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Holly Erskine

Monday, February 12, 2018

Most people think of heart arrhythmia as something they don't want. Indeed, atrial fibrillation, extra beats, and excessively slow or fast heart rates should have you seeking the advice of a cardiologist right away. But respiratory sinus arrhythmia, or RSV, appears to be an exception.


My dearest valentine, my Timmy, my love, you are the best therapy for my vagus nerve.


There are over 1400 research articles mentioning RSV on the National Library of Medicine's Pubmed database right now. There is a lot of information and misinformation. It's an exciting area of research. 



You may be having RSV right now, in fact.




A normal speeding up and slowing down of heart rate occurs as we inhale and exhale



Detecting your RSV
Feel for a pulse on your neck or wrist. As you breathe in, you may notice that your pulse speeds up some. As you breath out, your heart rate slows. This speeding and slowing of heart rate in tune with your breathing is RSV. If you are lucky enough to have a pet or a baby on our your lap, you can measure RSV on them, too. The bigger the difference between the speeding up and slowing down, the "stronger" the RSV.


Strong RSV found in strong minds and bodies
When RSV was first discovered in the 1700's, it was thought to be pathological. Bed rest was prescribed. Sir John Mackenzie's research in the early 1900's contradicted this conclusion. He dubbed RSV the "youthful type of irregularity".


Now we know there is an association of RSV with good health.

A flexible heart rate is a good thing
A resting heart rate can vary between 50 to 100 beats per minute. It was once thought that any sort of heart rate variation was pathological. Now we know that the most athletic and healthy people have heart rates that are flexible. Their hearts can speed up and down as needed, improving cardiovascular efficiency, and a low, but not too low, resting heart rate is associated with good cardiovascular health.


RSV is most prominent in mentally and physically healthy children, and less strong in children with depression, anxiety, emotional disorders, or chronic illness. RSV decreases as we grow older, but tends to remain strong in people who are extremely athletic.


A super-simplistic explanation of RSV
Involuntary actions like breathing, heart beat, digestion, etc., are controlled by our autonomic nervous system, or ANS. It's helpful to subdivide the ANS further into the sympathetic "fight, flight or freeze" nervous system (SNS) and the parasympathetic "rest and digest" nervous system (PSNS).


Sometimes we need to mobilize, and sometimes we need to rest and digest.

It is the balance of the SNS and PSNS that, through the natural pacemaker of the heart, the the sinoatrial node (the origin of the word "Sinus" in RSA) that causes the heart to speed up and slow down.


Different nerves and chemical messengers mediate messages in the SNS and PSNS.
These are not just static physical electrical wiring systems, but dynamic biological tissues. They remodel themselves according to how we use them.


The SNS does all the things you might imagine necessary for fight, flight, or freezing; speeding your heart, dilating your pupils, opening up the airways, increasing blood pressure, liberating blood and glucose to your muscles, shutting down your digestion and urinary tract (because who has time for that in an emergency?) Stress generally overrides the PSNS, which makes sense. Who needs to rest and digest in an emergency? Unfortunately the PSNS has important functions–I name just one below in terms of taming the immune system–and chronic stress weakens the immune-modulating power of the PSNS.


Anti-stress calming exercises increase RSV strength. I list a number of them at the end of this article.


The trendy vagus nerve and RSA
If you read anything these days about RSA you will immediately run across loads of information and misinformation on the vagus nerve, which affects RSA. I'll admit I've joined the fashionable crowd of scientists who are fascinated by the power of our tenth cranial nerve, the vagus. But the vagus is not "unique to mammals" (it's found in most vertebrates) and the vagus is not "the longest nerve" (that's the sciatic nerve). You would be surprised how often you can run across articles parroting those whoppers. Snakes would be offended to hear that they don't have a vagus. They do.


I am not an expert in this area so...
I must pick my way carefully here, lest I accidentally repeat any embarrassing howlers. Good articles can't afford to get sloppy with the truth, even in minor details. So please feel free to correct me if I get anything wrong here, (citing data and research).


The vagus nerve is, however, the longest nerve in the autonomic (involuntary) nervous system and a major branch of the parasympathetic nervous system, (although it has some sympathetic nervous system function as well.) Vagus is Latin for wander, as in vagabond. Our vagabond nerve wanders through the thorax and abdomen, touching many of your tissues and organs, like your esophagus, your larynx, your heart, your pancreas, your liver, your kidneys, your gall bladder, your spleen, and so on. It is a major conduit for informing your brain of sensory information from these organs. When you listen to your gut, you are using your vagus.



The vagus nerve is calming.


Beyond the "rest and digest" activities that the more primitive portion of the vagus promotes, there is a more evolved portion of the vagus found in mammals (the myelinated ventral vagus) that allows us to decrease stress by "tending and befriending". According to Stephen Porges's (known for his ideas on polyvagal theory) this more evolved system is stimulated by talking, listening, and making facial expressions.


Porges also writes in this article on music therapy about how mammalian ear bones have evolved to discriminate between calming, high pitched vocalizations(think "mothereese") and low pitched vocalizations which sound like a growling predator. (Another reason not to live near loud traffic.)


Strengthening your PSNS with calming "exercise"
Deliberately strengthening the PSNS portion of your nervous system means engaging in classic anti-stress activities like meditation, socializing, and reinforcing positive and compassionate emotions. We are used to the notion of exercising our sympathetic nervous system with physical exercise. It makes sense to consider health of the other half our involuntary nervous system as well. Some of these exercises are as easy as paying attention to our breathing (see below.)


RSV as a marker for vagal tone?
Lots of researchers are interested in measuring "vagal tone", a marker for the health of your PSNS. Since the vagus is responsible for the slowing portion of RSV, it seems reasonable to try to use RSV as a marker for the health of the PSNS.

There is, however, a respectable amount of controversy over just how to measure RSV, and whether or not it is an accurate measure of parasympathetic nervous system tone. However we can say that a strong RSV does seem associated with good health.


Aside: Electrify your vagus! A new alternative to expensive anti-inflammatory biologics?
Electrical vagal nerve stimulation has been used since the 90's for people with epilepsy and depression. What's interesting to me about this is that chronic depression is often associated with a state of inflammation (measured by elevated inflammatory cytokines and C-reactive protein in the blood) and we are just learning about how the vagus reduces inflammation through signals to the spleen.


Without diverting too much, there is a fascinating story emerging with work by Kevin Tracey on electrically stimulating the vagus nerve for treating other inflammatory conditions like rheumatoid arthritis. He discovered that a branch of the vagus affects the spleen to reduce the production of a major inflammatory signaling molecule called TNF-alpha. 


If you watch American television you have seen advertisements for expensive anti-TNF antibody injectable medications (Humira, Enbrel, etc). These are used by people with chronic inflammatory disorders such as rheumatoid arthritis, Crohn's disease, and psoriasis. I know someone who regularly injects one of these anti-TNF antibody treatments for ankylosing spondylitis. It's painfully expensive and a hassle. But it's really helped him, too. These biologics are the best thing a lot of these people have going right now.


It would be nice to have more alternatives.


Early trials appear promising for this vagal sort of pacemaker device, though are not without side-effects. Stimulating your vagus can also make you gag, throw up, faint, and lose control of your voice.


It is a story worth keeping our eyes on. In the meantime we can look at strengthening our vagus naturally.


Vagal tone exercises



These exercises are often taught to people with COPD and emphysema. Besides increasing respiratory efficiency, these exercises also happen to activate your PSNS. They are both ancient and modern. Pranayama is a major branch of yoga concerned with breathwork that I am quite ignorant about and I feel like I ought to learn more. If you want to know more about breathing exercises that might be a direction to check out.


1. Belly breathing
Instead of using your shoulders or chest to breathe, put something on your belly, even just your hands, and watch your belly move up and down as you breathe.


2. Breathe out longer than you breathe in.
This is a winner in my book! It soothes me. If you can count you can do this.


I have a remarkably accomplished friend who swears by the calming effect of what she calls 4-7-8 breathing. You breathe in for a count of four, hold the breath for a count of seven, and exhale for a count of eight. I don't like to hold my breath that long, I just extend my exhale for a couple counts. Find what works for you. Try it for a few minutes and see what happens.

Now, if you want to stimulate your sympathetic nervous system, and wake yourself up, you can inhale for longer than you exhale. There is nothing wrong with doing that as long as you know what you are doing. It's just another breathing exercise.

3. Breathe slowly.

But not so slowly that you feel panicky!


4. Pursed lip breathing

Breathe in through the nose and out through the mouth. Try pursing your lips as if you are blowing out through a straw. You might even make a sound as you breathe out. This helps slow your exhale.


5. Be careful.

Don't breathe in or out too forcefully. Don't do anything that makes you feel dizzy or faint. If you are feeling strange, stop! Breathing exercises should feel natural and gentle.


What else causes you to exhale longer than you inhale? (feel free to suggest additions to this list )
Reading aloud
Taking a long warm drink, perhaps of something relaxing like tea, coffee, or cocoa
Yawning (One of the authors of How God Changes Your Brain–which is a more objective and research-based book than the title might lead you to believe–is a huge advocate for the health benefits of intentional yawning! You have to admit a good solid yawn feels good. I will admit I haven't researched any papers for that one though.)


Tune into daily micro moments
Researcher Barbara Fredrickson is a fan of consciously engaging in what she calls "micro moments". This is a form of exercise where you are consciously tuning into daily moments of gratitude and love. I am a big fan of doing this. It just makes you a happier person. She has research suggesting it makes you more resilient during crises, too.


A lot of us probably soothe ourselves by stimulating the ventral vagus, which employs muscles of the mouth and face, by eating. I myself often find I am reflexively reaching for handfuls of peanuts when I am stressed, hungry or not. It works temporarily, but it is obviously not ideal, when most of us have no shortage of food and no shortage of commercial messages that food is equivalent to happiness. Better to dine consciously when you are hungry, and with friends, than while staring distractedly at a glowing rectangle. Socializing also stimulates the ventral vagus.


Listen to your gut
Before engaging in the aforementioned eating activity, you might want to ask yourself how hungry you are, on a scale from 1 to 10. Getting sensory signals from your gut is another way of strengthening your PSNS. If you are satisfied, make it a reflex to tune into that sensation, as a micro-moment of gratitude.


There are a number of studies suggesting that who engage in a regular meditation or contemplative practice have stronger RSA. These seems commonsense; tuning into your insides is a way of listening to your vagus nerve.



Art therapy for dementia by my mom,

who is naturally one of the happiest people I have ever known