Based on studies with dogs by Prof Leslie Geddes in the middle of last century, it is theorised that a current as low as 10 μA (microampere) directly through the heart, may send a human patient directly into ventricular fibrillation. Of course, the exact outcome is dependent on the duration of the current, the exact position of contact, the frequency of current oscillation, and the timing of the shock with the hearts rhythm e.g R on T phenomenon. It is feared that such a small current may be introduced unwittingly, and unobserved, creating a very perilous situation for the patient. To guard against this slim theoretical possibility then, modern medical devices include a range of protective measures to limit current in cardiac-connected circuits to the assumed safe levels of below 10 μA (microampere) . These measures include isolated patient connections, high impedance connections and current limiting circuits. Despite the in-built protections, and lack of observed incidents, microshock continues to be a concern to many practitioners of the fields of Biomedical and Clinical Engineering.