I found this on raptors.com
Originally Posted by Raptors.com
As a result of concerns raised during routine pre-season cardiac screening, Nathan Jawai will be held out of practice until further tests are conducted. It is anticipated that these tests will be concluded later this week.
The club acquired the draft rights to Jawai from the Indiana Pacers on July 9. He was the 41st overall selection in the 2008 NBA Draft. He is the first indigenous player from Australia to be drafted by an NBA team.