Shockwave lithotripsy is a well-established technique for breaking down kidney stones non-invasively. In this process cavitation bubbles are generated in the shockwave passage. From these cavitation bubbles, gas fragments remain, which shield the shockwaves and limit shock repetition rate, as time is needed for these fragments to dissolve or move away. To increase shock repetition rate, here we propose to use (microsecond-long) ultrasound pulses between subsequent shocks to coalesce the gas fragments and move them away from the shockwave passage region, such that the next shock can be released earlier. We study these processes using high-speed video imaging and show that indeed the amount of unwanted cavitation produced by the lithotripter shockwave is reduced.