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

Research output: ThesisDoctoral Thesis (compilation)

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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 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.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Clinical Physiology (Lund)
Supervisors/Advisors
  • Pahlm, Olle, Supervisor
Award date2007 Feb 5
Publisher
Print ISBNs91-85559-90-3
Publication statusPublished - 2007

Bibliographical note

Defence details

Date: 2007-02-05
Time: 13:15
Place: Föreläsningssal 1, Lund University Hospital

External reviewer(s)

Name: Kligfield, Paul
Title: Professor
Affiliation: Cornell University, New York, NY, USA

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<div class="article_info">E Trägårdh, O Pahlm, GS Wagner and J Pettersson. <span class="article_issue_date">2004</span>. <span class="article_title">Reduced high-frequency QRS components in patients with ischemic heart disease compared to normal subjects.</span> <span class="journal_series_title">J Electrocardiol</span>, <span class="journal_volume">vol 37</span> <span class="journal_pages">pp 157-162</span>.</div>
<div class="article_info">E Trägårdh, H Arheden, J Pettersson, GS Wagner and O Pahlm. <span class="article_issue_date">2006</span>. <span class="article_title">Determination of the ability of high-frequency ECG to estimate left ventricular mass in humans, determined by magnetic resonance imaging.</span> <span class="journal_series_title">Clin Physiol Funct Imaging</span>, <span class="journal_volume">vol 26</span> <span class="journal_pages">pp 154-162</span>.</div>
<div class="article_info">E Trägårdh, J Pettersson, GS Wagner and O Pahlm. <span class="article_issue_date">2006</span>. <span class="article_title">Reduced high-frequency QRS components in electrocardiogram leads facing an area of the heart with intraventricular conduction delay due to bundle branch block.</span> <span class="journal_series_title">J Electrocardiol</span>, (inpress)</div>
<div class="article_info">E Trägårdh, M Claesson, GS Wagner, S Zhou and O Pahlm. <span class="article_issue_date"></span>. <span class="article_title">Detection of acute myocardial infarction using the 12-lead ECG plus inverted leads (24-lead ECG) versus the 16-lead ECG (with additional posterior and right-sided electrodes).</span> (manuscript)</div>

Subject classification (UKÄ)

  • Cardiac and Cardiovascular Systems
  • Respiratory Medicine and Allergy

Keywords

  • heart disease
  • Physiology
  • Fysiologi
  • Cardiovascular system
  • Kardiovaskulära systemet
  • myocardial infarction
  • 16-lead ECG
  • electrocardiogram
  • 24-lead ECG
  • HF-QRS

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