A Holter monitor is a portable electrocardiogram (EKG) that monitors the electrical activity of an ambulatory (freely moving) patient’s heart while the person goes about daily activities. There are a few reasons a physician might request that a patient wear a Holter monitor, but the most common is to diagnose an abnormal heart rhythm (arrhythmia). They are also sometimes used to monitor existing pacemakers, diagnose a lack of oxygen-rich blood flowing to the heart (cardiac ischemia) and measuring variability in the heart rate.
