supraventricular tachycardia
"I'm 13 years old and have had tachycardia all of my life. Four years ago, I was given metoprolol and it changed my entire life. Before it always felt like my heart was trying to leap out of my chest, or hammering through my rib cage, or my heart was hammering away so hard I could feel it in my throat but metoprolol changed that. It has given me a  new freedom. I would recommend it to anyone with my problem."