I would DEFINITELY use opto-isolators (my EEG BCI had them) and would always run the ECG on a laptop with its AC adapter _unplugged_. Do you really want to risk

I would DEFINITELY use opto-isolators (my EEG BCI had them) and would always run the ECG on a laptop with its AC adapter _unplugged_. Do you really want to risk even a small chance of electrocution?