What’s going on in the left common iliac artery?

Fenelli et al1Fenelli C. Gargiulo M. Prendes C.F. Faggioli G. Stavroulakis K. Gallitto E. et al.Effect of iliac tortuosity on the outcomes after iliac branch procedures.J Vasc Surg. 2022; 76: 714-723.e1Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar recently presented results from a two-center retrospective and observational cohort study into outcomes from endovascular iliac branch device deployment in aortic aneurysms with iliac involvement (n = 256). Analysis is centered on three measures of iliac tortuosity: pelvic tortuosity index, external tortuosity index, and double iliac sign. Pelvic tortuosity index >1.4 was an independent predictor of endovascular complications and reinterventions, whereas external tortuosity index >1.7 predicted endoleak. The authors present an interesting study suggesting the added risk when intervening in particularly tortuous iliac arteries. Isolated common iliac artery aneurysms (CIAAs), without abdominal aortic involvement, have been of particular interest to us in recent years.2Parker L.P. Powell J.T. Kelsey L.J. Lim B. Ashleigh R. Venermo M. et al.Morphology and hemodynamics in isolated common iliac artery aneurysms impacts proximal aortic remodeling.Arterioscler Thromb Vasc Biol. 2019; 39: 1125-1136Crossref PubMed Scopus (18) Google Scholar,3Parker L.P. Powell J.T. Kelsey L.J. Venermo M. Koncar I. Norman P.E. et al.Morphology and computational fluid dynamics support a novel classification of common iliac aneurysms.Eur J Vasc Endovasc Surg. 2020; 59: 786-793Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar The image that Fenelli et al present to illustrate their measurements of iliac tortuosity is one that evokes déjà vu (Fig, center). In analyzing a small cohort of isolated CIAAs (n = 25) with computational fluid dynamics, we noted a very similar recurring morphology in eight patients. Seemingly, always occurring on the left side, the iliac artery kinks back on itself, forming an aneurysm immediately downstream. We therefore grouped these aneurysms under the term “kinked CIAA,” with all other cases being of fusiform and saccular morphologies.3Parker L.P. Powell J.T. Kelsey L.J. Venermo M. Koncar I. Norman P.E. et al.Morphology and computational fluid dynamics support a novel classification of common iliac aneurysms.Eur J Vasc Endovasc Surg. 2020; 59: 786-793Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar Our primary interest in this group was to analyze hemodynamics and how specific conditions related to rupture. Typically, we think of regions of stagnant flow as being at high risk of rupture with local changes to the endothelial cells driving further dilation. These kinked cases however retained high wall shear stress (low stagnation) as blood looped through the tortuous artery. They also had less calcification and thrombosis. Ten of our CIAA cases had ruptured, none of which were the kinked variety. Many questions remain about the kinked CIAA. Importantly, without longitudinal data it cannot be ruled out that over time they do not become saccular or fusiform. The origin of the kink is another unknown and may precede the aneurysm entirely. Perhaps the aneurysm is a result of such a tight bend and the resulting downstream hemodynamics. Further investigation to understand this unique morphology is worthwhile because our current understanding suggests that they are hemodynamically stable, rarely rupture, and as Fenelli et al suggest, are problematic to repair. Effect of iliac tortuosity on outcomes after iliac branch proceduresJournal of Vascular SurgeryVol. 76Issue 3PreviewTo report a two-centers evaluation of the effects of iliac axis tortuosity on iliac branch device (IBD) results. Full-Text PDF ReplyJournal of Vascular SurgeryVol. 77Issue 1PreviewParker et al,1,2 in recent years, investigated the inter-relationships of aortoiliac morphology, hemodynamic changes, and the clinical progression of 25 cases of isolated common iliac artery aneurysms (CIAAs), by reconstructing and simulating the fluid dynamics and the wall shear stress. In their interesting studies, the authors noted a recurring morphology in eight left iliac axes (“kinked” CIAAs with dilation downstream a severe angulation), and they proposed a novel classification of common iliac aneurysms: complex, fusiform, and kinked. Full-Text PDF