Heart Rate as a Non-Invasive Biomarker of Inflammation: Implications for Digital Health

Understanding the Pivotal Role of the Vagus Nerve in Health from Pandemics

“…The era of physiolomics has come [ 88 ]. HRV monitoring using commercial wearable devices or apps as sensitive but non-specific health indicators (as proposed during COVID-19 [ 89 , 90 ]) could be followed by a more specific diagnosis through blood or salivary microRNAs [ 91 ] and analyzed using machine learning systems in order to track, diagnose, and date infection [ 92 ]. For instance, a decrease in miR146a-5p may indicate HIV infection [ 93 ] and could serve as both a diagnostic and prognostic factor in COVID-19 [ 36 , 37 ].…”

Fetal heart rate variability: An ocean of meanings beyond ups and downs

“…4 Finally, the evidence that increased FHRV is a clinically useful index of fetal compromise has been implemented in the recent update of the National Institute for Health and Care Excellence (NICE) guidance on fetal monitoring in labour. 5 It is therefore unreasonable to suggest that simplifying the nuance and complexity of FHRV into standardised terminology (i.e. 'increased FHRV') robs it of its clinical predictive utility.…”

“…manifesting as fetal growth restriction). 5 When attempting to explain HRV, we can think of the ripples on the surface of an ocean. It is difficult to see them all at once and all the time, or to grasp how the pattern originated.…”

“…systemic or organ-specific response to an inflammatory stimulus or the memory of chronic hypoxia. 5 Another perspective is given by HRV 'feature engineering': a standard machine learning term meaning, in the present context, identifying and reproducibly extracting certain mathematical properties of the input signal, such as dynamic multidimensional patterns in HRV, and using these properties in a model to predict a clinical outcome. Feature engineering makes allowances for the noisy, low sampling rate nature of the signal, to ensure that these properties are captured with the highest possible fidelity.…”

Fetal heart rate variability: an ocean of meanings beyond ups and downs

“…These outcomes include the fetal inflammatory response syndromes (FIRS) or memory of past inflammation (predisposing to 'second hit' vulnerabilities, as is relevant for Zika virus infection), and of hypoxia (e.g., later manifesting as fetal growth restriction). 5,12…”