12 and 18 lead ecg

Hi i was wondering what the dufference of a 12 and 18 lead ecg all came out good but the er doc did nit explain what the difference was? Any thoughts would be great thanks

[ed34]

I believe the 12 lead ecg lacks sensitivity in the right ventricle and the back of the heart, so additional electrodes are used. There can be confusion too with the word 'lead'. Most people assume it means one of the wires coming from the ECG machine, but it isn't. For example, a 12 lead ECG uses 10 wires/electrodes. The word 'LEAD' refers to a signal received by the ECG machine from across 2 electrodes. One electrode can receive a signal from 2 other electrodes giving 2 inputs, hence a 10 electrode ECG giving the name 12 lead ECG.
I'm not sure, but I think an 18 lead uses 16 wires/electrodes but is far more sensitive.

[ed34]

Oh just to add, I think there's also a 15 lead ECG using 13 wires/electrodes