Breaking the rhythm w/o medication

  I am a 27 year old female, and I had my most serious episode of tachycardia last year.  My doctor told me that I would probably have one big episode per year and perhaps minor episodes at various points.  He gave me the option to go on medication, or to attempt to break the cycle naturally whenever an episode started.  I opted to not take medication.
  This morning, I had another serious episode, when my heart rate bounced up to 180 while I was standing in the shower.  I laid down in bed and did the exercise I was taught last year by the paramedics:  hold my breath and push as if I was giving birth.  For some reason, this slows my heart and it was successful in breaking the extremely fast rhythm only minutes after it started.
  Why is it that this exercise works?  My doctor also told me that other people have had success with washing their face with really cold water, and sometimes with rubbing their eyes.  It seems odd, so I'm curious how these kinds of things can actually help restore a natural heart rhythm.
  Thanks,
  -- lesa

[CCF CARDIO MD APS]

Dear Lesa,
Holding your breath and bearing down, placing your face in cold water, rubbing your eyeballs, or putting pressure on your carotid pulse in your neck are all stimulants
of vagal tone.  Vagal tone is one of many responses our bodies is able to perform; essentially all of us have vagal tone that is in balance with our sympathetic drive.
There are times when our bodies tilt the balance to one system (vagal or sympathetic) depending on the situation, the best example is in a fright or flight situation
(danger or when startled)the sympathetic system kicks in to overdrive and all of a sudden you have a lot of energy.  This all happens automatically and thus it is called your
autonomic nervous system.  The vagal system I speak of is really known as the parasympathetic system and this has the opposite function, i.e. kind of a relaxer type system.  
So when you get these tachycardias, and you perform one of the maneuvers mentioned above, you actually are stimulating your vagal system to go in to overdrive and this in turn
relaxes many organs in your body but most importantly your heart conduction system.  This is a very quick and non precise explanation, however it should help you to better understand
why and how it works.  Essentially you are taking advantage of a system that already exists in your body to break the tachycardia.  Just a word of warning if ever you feel dizzy or light headed with you tachycardias
or you notice that the vagal maneuvers are not breaking the tachycardia, call 911 for assistance, do not try to take yourself nor let someone else drive you to the hospital.  Sometimes the EMS people in the amblance can break the tachycardia.
Information provided in the Heart Forum is intended for general informational purposes only, actual diagnosis and treatment can only be made by your physician(s).