Viadana's day began badly when Daniel Yakop was sin-binned inside seven minutes, and Wasps took full advantage as Helu opened his account two minutes later.
Anthony Fenner kicked a penalty for the hosts before two tries in three minutes gave the Wasps a commanding lead.
The first was a penalty try after Viadana failed to cope with Wasps' scrum, while Kearnan Myall went over shortly afterwards.
Helu then touched down twice in as many minutes to secure a hat-trick on his first appearance for the club with five minutes still left in the opening period.
The visitors picked up where they left off at the start of the second half, scoring another try through Thompson within one minute of the restart. Thompson then completed a hat-trick of his own six minutes later.
Jack Moates edged Wasps closer to their record points tally in a European game with a try in the 52nd minute and went on to break the record himself eight minutes later with his second debut try.
Charlie Hayter scored his side's 13th try in the 71st minute before Viadana got another score back late on to make it 85-17.
Wasps were not finished yet, however, as they ended the game with yet another try, this time through Joe Simpson, to reach the 90-point mark, ensuring that they opened their Challenge Cup campaign in style.