High frequency filter circuit design
Assuming you want to measure cardio signals with a flat gain/phase response to 300 Hz and > 100 dB attenuation on  signals from arc noise from Electrosurgery > 100kHz.

I would chose RLD, STP cables ,active CM shield with CM chokes this attenuates by balancing the input signal to cancel mutual coupling of high stray E-B fields [V/m, A/m]

If your noise is less , pls specify.

I chose a 6th order RLC 10kHz filter, This would be differential "Pi filter" for differential signals with SMD Chokes with SRF assisting with attenuation.

Show below as single ended.



Simulation 

More practical L Values