Spacelabs Cardiocall VS20 Dual Mode ECG Event RecorderEvent Mode when the patient has a symptom, they place the electrode feet on the back of the recorder, directly onto their chest and press a button. The ECG is then recorded for a pre programmed duration. Loop Mode the CardioCall is attached to the patient by electrodes. When the patient senses a symptom they capture the ECG by pressing the event button. The recorder then stores the episode that includes ECG data that preceded, and followed the patient