Trycyclics will do that - thats why I cant try them for PN... but if they cant find any heart issues - maybe best thing to do to ask doc if you can go off them and try something more appropriate for what you are being treated for? I know withouth my beta blockers if I even miss a dose I start getting tachy - so unforutnately I'm stuck with them - but - the less meds the better and ifs theres something that would be more on point for you???????