question: I am a 45 year old white female, standing 5'4"and weigh 128 lbs.  I was diagnosed and treated for graves disease six years ago and no longer take medication for this.  The past 3 weeks I have been experiencing heart palpitations and a feeling of not being able to get a good breath.  I had my thyroid levels checked and they came back at the low end of normal.  I have had routine blood work, d diamer, chest x-ray, ekg all came back normal.   I have recently worn a holter monitor which came back showing PVC's.  The Dr prescribed Metoprolol 1/2 tab at night and this isn't really helping with either the palpitations or the breathing and now I am feeling light headed.  I am scheduled for an echo stress test tomorrow but I am wandering where this may be going or if you have any other thoughts as to what can be going on.  I have always been healthy and have only missed maybe 2 days work in the past 20 years for any type of illness.