The effect on vagal tone of lying on your right side

Just found this interesting piece of research............

The effect of the lateral decubitus position on vagal tone.

Chen GY, Kuo CD.
Department of Medicine, Provincial Tao-Yuan General Hospital, Republic of China.

The average person spends about one-third of their time in a recumbent position. However, little is known about the effect of recumbent posture on autonomic nervous activity. Manoeuvres which can increase vagal tone have been sought both in the normal subject and in patients with heart disease.

We have studied the autonomic effect of various recumbent positions, namely the supine, left lateral decubitus and right lateral decubitus positions, in healthy subjects by using spectral heart rate variability analysis. Both time- and frequency-domain measures were calculated and compared between the three recumbent positions.

The normalised high-frequency power was used as the index of cardiac vagal activity, the normalised low-frequency power as the index of cardiac sympathetic activity and the low-frequency power/high-frequency power ratio as the index of sympathovagal balance.

The normalised high-frequency power is highest in the right lateral decubitus position, followed in decreasing order by left lateral decubitus and supine positions. The low-frequency power/high-frequency power ratio has the reversed trend as compared with that of the normalised high-frequency power.

These results suggest that cardiac vagal activity is greatest when the right lateral decubitus position is adopted.

PMID: 9244024 [PubMed - indexed for MEDLINE]

Very interesting, thanks for this.

Ok, i must be running a little slow this morning. Please could somebody render this in colloquial english? A summary, even? Thanks in advance.
PeggyM

I agree with Peggy...what does it mean? Are we still to believe that lying on the left side is a trigger? Thanks for your replies.

Hello everybody,

I just love the English language :-).
Googling around lead me to:

decubitus - a reclining position (as in a bed)
posture, attitude, position - the arrangement of the body and its limbs; "he assumed an attitude of surrender"


The supine position is a position of the body; lying down with the face up, as opposed to the prone position, which is face down.
[en.wikipedia.org]

lateral recumbent position = Sims' position
A position to facilitate a vaginal examination, the patient lying on the side with the under arm behind the back, the thighs flexed, the upper one more than the lower.
[cancerweb.ncl.ac.uk]


"These results suggest that cardiac vagal activity is greatest when the right lateral decubitus position is adopted".

I understand the conclusion is that lying on the right side of your back results in a high vagal actvity. This may lead to AFIB (just as we expected).

Ritze

Ummmmm......... Ritze, you may well be correct in your interpretation of this rather dense text, but if it is lying on the right side that leads to afib episodes, then why is lying on the left side such a common trigger position?
PeggyM

PeggyM, you're right. The expected answer should be left.

All the article does is stating that vagal activity is greatest when lying on your right. It does not even mention LAF.

Anyway, it was fun trying to find the meaning of the medical terms for your body position when lying in bed.


Ritze

Yes, this seems to be saying the opposite to what we think here doesn't it? Aren't we trying to reduce high vagal tone and this research seems to indicate lying on the right causes it. Maybe we're all safest to sleep standing up in the broom cupboard till we can get further clarification.......

I have both sleep apnea and Afib/flutter. Sleep tests show I have far fewer apnea episodes lying on right side. Lying on left side produces more episodes and on back produces by far the most.
Lying on left side also seems to trigger Afib although it may only make me more aware of fibs.
This is only my experience. Not sure if there is any connection between apnea and fib experience.

Formerly vagal, a trigger for me was lying on the left side. My recent breakthrough arrhythmias have occurred apparently when I was on the left side...as I awoke conscious of afib and realized I was lying left. That's a departure from my old habits where I trained myself never to turn over to the left side. Ablation was 11/03; guess my training is wearing off.

Bill - there is evidence to support the apnea/afib connection. It's been reviewed here a few times - I believe fairly recently and definitely in the other closed BB.

Jackie

Out of curiosity, I looked at my monitored results for a 10 random samples during morning meditation, specifically at the high-frequency power/low-frequency power ratio (inverse of what is reported in the reference above). For the same sitting position on different days, the ratio varied from 3.5:1 (very vagal) to 1:1 (balanced vagal/sympathetic). One of the variables that can change this ratio is breathing. Specifically breathing at 5 breaths per minute will increase the ratio (make it more vagal).

From this limited sample, if there is that much variability within the same position from day to day I might conclude that the study results are hogwash.

If I'm bored some time, I may try recording all 3 positions and see what happens.

George

Now there is some colloquial english if i ever saw any. Thank you, George.
PeggyM

George
It would be interesting to know more about how breathing rates affect vagal tone when meditating. You say that five breaths a minute increase vagal tone, increase it from what?
When I first had AF I found that meditation itself was a trigger and I gave it up. I did not think about the breathing rate perhaps being a cause. What you have observed is very interesting.
A further question: is heart rate linked to breathing rate in the absence of other causal variables?
Peter

I am having PVC's now and laying on my right side makes them much worse. When I had AFib, it was my left side that gave me trouble. This all is so very interesting as well as such a challenge to live with. I am thankful for the ablation in Dec 03 for AFib. i have been Afib free which is great, but now these darned PVC's are a pain. Not as bad as AFib, but not nice.

Jackie, are you having AFib again? I hope and pray not. I thought I was but it tunred out to be PVC's.

Be Blessed all

Bob G Ocala

I have had several episodes after lying on my right side and then rolling on to
left and up when getting out of bed (I sleep on left side of bed). I have posted this before but am not sure everyone saw it. I have stopped episodes cold
by getting BACK into bed, lying on right side again and doing relaxation breathing
to slow heart rate. I have 'unwound' the episode by redoing the move.
I have NO idea what made me do this the first time, serendipity really. I
wish I knew what physiologically goes on when I do this. Anybody conjecture?

Peter,

This guy, Stephen Elliott, has done all kinds of work with the Heartmath Freezeframer and basically determined that the max "coherence" occurs at a breath rate of about 5 breaths/min. See: [www.coherence.com].

This is all great stuff for meditative like responses There is a device (respErate) that gets you to breathe at ~10 breaths/min and has been clinically shown to lower blood pressure [www.resperate.com].

From what I've seen, you can increase heart rate if you breathe fast enough - but this could be due to blowing off CO2 during hyperventillation. With the slow breathing, you end up with high heart rate variability, but I don't think the average heart rate slows - see Elliott's page.

I never found that meditation or breathing had any effect on afib (but obviously others may have a different experience.


"vagal tone, increase it from what" - there is always vagal and sympathetic tone in the body. The increase would be relative to what it was and make the vagal more dominant relative to the sympathetic tone.


George

George
Thanks for the links.
I shall give breathing at five breaths a minute a try. The form of meditation I practised, Zen, encouraged the practitioner to just follow the breath and I think that as a consequence my breathing became very slow and shallow.
Peter

George,
How are you measuring HF/LF power ratios? (software/hardware)

I found two downloadable software programs that let me look at my Polar R-R data, but wonder what you are using?