AC leakage currents cause complete hemodynamic collapse below the ventricular fibrillation threshold

In 1993, the American standard for leakage current through the heart under a single-fault condition was increased from 10 /spl mu/A to 50 /spl mu/A rms. Both the original 10 /spl mu/A standard and the new 50 /spl mu/A standard were based on estimates of the ability of 60 Hz AC current to induce ventricular fibrillation (VF). This basis was a logical choice, since VF causes systemic blood pressure collapse, which can quickly cause morbidity and death. However, Swerdlow et al. (1999) showed that systemic pressure collapse can result from 60 Hz AC leakage currents (84/spl plusmn/27 /spl mu/A rms) far below those required to induce VF (278/spl plusmn/226 /spl mu/A rms) in 32 closed-chest humans. In this work, we extend the human results to a dog model and show preliminary evidence for the mechanism of the collapse.