Arterial endofibrosis is a vascular disease that typically affects the external iliac artery in young patients who undergo extreme exercise, mainly bicyclists.1 The diagnosis is indirectly suspected when these extreme athletes undergo ankle-brachial indices (ABIs) before and after extreme exercise. Whereas the diagnosis can often be suggested by exercise ABIs and computed tomography angiography, the diagnosis is classically best defined by angiography. Dr Cherry and his group were one of the first to recognize this lesion when they described seven patients who underwent replacement or repair of the external iliac artery. Although originally skeptical as to whether this was indeed a “true” vasculopathy (ie, see median arcuate ligament syndrome and functional popliteal entrapment), with >7 years as Dr Cherry's partner and his being kind enough to share the films with us, I am completely convinced that this disease is real and often debilitating in these extreme athletes. One has to be willing to work hard to make the diagnosis in these typically young, ultrahealthy patients in whom standard walking tests are not adequate to drop the ABI. In our peripheral vascular laboratory, we actually purchased a stationary bicycle to assist in making this diagnosis.
In the paper by Posthuma and colleagues from The Netherlands, the authors have married our understanding of the impact of hemodynamic forces with the changes in the biology of the arterial wall. In this study of 19 mainly male bicyclists, the authors clearly document a disease whereby a hyperactive intima and media generate changes in the arterial wall that lead to lumen narrowing. The authors also note in this series that 14 of the 19 patients had disease primarily on the left, with no patient presenting with bilateral disease. This is in contrast to a recent series by Politano and Cherry, who suggested that 4 of 27 repairs were bilateral.
In this series, the authors performed endarterectomies only, no bypasses, on 19 patients for external iliac artery endofibrosis. The histopathologic features of these endarterectomized samples were then compared with cadaveric external iliac artery samples, which the authors state in their limitations paragraph are likely not the right controls (not age-matched normal). Regardless, we are able to get a nice snapshot of the impact of the hemodynamic process whereby the external iliac artery is pinned down in the pelvis by the internal iliac artery. A study also suggested that the relatively fixed inguinal ligament plays a role in this disease process as well.2 These arteries also often lengthen and become kinked. The extreme shear in a relatively fixed position leads to the activation and proliferation of myofibroblasts. This process looks similar to both neointimal hyperplasia and fibromuscular dysplasia. Fibromuscular dysplasia, which often occurs in ptotic kidneys that are “pinned” in the pelvis, probably represents a fibroproliferative arteriopathy. During the course of this proliferative process, extracellular matrix proteins like elastin, collagen, and vimentin are increased significantly, leading to arterial stenosis. In addition, thrombotic factors (factor X and tissue factor) and protein activated receptors (1 and 4) are also increased.
Perhaps vascular surgeons who are asked to see these patients might be unwilling to operate on this disease process, instead suggesting retirement from competitive cycling. Please recognize that many of these ultracompetitive athletes make a living performing extreme exercise. As a surgeon scientist, I applaud these authors for trying to understand the pathobiology of this disease process. I also suggest that we need more studies like the present one to help us not only biologically define the disease but, importantly, urge us to take the next natural step and start using our knowledge about this disease and its proliferative nature to develop an effective medical therapy. Sounds like a great KO8 project for an aspiring surgeon scientist.
The opinions or views expressed in this commentary are those of the author and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery.