Holter and event monitors are medical devices that record the hearts electrical activity. They are similar to an ECG and these monitors can be worn from 1 to 14 days on average. They help determine if your symptoms are related to an electrical problem in the heart.
In some cases, an implantable loop recorder (ILR) can be used to help diagnosis your symptoms. This is a device that is implanted under the skin for 1-2 years to monitor for abnormal rhythms.