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1、Technical Information Report AAMI TIR23:1999 AAMI Association for the Advancement of Medical Instrumentation Signal averaging Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resa
2、le, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- AAMI TIR No. 23:1999 Signal averaging Approved 15 March 1999 Abstract:The signal-averaged electrocardiogram (SAECG) facilitates noninvasive recording of low-amplitude cardiac signals such as ventricular
3、 late potentials. The SAECG has been used to predict life- threatening ventricular tachyarrhythmias in patients after acute myocardial infarction and with nonischemic dilated cardiomyopathy and to screen for inducible ventricular tachycardia in patients with unexplained syncope and with nonsustained
4、 ventricular tachycardia. This technical information report focuses on currently accepted methodology and clinical applications of the SAECG. Key words:signal-averaged electrocardiogram (ECG), ventricular tachycardia, sudden cardiac death, electrophysiologic study, syncope, myocardial infarction, ca
5、rdiomyopathy, atrial fibrillation Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS
6、-,-,- Published by the Association for the Advancement of Medical Instrumentation 1110 N. Glebe Road, Suite 220 Arlington, VA 22201-5762 Copyright 2000 by the Association for the Advancement of Medical Instrumentation All rights reserved. Publication, reproduction, photocopying, storage or transmiss
7、ion, electronically or otherwise, of all or any part of this document without the prior written permission of the Association for the Advancement of Medical Instrumentation is strictly prohibited by law. It is illegal under federal law (17 U.S.C. 101, et seq.) to make copies of all or any part of th
8、is document (whether internally or externally) without the prior written permission of the Association for the Advancement of Medical Instrumentation. Violators risk legal action, including civil and criminal penalties, and damages of $100,000 per offense. For permission regarding the use of all or
9、any part of this document, contact Kurt C. Larrick, Director, Technical Publishing, at AAMI, 1110 N. Glebe Road, Suite 220, Arlington, VA 22201. Phone: (703) 525-4890, Ext. 239; Fax: (703) 525-1067. Printed in the United States of America ISBN 1-57020-129-3 Copyright Association for the Advancement
10、of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- AAMI TECHNICAL INFORMATION REPORT A Technical Information Report (TIR)
11、 is a publication of the Association for the Advancement of Medical Instrumentation (AAMI) Standards Board that addresses a particular aspect of medical technology. Although the material presented in a TIR may need further evaluation by experts, there is value in releasing the information because of
12、 the immediate need for it by the industry and the professions. A TIR differs markedly from a standard or recommended practice, and readers should understand the differences among these documents. Standards and recommended practices are subject to a formal process of committee approval, public revie
13、w, and resolution of all comments. This process of consensus is supervised by the AAMI Standards Board and, in the case of American National Standards, the American National Standards Institute. A TIR is not subject to the same formal approval process as a standard. However, a TIR is approved for di
14、stribution by a technical committee and the AAMI Standards Board. Another difference is that although both standards and TIRs are periodically reviewed, a standard must be acted uponeither reaffirmed, revised, or withdrawnand the action formally approved usually every 5 years but at least every 10 y
15、ears. For a TIR, AAMI consults with a technical committee about 5 years after the publication date (and periodically thereafter) for guidance on whether the document is still usefulthat is, to check that the information is relevant or of historical value. If the information is not useful, the TIR is
16、 removed from circulation. A TIR may be developed because it is more responsive to underlying safety or performance issues than a standard or recommended practice, or because achieving consensus is extremely difficult or unlikely. Unlike a standard, a TIR permits the inclusion of differing viewpoint
17、s on technical issues. CAUTION NOTICE: This AAMI Technical Information Report may be revised or withdrawn at any time. Because it addresses a rapidly evolving field or technology, readers are cautioned to ensure that they have also considered information that may be more recent than this document. C
18、opyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- Contents Page Committee repre
19、sentationvi 1Scope.1 2 Definitions1 3State of the art of current SAECG device design3 3.1 Introduction.3 3.2 Architecture.3 3.3 Comparative table of specifications4 3.4 Summary of beat alignment and measurement methods 5 4Selection and alignment of normal sinus rhythm beats for ensemble averaging5 4
20、.1 Overview.5 4.2Selecting a normal sinus rhythm beat as a “template” 5 4.3Beat alignment techniques.6 4.4 Rejecting nonsinus rhythm beats .6 5Ensemble averaging6 5.1 Overview.6 5.2 Endpoint of signal averaging: quality control7 5.3 Rejection of adversely noisy beats.7 6SAECG analysis: digital filte
21、ring, lead combination, and measurements7 6.1 Overview.7 6.2 Digital filtering schemes8 6.3 Butterworth IIR filter, applied in a bidirectional mode .8 6.4 Spectral window filter8 6.5 FIR filter 8 6.6 Lead combination: vector magnitude waveform.8 6.7 SAECG measurements of late potentials.9 7Clinical
22、applications of SAECG .9 7.1 SAECG methodology.9 7.2 Clinical application of the SAECG11 7.2.1 Predischarge risk stratification after acute MI11 7.2.2 Using the SAECG in combination with other noninvasive test results to predict serious ventricular arrhythmias after MI.12 7.2.3 Clinical limitations
23、of the SAECG after MI .13 7.2.4 Interaction of invasive risk stratification with programmed ventricular stimulation and the SAECG15 7.2.5 The clinical utility of the SAECG in the thrombolytic era16 7.2.6 Prognostic value of the SAECG in patients with idiopathic dilated cardiomyopathy or with advance
24、d heart failure18 7.2.7 Predicting electrically induced ventricular tachycardia in the electrophysiology laboratory of patients with unexplained syncope.20 7.2.8 Predicting inducibility of sustained VT in patients with nonsustained VT21 8Emerging areas in signal-averaged ECG22 8.1 Frequency domain a
25、nalysis22 8.2 P-wave signal averaging and analysis methods .22 8.3 Application of P-SAECG to measurement of atrial activation.23 Annexes A Cited references 24 B Bibliography.30 Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS E
26、mployees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- 2000 Association for the Advancement of Medical Instrumentation I AAMI TIR No. 23:1999v Tables 1 Estimated value of the signal-averaged ECG combined wi
27、th other noninvasive variables for predicting serious arrhythmic events after myocardial infarction14 2 Prognostic value of the post-MI SAECG in the thrombolytic era.17 Figures 1Representative architecture of current SAECG devices .3 2The process of signal-averaged ECG recording and analysis11 3Odd
28、ratios for risk of arrhythmic event after MI14 4Plot of the proportional distribution of patients relative to filtered QRS (fQRS) duration according to treatment assignment in randomized trial of late thrombolytic therapy .16 5 Survival curves displaying freedom from death or sustained ventricular a
29、rrhythmia in heart failure patients with normal or abnormal signal-averaged (SA) ECG and bundle branch block19 6 Prediction of inducible ventricular tachycardia in patients with unexplained syncope, based on presence of single or combination noninvasive variables .21 Copyright Association for the Ad
30、vancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- 2000 Association for the Advancement of Medical Instrumentat
31、ion I AAMI TIR No. 23:1999vi Committee representation Association for the Advancement of Medical Instrumentation Electrocardiograph Committee This technical information report (TIR) was developed by the ECG/Signal Averaging Working Group of the AAMI Electrocardiograph Committee. Committee approval o
32、f the TIR does not necessarily imply that all committee members voted for its approval. At the time this document was balloted, the AAMI Electrocardiograph Committee had the following members: Cochairs:James J. Bailey, MD David Mortara, PhD Members:James J. Bailey, MD, National Institutes of Health
33、Alan S. Berson, PhD, National Heart, Lung, and Blood Institute Robert E. Bruce, Medicomp David Daly, U.S. Food and Drug Administration Arthur R. Eddy, Jr., ConMed Corp. Stacy Gehman, Quinton Instrument Co. Paul Lander, University of Oklahoma Health Sciences Center George Moody, Massachusetts Institu
34、te of Technology David Mortara, PhD, Mortara Instrument Inc. Shankara Reddy, PhD, GE-Marquette Medical Systems William Saltzstein, Medtronic Physio-Control Corp. Jonathan Steinberg, MD, St. Lukes Roosevelt Hospital Roy D. Wallen, Pure Pulse Technologies Alternates:Robert J. Cangelosi, U.S. Food and
35、Drug Administration At the time this document was balloted, the committees ECG Signal Averaging Working Group had the following members: CochairsPaul Lander William Saltzstein Jonathan Steinberg, MD Members:Edward J. Berbari, PhD, Indiana University Alan Berson, PhD, National Heart, Lung, and Blood
36、Institute Stacy Gehman, Quinton Instrument Company Paul Lander, University of Oklahoma Health Sciences Center Shankara Reddy, PhD, GE-Marquette Medical Systems William Saltzstein, Medtronic Physio-Control Corp. Craig Sellers, Spacelabs Burdick Mike Simson, MD, University of Pennsylvania Jonathan Ste
37、inberg, MD, St. Lukes Roosevelt Hospital Jerry Sweeten, Plastics One Inc. Sandy Weininger, U.S. Food and Drug Administration Alternates:Carole Carey, U.S. Food and Drug Administration Acknowledgement The ECG Signal Averaging Working Group gratefully acknowledges the contributions of former cochair E
38、dward Berbari, PhD, and contributor Eric Chan, PhD. NOTEParticipation by federal agency representatives in the development of this report does not constitute endorsement by the federal government or any of its agencies. Copyright Association for the Advancement of Medical Instrumentation Provided by
39、 IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:24 MDTNo reproduction or networking permitted without license from IHS -,-,- 2000 Association for the Advancement of Medical Instrumentation I AAMI TIR No. 23:19991 Signal averaging 1 S
40、cope Signal averaging of the electrocardiogram (SAECG) was devised 25 years ago to reveal low-amplitude cardiac signals in the microvolt range on the body surface. It was originally used to detect His-Purkinje activity (A.1). However, in the next decade the methods for SAECG were refined and develop
41、ed to determine the full extent of ventricular activation with the object of revealing delays relating to electrical instability of the ventricular myocardium. The purpose of this report is to provide an understanding of the fundamental principles underlying SAECG methodology, to define terminology,
42、 and to review its potential for clinical application. It includes a discussion of some of the major pitfalls that must be avoided. This report is directed partly to those who have an interest in the clinical use of the SAECG but also to those who are considering the development of SAECG methodology
43、 in a medical device. The following topics are covered: a)device architecture for data acquisition and processing; b) beat selection and alignment; c) ensemble averaging; d) filtering, lead combination, and measurement; e) clinical applications and emerging uses; f)a list of publications for further
44、 reference; g)terminology. 2 Definitions For the purposes of this technical information report, the following definitions apply. 2.1 bandpass filter: A filter that will pass frequencies within a desired range but will attenuate all other frequencies (e.g., a 40 to 250Hz filter would attenuate freque
45、ncies below 40 Hz and above 250 Hz). 2.2 baud rate: The number of bits per second that can be transmitted in a given computer system. NOTEWhen information is transmitted between two computer systems, each must be set to the same baud rate. 2.3 bidirectional filter: A type of digital filter that filt
46、ers the signal in a forward direction from its beginning to its midpoint and then filters from the end of the signal in a backward direction to the same midpoint. 2.4 Butterworth amplitude filter: A type of filter known for its filter quality on small signals; the filter of choice for the vector mag
47、nitude and late potential detection. 2.5 corner frequency: The frequency or frequencies selected to define a filter band (e.g., 40 to 250Hz Butterworth filter). 2.6 FFT: Fast Fourier Transform is a method by which a segment of time series data can be evaluated for its frequency components. 2.7 fiduc
48、ial point: A reliable, stable reference point that allows multiple beats to be aligned for averaging. NOTEOne fiducial point commonly used for SAECGs is the onset of the QRS or the time of maximum slope of the QRS. 2.8 filter: A device or software algorithm that passes information within signals of certain frequencies or frequency ranges while attenuating others. 2.9 finite impulse response (FIR) filter: A type of filter that relies only on previous input to generate its present output. 2.10 high pass filter: A filter that attenuates frequencies below a specified fr