Maybe by 'breathe' the doctor meant to breathe slow, steady breaths when palpitations occur?... How many beats are there per minute at rest when you are having an episode of palpitations? Are they even? How often does this happen? Do they come on after coffee or tea...like mine did?
When it happens does coughing or 'bearing down' like you are giving birth, help? One poster recently wrote that putting her face in cold water was the only thing that helped her heart simmer down.
If I were you, I would do 3 things:
1. Cut out all caffeine drinks/food and alcohol. Whenever I drank coffee, my heart would race.
2. Cut out all sugary foods and cut back on carbs in general which means upping the veggie/fruit intake to 6 - 10 servings per day.
3. Get out and exercise every day. To my doctor's absolute shock and surprise, I cured my serious case of atrial fibrillation (erratic and racing beats) by going to the gym every day for aerobic exercise.
The cardiologist told me that he only medicates (last resort) 1 in 10 patients who go to him with episodes of erratic heartbeats and palpitations. I was the 1 in 10 because my heart was constantly out of rhythm, racing and I felt faint...because not enough oxygen was getting to my brain. And I was only 46 years old. You are probably fine and just need to do a few lifestyle changes as I mentioned above. Think of the palpitations as your body warning you to get in shape, keep off the sugars and caffeine. The doctor must have found your palpitations to be non life threatening which is GOOD NEWS. Still, YOU are your own first 'health care provider' and you need to be aware of what is going on with your body, to do the necessary research and to take care of your body.
Think of it as your body is a wonderful gift that was given to you. It would be disrespectful to not treat it well and take good care of it.
Good luck!