Occasionally, despite thorough evaluation, patients continue to have infrequent fainting spells that defy explanation. In such cases, doctors may choose to implant a “Loop Recorder”.  This device is implanted under the skin and acts as a long-term ECG recorder, continuously monitoring the patient’s cardiac rhythm, for up to two years.  This device does not require activation by the patient and will record any cardiac rhythm disturbance that meets the definition of being abnormal, as defined by the implanting physician.  For example, if the patient has a rapid heart rate exceeding a specific rate, the internal ECG will automatically be recorded and saved for future examination by the doctor.  Similarly, if the heart rate drops below a predetermined rate, this will also be recorded for the doctor.  At an office visit, the memory of the device can be queried, and the doctor can see whether or not there is any correlation between the patient’s symptom, e.g., dizziness or fainting spells, and cardiac rhythm abnormalities.  Once this has been established, the device can be readily removed (a simple operation that takes only a few minutes) and the appropriate therapy offered to the patient.  Such therapy might be implantation of a permanent pacemaker (link), if slow heart rates were seen to correspond to episodes of dizziness or fainting.  Alternatively, if the patient had a rapid heart rate during such symptoms, medication or ablation might be offered to the patient.  As importantly, if the patient has had symptoms such as fainting and no cardiac rhythm disturbance is recorded, then the doctor can safely conclude that cardiac rhythm disturbances are not responsible for these symptoms.