Now we're going to attach the ECG electrodes which will measure heart rhythm overnight.

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The yellow electrode (for the upper left chest) has a useful colour coded diagram which indicates the correct positioning for all three of these electrodes - green corresponds to site 1 in our diagram, yellow to 2, and red to 3.

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Again, don't worry just yet about where to plug in the connector for this electrode bundle – we're about to come to that.