Electrocardiography

"ECG" and "EKG" redirect here. For other uses, see ECG (disambiguation) and EKG (disambiguation).
Not to be confused with other types of electrography or with echocardiography.

Electrocardiography
ECG of a heart in normal sinus rhythm
ICD-10-PCSR94.31
ICD-9-CM89.52
MeSHD004562
MedlinePlus003868
Use of real time monitoring of the heart in an intensive care unit in a German hospital (2015), the monitoring screen above the patient displaying an electrocardiogram and various values of parameters of the heart like heart rate and blood pressure

Electrocardiography is the process of producing an electrocardiogram (ECG or EKG[a]), a recording of the heart's electrical activity through repeated cardiac cycles.[4] It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart[5] using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including:

Traditionally, "ECG" usually means a 12-lead ECG taken while lying down as discussed below. However, other devices can record the electrical activity of the heart such as a Holter monitor but also some models of smartwatch are capable of recording an ECG. ECG signals can be recorded in other contexts with other devices.

In a conventional 12-lead ECG, ten electrodes are placed on the patient's limbs and on the surface of the chest. The overall magnitude of the heart's electrical potential is then measured from twelve different angles ("leads") and is recorded over a period of time (usually ten seconds). In this way, the overall magnitude and direction of the heart's electrical depolarization is captured at each moment throughout the cardiac cycle.[11]

There are three main components to an ECG:[12]

  • The P wave, which represents depolarization of the atria.
  • The QRS complex, which represents depolarization of the ventricles.
  • The T wave, which represents repolarization of the ventricles.

During each heartbeat, a healthy heart has an orderly progression of depolarization that starts with pacemaker cells in the sinoatrial node, spreads throughout the atrium, and passes through the atrioventricular node down into the bundle of His and into the Purkinje fibers, spreading down and to the left throughout the ventricles.[12] This orderly pattern of depolarization gives rise to the characteristic ECG tracing. To the trained clinician, an ECG conveys a large amount of information about the structure of the heart and the function of its electrical conduction system.[13] Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart's muscle cells or conduction system, the effects of heart drugs, and the function of implanted pacemakers.[14]

  1. ^ "Definition of EKG". Lexico Dictionaries. Archived from the original on 15 February 2020. Retrieved 20 January 2020.
  2. ^ "15.3.1 Electrocardiographic Terms", AMA Manual of Style, American Medical Association
  3. ^ "Merriam-Webster's Collegiate Dictionary". Merriam-Webster.
  4. ^ Bunce, Nicholas H.; Ray, Robin; Patel, Hitesh (2020). "30. Cardiology". In Feather, Adam; Randall, David; Waterhouse, Mona (eds.). Kumar and Clark's Clinical Medicine (10th ed.). Elsevier. pp. 1033–1038. ISBN 978-0-7020-7870-5.
  5. ^ Lilly, Leonard S. (2016). Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty, 6th Edition. Lippincott Williams & Wilkins. pp. 70–78. ISBN 978-1-4698-9758-5. OCLC 1229852550.
  6. ^ Lyakhov, Pavel; Kiladze, Mariya; Lyakhova, Ulyana (January 2021). "System for Neural Network Determination of Atrial Fibrillation on ECG Signals with Wavelet-Based Preprocessing". Applied Sciences. 11 (16): 7213. doi:10.3390/app11167213.
  7. ^ Hoyland, Philip; Hammache, Néfissa; Battaglia, Alberto; Oster, Julien; Felblinger, Jacques; de Chillou, Christian; Odille, Freddy (2020). "A Paced-ECG Detector and Delineator for Automatic Multi-Parametric Catheter Mapping of Ventricular Tachycardia". IEEE Access. 8: 223952–223960. Bibcode:2020IEEEA...8v3952H. doi:10.1109/ACCESS.2020.3043542. ISSN 2169-3536.
  8. ^ Bigler, Marius Reto; Zimmermann, Patrick; Papadis, Athanasios; Seiler, Christian (1 January 2021). "Accuracy of intracoronary ECG parameters for myocardial ischemia detection". Journal of Electrocardiology. 64: 50–57. doi:10.1016/j.jelectrocard.2020.11.018. ISSN 0022-0736. PMID 33316551. S2CID 229173576.
  9. ^ Prabhakararao, Eedara; Dandapat, Samarendra (August 2020). "Myocardial Infarction Severity Stages Classification From ECG Signals Using Attentional Recurrent Neural Network". IEEE Sensors Journal. 20 (15): 8711–8720. Bibcode:2020ISenJ..20.8711P. doi:10.1109/JSEN.2020.2984493. ISSN 1558-1748. S2CID 216310175.
  10. ^ Carrizales-Sepúlveda, Edgar Francisco; Vera-Pineda, Raymundo; Jiménez-Castillo, Raúl Alberto; Treviño-García, Karla Belén; Ordaz-Farías, Alejandro (1 November 2019). "Toluene toxicity presenting with hypokalemia, profound weakness and U waves in the electrocardiogram". The American Journal of Emergency Medicine. 37 (11): 2120.e1–2120.e3. doi:10.1016/j.ajem.2019.158417. ISSN 0735-6757. PMID 31477355. S2CID 201804610.
  11. ^ Aswini Kumar MD. "ECG- simplified". LifeHugger. Archived from the original on 2 October 2017. Retrieved 11 February 2010.
  12. ^ a b Lilly 2016, pp. 80.
  13. ^ Walraven, Gail (2011). Basic arrhythmias (7th ed.). Boston: Brady/Pearson. pp. 1–11. ISBN 978-0-13-500238-4. OCLC 505018241.
  14. ^ Braunwald, Eugene, ed. (1997). Heart Disease: A Textbook of Cardiovascular Medicine (5th ed.). Philadelphia: Saunders. p. 118. ISBN 0-7216-5666-8. OCLC 32970742.


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