Q 1: What does ST segment represent? 

Q 2: How do you evaluate ST segment?

Q 3: What is the significance of elevated ST segment?

Q 4: What is the significance of depressed  ST segment?

Answer

Answers

Q 1: What does ST segment represent? 

ST segment represents: this segment is important in identifying pathology such as myocardial infarctions (elevations) and ischemia (depressions). In normal situations, it serves as the isoelectric line from which to measure the amplitudes of the other waveforms.

Q 2: How do you evaluate ST segment?

When examining the ST segment, evaluate elevations or depressions 0.06 seconds after the J point (since the ST segment can at times be sloping). ST segments are usually isoelectric and normal.

Q 3: What does elevated  ST segment mean?

ST segment elevation

• In general, an ST segment elevation indicates infarction.
• ST segment elevation is a current of injury - can be seen in pericarditis as well as Prinzmetal's angina.
• Early repolarization causes ST segment elevation in the lead of normal EKG's.

The location of the ST elevations on the EKG can help to identify a location of the infarct:

• Anterior Wall Infarct (corresponding to Left Anterior Descending Artery): V1, V2
• Lateral Wall Infarct (Circumflex Artery): V3, V4
• Inferior Wall Infarct (can be combination of Circumflex or Right Coronary Artery): V5, V6, I, avl
• when in all leads suggests Pericarditis

Q 4: What does depressed ST segment mean?

• In general, an ST segment depression indicates Ischemia
• ST segment depression can be Ischemia as in exercise EKG's or subendocardial injury current.
• Digitalis causes ST segment sagging and shortens the Q-T interval.