If you were doing your normal routine and never, ever, had this problem - then maybe cause for concern. However, anxiety will do the same thing to you. I do know that in this recent study - "Stimulant medication for the treatment of attention-deficit/hyperactivity disorder (ADHD) in children with congenital heart disease (CHD) does not affect heart rate or blood pressure and can be safely administered in this patient population, new research suggests." From - http://www.medscape.com/viewarticle/852555?src=wnl_edit_tpal&uac=96999MR
Hope this helps.