Medical symptoms "There is an association between these two conditions, but we still don't know the exact mechanism," Gao said. His team said further research is warranted. where to buy viagra canadian viagra for sale Uncontrolled, potentially life-threatening abnormal heart rhythms Received September 30, 2003; de novo received December 21, 2003; revision received March 10, 2004; accepted March 17, 2004.