Arrythmias when supine

[goldy2]

I take adderall which I know is causing me heart palpitations but only when I am laying down or leaning foreward.  I realize palpitations are not good and I may be discontinuing the medication but I am just curious and have a question re: anatomy and physiology.  I am an RN and will understand medical terms.  Why do I only get these palpitations when I am laying down?  I never notice any heartbeat irregularity when standing or with activity but when I have taken the adderall and laid down I frequently get short, episodes of  tachycardia, fluttering and/or  heart pounding.  I never have chest pain or sob and it only lasts approx. 20 seconds.  Does laying down/leaning foreward alter the position of the heart so drastically that the electrical system is altered also?  How does position affect the heart's electrical system?  When I feel my radial pulse it feels regular despite what I am feeling in my chest.  Could my pulse remain regular despite irregular electrical activity?  goldy2

[TomFi]

In the early 1980s, I got a diagnosis of mitral valve prolapse as a cause of frequent irregular heartbeats.  I've been taking 10 mg of Inderal since then.  I am a 69 year- old male, married with children.  Recently I've been getting a return of the irregular beats despite taking the Inderal, and changed my dose to 15 mg daily, taken in half-tablet (5 mg) doses three times a day.  That seems to help.

If I exercise, as riding a bicycle, or trotting with the dog, any tendency for heartbeat irregularity seems to go away as long as the rate is elevated.  When I rest, the irregularity can return, especially if I should lie down.

At night I notice the irregular beats often accumpanied by "surges" under my collarbones when the heart seems to catch-up.

I was very surprised last night to find that if I sat up in bed my heartbeat became regular.  Then I tried the effect of lying supine (irregular beating), on either side (irregular beating) or prone (regular beating).  

So it appears this new irregular beat may be related to my position while lying-down.

I don't find it too easy to lie prone in bed because my face is against the pillow, or my neck is pressed against the edge of the mattress, but it is certainly more restful for my mental state!

[itdood]

The palps, I'm guessing, are ectopics and those probably are the result of enhanced automaticity exacerbated by the adderall.

I think the more medically accepted explanation would be vagal tone.   I'm more inclined to think this if the palps are tachy/brady but could also fit for ectopic beats.

Another possibility is heart irritation (from the pericardium) resulting from the the position changes.

These aren't easy to nail down with tests, i.e. might not be worth pursuing unless it gets worse.