Heart Is Not a Metronome: A Cardiologist on Breath, HRV and the Vagus Nerve

Patrick Obolgogiani (00:02)
Dr Boon Lim, thanks for inviting me to be here in your clinic today. Let's start with something that happened early on. So you did your PhD on autonomic control of the heart. And I'm curious to hear like what drew you towards studying the nervous system rather than I guess what normally would be the field of cardiology as a doctor.

Dr Boon Lim (00:26)
So I got drawn into it purely by chance. I was looking for a PhD, and it just so happened the PhD with a title The Role of the Autonomic Nervous System in Human Arrhythmogenesis came as an opportunity to me and I couldn't refuse that opportunity. And it turns out that studying the autonomic nervous system with respect to triggering arrhythmias or heart rhythm disorders such as atrial fibrillation was what I spent three years of my

Dr Boon Lim (00:56)
like doing and throughout this process learning about the intricate details of the cardiac intrinsic autonomic nervous system which is the brain of the heart became fascinating to me and how when you have a slight disorder in the brain that controls the heart you render yourself susceptible to developing heart rhythm abnormalities and from there the interest grew to the autonomic nervous system

Dr Boon Lim (01:26)
in its higher control form, so upstream of the heart, how that influenced physiological functions of the body, and then to expand that beyond the function of the autonomic nervous system on the heart into the rest of the organ systems. And that's how my interest got piqued.

Patrick Obolgogiani (01:47)
As far as understand, many of the cardiologists they speak about drugs when it comes to many things, which can be of course really important. But you talk a lot about breathing also as a tool, an important tool in the toolbox for cardiology. What when did it become interesting and something you actually had to use in the work you do with your patients?

Dr Boon Lim (02:10)
when it became personal, when it was able to shift my own emotional state, my mental state, my sleep, my physical well-being, and allowed me to see the impact that a very simple, free to use daily practice could have on one person's life who was pretty stressed out at the time, i.e. me. And so in in being able to really have this experiential

Dr Boon Lim (02:41)
Myself about the power of breathing and the impact of that on my own emotional, mental, physical health, I was blown away. With such a simple tool, you could manifest so many changes. What was truly inspirational were two things in my life that really anchored home breathing. One was James Nestor's book, Breath, which I which I really rated very highly. When I read it, I read it and

Dr Boon Lim (03:10)
Felt that I understood that this journalist had gone above and beyond to do the self-experiments, which sometimes were very cruel for James, in order to demonstrate very clearly. And the power of his storytelling really captivated me. The second thing which really made me double down on breath as an interesting therapeutic intervention was that I became a HeartMath

Dr Boon Lim (03:39)
coach. Now, HeartMath is a charitable organization who teaches their coaches how to guide clients into the control of breath together with a mindful exercise. So emotional self-regulation together with breath. This process itself, the heart math technique, was able to guide myself into this emotional calmness.

Dr Boon Lim (04:10)
And kind of mental stillness that I haven't felt for a long time throughout my medical career. And on this basis, I I double down on my efforts to understand the physiology of breath and then very interestingly to then communicate that to patients and then to have patients feedback to me that it's the one thing that really has changed their life.

Patrick Obolgogiani (04:10)
Yeah, that's very I definitely want get into many of the things you said, but before we do, it could be good to lay like a foundation here, like when it when it comes to physiology and the actual phenotyp anatomy. Maybe let's start with your heart. So I think a lot of people would assume that your heart is beating like a metronome.

Patrick Obolgogiani (04:50)
And there's this like maybe of course it goes up when you start exercising, but otherwise it's like regular. Like, could you explain, like, is that true and and what's actually wrong about that?

Dr Boon Lim (04:50)
Yeah, that's that's quite interesting. When your heart beats like a metronome, you're on death's door, because your heart should never beat like a metronome. And the heart's intrinsic variability with breathing, with circadian rhythm, which is the day-night diurnal variation, and obviously with stress, is what marks a healthy autonomic

Dr Boon Lim (05:20)
nervous system. As far as kind of a layperson's perspective is concerned, just imagine you have an accelerator and a break. And the autonomic nervous system has two components an accelerator and a break. So I like to think of the fright or flight response or the sympathetic nervous response as the accelerant. And so when we step on the gas and our heart rate goes up, that stress response or the fright or fright.

Dr Boon Lim (05:50)
response is allowing us to elevate our heart rate and yet when we step on a brake or pull off the gas our heart rate should slow down. Now

Dr Boon Lim (06:00)
It turns out that one very, very powerful way just to see this in action without actually feeling stress or without doing stress, i.e., running for a bus or physically exerting, is just to sit down and watch a patient or watch yourself and feel your pulse now. If you're listening to this podcast, just take your two fingers on one hand and feel either your radial pulse, which is where you feel your thumb, and take your thumb.

Dr Boon Lim (06:30)
Down to the wrist crease, go one finger breadth below that wrist crease, and then put two fingers there, and you should feel a bounding worm come in a pound, or at least in a regular rhythmic way, hit you so you can feel your pulse. The other way you can feel your pulse is to feel in your neck, just feel your thyroid gland or the Adam's apple, and just go lateral or to the side of it by about two centimeters, and you can feel your carotid pulse, and now take a deep.

Dr Boon Lim (07:00)
Breath in over six seconds and hold it at maximum inspiration and really feel the rhythm and the rate of your pulse. Now take a deep breath out. I'm gonna count for six seconds, four, five, six, and now hold it. And in the next four seconds, really discern your pulse. And then take a deep breath in again so that now you've felt your pulse. Five, six, hold it for two.

Dr Boon Lim (07:30)
three, four, and now breathe out fully three, four, five, six, and hold it for two

Dr Boon Lim (07:40)
Two, three. And Patrick, if you were doing this correctly, or if you were discerning with your pulse, you would have noticed that on the breath in, especially at the top or the apex of the breath, you should have noticed your heart rate quicken a little bit. And as you breathe out and at the nadir of the breath and held for another two seconds or so, your your heart rate would have slowed down. It turns out that watching somebody's heart rate variation with just breathing in and

Dr Boon Lim (08:10)
Out is a very sensitive marker of the health of your autonomic nervous system because it means you are flexible, it means that you are adaptable, and the stressor there is a stress of breathing, which we don't consider a stress, but it is enough to shift in a very careful way the flow of blood back into the heart to activate the so-called baroreflex that we can talk about later on.

Dr Boon Lim (08:40)
To then exert an immediate effect within two seconds to then control or regulate your heart rate or rhythm. And so your heart should be flexing up and down in concert, in line with your breathing. And this is what's known as heart rate variability or respiratory sinus arrhythmia, which defines how.

Dr Boon Lim (09:10)
You get your day-to-day heart rate variability when you breathe in and out. I know it's a long answer to a very seemingly simple question, but I hope if your audience listens to this again and didn't get it the first time, play back the the cues on the breathing in and out and really do feel your pulse. Because if you feel your pulse shifting even very subtly, that is a sign that you have got this ability to sense your heart rate variability on a beat.

Dr Boon Lim (09:40)
Beat basis varying with breath.

Patrick Obolgogiani (09:40)
And what's the distinction between those two kind of metrics? Because everyone's talking a lot about HRV, and I guess it's being measured by existing like these PPG-based optical devices, like the rings and the watches, based on, as you mentioned, the heart rate and the like the distinction of like how long it takes per beat between each other. But what's the what's the difference between that HRV, the way they measure it, and the

Patrick Obolgogiani (10:10)
RSA or the respiratory sinus arrhythmia, if any.

Dr Boon Lim (10:14)
I think once a technical measurement, one's a descriptor of what happens to describe the measurement. So j just to be clear, a smartwatch utilizing this green or red light technology, the photoplethysmograph, looks at the capillaries in your skin and the blood flow within the capillaries, which shine a signal back. and the signal when it's detected by a watch or ring will give you an indication of the pulse. So the pulse essentially is

Dr Boon Lim (10:44)
How many times the pulse rate is how many times your heart beats per minute. And you can quantify the interval between pulses. For example, if your heart beats 60 times per minute, the interval between each pulse is one second exactly. Now, what the smartwatches do is that they calculate the interval between heartbeats for every single consecutive beat. So, for example, it might start to make a list of rows and columns. So

Dr Boon Lim (11:14)
Row one, pulse one could be 1000 milliseconds or one second. Pulse two, the sequential pulse after that, could be 1.1 seconds, pulse 3 could be 1.3 seconds, pulse 4 could be on its way down back to 1.25 seconds, pulse five could be 0.9, and pulse 6 could be 0.8 seconds or 800 milliseconds, and so on and so forth. When you plot these pulses out sequentially on a diagram, you should approximate a

Dr Boon Lim (11:44)
Sinusoidal waveform where a gentle wave or a curve is seen meandering up and down to its peaks and its troughs. And the difference between the peak and the trough of a pulse, for example, between 800 milliseconds and 1200 milliseconds, that difference in amplitude between the peak and a trough is a measure of your variability in beat to beat over a prolonged period, let's say a one minute

Dr Boon Lim (12:14)
Minute recording period, and it is said that the higher your variability, the more heart rate variability you show. So, for example, you take a deep breath in and your pulse quickens to 80 beats a minute, and you take a deep breath out, it slows to 40 beats a minute, and when you take a mean or an average for a whole minute of the whole sinusoidal pattern, your mean is 60 beats a minute. Now that could be

Dr Boon Lim (12:44)
An exaggerated heart rate variability pattern. I see very few people who can do that. I'm sure you're one of those special individuals. But there are people who can express a much lesser heart rate variability, typically older populations who are diabetic, for example, poorly controlled, and they take a deep breath in as much as they can, and the heart rate goes from 60 to 62. And then they breathe out as hard as they can, it drops to 59 or 58. And that's all the oscillations that they do.

Dr Boon Lim (13:13)
Between 58 and 62, which is only four beats per minute oscillation around a 60 beat per minute average, as opposed to the example I gave you, which is 60 beats per minute average, but a 20 beat per minute oscillation. So one is a measure, the PPG is a measure of each sequential heartbeat displayed. The HRV is a calculation of the graph that you essentially plot over a fixed period. So you should actually quantify.

Dr Boon Lim (13:43)
Quantify heart rate variability over a period. For example, if you are sleeping in REM sleep or deep sleep.

Dr Boon Lim (13:53)
The HRV calculated in one epoch of sleep, like REM or deep, will be different. If I'm calculating your HRV now, when you're sitting down doing a podcast with me, as opposed to when you're running around in the gym or running on a treadmill, your HRV HRV will be very different. So it's very important to get the nuanced understanding that we need to always compare apples with apples. So HRV at night during a stable period of deep sleep to HRV at night.

Dr Boon Lim (14:24)
To a stable period of deep sleep. And this is something that I think the literature and consumers and patients often get confused about. Because there are many, many apps out there which allow you to calculate your HRV on demand. But look, if you've just had coffee, you've got a full bladder, if you've just rushed from a kind of meeting and you want to sit down and calibrate.

Dr Boon Lim (14:50)
It's gonna be all over the place. Ideally a HRV measure is done same time every every day or night. And that's why smart watches tend to really record and display overnight HRVs when things are a lot more stable. Well, for most, unless you have a sleep disorder.

Patrick Obolgogiani (14:50)
Makes sense. Yeah, I was gonna ask you like because it seems like everyone's talking about HRV these days and optimizing for it. And one of the tools used for that is of course breathing, because as you mentioned, almost looking in

Patrick Obolgogiani (15:19)
Apparently, just doing deeper breathing will support, even if it's only kind of during the moment you're doing it. But I guess some people claim that there's actual kind of trait changes that happen when you do that. But I think we'll get into that. But one thing I want to ask you is the vagus nerve. So where does that sit in all this? And what does something called vagal tone actually mean when a clinician is saying that?

Dr Boon Lim (15:48)
So the vagus nerve are actually vagus nerves and they come from a primitive part of the brain and is transmitted to the rest of the body through two bundles which go on either side of your your neck. And each of these bundles have about a hundred thousand nerves each.

Dr Boon Lim (16:09)
The vagus comes from the Latin word which describes a wanderer. So it's also known as the wandering nerve because it really does wander all over your body. And it is the nerve which controls all the functions which are automatic that you don't have to consciously think about. So it's part of the autonomic nervous system that serves as a breaking, resting, digesting function. And this vagal tone, when we consider that.

Dr Boon Lim (16:39)
To be high in say athletic folk who are training for a triathlon or marathon implies that the vagal expression is typically high at baseline, which means that, for example, one marker of a high vagal tone individual is that when they sleep, the heart rate's 38 or a very low resting heart rate, which you can sometimes discern if you're an athlete or you know people who are fairly good with ultra-long and

Dr Boon Lim (17:09)
Endurance distance. These patients of mine, I've seen an athlete with a resting heart rate of 32 beats per minute. That's perfectly fine for this person in light of their fitness. Now, a vagal tone, more broadly, taken beyond the athletic person, a high vagal tone means that you are you have a tendency to sit in vagal dominance. Now I like to think about the autonomic.

Dr Boon Lim (17:39)
nervous system as having or being depicted by the yin yang symbol. You know this Chinese yin yang symbol with an S in the middle with a black thing on the right and a white a a right semicircle. It's not really semicircle it's an S, right? Half moon with an S on the left. Now the black is the sympathetic nervous system and the white is the parasympathetic nervous system. What a high vagal tone means is that where we are supposed to be perfectly balanced

Dr Boon Lim (18:10)
A high vagal tone could imply somebody shifted in that balance to have say more white, say 60% white and 40% black. And that person with a high vagal tone is able to, let's say, be more relaxed, have a lower resting heart rate, a lower stress profile, and in general, a lower healthier blood pressure as well.

Dr Boon Lim (18:36)
if I go on and extend beyond that question, sure, the yin yang symbol, the way I describe it to my patients, and I see a fair few patients with autonomic dysfunction, typically if they're patients, Patrick, they will be shifted towards sympathetic dominance. And what they need to try and get to is balance or vagal dominance. Because when you're s in sympathetic dominance, and let's let's think about that yin yang symbol again.

Dr Boon Lim (19:06)
Black 60%, white 40%, so sympathetic more than parasympathetic or vagus, then you're very wired. You're expressing a high degree of metabolic demand. Your heart rate is higher, your breathing rate is higher, you're more hyper-vigilant with hypersensory awareness because you are ready to fight or flight. You are energetically consuming more because you want to generate energy, you want

Dr Boon Lim (19:35)
To mobilize glucose, you want to be able to run or fight for your life. And this state, when held over a chronic period, not of an hour, which is perfectly reasonable when you're when you're running in the gym, but held over months or years, can be very detrimental on many organ systems or the whole body system. So we are, I think, approaching an era of medical.

Dr Boon Lim (20:05)
medicine, which I I hope more people will embrace, of approaching root cause treatments for

Dr Boon Lim (20:15)
Typically chronic inflammatory diseases, but chronic diseases fed by sympathetic dominance. And my bias and my bias from my own practice, but also from observations of patients with autonomic dysfunction, is that when you go to the root cause and you re- or you learn to regulate the autonomic nervous system.

Dr Boon Lim (20:41)
You can express a manifest improvement in every domain that it affects. So all of a sudden, that chronic pain you've been feeling in your right shoulder, or the eczema or psoriasis that you've had in your skin, or the dermatitis, or the allergies that you've been suffering with, or the palpitations.

Dr Boon Lim (21:08)
Or the IBS, the irritable bowel syndrome, the chronic constipation alternating with diarrhoea. Instead of seeing an allergist, a gastroenterologist, a cardiologist, a rheumatologist,

Dr Boon Lim (21:25)
If you get to the root cause and you allow the body to do its magic, when you shift somebody from sympathetic dominance to balance or vagal dominance, you allow the body to heal in a very deep and meaningful way, which which transcends any organ system because the healing is holistic, because the autonomic nervous system and the vagus, the wandering nerve, which prompted your question, is so multifaceted in its reach. It reaches

Dr Boon Lim (21:55)
every organ system.

Patrick Obolgogiani (21:55)
Hmm. Super fascinating. I've come across the autonomous kind of dysfunction or dysfunction of the autonomous nervous system, but I I don't fully understand like what's happening there. Can you kind of help me

Patrick Obolgogiani (22:10)
Get a more holistic picture. You kind of mentioned that it's above a lot of these symptoms that people have, whether it's IBS or you know, heart palpitation or something else. But what's actually happening? Is it something people are born with? Is it something that you know your environment you tend to get stressed easily, and then when you don't, when you don't calm down, then it starts kind of making your nervous system go on haywire and and then lead to dysfunctional of the entire kind of ANS? You can just help me understand what's actually what's defined as dysfunctional.

Dr Boon Lim (22:43)
So I I think you'll recognize from my previous answer that one easy way to imagine a dysfunction in the nervous system is when you take the yin yang symbol and you and you shift it towards sympathetic dominance. Let's say a fifty-fifty is where it should be, and you get the sympathetic nervous system or black of the yin-yang at sixty percent and the white of forty percent. That means waking up from sleep, ready to hit the day, you're no longer balanced, you're already sixty-forty. And you could ask what shifts some

Dr Boon Lim (23:13)
somebody from 5050 to 6040. Like, why is it that you're provoked to wake up already like this? And this is really the golden question because this is where you take or you intuit with the patient in front of you where the struggle is why they're getting stressed. So clearly chronic pain, chronic inflammation, chronic infection,

Dr Boon Lim (23:42)
And l let's say from a physical point of view, there is a trigger to to have your adrenaline always trickling in and to shift yourself to sympathetic nervous system, for example, dealing with pain. That could be one reason. The other reason and the thing that I'm particularly interested in and what I look at in my day to day practice is orthostatic intolerance. So and patients who have

Dr Boon Lim (24:11)
Orthostatic intolerance have got a problem with blood pressure regulation. So they typically have low blood pressures, and when they stand up, for some reason, the blood pressures fall literally into the boots. And as the blood pressure falls, the system needs to accommodate or react to that fall by elevating adrenaline to make the blood pressure higher again. And as a natural consequence of having more adrenaline.

Dr Boon Lim (24:42)
In the system, your heart rate responds by elevating. So your heart rate increases, and your blood pressure has to cope with dropping to be bolstered by the adrenaline that's flooded in the system. And these patients are very significantly debilitated. And the term for to describe this is postural orthostatic tachycardia syndrome. It's a form of autonomic dysfunction that I see quite a lot of in my day-to-day clinic. So I'm I can I

Dr Boon Lim (25:11)
know of this particular trigger to anchor somebody in sympathetic dominance. But of course if we move away from the physical, and there are many other physical reasons, but if we move away from this, these physical reasons into other reasons. So one of the things that I often see is trauma or past childhood or adverse childhood events. And this childhood trauma can sit very deep

Dr Boon Lim (25:41)
seated inside the emotional state, that it sometimes gets hidden from conscious awareness. So when you ask a patient whether there's anything interesting to tell in the past history as childhood, they'll say no, no, no. And only when the sibling or the parent comes in will the parent remind them that actually you were bullied in school so badly that you cried every day for two years. And you get all these stories coming in.

Dr Boon Lim (26:11)
which are somehow hidden from the conscious mind because of the trauma. Yes. And that trauma can seed in a sympathetic a shift towards sympathetic dominance. And then a very interesting other thing that I'm starting to see emerging is the rise of neurodivergence, in particular patients with ADHD autism. And I don't know the exact reasons why there's there's an emerging almost epidemic of

Dr Boon Lim (26:41)
Particularly teenagers and even younger than that, and going into their early 20s. But these groups of individuals who are emerging are not able to process in the usual way the external stimulus around them. And that sits them at a very high stress load or sympathetic dominance. And there are many speculated reasons for that, which I won't get into. But you know, that's an emerging

Dr Boon Lim (27:11)
Phenomena that I've seen more and more in in the group of patients that I that I do come across. And then of course there is something that's very subtle, and I know I'm going above and beyond this question, but there is the sympathetic shift of an expectation gap. And this is more kind of almost philosophical, but it's when you don't accept

Dr Boon Lim (27:40)
That the present moment is where you need to be. And by that I saying but by by that saying I mean you are constantly chasing the next rainbow. And this inability to live and enjoy and express gratitude for the present moment is what anchors you in an expectation gap. You expect to be able to

Dr Boon Lim (28:06)
Be promoted to be able to find a relationship, to be able to earn more money, to be able to be fitter yourself, to be able to heal from your illness. When? Next six months, next year. But what you don't realize is so that that looking over and always seeing a pot at the end of the rainbow, meaning you have to climb the next hill to get to that rainbow. What you don't see in that technique is you don't look back at the five hills that you've overcome and the five previous rainbows that you

Dr Boon Lim (28:36)
Thought, if only I get to the end of that rainbow, I'll be satisfied. And the answer to the question well, the answer to that expectation gap is take your spade, if you're looking for the pot of gold, take that spade and plant it where you are now because you are at the pot of rainbow that you thought you'd never get to six months ago. It's just that when you get there, you you don't see it as a triumph anymore, and you're not satisfied. This eternal lack of satisfaction somehow in the society that

Dr Boon Lim (29:06)
We live in, which constantly flash images of the perfect holiday, the perfect body, the perfect way to do an Instagram reel to get the most followers, is what keeps you away from being grounded in the present moment and always chasing something that you're never able to ever get to as much as far as you've come.

Dr Boon Lim (29:31)
And this is an expectation gap problem which seeds you in sympathetic shift. So how can you ever be satisfied, grounded, steady, and truly autonomically balanced when you feel your life is not good enough? This not good enough. I need to be somewhere else and anywhere else apart from here and now is what I would consider one of the major crises that we all face as a society now that shifts the whole

Dr Boon Lim (30:01)
Society a bit towards sympathetic dominance? Long answer to a short question, I know, but you know, I just have to get that out.

Patrick Obolgogiani (30:01)
No, thank you for that. It's interesting how the mind is so powerful that it can drive our entire autonomous nervous system in such a way, as you mentioned. Before we go into solution space, which I think everyone wants to hear about, just ask something I was curious about: is like, is it normal that people that have like

Patrick Obolgogiani (30:30)
POTS or like any kind of autonomous dysfunction, they come to cardiologists? Is that how it's being usually treated? Or can you just talk about what's the usual kind of treatment?

Dr Boon Lim (30:30)
They they don't always have to go to cardiologists.

Dr Boon Lim (30:43)
I see pots as a disease which has parallels with the parable of the six blind men of Hindustan. And I don't know if you've heard this parable, Patrick.

Patrick Obolgogiani (30:43)
But they describe the same thing in different angles?

Dr Boon Lim (30:43)
That's right. So if you're a blind person and you approach the elephant and you touch his tusk, you'll say the elephant is just like a spear. And if you touch its tail, you'll say the elephant is like a rope, and if you touch his side it's like a wall. And all the six blind men are describing a truth but a limited truth of

Dr Boon Lim (31:12)
Of their perception. Yes. And in POTS, it is a multi-system presentation with multiple organs. So you can have gut issues, you can have breathing issues, and you can have palpitations issues. So the answer to the question is: if the dominant issue is fainting or palpitations, sure, they'll get to see a cardiologist. But some patients actually start off with gastro issues or allergy issues, and then they'll go down a different route to see a gastroenterologist or a dermatologist or an allergist.

Dr Boon Lim (31:42)
But by its very definition and its title, POTS, postural orthostatic tachycardia syndrome. Tachycardia means a heart rate of more than 100 beats per minute, but for the purposes of POTS, a heart rate that rises more than 30 beats per minute from sitting to standing, they often gravitate towards cardiologists because we are the palpitation special speciality. Right. So that's how we get a disproportionate number of patients with POTS.

Patrick Obolgogiani (32:12)
Okay, that makes sense. It's like the symptoms that many of them have kind of guided towards the cardiology and then you then at some point understand it probably is part of something maybe larger or like something that happened earlier in the heart.

Dr Boon Lim (32:12)
That's right.

Patrick Obolgogiani (32:12)
Okay, let's talk about actual solutions. So if we focus on let's say the sympathetic dominance and maybe we

Patrick Obolgogiani (32:36)
start with someone who's maybe not yet in your clinic, so not like yet quote unquote patient, but they're definitely have the synthetic dominance. They can recognize that in the way they wake up, in the way they they live their life. Where do we start? Like what would you tell that person like how do they start maybe changing towards that balance when it comes to the yin and yang metaphor?

Dr Boon Lim (32:57)
I think having a a grounding in education and understanding of where they are would be a good start. So I think always start change with education. And education needs to have part of it, empowerment, which means that a patient needs to be empowered to s to know that they can make a change themselves. They don't need to go to some guru or some medic to say this is how you fix yourself. And what I'm gonna say about that is that

Dr Boon Lim (33:24)
Once the patient understands and truly comprehends the multifaceted nature of the autonomic nervous system, they can then recognize in themselves that the root cause problem that needs to be solved is the autonomic nervous system. And when they go there, they'll find that actually the simplest route to get in there is A to just make sure there's nothing lingering. So there's no chronic significant.

Dr Boon Lim (33:54)
Significant pain, or there is no significant trauma that hasn't been resolved. Once you have identified all these bits of your history and of your presentation that can cause this autonomic nervous system to be shifted, then we can talk about how to

Dr Boon Lim (34:17)
self-regulate your autonomic nervous system. And I see this as a two stranded technique. and the way I describe it to my patients is that you can take a bottom-up and a top-down approach. So the bottom-up approach, if you think about a triangle and if you just imagine a guy sitting in a meditative position and you draw a pyramid or triangle around him.

Dr Boon Lim (34:45)
The apex of the triangle is at your head, so your thoughts, and beyond that is your behavior. So above the head is your behavior. Now, if you come down from your thoughts, you come towards your feelings, and the feelings I think are held, or at least from my visu the visual cue I want your listeners to listen to kind of get is you're looking at this guy sitting in a lotus position, thoughts are in your head, feelings are held in your heart, emotions.

Dr Boon Lim (35:17)
And then physiology is held throughout your whole body. And what the hell does physiology mean? It means the normal bodily functions. And one of the things that we think as the correct paradigm for health or illness is that mind over body. So you can think a bad thought and have a bad feeling, and that bad feeling

Dr Boon Lim (35:47)
Triggers a negative emotion. The negative emotion shifts your physiology, makes you feel bloated and constipated. What I'd like our listeners to consider is that let's reverse the triangle. What if your physiology was off? Let's say, for example, give you a clear and maybe too vivid example: you are super constipated, Patrick. And that constipation is giving you this throbbing rectal pain.

Dr Boon Lim (36:17)
There is no way you're gonna be comfortable in your emotional state. And there's no way you're gonna have good feelings about anything because all you want is to defecate. And there's no way you're gonna have a clear thought because you are governed by this great physiological discomfort.

Dr Boon Lim (36:36)
Now, when you ease that physiological discomfort, you get rid of the pain, you defecate, and you come back. Your mind can sharpen, the behavior changes, the feelings lift, and the emotions shift. And this is the power that your physiological system has on the whole body. And so the greatest physiology that we have control over, as far as the autonomic nervous system is concerned.

Dr Boon Lim (37:06)
Is your breath because if you think about all the organ systems that are controlled by the vagus and the sympathetic nervous system, they're all subconsciously controlled. So if I said to you, Patrick, increase your heart rate now by 10 points, you can't think it. If I said start to produce urine, or start to pr start to make your bowels move so that you'll let out a burp or start to defecate or start to feel that you need to take a crap. It just doesn't happen, right? It happens when it happens.

Dr Boon Lim (37:36)
When you're comfortable enough, when you're and if I said to Patrick, start sweating now, you won't be able to sweat. But if I said I want you to recall a very negative period in your life.

Dr Boon Lim (37:51)
You might get palpitations, you might get a fluttering in your tummy, you might start sweating, you might start getting hot. These are all under autonomic control. So the subconscious control comes from feelings and emotion. Higher control, like what we're doing with my voice box as I as I verbalize my thoughts or move my fingers up and down or or step up and down, is more conscious control or somatic nervous system. So the autonomic nervous system controls those baseline functions. And in

Dr Boon Lim (38:21)
The absence of conscious thought, your breathing is subjected to by the autonomic nervous system. Because when you're not thinking about it, you will breathe anyway, but at a rate that your autonomic nervous system controls it to breathe. So, for example, if you're stressed but you're not conscious about breathing, you'll breathe shallow, upper chest, quickly.

Dr Boon Lim (38:47)
And so this wonderful organ which is your lung has got dual control. It's got a higher brain control because I can hold my breath just like I can move my finger.

Dr Boon Lim (38:59)
But I can't hold my heart, can I? I can't stop my heart, and I can't increase my heart rate by thought, but I can do with breath. So the breath control is one of the wonderful windows into the autonomic nervous system, which is why it's such a powerful ancient tool that had been used by many, many ancient traditions for thousands of years to have almost supernatural kind of experiences and abilities. And I would start with the bottom.

Dr Boon Lim (39:29)
up approach through controlling your physiology of breath. Yes. And use that breath to force a shift in your autonomic nervous system from sympathetic to parasympathetic or vagal dominance. And that is the bottom up approach.

Dr Boon Lim (39:46)
And we can talk about ways to try and or breath techniques that can actually do this in the most rapid and long-lasting way. And then the magic, which is the the top-down approach.

Dr Boon Lim (40:01)
is to also bring in a positive thought, translating to a positive feeling and emotional state. And that combination of a bottom-up with breath and top-down with a meditation and a positive feeling coming in is what I feel shifts your autonomic nerve system most rapidly.

Dr Boon Lim (40:25)
On the proviso you're not say dealing with chronic pain, a leg falling off, or you know, an emergency yet 'cause your boiler broke. So in the calm state, these are the levers you can pull for maximum immediate benefit and shift in your autonomic nervous system.

Patrick Obolgogiani (40:25)
Mm. Yes. At least for technical people describe what you just said is that a lot of the biosignals that we measure, whether it's heart rate or HRV, they're kind of read only, whereas breath is when they only read and then write.

Dr Boon Lim (40:46)
Yes, exactly right.

Patrick Obolgogiani (40:46)
Yeah that's And that's to like, click with some people like, okay now I'll get it. It's a different kind of biosignal that you can both

Patrick Obolgogiani (41:07)
measure and it's actually what like if you look at the nuance here around brain mechanics can give you a lot of interesting insights like you mentioned about this physiology and the emotion state and then but also it's the only way you can we can shift subconsciously which makes it interesting for a for a wearable. But let's talk about then the specifics. So I assume

Patrick Obolgogiani (41:29)
you're gonna talk about resonance breathing, but feel free to take us wherever you want. Like is which specific techniques would you say are the most long lasting and generate that shift towards the parasympathetic nervous system?

Dr Boon Lim (41:29)
So it's quite interesting. In my heart math training I used a device called the Inner Balance. And that was device that was a device that I used

Dr Boon Lim (41:53)
daily or at least five times a week, to train myself with a ten minute practice anchoring in a coherent breathing technique. Now you use the word resonance, I'm using the word coherence and it could all sound gobbledygook to your listeners, but i essentially the long and short is that we our human physiology

Dr Boon Lim (42:22)
is cyclical just like you know circadian rhythm is cyclical and there are very many intrinsic rhythms in us that we might not be fully aware of that follow the ebbs and flows of what is needed to give us that perfect physiological state and it turns out that there is a

Dr Boon Lim (42:51)
Central oscillator in our brain that creates what's called a Mayer wave. And this Mayer wave is a central sympathetic oscillator that has a cyclical variation of about 0.1 hertz or a cycle period of 10 seconds. So every 10 seconds you undergo a cycle of a sympathetic nervous system push and pull.

Dr Boon Lim (43:17)
And that is when you measure it with the technical detail of a heart rate monitor and you plot out this graph, it's a sinusoidal pattern at around 0.1 hertz or 10-second cycle. And that's said to be the low frequency component of your heart rate variability. Okay? So if you just park that aside as a baseline oscillator in most patients, and in truth, of course, it varies from person to person.

Dr Boon Lim (43:47)
might be 0.08 hertz to 0.12 hertz. So it it it really depends on the age and how fit and how stressed you are. On the other hand, everything we've been talking about with the breath control of your heart rate falls in the domain of high frequency, which is a 0.4 hertz or 2.5 second period. And it turns out that when most people breathe at the normal breathing rate 12 to 18 breaths per minute

Dr Boon Lim (44:17)
That oscillation gives you a period which is distinct from the sympathetic oscillation. So the high frequency is said to be parasympathetic, or the respiratory sinus arrhythmia frequency is the parasympathetic at 0.4 hertz. The sympathetic frequency is 0.1 hertz, low frequency, high frequency vagus, low frequency sympathetic nerve system. And that's the kind of graph that we will plot technically on what's called a power spectral density map. We don't have to go into the details.

Dr Boon Lim (44:47)
But it turns out that phenomenally, when you can slow your breathing down and you can match the power of your high frequency and bring it into the domain of the low frequency, you amplify the oscillations.

Dr Boon Lim (45:06)
So, in other words, you have this baseline thing going every 10 second every 10 seconds, 0.1 hertz. It's going up and down and up and down. And you have another thing going with your breath, which is every two and a half seconds, which is different in its rhythm. And you slow your breath down, and gradually you superimpose those two graphs. You have a massive, massive shift in your heart rate variation.

Dr Boon Lim (45:34)
And this resonant or coherent frequency where you can amplify the changes in your heart rate because you're bringing together synchronicity between the high and the low frequency in a domain at around 0.1 hertz, but you know it's variable in a window. What you do is you amplify HRV.

Dr Boon Lim (45:56)
Because when those two waves are distinct, you might get an impact which are which which are not synchronized. When you synchronize them and they double down synergistically, your HRV will increase. And as you increase the power of your HRV, the heart's electrical signaling to the rest of the body being in that dominant frequency of oscillation, which is nice and slow, will entrain.

Dr Boon Lim (46:27)
By a process of biofeedback, sending signals up the vagus predominantly, because the vagus nerve, as I said, is 100,000 fibers on each side. 80 to 85% of them are sensory fibers. So they're carrying information from your organs to your brain, to feedback to your brain about what is going on in your system. And when it feels this coherence in your heart, dominantly in your heart, triggered by slowing your breathing.

Dr Boon Lim (46:56)
Down, it sends this slowed wave of oscillations back to the brain and it triggers your brain, your heart, and your breathing to be perfectly synchronized and aligned in what's called a coherent state. Now

Dr Boon Lim (47:12)
I appreciate that some of you listening right now will be completely lost if you're not following this. So either listen to it again slowly or even better, slow your breathing right now and take the next two minutes whilst listening to the rest of this podcast to really feel.

Dr Boon Lim (47:35)
The feeling of a coherent state as you slow your breath to a six-second cycle in, six-second cycle out. We can start like that.

Dr Boon Lim (47:46)
And after two minutes or so, notice if your shoulders have now relaxed completely back in your chair. Notice if you close your eyes whether the thoughts are racing or they are calm. Notice whether you're fidgeting. Notice the emotional state or the energy in motion, emotion state of your body, and whether that's calming or whether that's still ready for battle. And those of you who are listening.

Dr Boon Lim (48:16)
Right now, who feel a perceptible shift have taken your first step towards calming your autonomic nervous system in a two-minute window. And Patrick, like I I'm not really making this up, but in between patients in a busy clinic, I sometimes take a minute or two to just slow my breathing consciously, not think of writing up my notes or

Dr Boon Lim (48:46)
reading up about the next patient, but just focusing on my breath. And in just two minutes, I can notice a perceptible change in my state. There's a state shift in my autonomic nervous system that energizes me and makes me prepared for the next patient if it's been a particularly stressful, kind of long consult on the previous one. So that is a tangible feeling that I have, an emotional state that I shift into with just too many.

Dr Boon Lim (49:16)
minutes of breath work practice. And that's just breath work, Patrick. I haven't even brought in the positive emotional state, which is what I tend to do when I practice my nighttime meditation before I go to bed and the morning meditations. Because that's when you're not

Dr Boon Lim (49:31)
confronted with a pressure that coming in the next two minutes and you have a bit more time, say in a ten minute practice window, to really anchor down that top down approach, which is gonna be challenging for some of your patients who are in day to day practice. But this is the top tip for a immediate two minute hack. Shift your state by doing some coherent breathing.

Patrick Obolgogiani (49:56)
So the minimum viable dose is basically whenever you feel that need to like you feel yourself being in the sympathetic state. It's two minutes.

Patrick Obolgogiani (50:08)
And focus on your breath and take it to is that six seconds in, six seconds out.

Dr Boon Lim (50:08)
That's right. I mean the ideal breath is a has a cadence of exactly as you said, six in, six out. It actually is described in James Nestor's book as five and a half in, five and a half out. But who wants to do eleven second cycle breath is just stupid. So you either choose eight seconds, ten seconds or twelve seconds. My kind of resonant breathing

Dr Boon Lim (50:38)
is probably 16 seconds. So when I feel the most calm and I feel everything shift is when I take eight in and eight out. I appreciate that's a much slower breath than most, but I feel like this perceptible shift when I can slow down. And it's very interesting, Patrick. Even if I'm sitting down on a table on my laptop, if I'm not emotionally grounded, I can't do that eight seconds. I c I simply cannot, because my autonomic nervous system

Dr Boon Lim (51:08)
does not allow me to get there easily. I can almost always easily get five or six, but eight is only accessible to me when I've done a bit of five and six to calm myself down. And it just goes to show that your nervous system reset engenders the ability to launch further into deeper practices. And so I'm convinced that my resonant breathing frequency is longer than six seconds.

Dr Boon Lim (51:38)
But let's not get into that. It's it's a bit it's a bit more nuanced than we've already gone into unless you really want to go in. But for most of us listening, it will be five or six seconds in, five or six seconds out, and that's all you need. Close your eyes, relax your shoulders,

Dr Boon Lim (51:56)
and just clear any thoughts and all you do is focus on the breath. And those of you who recognize meditation or who perform meditation or have joined a basic meditation class

Dr Boon Lim (52:08)
The first practice is always to notice your breath, right? They don't get you to do any other funky stuff with your thoughts or your imagination or trying to manifest things. Is always just notice your breath. Because that is the fundamental basis of the meditation practice.

Patrick Obolgogiani (52:08)
Yes. Yeah, actually. Remember listening that each of us have a different cadence or oscillation as you mentioned, like the what is ideal for us. and at least we're hoping to we haven't proved yet, but we're hoping to actually show the obvious user of like what is yours. So then it's easy to kind of practice that you personalized with them. But actually something that you mentioned. I remember reading that when they studied like these monks who do a lot of meditation, they had like the longest, basically the the oscillation was the slowest, basically, and it's gonna be interesting if

Patrick Obolgogiani (53:00)
there's like something we can learn about the that as almost like a sign of resilience of the nervous system, both for yourself but also to make it like imparable in a in a good way, like when you're

Patrick Obolgogiani (53:11)
Are you improving yourself when you're doing the practice? Because I think most of us we kind of crave for feeling of progress. and it's dangerous, I know.

Dr Boon Lim (53:11)
Careful, careful, careful. Remember the the the rainbow that you keep chasing? Yes, that's a that's an expectation gap as well. And I think we must all be if you're listening to this now and you just had a shift in your nervous system just with that two minutes of practice, plant the spade down now and ground yourself in that base practice. But I get what you're saying. You've

Dr Boon Lim (53:41)
Got a device that potentially has the ability to go above and beyond this baseline standard coherent breathing rate for everyone and to work out the resonance frequency, which I think is a remarkable thing if we if we could do it. I think the caution here is the enemy of good is perfect.

Dr Boon Lim (54:02)
And when we're striving for perfection, that's when we can shift back into sympathetic dominance. So you know Yeah. I'm just gonna push back a little bit, just to say that, you know, the baseline practice is super key. Yes. And everyone can do it today. Anyone can do it right here, right now. Yes, yes.

Patrick Obolgogiani (54:25)
It might feel like a bit of a left turn here, but I wanna stop about something you worked on a lot, which is fainting. And you have a website, stopfainting.com. Can you talk a little bit about like what started that, but also like what actually is happening there? Like we all

Patrick Obolgogiani (54:41)
see in the movies, people fainting when they are shocked. But that's probably not quite the day to day when it actually happens. Can you speak about the physiology of what's happening and then what drew you towards that whole area?

Dr Boon Lim (54:41)
Yeah, I've been doing this fainting business for a very long time, since for the last fifteen years at least, and I still don't understand what eventually makes people faint, which is which is quite in itself sobering.

Dr Boon Lim (55:12)
But it's also known as vasovagal syncope. And the kind of fainting that I come across are mainly patients with what's called reflex neurocardiogenic syncope. And this is v a form of vasovagal syncope where patients suddenly activate the vagus nerve. And when the vagus, which is the rest and digest nerve, that relaxes and slows the heart rate down, we know it's a break, isn't it? As opposed to the accelerator of the sympathetic nervous system.

Dr Boon Lim (55:42)
When you break on your on your blood pressure, when you break on your heart rate, what happens is that your blood pressure drops precipitously, your heart rate can fall, and there's not enough circulation glucose and oxygen arriving at your brain. The brain is critically dependent on beat-to-beat glucose. It's it cannot be starved of oxygen for any more than six seconds, or with a blood pressure that's lower than around 60 millimeters systolic. And so after

Dr Boon Lim (56:12)
short period you collapse and you could argue like why the hell would

Dr Boon Lim (56:20)
Human, the human designer, design a human that could collapse in this way that whose vagus nerve activity could overwhelm the system so that they could collapse. And one potentially evolutionary advantage is to think of the great chase when you're a prey confronted by a much larger predator who's faster, stronger, quicker, and you're cornered. There's nowhere else to run.

Dr Boon Lim (56:50)
Playing dead is a pretty last-ditch effort to ensure that you're not eaten. And by playing dead, you could I mean to really play dead, you need to be dead so the vagus comes in and shuts down your cardiovascular system so that you really drop, and there's no way you can move or do anything when you're dead because you don't have a heartbeat and you don't have a blood pressure, and sometimes a predator walks away, sometimes you're dead anyway.

Dr Boon Lim (57:20)
That could be one way to think about why the reflex has evolutionarily been advantageous instead of just fighting or running, because when you're when and it's also known as a freeze reflex. So there's a fright, flight and freeze, right?

Dr Boon Lim (57:35)
And the freezing or playing dead is when you go around the other way and you say, Look, I can't fight or flight anymore, I've got to stop here because I know I'm gonna die, so I might as well play dead. So that's one way to think about it. The other interesting kind of evolutionary advantage is if you stepped on, say, a landmine, you blew your leg off, and you were bleeding.

Dr Boon Lim (58:01)
You don't want a high blood pressure when you're bleeding out because you would only hose more blood. So let's lower the blood pressure, let's lower the heart rate, and let's make you not only fall to the ground, but let's keep your blood pressure very, very low and your heart rate low so you don't hose out. I I think it's very difficult to prove this either way, in terms of studies like how would you do that study? It's impossible. Yeah. But but you could see that degree of evolutionary advantage to having this vasovagal.

Dr Boon Lim (58:31)
reflex which comes on so strongly to make it pass out. And clearly it's an abnormal reflex in day-to-day life. Like why why is it normal to whatever come down the stairs or chopping vegetables, you cut your finger, you see blood and you faint?

Dr Boon Lim (58:46)
Should you faint? Well, you know, it turns out that that frightening jolt of fear and anxiety that something bad is gonna happen triggers that kind of playing dead response in your nervous system. So the vasovagal reflex is overwhelming and can make you pass out with a slow heart rate and a low blood pressure.

Patrick Obolgogiani (58:46)
And is the solution then to kind of develop develop the resilience we talked about in the nervous system, or what do you then do when you have people

Dr Boon Lim (59:17)
Yeah, so it depends on the cause. So for people with situational syncope who are afraid of say blood or afraid of being involved in a medical procedure or watching Saw 3, you know, the the kind of scary gore movie, then sometimes exposure therapy can work to trick the brain into thinking, actually this is not a threat to my life and so I don't have to escalate and get the vasovagal reflex.

Dr Boon Lim (59:46)
But more often than not, vasovagal syncope is a condition that occurs in patients who have a low resting blood pressure and who are triggered in certain environments, alcohol, heat, standing still for a long time, overexertion, and avoiding these triggers and having more hydration and salt and compression and keeping cool are the mainstay of treatment for vasovagal syncope.

Patrick Obolgogiani (60:13)
We've been going for almost an hour, so as we start drawing to a close soon, maybe a couple of these kind of more rapid fire questions and then we'll start closing down. what's one maybe heart related myth you'd like to to bust that people might have?

Dr Boon Lim (60:30)
gosh, I would say that Coronary disease is not all about cholesterol. Coronary disease is a disease of inflammation.

Patrick Obolgogiani (60:52)
And people still think that cholesterol being high is the cause for that.

Dr Boon Lim (60:52)
Correct. Yeah. And I think most people should start to consider reducing inflammation as the primary target. And cholesterol is also a target, but it's not the primary target in minimizing progression of coronary atherosclerosis.

Patrick Obolgogiani (60:52)
Interesting. What's the most common thing people get wrong about HRV?

Patrick Obolgogiani (61:22)
Which we touched on later.

Dr Boon Lim (61:22)
Can you say that again? Where people get wrong.

Patrick Obolgogiani (61:22)
Yeah, the most common thing people get wrong about HRV.

Dr Boon Lim (61:22)
Yeah. Difficult thing to explain to a patient is when they compare themselves to others. And the HRV score for an 18-year-old is bound to be vastly different from a 50-year-old HRV. And HRV for a long distance runner at 50 is going to be very different from an office worker who hits the gym for weight training at 50. So these metrics are kind of useful for serial assessments in the same individual.

Dr Boon Lim (62:03)
When you're comparing yourself with others, I think the numbers sometimes don't make sense.

Patrick Obolgogiani (62:03)
And lastly, what's the one thing about the heart that still amazes you after these 20 years of work?

Dr Boon Lim (62:19)
not not that it amazes me now, but it's a kind of newfound respect that the heart carries its own intelligence. And this is something of a more deeper dive into what I've started to experience recently, which is the saying that you kind of lead and love from the heart.

Dr Boon Lim (62:45)
And I believe the heart is also beyond the brain a seat of memories and emotions, which allows an expression in a way that the brain cannot express. In other words, the little brain of the second heart doesn't only control the workings, the mechanical and electrical workings of the heart, it actually can open up a whole new way of feeling and being.

Dr Boon Lim (63:15)
feeling from the heart to my mind is becoming a real phenomena for me and when I think about sending a positive feeling or a or a good emotion I'm now radiating that from my chest not from my brain which is an interesting shift in the way my belief structure has been but that's very personal.

Patrick Obolgogiani (63:15)
Yes. No it's a beautiful beautiful place to close.

Patrick Obolgogiani (63:44)
Thank you. we'll definitely link to all the drboonlim.co.uk, stopfainting.com if anyone wanna learn more. Is there anything else you wanna leave people with or point to if they want to learn more?

Dr Boon Lim (63:44)
I would say also that if you're just looking to gain an understanding of your heart health in general, I've written a book called Keeping Your Heart Healthy. You can find it online and

Dr Boon Lim (64:12)
It has got several chapters touching on a lay person's perspective on how to manage hypertension, atherosclerosis, cholesterol management, fainting, obviously, and arrhythmia such as atrial fibrillation. So if you want to learn more, then you can pick up the book on Amazon.

Patrick Obolgogiani (64:12)
Amazing. Well definitely check that out. It feels like there would there's another episode that we need to cover around all those topics that he just mentioned, because like AFib keeps coming up again and again and

Patrick Obolgogiani (64:41)
Yeah, we just need to learn more. But for now, thank you.

Dr Boon Lim (64:41)
Thank you for having me on, Patrick. Much appreciated.

Patrick Obolgogiani (64:41)
Likewise.