Cardiology Teaching Package
A Beginners Guide to Normal Heart Function, Sinus Rhythm & Common Cardiac Arrhythmias
The ST Segment
There is a brief period between the end of the QRS complex and the beginning of the T wave where there is no conduction and the line is flat. This is known as the ST segment and it is a key indicator for both myocardial ischaemia and necrosis if it goes up or down.
Image: The ST Segment
So now you can see the 3 phases of the cardiac cycle which represents one heart beat. The previous example shows a rhythm strip of sinus rhythm. Here you can clearly see how each heart beat is made up of 3 distinct waves: a p wave; QRS complex, and t wave.
When you have a lot more experience you will be able to evaluate all 5 waves, but for now stick to 3.
