Electrocardiography
hideElectrocardiography (ECG or EKG) is a transthoracic interpretation of the electrical activity of the heart over time captured and externally recorded by skin electrodes. It is a noninvasive recording produced by an electrocardiographic device. The etymology of the word is derived from electro, because it is related to electrical activity, cardio, Greek for heart, graph, a Greek root meaning "to write".
Electrical impulses in the heart originate in the sinoatrial node and travel through the intrinsic conducting system to the heart muscle.The impulses stimulate the myocardial muscle fibres to contract and thus induce systole. The electrical waves can be measured at selectively placed electrodes (electrical contacts) on the skin. Electrodes on different sides of the heart measure the activity of different parts of the heart muscle. An ECG displays the voltage between pairs of these electrodes, and the muscle activity that they measure, from different directions, also understood as vectors. This display indicates the overall rhythm of the heart and weaknesses in different parts of the heart muscle. It is the best way to measure and diagnose abnormal rhythms of the heart, particularly abnormal rhythms caused by damage to the conductive tissue that carries electrical signals, or abnormal rhythms caused by levels of dissolved salts (electrolytes), such as potassium, that are too high or low. In myocardial infarction (MI), the ECG can identify damaged heart muscle. But it can only identify damage to muscle in certain areas, so it can't rule out damage in other areas. The ECG cannot reliably measure the pumping ability of the heart; for which ultrasound-based (echocardiography) or nuclear medicine tests are used.
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News tagged with electrocardiogram
Regular electrocardiograms may help physicians identify patients at risk of sudden cardiac death
Aug 27, 2009 |
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QRS duration (QRSd) is one of several measures of heart function recorded during a routine electrocardiogram (ECG). It is a composite of waves showing the length of time it takes for an electrical signal to get all the way ...
Radiation dose drastically reduced during whole chest MDCT
Jun 24, 2009 |
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Emergency physicians who evaluate patients with non-specific chest pain using whole chest multi-detector CT (MDCT) combined with retrospective electrocardiogram (ECG) gating can reduce the patient radiation dose by 71% using ...
Heart electrical conduction abnormality believed not to be serious may pose cardiovascular risks
Jun 23, 2009 |
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New research indicates that a finding on a routine electrocardiogram that signals a disorder of the electrical conducting system in one part of the heart and previously believed to be benign is associated with an increased ...
Common ECG finding may indicate serious cardiac problems
Jun 23, 2009 |
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A common electrocardiogram (ECG) finding that has largely been considered insignificant may actually signal an increased risk of atrial fibrillation (a chronic heart rhythm disturbance), the future need for a permanent pacemaker ...
Irregular heart rhythm before or after cardiac catheterization linked to risk of death
May 05, 2009 |
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Certain heart attack patients who experience a rapid, abnormal heart rhythm before or after a coronary artery intervention or stent placement have a significantly higher risk of death within 90 days of the procedure, according ...
Researchers identify stroke predictors in black patients
Apr 29, 2009 |
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Predictors of atrial fibrillation (AF or afib) might offer physicians a better way to prevent stroke in blacks, according to a new study done by researchers at Wake Forest University School of Medicine.
New imaging technology reveals prevalence of 'silent' heart attacks
Apr 21, 2009 |
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So-called "silent" heart attacks may be much more common than previously believed, according to researchers at Duke University Medical Center.
