Advanced

Adjuncts to the Conventional 12-Lead ECG: Assessment of High-Frequency QRS Components and Additional Leads

Trägårdh, Elin LU (2007) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2007:22.
Abstract (Swedish)
Popular Abstract in Swedish

Vanligt viloelektrokardiogram (EKG) med 12 avledningar är ett av de mest använda redskapen för diagnostik av hjärtsjukdom. Tidigare forskning har visat att detta EKG ej är optimalt, men att nya EKG-metoder kan ge viktig tilläggsinformation. En metod som i flera tidigare studier visat sig innehålla diagnostisk potential är analys av de högfrekventa signalkomponenterna i EKG. Registrering av EKG för högfrekvensanalys ställer speciella krav på utrustningen. Ett krav är att man måste kunna mäta signalstyrkan i EKG minst 1000 gånger per sekund. Ett annat krav är att man måste kunna ta bort mycket brus ur signalen eftersom det högfrekventa innehållet har låg signalstyrka. Metoder för att analysera... (More)
Popular Abstract in Swedish

Vanligt viloelektrokardiogram (EKG) med 12 avledningar är ett av de mest använda redskapen för diagnostik av hjärtsjukdom. Tidigare forskning har visat att detta EKG ej är optimalt, men att nya EKG-metoder kan ge viktig tilläggsinformation. En metod som i flera tidigare studier visat sig innehålla diagnostisk potential är analys av de högfrekventa signalkomponenterna i EKG. Registrering av EKG för högfrekvensanalys ställer speciella krav på utrustningen. Ett krav är att man måste kunna mäta signalstyrkan i EKG minst 1000 gånger per sekund. Ett annat krav är att man måste kunna ta bort mycket brus ur signalen eftersom det högfrekventa innehållet har låg signalstyrka. Metoder för att analysera högfrekventa EKG-komponenter har utvecklats tillsammans med institutionen för elektrovetenskap vid Lunds tekniska högskola.



En annan metod för att finna mer diagnostisk information i ett EKG är att lägga till elektroder för att skapa nya avledningar, som ser delar av hjärtat som inte täcks in av de konventionella. Detta skulle t.ex. vara kliniskt användbart vid diagnostik av akut hjärtinfarkt, då det är viktigt att rätt diagnos ställs så snabbt som möjligt för att kunna ge patienten rätt vård innan hjärtskadan blivit alltför utbredd.



Målsättningen för avhandlingen var att undersöka om analys av högfrekventa EKG-komponenter kan tillföra diagnostisk information som inte finns tillgänglig i standard-EKG, samt att undersöka om information i extra EKG-avledningar kan förbättra diagnostiken av akut hjärtinfarkt.



I delarbete I visades att patienter med kranskärlssjukdom hade signifikant lägre amplituder av högfrekventa EKG-komponenter än friska individer. Det kan dock vara svårt att använda denna information kliniskt, då spridningen i storleken på de högfrekventa EKG-komponenterna mellan patienterna var stor. Studien visade även att det inte finns något samband mellan kön eller ålder och de högfrekventa EKG-komponenternas storlek.



I delarbete II undersöktes om storleken på högfrekventa EKG-komponenter korrelerar med massan på vänster hjärtkammare, vilket har visat sig vara fallet i studier på kaniner. Vår studie visade dock att analys av högfrekventa EKG-komponenter inte är bättre än analys av vanligt 12-avlednings-EKG för att avgöra vänsterkammarmassan.



I delarbete III visades att retledningshinder i hjärtat ger lägre amplituder av högfrekventa EKG-komponenter i avledningar som har elektroder ovanför områden med förlångsammad retledningshastighet. I områden där retledningshastigheten är normal var de högfrekventa EKG-komponenterna normala eller i stort sett normala. Fynden stödjer teorin att storleken på de högfrekventa EKG-komponenterna påverkas av retledningshastigheten i hjärtat.



I delarbete IV undersöktes om extra avledningar kan förbättra diagnostiken av akut hjärtinfarkt. Tidigare studier har visat att EKG är dåligt på att hitta akuta hjärtinfarkter då vissa kranskärl är drabbade. EKG-fynden vid konventionellt 12-avlednings-EKG jämfördes med 16-avlednings-EKG (12-avlednings-EKG plus 2 extra elektroder till höger på bröstkorgen och 2 på ryggen) och 24-avlednings-EKG (12-avlednings-EKG plus invertering av dessa 12 avledningar). Vi fann att 24- och 16-avlednings-EKG hittade fler akuta hjärtinfarkter än 12-avlednings-EKG. Däremot ökade andelen falskt positiva något. Om målet är att hitta fler hjärtinfarkter med hjälp av EKG bör man därför använda 24-avlednings-EKG eftersom inga extra elektroder krävs. (Less)
Abstract
The standard 12-lead electrocardiogram (ECG) is one of the most commonly used methods for diagnosing heart disease. Standard ECG is not always optimal, however, and new ECG methods can provide additional information. Analysis of high-frequency QRS components (HF-QRS) has been shown to increase the diagnostic performance of the ECG. Since the amplitudes of the HF-QRS are low compared with those visible in the standard ECG, analysis of HF-QRS requires a low noise level, a sampling rate of at least 1000 Hz, and multibeat signal averaging. Methods for analyzing HF-QRS have been developed in collaboration with the Department of Electroscience at the Faculty of Engineering, Lund University.



Another method for increasing the... (More)
The standard 12-lead electrocardiogram (ECG) is one of the most commonly used methods for diagnosing heart disease. Standard ECG is not always optimal, however, and new ECG methods can provide additional information. Analysis of high-frequency QRS components (HF-QRS) has been shown to increase the diagnostic performance of the ECG. Since the amplitudes of the HF-QRS are low compared with those visible in the standard ECG, analysis of HF-QRS requires a low noise level, a sampling rate of at least 1000 Hz, and multibeat signal averaging. Methods for analyzing HF-QRS have been developed in collaboration with the Department of Electroscience at the Faculty of Engineering, Lund University.



Another method for increasing the diagnostic performance of the ECG is to add electrodes to provide leads that see parts of the heart not covered by conventional leads. This could be particularly interesting in diagnosing conditions such as acute myocardial infarction (MI), for example, for which it is important to initiate reperfusion treatment as soon as possible.



The overall objectives of the thesis are to investigate whether analysis of HF-QRS has the ability to provide information not available from the standard ECG and to investigate whether information from additional ECG leads can improve the diagnosis of acute MI.



In Study I, patients with ischemic heart disease had significantly lower HF-QRS compared with normal individuals. There was substantial interindividual variability, however, which probably limits the clinical usefulness of this method. The study also showed that HF-QRS are not related to sex or age.



In Study II, we investigated whether the amplitude of HF-QRS correlates to the left ventricular mass. This has been shown to be the case in previous studies in rabbits. Our study, however, showed that analysis of HF-QRS is no better than analysis of standard 12-lead ECG for determination of left ventricular mass.



In Study III, patients with intraventricular conduction delay had lower HF-QRS in leads with a positive electrode facing the area of the heart with the conduction delay. In areas of the heart with normal conduction velocity, the amplitudes of HF-QRS were normal or almost normal. These findings support the theory that HF-QRS relate to the conduction velocity of the heart.



In Study IV, we investigated whether additional leads can improve the diagnosis of acute MI. The accuracy of the conventional 12-lead ECG is poor for finding acute MI when certain coronary arteries are involved. Conventional 12-lead ECG was compared with 16-lead ECG (12-lead ECG plus 4 additional electrodes) as well as with 24-lead ECG (12-lead ECG plus the inverted leads of these 12 leads). The sensitivity for detecting acute MI increased when using the 16-lead or 24-lead ECG compared with the 12-lead ECG. The specificity, however, decreased slightly. If the aim is to increase sensitivity for detecting MI, clinicians should be advised to use the 24-lead ECG, since no additional electrodes are required. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Kligfield, Paul, Cornell University, New York, NY, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
heart disease, Physiology, Fysiologi, Cardiovascular system, Kardiovaskulära systemet, myocardial infarction, 16-lead ECG, electrocardiogram, 24-lead ECG, HF-QRS
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2007:22
pages
98 pages
publisher
Department of Clinical Physiology, Lund University
defense location
Föreläsningssal 1, Lund University Hospital
defense date
2007-02-05 13:15
ISSN
1652-8220
ISBN
91-85559-90-3
language
English
LU publication?
yes
id
ba7d2ddc-59ef-4da1-b892-6a31d20ef5a7 (old id 547765)
date added to LUP
2007-10-01 14:21:35
date last changed
2016-09-19 08:44:53
@phdthesis{ba7d2ddc-59ef-4da1-b892-6a31d20ef5a7,
  abstract     = {The standard 12-lead electrocardiogram (ECG) is one of the most commonly used methods for diagnosing heart disease. Standard ECG is not always optimal, however, and new ECG methods can provide additional information. Analysis of high-frequency QRS components (HF-QRS) has been shown to increase the diagnostic performance of the ECG. Since the amplitudes of the HF-QRS are low compared with those visible in the standard ECG, analysis of HF-QRS requires a low noise level, a sampling rate of at least 1000 Hz, and multibeat signal averaging. Methods for analyzing HF-QRS have been developed in collaboration with the Department of Electroscience at the Faculty of Engineering, Lund University.<br/><br>
<br/><br>
Another method for increasing the diagnostic performance of the ECG is to add electrodes to provide leads that see parts of the heart not covered by conventional leads. This could be particularly interesting in diagnosing conditions such as acute myocardial infarction (MI), for example, for which it is important to initiate reperfusion treatment as soon as possible.<br/><br>
<br/><br>
The overall objectives of the thesis are to investigate whether analysis of HF-QRS has the ability to provide information not available from the standard ECG and to investigate whether information from additional ECG leads can improve the diagnosis of acute MI.<br/><br>
<br/><br>
In Study I, patients with ischemic heart disease had significantly lower HF-QRS compared with normal individuals. There was substantial interindividual variability, however, which probably limits the clinical usefulness of this method. The study also showed that HF-QRS are not related to sex or age.<br/><br>
<br/><br>
In Study II, we investigated whether the amplitude of HF-QRS correlates to the left ventricular mass. This has been shown to be the case in previous studies in rabbits. Our study, however, showed that analysis of HF-QRS is no better than analysis of standard 12-lead ECG for determination of left ventricular mass.<br/><br>
<br/><br>
In Study III, patients with intraventricular conduction delay had lower HF-QRS in leads with a positive electrode facing the area of the heart with the conduction delay. In areas of the heart with normal conduction velocity, the amplitudes of HF-QRS were normal or almost normal. These findings support the theory that HF-QRS relate to the conduction velocity of the heart.<br/><br>
<br/><br>
In Study IV, we investigated whether additional leads can improve the diagnosis of acute MI. The accuracy of the conventional 12-lead ECG is poor for finding acute MI when certain coronary arteries are involved. Conventional 12-lead ECG was compared with 16-lead ECG (12-lead ECG plus 4 additional electrodes) as well as with 24-lead ECG (12-lead ECG plus the inverted leads of these 12 leads). The sensitivity for detecting acute MI increased when using the 16-lead or 24-lead ECG compared with the 12-lead ECG. The specificity, however, decreased slightly. If the aim is to increase sensitivity for detecting MI, clinicians should be advised to use the 24-lead ECG, since no additional electrodes are required.},
  author       = {Trägårdh, Elin},
  isbn         = {91-85559-90-3},
  issn         = {1652-8220},
  keyword      = {heart disease,Physiology,Fysiologi,Cardiovascular system,Kardiovaskulära systemet,myocardial infarction,16-lead ECG,electrocardiogram,24-lead ECG,HF-QRS},
  language     = {eng},
  pages        = {98},
  publisher    = {Department of Clinical Physiology, Lund University},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Adjuncts to the Conventional 12-Lead ECG: Assessment of High-Frequency QRS Components and Additional Leads},
  volume       = {2007:22},
  year         = {2007},
}