The club said Friday that the procedure was performed in London, Ontario, by the same medical specialists who treated Gustavsson last season, when he was first diagnosed. He has since had two surgeries to treat the condition and should be cleared to practice in about seven days.
The Swedish goaltender had been with the minor league Toronto Marlies when he was pulled from a game Wednesday because of an elevated heart rate. It was his second straight start since being assigned to the AHL for a two-week conditioning stint.
Gustavsson has played in 23 games for the Maple Leafs this season, going 6-13-2.