Elsevier

Heart Rhythm

Volume 4, Issue 3, March 2007, Pages 394-412
Heart Rhythm

AHA/ACC/HRS scientific statement
Recommendations for the standardization and interpretation of the electrocardiogram: Part I: The electrocardiogram and its technology: A Scientific Statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology

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Abstract

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Section snippets

The ECG and its technology

The purposes of this statement are (1) to examine the relation of the resting ECG to its technology, (2) to increase understanding of how the modern ECG is derived and recorded, and (3) to promote standards that will improve the accuracy and usefulness of the ECG in practice. Special emphasis will be placed on the digital recording methods and computer-based signal processing that are used in current electrocardiographs to provide automated measurements that lead to computer-generated

Previous standards and reviews

A number of recommendations for the standardization of ECG recording and guidelines for ECG interpretation in the computer era have appeared during the past several decades. The most recent comprehensive AHA recommendations for the standardization of leads and general technical requirements of ECG instruments were published in 1975.5 In 1978, task forces of the American College of Cardiology produced a collection of reports on optimal electrocardiography,7 which addressed standardization of

The ECG signal and its processing

Automated analysis of the digital 12-lead ECG involves signal analysis and diagnostic classification.28 Processing of the ECG occurs in a series of steps, each of which requires adherence to methodological standards. These steps include (1) signal acquisition, including filtering; (2) data transformation, or preparation of data for further processing, including finding the complexes, classification of the complexes into “dominant” and “nondominant” (ectopic) types, and formation of an average

Technology

The standard 12-lead ECG5, 24 consists of 3 limb leads (leads I, II, and III), 3 augmented limb leads in which the Goldberger modification of the central terminal of Wilson serves as a derived indifferent electrode that is paired with the exploring electrode (leads aVR, aVL, and aVF), and 6 precordial leads in which the Wilson central terminal serves as a derived indifferent electrode that is paired with the exploring electrode (V1 through V6). All leads are effectively “bipolar,” and the term

Technology

Noise from motion of the arms and legs during ambulatory and exercise electrocardiography can be reduced by placement of the limb leads on the torso. In these diagnostic applications, 12-lead ECGs have been recorded with the Mason-Likar lead position,105 in which the arm electrodes are placed in the infraclavicular fossae medial to the deltoid insertions and the left leg electrode is placed midway between the costal margin and iliac crest in the left anterior axillary line. More recent

Technology

Lead switches (or more correctly, electrode cable switches) occur when a dedicated lead wire and electrode combination is misplaced or when there is erroneous attachment of a dedicated lead wire to individually placed electrodes. Color coding of lead wires is a feature of manufacturing standards for electrocardiographs,24 but even so, it is possible to misconnect lead wires at the cable terminal. Time-coherent P-wave morphology can be used to clarify lead switches,132 and these principles

Summary

The present document outlines the relation of the modern digital electrocardiograph to its technology. Individual features of ECG processing and recording are considered in terms of their clinical implications. Recommendations focus on progress toward optimal use of the ECG. It is hoped that the standards set out in this document will provide a further stimulus to the improvement of ECG recording and interpretation.

Disclosures

Writing group disclosures

Writing group memberEmploymentResearch grantOther research supportSpeakers’ bureau/honorariaOwnership interestConsultant/Advisory BoardOther
Paul KligfieldWeill Medical College of Cornell UniversityNoneNoneNoneUnilead (ECG electrode technology)–limited partner†Philips Medical, Mortara Instrument, GE Healthcare, Quinton Medical, MDS Pharma Services,† Cardiac ScienceNone
James J. BaileyNational Institutes of HealthNoneNoneNoneNoneNoneNone
Rory ChildersUniversity of

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  • Cited by (0)

    Other members of the Standardization and Interpretation of the Electrocardiogram Writing Group include Mark Josephson, MD, FACC, FHRS; Jay W. Mason, MD, FAHA, FACC, FHRS; Peter Okin, MD, FACC; Borys Surawicz, MD, FAHA, FACC; and Hein Wellens, MD, FAHA, FACC.

    The American Heart Association, the American College of Cardiology, and the Heart Rhythm Society make every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.

    This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on October 26, 2006, by the American College of Cardiology Board of Trustees on October 12, 2006, and by the Heart Rhythm Society on September 6, 2006.

    When citing this document, the American Heart Association, the American College of Cardiology Foundation, and the Heart Rhythm Society request that the following citation format be used: Kligfield P, Gettes LS, Bailey JJ, Childers R, Deal BJ, Hancock EW, van Herpen G, Kors JA, Macfarlane P, Mirvis DM, Pahlm O, Rautaharju P, Wagner GS. Recommendations for the standardization and interpretation of the electrocardiogram: part I: the electrocardiogram and its technology: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Heart Rhythm 2007;4:394–412.

    This article has been copublished in the March 13, 2007, issue of Circulation and in the March 13, 2007 issue of the Journal of the American College of Cardiology.

    Copies: For copies of this document, please contact Elsevier Inc. Reprint Department, fax (212) 633-3820, e-mail [email protected].

    Permissions: Modification, alteration, enhancement, and/or distribution of this document are not permitted without the express permission of the American Heart Association. Instructions for obtaining permission are located at http://www.americanheart.org/presenter.jhtml?Identifier=4431. A link to the “Permission Request Form” appears on the right side of the page.

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