Different wave forms are shown in electrocardiograms, and the varying pulse rates and charts are explained. A boy with atrial tachycardia is shown and his pulse measured. This section is entitled 'Atrial fibrillation' and is narrated by Paul Wood. An electrocardiograph of atrial fibrillation is shown and described in detail, then shown in close-up in the neck of a young woman and the veins of her legs.