Schematic representation of normal ECG

In electrocardiography, the ST segment connects the QRS complex and the T wave and has a duration of 0.005 to 0.150 sec (5 to 150 ms).

It starts at the J point (junction between the QRS complex and ST segment) and ends at the beginning of the T wave. However, since it is usually difficult to determine exactly where the ST segment ends and the T wave begins, the relationship between the ST segment and T wave should be examined together. The typical ST segment duration is usually around 0.08 sec (80 ms). It should be essentially level with the PR and TP segments.

The ST segment represents the isoelectric period when the ventricles are in between depolarization and repolarization.


In fetal monitoring

In fetal electrocardiography, ST waveform analysis (sometimes abbreviated STAN) is used to get an indication of increasing levels of fetal base deficit.[3]


  1. ^ Sabatine MS (2000). Pocket Medicine (Pocket Notebook). Lippincott Williams & Wilkins. ISBN 0-7817-1649-7.
  2. ^ "Reading an EKG". 2010-03-25. Archived from the original on 2010-03-25. Retrieved 2021-11-04.((cite web)): CS1 maint: unfit URL (link)
  3. ^ Mansano, R. Z.; Beall, M. H.; Ross, M. G. (2007). "Fetal ST segment heart rate analysis in labor: Improvement of intervention criteria using interpolated base deficit". Journal of Maternal-Fetal and Neonatal Medicine. 20 (1): 47–52. doi:10.1080/14767050601055279. PMID 17437199. S2CID 10815181.