supraventricular tachycardia
"I love this medicine! It has quite literally saved my life, and has made my life much more livable. Whenever I would do anything physical, my heart would beat so fast that I would frequently faint. I went to my cardiologist, and she gave me a holter monitor. She saw what I was talking about and gave me 50mg of Toprol-XL everyday. That was over 3 years ago, still on the same dosage, and it is wonderful. For the first few months, I was a little over tired, but that side effect quickly went away."