Near-Infrared Spectroscopy Is Promising to Detect Iliac Artery Flow Limitations in Athletes: A Pilot Study

Abstract

Endurance cyclists have a substantial risk to develop flow limitations in the iliac arteries during their career. These flow limitations are due to extreme hemodynamic stress which may result in functional arterial kinking and/or intravascular lesions. Early diagnosis may improve outcome and could prevent the necessity for surgical vascular repair. However, current diagnostic techniques have unsatisfactory sensitivity and cannot be applied during exercise. Near-infrared spectroscopy (NIRS) has shown great diagnostic potential in peripheral vascular disease and might bring a solution since it measures tissue oxygenation in real time during and after exercise. This report describes the first experiences of the application of NIRS in the vastus lateralis muscle during and after maximal graded cycling exercise in ten healthy participants and in three patients with flow limitations due to (1) subtle functional kinking, (2) an intravascular lesion, and (3) severe functional kinking. The results are put into perspective based on an empirically fitted model. Delayed recovery, showing clearly different types of patterns of tissue reoxygenation after exercise, was found in the affected athletes compared with the healthy participants. In the patients that had kinking of the arteries, tissue reoxygenation was clearly more delayed if NIRS was measured in provocative position with flexed hip. In this pilot experiment, clearly distinctive reoxygenation patterns are observed during recovery consistent with severity of flow limitation, indicating that NIRS is a promising diagnostic tool to detect and grade arterial flow limitations in athletes. Our findings may guide research and optimization of NIRS for future clinical application.

Figures

Figure 1

Visual presentation of the used postures (CP and NP for the left and right picture, resp.). This was also the racing position during cycling. In the photographs, the position in recovery is illustrated when measuring ABI (black circles denotes the placement of the blood pressure cuffs while the white circle denotes the NIRS devices without the black cloth in order to expose the measurement device in this picture).

Figure 2

Visual presentation of TSI with the variables during and after the maximal provocative exercise. W: warm-up; E: exercise; R: recovery. The thick grey curve represents the best fit of the monoexponential model (tau).

Figure 3

The first patient (A, B) shows subtle kinking, the second patient (C, D) shows an intravascular lesion, and the third patient (E, F) shows severe kinking. The circles denote the place of abnormality in the artery.

Figure 4

TSI and O2Hb patterns during warm-up (W), RAMP exercise protocol (E), and recovery (R); solid vertical lines denote phase transitions, the dashed line in CP with severe kinking represents the sudden change from CP to NP.

Figure 5

O2Hb patterns of the left (black) and right (red) leg in CP during warm-up (W), RAMP exercise protocol (E), and recovery (R); solid vertical lines denote phase transitions. The dashed line in CP with severe kinking represents the sudden change from CP to NP to demonstrate the effect of severe kinking on oxygenation. The data within the black solid circle in the patient with an intravascular lesion shows inaccurate data due to movement artefacts of the patients' right leg which slipped of the resting platform.