I am a 24 year old female and I believe that there is a direct correlation with PVC's and hormones. I have had PVC's since I was 19 and I have done a lot of research and experiments with them. I have noticed that caffeine, stress, excitement, exercise and alcohol all trigger PVC's for me. All of these also increase adrenaline. Another thing that makes me think it could be hormone related is that about a year and a half ago I went vegan. While I was vegan I had no constipation or PVC's. I suffer from severe constipation. Our diary and meat are full of hormones. The only reason I started eating dairy again is because I was losing a lot of hair. I wasn't supplementing correctly. I am going try going vegan again. I will keep you updated on how it turns out.
You may want to check out the Heart Rhythm community:
There's also a heart rhythm tracker: http://www.medhelp.org/trackers/list/78