He first met [[Trent Reznor]] at their high school in Pennsylvania. They reconnected later in Cleveland, Ohio, in the mid-1980s when they were roommates and both played in a local band called the [[Exotic Birds]]. Additionally, Vrenna has been credited as an engineer for ''[[Pretty Hate Machine]]'' and ''[[The Downward Spiral (halo)|The Downward Spiral]]'', as well as playing live drums on the latter. He can be seen in the [[Nine Inch Nails music videos|music videos]] for "[[Down In It (song)|Down In It]]", "[[Head Like A Hole (song)|Head Like A Hole]]", "[[Wish (song)|Wish]]", "[[Gave Up]]", "[[March Of The Pigs (song)|March Of The Pigs]]", "[[Hurt (song)|Hurt]]" (live), "[[Eraser]]" (live), "Wish" (live) and "[[The Perfect Drug (song)|The Perfect Drug]]".
After leaving NIN, Vrenna formed the band [[Tweaker]]. The band has three full-length albums entitled ''The Attraction to All Things Uncertain'', ''2 A.M. Wakeup Call'' and ''Call The Time Eternity''. Vrenna's inspiration is derived mainly from surreal paintings and dreams. The inspiration for ''2 A.M. Wakeup Call'' came from his wife. She had trouble sleeping and would wake up each night at exactly 2 A.M. This gave Vrenna the idea for the album. He compiled several artists together for the album and told them that it would be based off of dreams and feelings that occur at night time. [[wp:Robert Smith|Robert Smith]] contributed to this album.
Vrenna has toured, both as Tweaker and as a touring musician for various bands. In 2006 he was a touring drummer for Gnarls Barkley, even wearing the original Chewbacca costume for the group's ''Star Wars''-themed performance at the 2006 MTV Movie Awards. He also toured with the former [[Nothing Records]] signed band, [[Marilyn Manson (band)|Marilyn Manson]] from 2007 to 2011, as a drummer and later a keyboardist. His career as a live/touring drummer ended after having torn his rotator cuff twice, and he is now a teacher at Calhoun Community College in Decatur, Alabama.[https://www.al.com/life-and-culture/erry-2018/10/2b578ecb8a5013/why-is-nine-inch-nails-marilyn.html]