Answer:
when a person is not breathing
Explanation:
The electrocardiogram shows the cardiac action of the heart as a means of the sinusoidal waves. However, the waves have a different structure as they show the pumping phase, breathing and the resting phase of the heart. The waves continues to be displayed as long as there is systolic and diastolic pressure in the heart muscles. When there is no action, such as the cessation of brain activity, action ceases.
