Extracting new information from old waveforms: Symmetric projection attractor reconstruction: Where maths meets medicine

Abstract

New Findings What is the topic of this review?Symmetric Projection Attractor Reconstruction (SPAR) is a relatively new mathematical method that can extract additional information pertaining to the morphology and variability of physiological waveforms, such as arterial pulse pressure. Herein, we describe the potential utility of the method for more sensitive quantification of cardiovascular changes. What advances does it highlight?We use a simple example of a human tilt table to illustrate these concepts. SPAR can be used on any approximately periodic waveform and may add value to experimental and clinical settings, where such signals are collected routinely. Abstract Periodic physiological waveform data, such as blood pressure, pulse oximetry and ECG, are routinely sampled between 100 and 1000 Hz in preclinical research and in the clinical setting from a wide variety of implantable, bedside and wearable monitoring devices. Despite the underlying numerical waveform data being captured at such high fidelity, conventional analysis tends to reside in reporting only averages of minimum, maximum, amplitude and rate, as single point averages. Although these averages are undoubtedly of value, simplification of the data in this way means that most of the available numerical data are discarded. In turn, this may lead to subtle physiological changes being missed when investigating the cardiovascular system over time. We have developed a mathematical method (symmetric projection attractor reconstruction) that uses all the numerical data, replotting and revisualizing them in a manner that allows unique quantification of multiple changes in waveform morphology and variability. We propose that the additional quantification of these features will allow the complex behaviour of the cardiovascular system to be mapped more sensitively in different physiological and pathophysiological settings.

Monitoring haemodynamic changes in rodent models to better inform safety pharmacology: Novel insights from in vivo studies and waveform analysis

“…In-depth characterisation of recorded waveforms may provide more extensive information on the condition of the heart and vasculature when exposed to pharmacological agents. 27 …”

Detecting paroxysmal atrial fibrillation from normal sinus rhythm in equine athletes using Symmetric Projection Attractor Reconstruction and machine learning

“…Attractor Reconstruction (SPAR) method, [21][22][23] which provides a novel and innovative means of visualizing and quantifying the shape and variability of an approximately periodic waveform, such as the ECG. The technique overcomes the challenge of detecting and extracting features directly from a signal, and uses all the available data to encapsulate the waveform morphology in a two-dimensional image, while reducing the effect of baseline wander and being robust to signal outliers.…”

“…The ECG data used in this work were obtained during periods of sinus rhythm in the subject to assess whether abnormalities could be detected in such baseline electrical signals that might reflect a predisposition to AF episodes. We investigated the indication of subtle differences in the signals by applying the recently developed Symmetric Projection Attractor Reconstruction (SPAR) method, 21 , 22 , 23 which provides a novel and innovative means of visualizing and quantifying the shape and variability of an approximately periodic waveform, such as the ECG. The technique overcomes the challenge of detecting and extracting features directly from a signal, and uses all the available data to encapsulate the waveform morphology in a 2-dimensional image, while reducing the effect of baseline wander and being robust to signal outliers.…”

Symmetric Projection Attractor Reconstruction: Sex Differences in the ECG

“…We have recently developed an approach to signal analysis that allows us to easily quantify information from the morphology of the whole waveform using all of its underlying high fidelity time-series data. Symmetric Projection Attractor Reconstruction (SPAR) is a method for visualizing and quantifying the morphology and variability of any approximately periodic signal (8)(9)(10), effectively replotting all the underlying data into a simpler two-dimensional representation, which we call an 'attractor'. We have previously applied SPAR to various physiological signals, including the ECG (11,12), arterial blood pressure (8)(9)(10)13) and photoplethysmogram (PPG) (14), where it has been shown to supplement standard cardiovascular assessment.…”