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Alternative Lead Systems for Diagnostic Electrocardiography: Validation and Clinical Applicability

Welinder, Annika LU (2009) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2009:115.
Abstract (Swedish)
Popular Abstract in Swedish

Standard-12-avlednings-EKG är fortfarande ett av de viktigaste och vanligaste redskapen för att diagnostisera hjärtsjukdom trots att ett flertal olika undersökningstekniker har utvecklats under åren. Vid standard-EKG används 10 elektroder, 6 på bröstkorgen och 4 distalt på armar och ben. Inom både industrin och akademin har många års arbete lagts ned på utveckling av de tolkningskriterier som används vid tolkning av ett “vilo”-standard-EKG och det är EKG-mönstren vid standard-EKG som lärs ut under läkarutbildningen

I flera situationer är det dock inte optimalt att använda standard-EKG pga riklig förekomst av muskelstörningar, t ex vid registrering av EKG under en längre tid eller vid... (More)
Popular Abstract in Swedish

Standard-12-avlednings-EKG är fortfarande ett av de viktigaste och vanligaste redskapen för att diagnostisera hjärtsjukdom trots att ett flertal olika undersökningstekniker har utvecklats under åren. Vid standard-EKG används 10 elektroder, 6 på bröstkorgen och 4 distalt på armar och ben. Inom både industrin och akademin har många års arbete lagts ned på utveckling av de tolkningskriterier som används vid tolkning av ett “vilo”-standard-EKG och det är EKG-mönstren vid standard-EKG som lärs ut under läkarutbildningen

I flera situationer är det dock inte optimalt att använda standard-EKG pga riklig förekomst av muskelstörningar, t ex vid registrering av EKG under en längre tid eller vid arbetsprov. I dessa situationer placeras arm- och benelektroderna vanligen proximalt, ofta på bröstet, och s.k. Mason-Likar (M-L) placering är vanligt förekommande. Standard¬elektrod¬placeringen kan också interferera med och därmed utgöra problem vid andra undersökningar, såsom ultraljudsundersök-ning av hjärtat. Ett alternativt EKG-system med färre elektroder och utan elektroder på armar och ben, som resulterar i ett 12-avlednings-EKG snarlikt standard-EKG vore värdefullt. Vid det s.k. EASI-systemet används endast 4 registrerings¬elektroder på lätt identifierbara punkter på bröstkorgen, från vilka samtliga 12 avledningar kan beräk-nas. EASI-systemet har utvärderats för vuxna i flera kliniska situatio-ner och befunnits vara väl användbart.

Ett problem är att läkare som dagligen använder EKG i sitt kliniska arbete ofta inte är medvetna om de skillnader som finns mellan 12-avlednings-EKG registrerade från standard respektive alternativa elektrodpositioner och använder de kriterier som utvecklats för standard-EKG även när de tolkar EKG från alternativa avledningssystem. Detta kan leda till feltolkningar och få konsekvenser för de berörda patienterna. Eftersom distal placering av arm- och benelektroderna inte alltid är möjlig, skulle optimering av de proximala positionerna, för bättre överensstämmelse med standard-12-avlednings-EKG, vara av stort värde för förbättrad diagnostik. En version av det s.k. Lund (LU)-avledningssystemet har rapporterats stämma bättre överens med standard-EKG än vad M-L gör, avseende både den s.k. Q-vågsbredden och den s.k. elektriska axeln. För att nå en enhetlig konvention för EKG-registrering, i vila och under längre tid, måste en registrering ha ett EKG-utseende som är mycket likt det som erhålls från standard-EKG och störningskänslighet åtminstone motsvarande den hos M-L.

Avhandlingens övergripande mål var 1) att ytterligare utvärdera EASI-systemet och därmed vinna mer kunskap om överensstämmel-sen mellan EASI-beräknat och standard-12-avlednings-EKG, samt 2) försöka optimera placeringen av proximalt placerade arm- och ben-elektroder.



EASI-studier

I studie I utvecklades åldersspecifika konstanta faktorer som används för att beräkna 12-avlednings-EKG från EASI-signalerna. Överensstämmelsen hos vågformationerna mellan samtidigt registrerade standard- och EASI-beräknade 12-avlednings-EKG hos barn (friska och med olika hjärtfel) studerades. För barn visade det sig bättre att använda åldersspecifika konstanta faktorer än de faktorer som används för vuxna. Överensstämmelsen mellan standard- och EASI-beräknade EKG var mestadels bra.

I studie II jämfördes variationen i tolkningen av ett standard-12-avlednings-EKG från en gång till en annan med variationen i tolkningen mellan standard- och EASI-beräknade 12-avlednings-EKG hos barn (samma studiepopulation som i studie I). Variationen i tolkningen mellan standard- och EASI-EKG var endast något större än gång till gång variationen i tolkningen av standard-EKG.

I studie III jämfördes utslagen från muskelstörningar och s.k. baslinjevariationer mellan samtidigt registrerade EASI-beräknade och

M-L-12-avlednings-EKG, hos friska vuxna. Totalt sett hade de två avledningssystemen likartad känslighet för baslinjevariationer, men jämfört med M-L-systemet var EASI-systemet mindre känsligt för muskelstörningar.

I studie IV jämfördes skillnaderna i s.k. Selvesterpoäng (ett mått för att utifrån EKG beräkna hjärtinfarktstorlek) för genomgången hjärtinfarkt från standard- och EASI-beräknade 12-avlednings-EKG hos patienter som haft en episod med bröstsmärta talande för akut hjärtsjukdom. Dessa poäng jämfördes med uppmätt hjärtinfarktstorlek vid magnetkameraundersökning (MRI). Det var ingen signifikant skillnad i Selvesterpoäng mellan standard och EASI, men varken sambandet eller överensstämmelsen mellan MRI och respektive EKG-avledningssystem var särskilt stark.



Studie för att optimera proximala placeringen av arm- och benelek-troder

I studie V jämfördes EKG-vågor från LU- och M-L-systemen med dem från standard-EKG, med avseende på den elektriska axeln i frontalplanet och EKG-förändringar som tyder på inferior hjärtinfarkt. Störningskänsligheten hos standard-, LU- och M-L-systemen jämfördes också. LU-systemet gav EKG-utseende som bättre stämde överens med standard-EKG, än vad EKG-utseendet från M-L-systemet gjorde. Vidare var LU-systemet mindre störningskänsligt än standard-systemet och störningskänsligheterna hos LU- och M-L-systemen var jämförbara. (Less)
Abstract
The standard 12-lead electrocardiogram (ECG) remains one of the most important and most frequently used tools for diagnosing cardiac diseases, although several different examination modalities in cardio¬logy have been developed over the years. The standard ECG uses 10 electrodes placed on well-defined positions on the body, 6 on the torso and 4 distally on the limbs. Both industry and academia have invested many years in development of the criteria used to interpret the “diagnostic” standard ECG, and the waveform patterns are taught in medical school.

In several situations, however – such as during long-term ECG monitoring or stress testing – use of the electrode positions of the standard ECG is not optimal because of the... (More)
The standard 12-lead electrocardiogram (ECG) remains one of the most important and most frequently used tools for diagnosing cardiac diseases, although several different examination modalities in cardio¬logy have been developed over the years. The standard ECG uses 10 electrodes placed on well-defined positions on the body, 6 on the torso and 4 distally on the limbs. Both industry and academia have invested many years in development of the criteria used to interpret the “diagnostic” standard ECG, and the waveform patterns are taught in medical school.

In several situations, however – such as during long-term ECG monitoring or stress testing – use of the electrode positions of the standard ECG is not optimal because of the abundance of noise. In these situations, the limb electrodes must be placed proximally, often even on the torso, and the Mason-Likar (M-L) positions are commonly used. Interference with other clinical procedures, such as echocardiography, can also constitute a problem. An ECG-recording system with fewer electrodes and without any electrodes on the limbs that provides a 12-lead ECG similar to the standard ECG would be valuable. The so-called EASI system uses only 4 recording electrodes in easily determined locations on the torso from which the full 12-lead ECG can be derived. The 12-lead ECG derived from the EASI system has been evaluated in adults in several clinical situations.

Physicians who use ECGs in their day-to-day work are often not aware of the differences between 12-lead ECGs recorded from standard versus alternative electrode positions, and they might use criteria developed for the standard ECG when interpreting an ECG obtained from an alternative lead system. This can lead to misinterpretation with the risk of potentially serious consequences for the patient.

Optimizing the proximal positions for better concordance with the standard ECG would be of great value for improved diagnostic performance. A version of the “Lund” (LU) lead system has been reported to agree better with the standard lead system than does the M-L lead system, with regard to both Q-wave width and QRS frontal plane axis. To develop a uniform convention for ECG recording, i.e. both for diagnostic ECG and for monitoring, a recording must produce waveforms that have morphologies approximating those obtained with standard ECG and that has noise immunity close to that of M-L.

The overall objectives of this thesis were 1) to further validate the EASI system to gain more knowledge about the agreement between EASI-derived and standard 12-lead ECGs, and 2) to investigate the possibility of optimizing the positions of proximally placed limb electrodes.



EASI studies

In Study I, age-specific transformation coefficients were determined for use in deriving 12-lead ECGs from the EASI signals. The agreement of the waveforms between simultaneously recorded standard and EASI-derived 12-lead ECGs in children (healthy and with various cardiac diagnoses) was studied. For children, it was better to use age-specific transformation coefficients than adult coefficients. The agreement between standard and EASI-derived ECGs was mostly good.

In Study II, the intrareader variation of interpretations of 2 standard 12-lead ECGs was compared with the variation of interpretations of standard versus EASI-derived 12-lead ECGs in children (Study I population). The variation of the interpretation of standard versus EASI-derived ECGs was only slightly larger than the intrareader variation of interpretations of standard ECGs.

In Study III, the amplitudes of myoelectric noise and baseline wander were compared between simultaneously recorded EASI-derived and M-L 12-lead ECGs in healthy adults. Overall, the 2 lead systems had similar susceptibilities to baseline wander, but EASI was less susceptible than

M-L to myoelectric noise.

In Study IV, differences in the estimated size of myocardial infarction (MI), as assessed by Selvester scores, were compared between standard and EASI-derived 12-lead ECGs among patients who had had an episode of chest pain suggestive of an acute coronary syndrome. These scores were also compared with MI size measured by cardiac magnetic resonance imaging (MRI). Estimated MI size did not differ significantly between the 2 lead systems, but neither the correlation nor the agreement between MRI and either of the 2 lead systems was very strong.



Study to optimize the proximal positions of the limb electrodes

In Study V, waveforms from the LU and M-L systems were compared with those from standard ECGs with regard to the QRS axis in the frontal plane and QRS changes of inferior MI. The noise immunities of the standard, LU, and M-L systems were also compared. LU produced ECG waveforms that more closely resembled those obtained with standard ECG than did M-L. The LU system was more noise-immune than was the standard system, and the noise immunities of the LU and the M-L systems were comparable. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Macfarlane, Peter, University of Glasgow, Storbritannien
organization
publishing date
type
Thesis
publication status
published
subject
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2009:115
pages
144 pages
publisher
Department of Clinical Physiology, Lund University
defense location
Föreläsningssal 3, Centralblocket, Universitetssjukhuset i Lund
defense date
2009-12-10 09:00
ISSN
1652-8220
ISBN
978-91-86443-04-7
language
English
LU publication?
yes
id
6cace3ce-9cf1-4bd8-a548-9ca12576fbff (old id 1503985)
date added to LUP
2009-11-24 11:33:39
date last changed
2016-09-19 08:44:51
@phdthesis{6cace3ce-9cf1-4bd8-a548-9ca12576fbff,
  abstract     = {The standard 12-lead electrocardiogram (ECG) remains one of the most important and most frequently used tools for diagnosing cardiac diseases, although several different examination modalities in cardio¬logy have been developed over the years. The standard ECG uses 10 electrodes placed on well-defined positions on the body, 6 on the torso and 4 distally on the limbs. Both industry and academia have invested many years in development of the criteria used to interpret the “diagnostic” standard ECG, and the waveform patterns are taught in medical school.<br/><br>
In several situations, however – such as during long-term ECG monitoring or stress testing – use of the electrode positions of the standard ECG is not optimal because of the abundance of noise. In these situations, the limb electrodes must be placed proximally, often even on the torso, and the Mason-Likar (M-L) positions are commonly used. Interference with other clinical procedures, such as echocardiography, can also constitute a problem. An ECG-recording system with fewer electrodes and without any electrodes on the limbs that provides a 12-lead ECG similar to the standard ECG would be valuable. The so-called EASI system uses only 4 recording electrodes in easily determined locations on the torso from which the full 12-lead ECG can be derived. The 12-lead ECG derived from the EASI system has been evaluated in adults in several clinical situations.<br/><br>
Physicians who use ECGs in their day-to-day work are often not aware of the differences between 12-lead ECGs recorded from standard versus alternative electrode positions, and they might use criteria developed for the standard ECG when interpreting an ECG obtained from an alternative lead system. This can lead to misinterpretation with the risk of potentially serious consequences for the patient. <br/><br>
Optimizing the proximal positions for better concordance with the standard ECG would be of great value for improved diagnostic performance. A version of the “Lund” (LU) lead system has been reported to agree better with the standard lead system than does the M-L lead system, with regard to both Q-wave width and QRS frontal plane axis. To develop a uniform convention for ECG recording, i.e. both for diagnostic ECG and for monitoring, a recording must produce waveforms that have morphologies approximating those obtained with standard ECG and that has noise immunity close to that of M-L.<br/><br>
The overall objectives of this thesis were 1) to further validate the EASI system to gain more knowledge about the agreement between EASI-derived and standard 12-lead ECGs, and 2) to investigate the possibility of optimizing the positions of proximally placed limb electrodes.<br/><br>
<br/><br>
EASI studies<br/><br>
In Study I, age-specific transformation coefficients were determined for use in deriving 12-lead ECGs from the EASI signals. The agreement of the waveforms between simultaneously recorded standard and EASI-derived 12-lead ECGs in children (healthy and with various cardiac diagnoses) was studied. For children, it was better to use age-specific transformation coefficients than adult coefficients. The agreement between standard and EASI-derived ECGs was mostly good.<br/><br>
In Study II, the intrareader variation of interpretations of 2 standard 12-lead ECGs was compared with the variation of interpretations of standard versus EASI-derived 12-lead ECGs in children (Study I population). The variation of the interpretation of standard versus EASI-derived ECGs was only slightly larger than the intrareader variation of interpretations of standard ECGs. <br/><br>
In Study III, the amplitudes of myoelectric noise and baseline wander were compared between simultaneously recorded EASI-derived and M-L 12-lead ECGs in healthy adults. Overall, the 2 lead systems had similar susceptibilities to baseline wander, but EASI was less susceptible than<br/><br>
M-L to myoelectric noise.<br/><br>
In Study IV, differences in the estimated size of myocardial infarction (MI), as assessed by Selvester scores, were compared between standard and EASI-derived 12-lead ECGs among patients who had had an episode of chest pain suggestive of an acute coronary syndrome. These scores were also compared with MI size measured by cardiac magnetic resonance imaging (MRI). Estimated MI size did not differ significantly between the 2 lead systems, but neither the correlation nor the agreement between MRI and either of the 2 lead systems was very strong.<br/><br>
<br/><br>
Study to optimize the proximal positions of the limb electrodes<br/><br>
In Study V, waveforms from the LU and M-L systems were compared with those from standard ECGs with regard to the QRS axis in the frontal plane and QRS changes of inferior MI. The noise immunities of the standard, LU, and M-L systems were also compared. LU produced ECG waveforms that more closely resembled those obtained with standard ECG than did M-L. The LU system was more noise-immune than was the standard system, and the noise immunities of the LU and the M-L systems were comparable.},
  author       = {Welinder, Annika},
  isbn         = {978-91-86443-04-7},
  issn         = {1652-8220},
  language     = {eng},
  pages        = {144},
  publisher    = {Department of Clinical Physiology, Lund University},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Alternative Lead Systems for Diagnostic Electrocardiography: Validation and Clinical Applicability},
  volume       = {2009:115},
  year         = {2009},
}