Aaron will have a tonsillectomy, a media release from Champions League said.
"The Karbonn Smart Champions League Twenty20 Technical Committee has today confirmed a change to the Delhi Daredevils squad. Aavishkar Salvi has replaced Varun Aaron after the 22-year-old India international was advised he will need to have a tonsillectomy which will rule him out of the tournament," the release stated.
Salvi, 30, is a right-arm medium bowler who played four ODIs for India in 2003. He has taken seven wickets in as many IPL games for the Delhi Daredevils.
Delhi Daredevils will open their Champions League Twenty20 campaign on the opening day of the Group Stage, Saturday 13 October, against Kolkata Knight Riders at Centurion.