supraventricular tachycardia
"I first had SVT when I was 13 but undiagnosed until 18. I had episodes that lasted 1-36 hours. Episodes occurred 1-5 times/month. Average BPM was 190 and upon reaching 235  BPM I would start to loose consciousness. I tried all varieties of maneuvers to trigger the SVT to stop but none worked. If it laster longer than an hour I was transported to the ER where I was given Adenosine to restart my heart. I was given an Rx for Metoprlol Tartrate a few months before my first ablation when I was 20. I was started on 25mg/day. 9 days after my ablation, I had more episodes and was bumped up to 50mg, 100mg, then 150mg/day before my second ablation when I was 21. Had it been unsuccessful, I'd have been switched to an Ace-inhibitor."