An electrocardiogram (ECG or in the US commonly EKG) is a recording of the electrical activity of the heart with respect to time. The ECG can be recorded on paper or presented visually on a screen.
Usually the recording is made at the body surface (surface ECG). More rarely an electrocardiogram can be measured at the heart surface by direct contact with electrodes and in some electrophysiological studies via an oesophageal probe.
The best way to learn how to interpret an Electrocardiogram is to look at a lot and keep looking at a lot more, correlating the findings on the ECG with the history and findings from the patient. Follow a regular and logical pattern of analysis. There are books and websites which can help  but they are no substitute to experience in pattern recognition. If you need revision to acute physician level try Dr Smith's ECG blog as it brings multiple internet resources together. Many modern machines will produce an electronic report. Such reports are not infallible and you know enough when you start picking up a machines mistakes for something like QTc interval when other rare pathology causes a wave form issue.
- How a 12-lead ECG is performed
- How to interpret an ECG
- Normal intervals
- Normal variants
- Adopt a methodical approach to analysing ECG to avoid missing things
- Treat the patient, not ECG.
- Conversely, a normal ECG does not exclude pathology
- Heart block
- Sinus tachycardia
- Supraventricular tachycardia
- Atrial fibrillation
- Atrial flutter
- Atrial tachycardia
- Idioventricular rhythm
- Bigeminy ECG
- Ventricular tachycardia including Torsade de pointes
- Ventricular fibrillation
Ischaemic Heart Disease
Ischaemic heart disease can cause several different types of ECG abnormalities. That this was the case was first demonstrated in experiments in dogs published in 1918. Previous infarcts can give rise to Q-waves, which signify previous full-thickness infarction. Other non-specific findings include T-wave inversion and conduction abnormalities.
In the setting of acute chest pain, an ECG is performed immediately to look for evidence of myocardial infarction or ischaemia. This is of particular importance as thrombolysis is indicated if certain criteria are met.
Hypertensive heart disease
The ECG in chest disease
Metabolic and others
Congenital heart disease
Resources for learning about ECG
- ↑ http://www.ecglibrary.com/ ecglibrary
- ↑ Cooper JK. Electrocardiography 100 years ago. Origins, pioneers, and contributors. The New England journal of medicine. 1986;315:461-4.
- ↑ Fye WB. A history of the origin, evolution, and impact of electrocardiography. The American journal of cardiology. 1994;73:937-49.