Squeak,
The heart does this to unexpected people. It is an electrical imbalance. It is not fatal. If it happens again, you are to pour ice cold water on your face, neck, etc., as to shock it to a regular beat until emergency medical assistance arrives. Another tactic is to hold your breath as long as possible and exhale hard. What meds do in extreme case is to medically stop and restart the heart to its proper rhythym. It is very scary.
zuki