Morphological Changes of the QRS Complex

Heart rate variability (HRV) have been used as quantitative markers of autonomic modulation of cardiac rhythm. These markers have a common limitation, which is the dependency of accurate detection of a fiducial point for each heart beat, since inaccurate detection will lead to distortion of the results. Furthermore, the different measures of HRV is sensitive to ectopic beats and missing beats, which needs to be handled prior to HRV analysis. Regardless of how the ectopic and missing beats are handled, it will impose an error on the analysis. Thus, HRV analysis is sensitive to exact location of fiducial points and missing and ectopic beats. In addition, different frequency measures used to express HRV requires a resampling of the heart rate signal prior to the analysis, which demands a reliable heart rate signal. Therefore, markers independent on exact location of fiducial points, ectopic and missing beats are desirable. The aim of this project was to investigate if the autonomic cardiac regulation is reflected in the morphology of individual QRS complexes.