endovascular repair of abdominal aortic aneurysms. , 2000, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[11]  J. Matsumura,et al.  A multicenter controlled clinical trial of open versus endovascular treatment of abdominal aortic aneurysm. , 2003, Journal of vascular surgery.

[12]  J. Alsac,et al.  Short- and long-term outcome following endovascular aneurysm repair. How does it compare to open surgery? , 2004, The Journal of cardiovascular surgery.

[13]  R. Sayers,et al.  Factors affecting the displacement force exerted on a stent graft after AAA repair--an in vitro study. , 2003, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[14]  S. Money,et al.  Influence of endograft oversizing on device migration, endoleak, aneurysm shrinkage, and aortic neck dilation: results from the Zenith Multicenter Trial. , 2004, Journal of vascular surgery.

[15]  E. Buskens,et al.  Quality of Life after Endovascular and Open AAA Repair. Results of a Randomised Trial , 2004 .

[16]  C. Zarins,et al.  Eccentric stent graft compression: an indicator of insecure proximal fixation of aortic stent graft. , 2001, Journal of vascular surgery.

[17]  M. Lindh,et al.  Endovascular AAA exclusion: will stents with hooks and barbs prevent stent-graft migration? , 1998, Journal of endovascular surgery : the official journal of the International Society for Endovascular Surgery.

[18]  T. Resch,et al.  The impact of stent design on proximal stent-graft fixation in the abdominal aorta: an experimental study. , 2000, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[19]  Rodney A. White,et al.  Stent-Graft Migration following Endovascular Repair of Aneurysms with Large Proximal Necks: Anatomical Risk Factors and Long-term Sequelae , 2002, Journal of endovascular therapy : an official journal of the International Society of Endovascular Specialists.

[20]  C. Zarins,et al.  Aneurysm-related death: primary endpoint analysis for comparison of open and endovascular repair. , 2002, Journal of vascular surgery.

[21]  M. Horrocks,et al.  Experimental assessment of proximal stent-graft (InterVascular) fixation in human cadaveric infrarenal aortas. , 1999, European Journal of Vascular and Endovascular Surgery.

[22]  J. Lindholt Endovascular aneurysm repair , 2004, The Lancet.

[23]  Larry H Hollier,et al.  Mechanical failure of prosthetic human implants: a 10-year experience with aortic stent graft devices. , 2003, Journal of vascular surgery.

[24]  G. Ramaswami,et al.  Endovascular stent grafting in the presence of aortic neck filling defects: early clinical experience. , 2001, Journal of vascular surgery.

[25]  G. Moneta,et al.  Comparison of Endovascular Aneurysm Repair With Open Repair in Patients With Abdominal Aortic Aneurysm (EVAR Trial 1), 30-Day Operative Mortality Results: Randomised Controlled Trial , 2006 .

[26]  C. Zarins The US AneuRx Clinical Trial: 6-year clinical update 2002. , 2003, Journal of vascular surgery.