Objective: In endurance athletes, flow limitations in the iliac arteries are commonly ascribed to mechanically induced intravascular lesions (endofibrosis). We hypothesize that kinking of the vessels, occurring during exercise, can also cause such flow limitations. Conventional diagnostic tests fail to demonstrate such kinking.
Methods: In the current study, the iliac arteries were examined in 50 endurance athletes suffering from flow limitations in the iliac arteries with color Doppler using provocative maneuvers of hip flexion, isometric psoas contraction and exercise. Five had both-sided complaints resulting in 55 symptomatic legs and 45 asymptomatic legs. Sixteen national level competitive cyclists served as control subjects resulting in 32 healthy reference legs.
Results: The iliac arteries could be visualized accurately in 127/132 (96%) of the legs. The legs with insufficient image quality were not scored in the further analysis. In the external iliac artery, kinks were detected in 21/54 symptomatic legs (39%) compared to none in 28 reference legs. Intravascular lesions could be detected in 33/54 symptomatic legs (61%) compared to only 1/28 reference legs (4%). In the symptomatic legs Doppler measurements showed significantly higher peak systolic velocities in all test conditions compared to the reference legs (P<0.05). These differences increased significantly with provocative maneuvers (P<0.05).In the common iliac artery, kinks were demonstrated in 3/54 symptomatic legs (6%) and an intravascular lesion in 2/54 symptomatic legs (4%) only. Neither kink nor intravascular lesions were demonstrated in the reference legs. Peak systolic velocity measurements in the common iliac artery were in line with these observations and did not show differences between symptomatic and reference legs. The incidence of intravascular lesions in the external and common iliac artery is as expected, however, the incidence of kinks in the common iliac artery is much lower than reported from magnetic resonance angiography. This discrepancy is most probably caused by the fact that kinks in the common iliac artery are predominantly situated in the coronal plane, which cannot be visualized by color Doppler.
Conclusion: Both kinks and intravascular lesions are associated with flow limitations in the iliac arteries in endurance athletes. Color Doppler appears to be an effective technique to visualize and scale kinks and intravascular lesions in the external iliac artery and to visualize and scale intravascular lesions in the common iliac artery.