S-T segment


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S-T segment

an isoelectric line after the QRS complex on the electrocardiogram. It represents phase 2 of the cardiac action potential. Elevation or depression of the S-T segment is the hallmark of myocardial ischemia or injury and coronary artery disease.

segment

(seg'ment) [L. segmentum, a portion]
1. A part or section, esp. a natural one, of an organ or body.
2. One of the serial divisions of an animal.

anterior segment

1. In ophthalmology, the ciliary body, cornea, iris and lens of the eye.
2. In dentistry, the canine and incisor teeth.

bronchopulmonary segment

A small subdivision of the lobes of the lung.

hepatic segment

A subdivision of the lobes of the liver.

interannular segment

The portion of a neuron between the two nodes of Ranvier.

mesodermal segment

A somite.

P-R segment

The line on an electrocardiogram that begins with the end of the P wave and ends with the beginning of the QRS. It corresponds to the period between the end of atrial depolarization and the onset of ventricular depolarization.

Q-T segment

Q-T interval.

ST segment

, S-T segment
The line on an electrocardiogram that begins with the end of the QRS complex and ends at the beginning of the T wave. The height of the ST segment is normally equal to that of the P-R interval and the TP interval. ST segment elevation is found in patients with acute myocardial infarction and other conditions. ST segment depression is an indicator of coronary ischemia.

uterine segment

One of the two functional divisions of the uterine musculature during labor. During labor the upper uterine segment forcibly contracts, becoming progressively shorter and thicker, exerting traction on the more passive lower segment, and increasing the hydrostatic pressure against the cervix. The combination of forces and traction gradually cause the lower segment to thin, resulting in cervical effacement and dilation. See: physiologic retraction ring

ST segment

, S-T segment
The line on an electrocardiogram that begins with the end of the QRS complex and ends at the beginning of the T wave. The height of the ST segment is normally equal to that of the P-R interval and the TP interval. ST segment elevation is found in patients with acute myocardial infarction and other conditions. ST segment depression is an indicator of coronary ischemia.
See also: segment

S-T segment

the portion of an electrocardiogram between the end of the QRS complex and the beginning of the T wave. It represents the period of slow repolarization of the ventricles.