Harmonic analysis of finger photoplethysmography for assessing vascular alterations associated with metabolic syndrome in the elderly population: A prospective cross-sectional study.

ObjectivePeople with metabolic syndrome are more likely to develop cardiovascular disease, where alterations in peripheral circulation may take part. Photoplethysmography (PPG) is a noninvasive device for the detection of blood flow volumetric change. We performed finger PPG measurements with harmonic analysis in the elderly population to evaluate the influence of metabolic syndrome on the peripheral pulse waveform.MethodsIn this prospective cross-sectional study, 75 participants were categorized into three groups: healthy control, pre-metabolic syndrome (pre-MetS), and metabolic syndrome (MetS) group. 1-minute measurements of PPG were conducted, and harmonic analysis was performed to calculate the amplitude proportion (Cn), standard deviation (SDn), and coefficient of variation (CVn) for the first ten harmonics.ResultThe healthy control group exhibited higher Cn values than the pre-MetS and MetS groups. Post-hoc analysis indicated significant differences in C1, C2, C3, and C6. Besides, the regression models indicated a decrease in C1, C2, C3, C4, C6, and C7 values in the unadjusted model, and a decrease in C1, C2, C3, and C6 values in the adjusted model, which were identified as independent risk markers for the presence of pre-MetS or MetS.ConclusionThis study showed the potential value of harmonic analysis of finger PPG for identifying vascular functional alterations associated with MetS.