ST Segment Elevation or Depression

[blur411]

Hi, I'm having some trouble figuring out exactly what ST segment elevation and ST segment depression is. I know my professor talked about it in class, but I've been unable to find it in my text book. Does one have to do with Angina and the other one have to do with a heart attack?

What I do know: ST segment is early ventricular repolarization. The book states if it is above or below the line it may be a sign of cardiac ischemia. But is there a difference if its above the line or below it?

Of all the parts of cardiac, the ECGs are the most difficult for me to understand!

Thanks for any input!:heartbeat

[Daytonite, BSN, RN]

from http://www.12leadecg.com/intro/. . ."definition of st segment: the section of the complex from the end of the qrs complex to the beginning of the t wave. electrically, it represents the period of inactivity between ventricular depolarization and repolarization. mechanically, it represents the time that the myocardium is maintaining contraction."

hope you find the following webpage from the ekg learning center helpful:

• http://library.med.utah.edu/kw/ecg/ecg_outline/lesson10/index.html - st segment abnormalities

[neneRN, BSN, RN]

ST elevation is "above the line" and indicates myocardial injury. This is an acute MI (heart attack).

ST depression is "below the line" and indicates myocardial ischemia. If this isn't treated, it can worsen to injury (MI). You can see ischemia for a variety of reasons so the underlying cause needs to be addressed to prevent injury. For example, an anemic patient with a very low hemoglobin may have ischemia on an EKG because not enough oxygen is getting to tissues; this patient needs blood. Another example is a cardiac patient that may have a blockage, but has developed enough collateral flow to the heart muscle that an MI has not yet occurred. Lots of different scenerios.

Remember that ELEVATION equals INJURY and DEPRESSION equals ISCHEMIA.

(There are some exceptions; pts with pericarditis may have slight elevation all throughout their EKG, but not be having an MI. Also might see diffuse elevation in younger pts with early repolarization and this isn't an MI either. But these are fairly rare occurances and an MI is suspected with elevation until otherwise ruled out)

[blur411]

Thank you both very much for clarifying! I will check out the ECG site tomorrow when I have more time for additional research.