Cardiac stimulator for the study of refractory period control using current pulses of programmable duration and shape.

A programmable current stimulator has been developed that allows unipolar current pulses of complex shape, long duration and high current to be generated. The stimulator conforms to the safety requirements for devices connected directly to the heart. It incorporates additional safety features to prevent unintended current being delivered, even under fault conditions. The stimulator has been used to investigate the effects of long duration current pulses on the refractory period of cardiac tissue. The flexibility of the device suggests that it may well have uses in other fields of electrophysiology.