Constant current pacing apparatus with protection from high voltage pulses

A method of providing constant current pacing to a patient, wherein the method comprises:

• providing an H-bridge circuit comprising a high side and a low side, wherein the H-bridge circuit comprises first and second legs connected between the high side and low side thereof, wherein the first leg of the H-bridge circuit comprises first and second current switching elements and the second leg of the H-bridge circuit comprises at least a third current switching element, wherein a patient is connectable to the first leg of the H-bridge circuit between the first and second current switching elements and to the second leg of the H-bridge circuit, wherein one of the first and second current switching elements along with the third current switching element define a pair of current switching elements such that, when the constant current pacing apparatus is operational and the pair of current switching elements are selected, a pacing stimulus having a first polarity is applied to the patient;
• providing a constant current source connected to the high side or the low side of the H-bridge circuit, wherein the constant current source comprises a voltage source and a controlled current output circuit connected between the voltage source and the H-bridge circuit;
• applying a control signal to the controlled current output circuit representative of a pacing stimulus to be applied to the patient, wherein the control signal is based on an arbitrary input waveform;
• and
• generating a constant current output based on a relationship defined by the controlled current output circuit between the control signal applied to the controlled current output circuit and the current flow through the controlled current output circuit, the constant current output being applied to the H-bridge circuit for application of a pacing stimulus to the patient upon selection of the pair of current switching elements.