A medical device, such as an electrocardiogram (ECG) monitoring apparatus, provides galvanic isolation between low voltage electronics and a plurality of externally exposed ECG (patient contact) lead wires and electrodes. The ECG lead wires and/or electrodes can potentially make unwanted contact with sources of high voltage, such as from defibrillation pulses generated by defibrillation devices. The defibrillation pulses can cause damage to the low voltage electronics within the ECG monitoring apparatus. Electrical resistance is provided outside of the ECG lead wires and electrodes and separate from the low voltage electronics to protect against misdirection of a defibrillation pulse towards the low voltage electronics, and to protect against misdirection of a defibrillation pulse away from the patient for which the benefit of the defibrillation pulse is intended.