The stimulus artifact can be reduced to an acceptable level by either increasing the input impedance of the differential recording amplifier or increasing the impedance between the stimulator output and ground.1 A stimulator with a grounded output (stimulator to ground impedance is approximately zero) can be used if a differential amplifier with a high input impedance is used to avoid overloading the amplifier. Normally, however, an isolated stimulator (stimulator to ground impedance is very high) is used so that the input impedance of the amplifier is less critical.
Veale JR. Tests in Patients With Pacemakers-Reply. JAMA. 1977;238(14):1501. doi:10.1001/jama.1977.03280150071022