Unknown circuit symbol ("10 NP")
It is a 10uF non-polarized electrolytic capacitor. 

Here's a similar ECG front-end circuit that uses the AD620 as an electrode amplifier (from this site, en Francais): 



In that case, the designer used a 2,2uF film capacitor with a 2,2M resistor to form a 0.033 Hz high pass filter (\$ f_C = \frac {1}{2\pi RC})\$. 

As has been pointed out, the symbol is not quite correct. Here are a couple suggested symbols for non-polarized (NP) capacitors (also BP bipolar capacitors, which some manufacturers distinguish)- from this site here.