I am really confused about the Representation of potential in an ECG graph.
First i will ask what is on the vertical axis? (I guess it is electrical potential in millivolts) But again it changes for various positions and the graph takes a different shape. These are called Lead positions ( correct me if i am wrong ) I don't understand why the waveform changes for different Lead positions. Basically I do not understand how the ECG machine works in relation to what happens in the heart ( i.e. the action potentials from SA nodes and so on...)
This diagram shows what I meant. How am I supposed to interpret the data if it is different depending on direction.
I will be grateful if someone can also provide some information on the cardinal directions in these cases.