A loop recorder is a device which is capable of recording your heart rhythm for small periods of time. It attaches to the patient with wires (leads) like a Holter monitor but is typically much smaller and uses a fewer number of leads. It can be removed for periods of time to enable the patient to shower or bathe and can be reattached by the patient.A loop recorder is usually performed to evaluate intermittent and/or brief symptoms of palpitations, dizziness, or lightheadedness when an arrhythmia is the suspected cause. This device is preferred over an event monitor when loss or impairment of consciousness might be an issue and/or when symptoms are of brief duration. This device might be employed if a Holter monitor recording does not elucidate the cause of symptoms. Since arrhythmias can sometimes be intermittent, a single 24 hour Holter recording or even many 24 hour Holter recordings might not be adequate to capture the arrhythmia. The loop recorder works by continuously recording your heart rhythm onto a memory chip. When you have a symptom, pressing the button on the device freezes the previously recorded information and continues to record and store your heart rhythm. The amount of time of your heart rhythm that the device stores before and after the button is pressed is usually programmable but is typically 30 seconds and 1 minute, respectively. When finished, the rhythm can then be transferred via the telephone to a station where it is printed on paper and faxed to a physician. This device can be very helpful in correlating an arrhythmia with a symptom. The device itself is smaller than a Holter monitor and the leads can be removed and replaced by the patient so it can typically be used for weeks at a time with minimal inconvenience. The drawback of the device is that it does need to be attached to the patient and can therefore be inconvenient to use for long periods of time. There is also an implantable loop recorder available which is similar in function to the external loop recorders except that it is implanted underneath the patient's skin. This device is typically used in patients who are passing out (syncope) infrequently without a clear cause for the episodes. The device can be activated by the patient after they regain consciousness or can be set to activate itself for very slow or fast heart rhythms. It can then be interrogated through the skin by their physician at a later time. When the cause of the syncopal episodes is finally elucidated, the device can then be removed and appropriate treatment can be initiated. The battery in these devices usually lasts 18-24 months.