Relationship between QT and RR intervals in electrocardiogram
Kanniainen, Matias (2021)
Kanniainen, Matias
2021
Tekniikan ja luonnontieteiden kandidaattiohjelma - Bachelor's Programme in Engineering and Natural Sciences
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2021-05-24
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202105165047
https://urn.fi/URN:NBN:fi:tuni-202105165047
Tiivistelmä
The electrical activity of the heart can be monitored with electrocardiography. An electrocar- diogram is a graph of voltage as a function of time presenting the electrical activity in the heart cells. From the electrocardiogram, it is possible to indentify the QT interval, which represents the de- and repolarization of the heart ventricles, and the RR interval, which represents the time between two subsequent heartbeats. It has been proved that between the two intervals there is a relationship. There are several heart conditions related to the QT interval, for example the long QT syndrome, which can even lead to death. The quantitative measurement of QT interval is im- portant to be able to diagnose different QT-related conditions. Therefore the relationship between QT and RR needs to be understood in detail.
In this thesis, the relationship between QT and RR is examined. The purpose of the thesis is to prove the existence of the relationship, present the tools to remove the relationship and underline the importance of measuring the QT interval precisely. Also, the physiology of the heart and fun- damentals of the electrocardiography are discussed. The most common methods to remove the relationship are Bazett’s, Fridericia’s, Hodges’ and Framingham’s QT correction methods. The methods are however shown to be inefficient and universally incompetent computational sim- plifications of a complex phenomenon. In the thesis, the methods are presented and they are analyzed and visualized. The main objective of the QT correction methods is to remove the rela- tionship between the QT and RR, and the success of the objective is analyzed in the thesis.
In the experimental part of the thesis, the relationship between QT and RR is examined with several methods. Time series analysis is used to visually verify the relationship, and also the dynamical behaviour of the intervals is analyzed. Polynomial fitting is applied to point clouds, and the results are analyzed with respect to the relationship. Finally, the QT correction methods are analyzed with the help of density plots, with which the behaviour of the QT correction methods can be visualized clearly. The effects of the QT correction methods are shown on both healthy and long QT syndrome subjects.
This thesis shows, both qualitatively and quantitatively, that the QT and RR intervals are in- terdependent. The deficiencies of the different QT correction methods are demonstrated, and especially the Bazett’s formula was shown to overcorrect QT values, often indicating abnormally long QT values for a healthy subject. Because of the unreliability of the conventional QT correc- tion methods, a principle of a new QT correction method based on transfer entropy is presented as a promising novel tool.
In this thesis, the relationship between QT and RR is examined. The purpose of the thesis is to prove the existence of the relationship, present the tools to remove the relationship and underline the importance of measuring the QT interval precisely. Also, the physiology of the heart and fun- damentals of the electrocardiography are discussed. The most common methods to remove the relationship are Bazett’s, Fridericia’s, Hodges’ and Framingham’s QT correction methods. The methods are however shown to be inefficient and universally incompetent computational sim- plifications of a complex phenomenon. In the thesis, the methods are presented and they are analyzed and visualized. The main objective of the QT correction methods is to remove the rela- tionship between the QT and RR, and the success of the objective is analyzed in the thesis.
In the experimental part of the thesis, the relationship between QT and RR is examined with several methods. Time series analysis is used to visually verify the relationship, and also the dynamical behaviour of the intervals is analyzed. Polynomial fitting is applied to point clouds, and the results are analyzed with respect to the relationship. Finally, the QT correction methods are analyzed with the help of density plots, with which the behaviour of the QT correction methods can be visualized clearly. The effects of the QT correction methods are shown on both healthy and long QT syndrome subjects.
This thesis shows, both qualitatively and quantitatively, that the QT and RR intervals are in- terdependent. The deficiencies of the different QT correction methods are demonstrated, and especially the Bazett’s formula was shown to overcorrect QT values, often indicating abnormally long QT values for a healthy subject. Because of the unreliability of the conventional QT correc- tion methods, a principle of a new QT correction method based on transfer entropy is presented as a promising novel tool.
Kokoelmat
- Kandidaatintutkielmat [7051]