supraventricular tachycardia
"I was put on 50 mg 3 X a day for rapid, arrhythmic heartbeat and high blood pressure, in November last year.  At first, it made me very sleepy and dizzy, but I have gotten over that. It lowered my heart rate into the low 60's and 50's, occasionally upper 40's. Halving the dose has not changed this; I am hoping to be off it, or at least on an even lower dose, after my next cardiology appointment in June.  I think it is making me forgetful. That has definitely been a problem since taking it, although I was a bit of an absent-minded professor before. It may also have helped lower my blood pressure, although I have made some diet and lifestyle changes that would affect that, also."