I bought a stethoscope. I always used to think that the heart went "Ta-Bum ... Ta-Bum ... Ta-Bum ... Ta-Bum ..." but I find that it actually goes "Tiddy-Bum ... Tiddy-Bum ... Tiddy-Bum ... Tiddy-Bum ..." Except that sometimes mine goes "Tiddy-Bum Uh-Oh ... Tiddy-Bum ... Tiddy-Bum ... Tiddy-Bum Uh-Oh ... " The "Uh-Oh's" are probably PAC's (premature atrial contractions) which I get sometimes (confirmed by EKG). Sometimes it goes "Tiddy-Bum Uh ... Tiddy-Bum Uh ... " and I think that's probably PVC's (premature ventricular contractions, which I get much less often - also confirmed by EKG). The creepiest is when it goes totally bonkers, no pattern at all, and I figure that's atrial fibrillation (likewise confirmed by EKG) Confirmed, that is, that I have all these things. I am guessing that certain patterns I hear correspond to certain types of irregularities I know I get. But the real point of this post is to ask if anyone knows what the normal Tiddy-Bum represents? The Tiddy is two distinct sounds so close together as to be touching, and the Bum is separate. (My heart operation is normal, except for the irregularity. No valve problems.) So there's an atrial contraction, followed by a ventricular contraction, but I hear three distinct sounds. Am I hearing the valves? Or am I hearing the rebound after the pumping stroke? Or something else entirely? Maybe Evan can explain? Or do we have another doctor in the house? Maybe a cardiologist?