Holter monitoring. A technician attaches several electrodes to your chest to monitor your heart’s electrical activity. A small device worn on a belt or shoulder strap records the information. At the end of the testing period—typically one to two days—you return the monitor so the data recorded can be analyzed.

Event loop monitoring. This device is attached in much the same way as a holter monitor. When you feel symptoms of a heart problem, such as palpitations, you press a button on the monitor. Information on your heart’s electrical activity is then sent to your doctor for analysis. This device can be removed for bathing. At the end of the testing period—typically one to four weeks—you return the monitor so the recorded data can be analyzed.