A Holter monitor is an electrical medical device that can automatically take action for a certain period of time. In most cases, the Holter is an ambulatory device worn directly by the patient for a 24-hour period. The two types of Holter that are the most popular are the cardiac holter or the Holter-ECG, and the blood pressure holter. The Holter-ECG can record the heart rate over a longer period and enables the detection of certain cardiac pathologies which are intermittently present, such as a premature heartbeat, or certain types of cardiac arrhythmias by atrial fibrillation (ACFA) when they are paroxysmal. The blood pressure holter meanwhile performs several functions day and night, and reflects more accurately the actual blood pressure values of the patient in his everyday life.