During open heart surgery a child's chest cavity can be filled with an icy slush to slow the heart's oxygen requirement and give the surgeon a longer window of operating time.
Ms Himona said this year they were looking at getting more high schools and intermediates involved, to try and raise awareness of the connection between rheumatic fever and heart problems.
She said teams could be made up of four to six people who together spend five minutes in the chilled pool.
The challenge will take place on July 3 between 11am and 2pm at the Rotorua Aquatic Centre.
To register go the Heart Kids Rotorua page on Facebook or register online at www.heartstopper.org.nz.