Abstract
Electrical activity in the heart arises from the movement of positively and negatively charged ions across the cell membrane of cardiac cells. The movement of these ions occurs in an organized and repetitive fashion that generates a sequences of voltage changes called the action potential. The action potential activates the heart and initiates contraction. It also generates potential differences between different parts of the heart that can be recorded from the surface of the heart. It can also be recorded by electrodes attached to the surface of the skin, generating the electrocardiogram (ECG). Recording the ECG from multiple standardized positions allows clinically useful conclusions to be made regarding the sequence of activation of the heart and about the presence of pathology. Analog recording of ECGs has largely been supplanted by digital recording. The ECG signal is processed by high pass and low pass filters to allow maximal fidelity while minimizing electrical noise. A technique called common mode rejection rejects signals that appear at the same amplitude at each electrode since such signals most likely represent artifact. Analog to digital conversion typically occurs at a high sampling rate of 500 Hz. Some devices use variable sampling rates, reducing it for portions lower frequency portions of the signal. This preserves the fidelity of the ECG while creating smaller files. Many ECG recorders provide automated analysis of the waveform. To do this, they form a template of the ECG waveform using techniques such as signal averaging to create an average or median waveform, selecting fiduciary points to align the elements of the ECG waveform, and using features such as changes in amplitude and slope to identify key elements of the waveform. Complex decision trees are used by programs to make diagnostic statements regarding the waveform. While reliable, computerized ECG analysis programs have been outperformed by expert human readers. Since the greatest accuracy may be achieved by combining computerized interpretation with over-reading by humans, current standards call for physician review of all ECGs.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsReferences
Bayes de Luna AJ. Textbook of Clinical Electrocardiography. Dordrecht: Martinus Nijhoff; 1987.
Holland RP, Arnsdorf MF. Solid angle theory and the electrocardiogram: physiologic and quantitative interpretations. Prog Cardiovasc Dis. 1977;19(6):431–457.
Cheng LK, Bodley JM, Pullan AJ. Effects of experimental and modeling errors on electrocardiographic inverse formulations. IEEE Trans Biomed Eng. 2003;50(1):23–32.
Wilson FN, Johnston FD, Macleod AG, Barker PS. Electrocardiograms that represent the potential variations of a single electrode. Am Heart J. 1934;9(4):447–458.
Goldberger E. A simple, indifferent, electrocardiographic electrode of zero potential and a technique of obtaining augmented, unipolar, extremity leads. Am Heart J. 1942;23(4):483–492.
Bailey JJ, Berson AS, Garson A Jr, et al. Recommendations for standardization and specifications in automated electrocardiography: bandwidth and digital signal processing. A report for health professionals by an ad hoc writing group of the Committee on Electrocardiography and Cardiac Electrophysiology of the Council on Clinical Cardiology, American Heart Association. Circulation. 1990;81(2):730–739.
Tayler DI, Vincent R. Artefactual ST segment abnormalities due to electrocardiograph design. Br Heart J. 1985;54:121–128.
Berson AS, Pipberger HV. The low-frequency response of electrocardiographs, a frequent source of recording errors. Am Heart J. 1966;71(6):779–789.
Kossmann CE, Brody DA, Burch GE, et al. Recommendations for Standardization of Leads and of Specifications for Instruments in Electrocardiography and Vectorcardiography. Circulation. 1967;35(3):583–602.
Ahlstrom ML, Tompkins WJ. Digital filters for real-time ECG signal processing using microprocessors. IEEE Trans Biomed Eng. 1985;32(9):708–713.
Golden DP, Wolthuis RA, Hoffler GW. A spectral analysis of the normal resting electrocardiogram. IEEE Trans Biomed Eng. 1973;20(5):366–372.
GE Healthcare (2003–2006). Marquette™ 12SL™ ECG Analysis Program: Physician’s Guide; Revision D (2003–2006). General Electric Company.
Barr RC, Spach MS. Sampling rates required for digital recording of intracellular and extracellular cardiac potentials. Circulation. 1977;55(1):40–48.
Kligfield P, Gettes LS, Bailey JJ, et al. 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. Circulation. 2007;115(10):1306–1324.
Zywietz C, Willems JL, Arnaud P, et al.; The CSE Working Party. Stability of computer ECG amplitude measurements in the presence of noise. Comput Biomed Res. 1990;23(1):10–31.
Farrell RM, Rowlandson GI. The effects of noise on computerized electrocardiogram measurements. J Electrocardiol. 2006;39(4 suppl):S165–S173.
Willems JL, Zywietz C, Arnaud P, et al. Influence of noise on wave boundary recognition by ECG measurement programs. Recommendations for preprocessing. Comput Biomed Res. 1987;20(6):543–562.
Mason JW, Hancock EW, Gettes LS, et al. Recommendations for the Standardization and Interpretation of the Electrocardiogram: Part II: Electrocardiography Diagnostic Statement List: 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. Circulation. 2007;115(10):1325–1332.
Surawicz B, Uhley H, Borun R, et al. Task force I: standardization of terminology and interpretation. Am J Cardiol. 1978;41:130–145
Willems JL, Arnaud P, van Bemmel JH, et al. A reference data base for multilead electrocardiographic computer measurement programs. J Am Coll Cardiol. 1987;10(6):1313–1321.
Willems JL, Arnaud P, van Bemmel JH, et al. Assessment of the performance of electrocardiographic computer programs with the use of a reference data base. Circulation. 1985;71(3):523–534.
Willems JL, Abreu-Lima C, Arnaud P, et al. The diagnostic performance of computer programs for the interpretation of electrocardiograms. N Engl J Med. 1991;325(25):1767–1773.
Brailer DJ, Kroch E, Pauly MV. The impact of computer-assisted test interpretation on physician decision making: the case of electrocardiograms. Med Decis Making. 1997;17(1):80–86.
Willems JL, Abreu-Lima C, Arnaud P, et al. Effect of combining electrocardiographic interpretation results on diagnostic accuracy. Eur Heart J. 1988;9(12):1348–1355.
Tsai TL, Fridsma DB, Gatti G. Computer decision support as a source of interpretation error: the case of electrocardiograms. J Am Med Inform Assoc. 2003;10(5):478–483.
Jalaleddine SM, Hutchens CG, Strattan RD, Coberly WA. ECG data compression techniques – a unified approach. IEEE Trans Biomed Eng. 1990;37(4):329–343.
Reddy BR, Christenson DW, Rowlandson GI, Zywietz C, Sheffield T, Brohet C. Data compression for storage of resting ECGs digitized at 500 samples/second. Biomed Instrum Technol. 1992;26(2):133–149.
Fozzard HA, DasGupta DS. ST-segment potentials and mapping. Theory and experiments. Circulation. 1976;54:533–537.
Boron WF, Boulpaep EL. Textbook of Medical Physiology. Philadelphia, PA: W.B. Saunders Company; 2002.
Thaler MS. The Only EKG Book You’ll Ever Need. Philadelphia, PA: Lippincott Williams & Wilkins; 2003.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2010 Springer London
About this chapter
Cite this chapter
Rosenthal, J.E. (2010). Electrocardiography. In: Goldberger, J., Ng, J. (eds) Practical Signal and Image Processing in Clinical Cardiology. Springer, London. https://doi.org/10.1007/978-1-84882-515-4_10
Download citation
DOI: https://doi.org/10.1007/978-1-84882-515-4_10
Published:
Publisher Name: Springer, London
Print ISBN: 978-1-84882-514-7
Online ISBN: 978-1-84882-515-4
eBook Packages: MedicineMedicine (R0)