Lewis offset

Lewis offset is a term used in cardiology to describe a specific pattern seen on an ECG that is associated with certain heart conditions. It is named after Sir Thomas Lewis, a British cardiologist who was a pioneer in the field of electrocardiography.

Definition

The Lewis offset is defined as the difference in time between the onset of the P wave and the onset of the QRS complex on an ECG. This offset is usually measured in milliseconds (ms).

Clinical significance

The Lewis offset can be used as a diagnostic tool in cardiology. An increased Lewis offset is associated with conditions such as atrial fibrillation, atrial flutter, and pre-excitation syndromes. Conversely, a decreased Lewis offset can be seen in conditions such as atrioventricular block and sick sinus syndrome.

Measurement

The Lewis offset is measured using an ECG. The onset of the P wave is identified, and the onset of the QRS complex is also identified. The difference in time between these two points is the Lewis offset.

Limitations

While the Lewis offset can be a useful diagnostic tool, it is not without its limitations. The accuracy of the measurement can be affected by factors such as the quality of the ECG recording and the presence of other cardiac abnormalities. Furthermore, the Lewis offset is only one piece of the diagnostic puzzle and should be used in conjunction with other clinical information.

See also

• Electrocardiogram
• P wave
• QRS complex
• Atrial fibrillation
• Atrial flutter
• Pre-excitation syndromes
• Atrioventricular block
• Sick sinus syndrome

Lewis offset Resources
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