This records the heart’s electrical activity while the patient goes about their usual daily activities. The ambulatory test procedure allows the patient to walk and perform other daily activities during the test. Also called ambulatory EKG, 24-hour EKG, cardiac event monitor, heart rate monitor or Holter monitoring. Portable event recorders are worn by the patient for specified periods of time to reveal longer-term heart functioning. A heart rate monitor does exactly what the name suggests: it monitors a patient’s heart rate.