Morphological Changes of the QRS Complex as a Marker of Autonomic Modulation of the Heart Rate
Authors
Fisker, Katrine ; Chreiteh, Shadi
Term
4. term
Publication year
2009
Pages
91
Abstract
Projektet undersøgte, om autonom kardiel modulation—det autonome nervesystems styring af hjertet—afspejles i formen af individuelle QRS-komplekser i elektrokardiogrammer (EKG). QRS-komplekset er den del af EKG'et, der viser hjertets ventriklers sammentrækning. Vi analyserede EKG-optagelser fra 20 raske deltagere og 18 deltagere diagnosticeret med komplekst regionalt smertesyndrom (CRPS) type I under en vippeleje-test, en undersøgelse der ændrer kropsposition for at påvirke blodtryk og puls. Derudover analyserede vi EKG'er fra 11 raske deltagere med capsaicininduceret smerte (capsaicin er det aktive stof i chili). For hvert QRS-kompleks udtrak vi to egenskaber: den stejleste stigende hældning (hvor hurtigt signalet stiger) og den skala, hvor en persontilpasset wavelet havde den højeste korrelation med QRS-komplekset (en wavelet er et matematisk mønster til at beskrive signalform). Disse egenskaber blev derefter sammenlignet med middel NN-interval (den gennemsnitlige tid mellem normale hjerteslag) og SDNN (standardafvigelsen af NN-intervallerne, en almindelig måling af hjertefrekvensvariabilitet).
This project investigated whether autonomic cardiac modulation—the autonomic nervous system’s control of heart activity—is reflected in the shape of individual QRS complexes in electrocardiograms (ECGs). The QRS complex is the part of an ECG that shows the ventricles contracting. We analyzed ECG recordings from 20 healthy participants and 18 participants diagnosed with Complex Regional Pain Syndrome (CRPS) type I during a tilt table test, a procedure that changes body position to affect blood pressure and heart rate. We also analyzed ECGs from 11 healthy participants experiencing capsaicin-induced pain (capsaicin is the active compound in chili peppers). For each QRS complex, we extracted two features: the steepest ascending slope (how quickly the signal rises) and the scale at which a subject-specific wavelet had the highest correlation with the QRS complex (a wavelet is a mathematical pattern used to capture signal shape). We then compared these features with the mean NN interval (the average time between consecutive normal heartbeats) and SDNN (the standard deviation of NN intervals, a common measure of heart rate variability).
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