Slowing of heartbeat following surprise/shock

When I was younger I passed out several times in situations like a scary movie, sight of too much blood, excessive worry, etc. I wouldnt pass out quickly, rather I knew it was coming and could recognize it was happening and lay down before fully blacking out.  I wore a halter monitor for a while, but the doctors never found anything. They suspected some sort of over-reaction to adrenaline but I didnt really understand what they meant at the time.

Last week, I broke my nose. The shock from it was much worse than the actual injury, as my heart rate slowed to about 20 bpm, and was barely noticeable my pulse at the wrist and neck. I was barely able to remain conscious, and couldnt stand without coming to the brink of passing out. After about 10-15 minutes my heart rate went back to normal.

One other note is that I have had random bouts of atrial fibrillation. They seem to come more often from lack of sleep or when Ive had too much caffeine, nicoteine, etc. Ive since cut out the latter 2 from my diet, but I figured I would mention this since it seems relevant. I have a prescription for Cardizem.

Im having surgery on my nose tomorrow where I'll have to be put under for about 30 minutes. I have two questions.

1. Does anyone know what might be causing this massive reactionary slowdown? I would expect my heart to race in such situations like breaking a bone, etc., but its doing the exact opposite.
2. I realize I cant take this as official consult, but what is your hunch on the anesthesia? In your opinion, would it be ok for someone with the described conditions to go under?

Thanks in advance!

[Hoggle]

Well I got through the surgery/anesthesia just fine. Still wondering if anyone has an explanation for why my heart slows down so badly following shock/surprise?

[jkfrench]

It is called a vaso vagal attack I think.  Instead of the heart speeding up, it slows down and beats really slow and hard for a few minutes.  It has to do with the parasympathetic nerves.  These nerves hold the adrenalin-releasing nerves in check.  In this case (or your case) they check too severely and the heart slows to an uncomfortable rate.  (this is a direct quote from Hope and Help for your Nerves by Dr. Claire Weeks).
From what I understand it isn't anything to worry about except it is really disturbing and uncomfortable.
Frenchie

[kim8400]

I actually had the same thing happen to me about 6 months ago when I sprang my ankle really bad. My heart skipped a few times first, then I got really dizzy, my bp dropped to 80/40 and my heartrate was 33. Of course, I only knew this b/c my neighbor called 911 when she saw me fall in the yard. I couldn't stand up or anything without blacking out. They checked me out and said that it was vaso vagal response or something like that. They said its normal when your body is 'shocked', like with an injury. I'm still kinda worried about it though, as I'm sure there will be other times in my life when I will get hurt, I hope it doesn't happen again, it really freaked me out!!

[MARIE7228]

Not sure what might be causing your problem.  I will tell you about mine.  I was 10 yrs old and having warts removed from my arm.  I passed out.  Doctor said I had epilepsy and put me in the hospital for 2 weeks.  I was put on phenerbarbatal.  I continued to pass out when I would get scared, or hurt (hit my knee and get a sharp pain).  It became so common to pass out that I would lay down before I fell down.  They always checked my head out, but never gave a real reason for the passing out.  I started throwing away my meds (telling my mom I was taking them) the meds made me feel strange and they did not stop  the passing out, so I did not see any since in takeing them.

At 16, I gave blood at my highschool,  I was there for hours with them trying to get enough blood from me for a donation.  You would have thought they would have thought something was wrong.  I went home that day and passed out without getting hurt or scared. I was out for minutes and was very slow at getting my strength back.  My mom took me to the doctor, they checked me out. I could no longer play my flute and march in the band, I tired to easy.  Now when I would hiccup and get a sharp pain in my back I would pass out.  Still no one knew what was wrong.

At the age of 19 and pregnant my OB doctor noticed a slow heart rate.  He would not let me leave his office until I had an appt. with a cardiologist.

They put me in the hospital and monitored my heart,  I was dropping below 20bpm at night.  They implanted a dual lead pacemaker.

I am now 39, on my  4th pacer with one lead extraction.

My sister has slow rates on and off, they tell her she will need a pacer some day.

It took 10 yrs and being pregnant for my heart to be under such a strain for a doctor to detect my av block.