My grandfather used to have an old megger (megaohmmeter), probably from the mid-1950s. This meter was from a time long before the VTVM and very long before the FET-amplified meter, and used a 500 volt hand-crank dynamo to generate the power needed for a resistance test! I once experimentally touched the terminals on it while cranking, and it was quite uncomfortable.
I have no doubt that the voltage from this meter, applied in the proper fashion, could interrupt the beating of the heart. Of course, I'm fairly sure that it would have no effect on me, though, as I've taken a blast of 480 volts AC with no noticeable ill effects (aside from two small surface burns... entry and exit). That which does not kill me, makes me stronger.