Medical ECG Monitors using the AD620 Instrumentation Amplifier

One of features of the AD620 instrumentation amplifier is low current noise, this benefit allows its use in theElectrocardiography (ECG) monitors. A medical ECG Monitor Circuit is shown in the following picture, please click to enlarge the picture.
The picture tells the use of AD620 in ECG monitors where high source resistances of 1 MOhm or higher are not uncommon. It can improve the dynamic range for better performance when low bias current and low current noise coupled with the low voltage noise of the AD620.

Capacitor C1 maintains the stability of right leg drive loop. An isolation addition to this circuit may protect the patient from possible danger. You may see the datasheet here (source: http://www.hqew.net/circuit-diagram/Medical-ECG-Monitors-using-the-AD620-Instrumentation-Amplifier_5488.html).