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Generally, ECG signals are recorded using regular contact electrodes and are amplified (using a specialized isolated bioamplifier) with a gain of about 1000 and have a high-pass filter of about 0.5-1Hz and a low-pass filter of 30-50Hz. These filter settings eliminate the baseline wander due to movement artifact and respiration and reduce the wideband noise and power-line hum to produce a clean ECG signal ready to be analyzed.
If the signal that you have to work with was not already filtered (or the filter settings were not sufficient) you can easily apply a regular low-pass, high-pass, or band-pass filter to the data using the standard LabVIEW FIR or IIR filter VIs. There are lots of example that show you how to use these filters. Normally there is no need to get fancy here unless the ECG signal is badly buried in noise that you cannot control with good recording technique. As far as sampling rate, 500Hz is usually plenty fast enough to acquire the signal with enough fidelity for detailed analysis.
Steve
