Feasibility of Estimating Brachial Artery Impedance During Flow-Mediated Dilation Intervention

To detect pathologies early, brachial artery parameters are crucial. Non-invasive measurements from the brachial artery can quantify blood pressure, assess arterial stiffness and endothelial reactivity. Compared to Photoplethysmography (PPG) and ultrasound-based methods, bioimpedance measurements are versatile. They require no skilled operator, and scanning at various depths is possible by adjusting the frequency. A high-frequency, low-amplitude current is applied to the region of interest, and the voltage across that region is measured to calculate impedance values. Flow-mediated dilation (FMD) is the gold standard for evaluating endothelial reactivity, determined by the relative change in diameter before and after ischemia. In this study, shear stress was induced using the FMD procedure, and changes in impedance and diameter pre- and post-intervention were measured. BIOPAC non-invasive cardiac output modules, MP-160 data acquisition, and Sonix Touch+ ultrasound imaging system were used for data collection. Eight healthy participants were included, and measurements were conducted according to the guidelines. Continuous cycles of brachial impedance were recorded, with the best 15 cycles and CoV less than 15% considered for analysis. The average impedance across the population was 71.0 ± 17.5 ohm. A comparison of post-intervention changes in diameter and impedance relative to baseline showed a strong correlation (r=0.78). This suggests that quantifying impedance from the brachial artery can be valuable for assessing vessel function and parameters, as there is a strong correlation between changes in artery diameter and impedance.