What Causes Missed Heart Beats After Taking Hydroxyzine?

My heart seems to stop by itself then it starts back up with a huge thump. I always have to take a deep breath when this happens. I am currently battling Pericarditis but this beating problem didn t start until after I took one pill of Hydroxyzine for panic attacks. That was on the 18th of This month, but I am still feeling this thumping. It s really scaring me.