Ohh, that's what you mean. I'm an expert on chronic... Actually, let's stop that sentence mid-structure. You don't want to hear the end of that.
Gist of things is that too much stress on the reproductive parts causes faster heart rates, as does using the bathroom. So if you're really constipated or bad in bed, your heart might beat so fast, it'll explode. Emotions and thoughts associated with, well, reproduction, will send up your heart rate (And maybe your blood pressure too,) thus the "Love organ."
It's all a matter of stress. Too much stress on anything, be it caused by your mind or your physical pieces, will cause your heart to beat faster. This partially contributes to the unpredictable nature of heart attacks. Sure, you'll get them more if you're fat, but thin people get them too.