Hey thanks for the comment! Great to hear you enjoyed it :) The medical condition that you are clearing the blockages from is actually a plaster along the wall of the artery in real-life. So our original goal was for the player to grind it away from the edges and get a speedup from that. Later on we changed that during our playtests, but we kept the grinding since it was just really fun to grind along :) So currently you get increased max-speed and increased impulse from the heartbeat the longer you grind.
We should probably make this all way more clear in a next version. We had a lot of feedback that it wasn't really clear if grinding was good or bad since it looks like damaging.