Bisoprolol, Adrenaline and ADHD/Autism relationship

I was recently kept in hospital after an episode of P.S.V.T (genetic, very fast arrhythmia) for which I have already been taking Bisoprolol. External noise coupled with stress and anxiety at getting stuck in a thought-loop when trying to progress a writing task for university (I've been at the same work for several weeks). The dosage of Bisoprolol (a low one ) was doubled which reduced my heart rate after a few hours. On the one hand my mind was relaxed and I spent all that night in hospital 'writing' my essay. When I returned home I woke up dopy and depressed. I have struggled to find any energy or motivation and I am back to square one with the writing. I need adrenaline for confidence, yet I cannot do anything that might spark a recurrence of the heart problem. (On this occasion it got very scary as the solution might have been to stop my heart with an intravenous injection of Adenosyne allowing it to restart. The doctors were reluctant (fortunately) to subject me to what they termed 'a very unpleasant procedure'.) Any suggestions as to how I can get out of being unstuck?