supraventricular tachycardia
"this medication almost took my life.  during the 6 years I was on it my cardiologist kept raising the  dose. I had difficulty standing on my feet, developed severe headaches, slurred speech and dark veiled vision. over time my fingers turned dark purple like grape juice. I reached the point where I could not sit up one morning without help. my daughter discovered my back was dark purple as well. the emergency room doctor took me off immediately stating a severe reaction."