Holter is a portable ECG recorder which is attached to patient’s chest. It records ECG continuously for 24 hours or more. It is useful in evaluation pf palpitations & rhythm disturbances which are episodic & not continuous.
Externel Loop Recorder (ELR) is a patch which is stuck to patient’s chest which records ECG for more about 3 days to 1 week. It uses internet enabled phone to transmit the data.
Implantable Loop Recorder (ILR) is a small device implanted under skin below the shoulder blade. This records ECG for prolonged time (3- 6 months).