ventricular tachycardia
"I was prescribed this temporarily for a bout of rapid resting heart rate.  I was unfortunate enough to have some of the severe side effects, including depression.  I was inconsolable as every tiny little thing set me off to bawling!  I also had tightness in the chest when I tried to walk down the street.  Definitely did what it was supposed to do, which was slow my heart, but the side effects were too much."