Detection of takeoff potential from intracellular recordings

The measurement of takeoff potential from intracellular recordings of the cardiac action potential may be useful in the study of the cardiac action potential may be useful in the study of spontaneous automaticity and of the effects of cardioactive drugs on active propagation. We describe a circuit capable of detecting and storing the membrane potential at a point where the slope of the membrane potential exceeds a preset value. The capability of this circuit to track the takeoff potential was tested using intracellular recordings from cardiac Purkinje fibers during spontaneous automaticity as well as during electrical stimulation.