ecgsegment

An ECG segment refers to a specific portion of an electrocardiogram (ECG) tracing. The ECG itself is a recording of the electrical activity of the heart over time, displayed as a series of waves and lines. These components are conventionally divided into segments and intervals. Segments are the periods of time between the end of one wave and the beginning of the next. The most commonly discussed segments are the PR segment and the ST segment.

The PR segment begins at the end of the P wave, which represents atrial depolarization, and continues until the beginning of the QRS complex, which signifies ventricular depolarization. This segment reflects the delay in electrical conduction at the atrioventricular (AV) node, allowing the atria to fully contract before the ventricles. The PR segment is typically isoelectric, meaning it lies on the baseline of the ECG.

The ST segment starts at the end of the S wave (the final deflection of the QRS complex) and ends at the beginning of the T wave, which represents ventricular repolarization. Like the PR segment, the ST segment is also usually isoelectric. Deviations in the ST segment, such as elevation or depression, can be significant indicators of cardiac pathology, particularly myocardial ischemia or infarction. Analyzing the duration, shape, and baseline position of these segments is crucial for diagnosing various heart conditions.