Hi,
I am a 19 year old male (215 lbs) who about a year ago experienced a rather scary heart arrhythmia while masturbating, along with shortness of breath, palpitations, and very minor chest pain. The episode itself lasted only a couple of minutes or less, but was very worrisome. Since then, I have had at least five very similar episodes while masturbating. Also, I do not exercise often, but when I do I tend to get shortness of breath easily along with palpitations. Once I became nauseous after exercising as well; however, I have never experienced any form of heart arrhythmia (that I can recall) while exercising, only while masturbating. For the record, I masturbate at least twice a day, and most of the time I do not think I have any problems while doing so, but I am terrified that something could be amiss with my heart. Once I might have even briefly fainted after having an orgasm, but it is hard to tell.