A shock wave device (500) comprising an axially extending elongate member (502). The device further comprising a first electrode assembly (100) with first and second electrode pairs, wherein the first electrode assembly is carried by the elongate member and positioned within a conductive fluid. A controller (120) is coupled to the first electrode assembly, and configured to deliver a series of individual voltage pulses to the first electrode assembly such that each of the voltage pulses creates a shock wave in the conductive fluid. The controller includes a voltage source (122) having a constant polarity followed by a voltage polarity switch (124) for switching the polarity of the voltage source and causing current to flow through the electrode assembly in a first direction for some of the pulses in the series and in a second direction opposite the first direction for the remaining pulses in the series and wherein the voltage polarity switch only operates between the delivery of individual voltage pulses so each voltage pulse delivered to the electrode assembly has a single direction of current flow.
