Teaching Medicine - Tutorial: ACS Plus

ECG

Level 3

Tutorial: ACS Plus

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Tutorial: ACS Plus

Learn diagnostic criteria for Acute Coronary Syndromes, as well as other diagnoses that could be confused with them: early repolarization, pericarditis and non specific ST-T wave changes.

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Tutorial: ACS Plus The ST Segment

Lessons

Times Practiced

1284

Cases Completed

1h 24m

Total Time spent

1m 24s

Average Time

Progress

Accuracy

Efficiency

Accuracy

Efficiency

	1	The J Point The J Point
	2	The ST Segment The ST Segment
	3	The T wave The T wave
	4	Pericarditis Pericarditis
	5	Ischemia Ischemia
	6	Infarction Infarction

The ST Segment

The J point can be thought of as the start of the ST segment. The ST segment should be evaluated after the J point is evaluated. Features that are important to analyze in the ST segment include:

absolute position: elevation vs. depression
slope: upsloping vs. downsloping vs. none
shape: flat vs. concave vs. convex

In the previous lesson on J point, we have described J point elevation and depression. ST segment absolute position (elevation and depression) is the same concept. Here is an example of ST segment elevation:

In the above example, can you see that the J point is more that 3 little red squares above the baseline, which is 0.3 mV. The blue dotted line shows the baseline and the red dotted line indicates the starting elevation of the ST segment:
ST segment elevation

Here is an example of ST segment depression:

The blue line is the baseline and the red line indicates the degree of ST depression. The ST depression is 2 little squares in this example, which is 0.2 mV:
ST segment depression

After you analyze the elevation or depression of the ST segment, next analyze the slope of the ST segment. It be: upsloping, downsloping, or have no slope.

This ECG has an upsloping ST segment. The blue dotted line is the zero degrees baseline. The red dotted line is parallel with the ST segment and is angled/sloped upwards:
ST elevation

The above example also shows ST segment elevation. Do not confuse absolute position with sloping. The above example has ST segment elevation that is upsloping.

Here is an example of ST depression with downsloping:

Here is an example of ST depression with no sloping:

Lastly, analyze the shape of the ST segment. It can be flat, concave, or convex. The concave shape is sometimes also called "scooped".

This ECG shows a diffuse J point with ST segment elevation that is concave upward:
ST segment scooped

The blue line travels from the J point (approximately) to the peak of the T wave. The red arrow indicates the space under the blue line to show the ST segment is concave upward.
ST segment scooped

The opposite of concave up is convex up. Here is an example of convex up, where the ST segment is above the blue line that connects the J point and the top of the T wave. The red arrow shows the space between the ST segment and the blue line:
ST segment elevation

The ST segment can also be concave down which can occur with ST depression. Note that the T wave in this example is downgoing and contributes to the overall shape of the ST segment. The blue line connects the J point and the tip of the T wave and the red arrow shows the space between the blue line and the ST segment.
ST segment depression

Compare now with examples of flat ST segments. This ECG has ST elevation that is upsloping and flat:
ST segment elevation

This ECG has ST depression, has no slope and is flat:
ST segment depression

This ECG has ST depression, is downsloping and is flat:
ST segment depression

Summary:

Analysis of the ST segment must include the 3 details:

absolute position: elevation vs. depression
slope: upsloping vs. downsloping vs. none
shape: flat vs. concave vs. convex

Analysis of the ST segment is very important because many diagnoses are established by analysing the ST segment.