28
Participants
Start Date
December 31, 2007
Primary Completion Date
April 30, 2009
Study Completion Date
July 31, 2009
Sildenafil
One 20 mg capsule of sildenafil will be taken by mouth three times-a-day.
Placebo
One placebo capsule will be taken by mouth three times-a-day.
The Mark H. and Blanche M. Harrington Foundation
UNKNOWN
Children's Hospital of Philadelphia
OTHER