What was the cause of heart palpitations?

Many: Everybody's heart does a flipflop (unexpected beat) every once in a while. More than 5/minute -- try cutting back the caffeine, &/or get with your physician. Runs of very fast rhythm, or chest pain or syncope with the palpitations should prompt an office visit.

Palpitations: These are caused by many things. Stress, excitement, irritants both physical and chemical, pressure like a hiatal hernia or esophageal push or pull, and primary heart things, the causes are very many in number.