Re: I have heard that a normal hearbeat is not perfectly regular, and that...

Oh, well!!!! lets see.....Why dont you check it for yourself? In faact u 
will be surprised to know that our heart beats are in fact very regular 
except for a little bit of irregularity, that cant  be very well 
recognised, and that's perfectly normal. 
So, what you have heard is absolutely right, that our heartbeats are not 
perfectly regular, but that does not mean that to have regular heart beats 
is abnormal. 
Actually, the little bit of irregularity that is found is due to our 
breathing. Notice very carefully, and you will find that our beats go up a 
little when we breathe in and go down when we breathe out. This is a 
normal mechanism, and there is nothing to worry about it. This 
irregularity is often not discernible.
the reason for our heart beating faster during breathing in is that as our 
chest expands, there is a negative pressure created inside. This causes a 
rush of blood from the extremities into the heart, making it beat faster 
to remove the excess load. The opposite happens when we breathe out - the 
pressure increases, blood flow into the heart is reduced and the rate goes 
down.