Melanie Cole, MS (Host): Welcome to Bryan Health Podcast. I'm Melanie Cole. And today, our discussion focuses on resting heart rates and how to know when your heart rate is outside the range. Joining me is Dr. Grant Wallace. He's a cardiac electrophysiologist with Bryan Heart.

Dr. Wallace, thank you so much for being with us today. Why don't we start by telling people what you do? What is electrophysiology and how does a cardiologist come to specialize in this area? Tell us a little bit about your field.

Grant Wallace, MD: Well, first off, Melanie, thanks for having me. Like you had mentioned, I'm a cardiac electrophysiologist, which is basically just saying that in a fancy way that I'm a heart rhythm doctor. So, the field of Electrophysiology is a subset of Cardiology. And our focus is on the diagnosis and management of heart rhythm disorders, anything from slow heart rates to fast or irregular heart rates or rhythms.

We take care of patients through the entire age spectrum from teens, young adults, all the way up to elderly patients, and through that spectrum, a variety of different heart rhythm disorders.

Melanie Cole, MS: Thank you for that. So, let's talk about heart rate. What does it actually measure? And why is it important to know your heart rate and certainly your resting heart rate?

Grant Wallace, MD: At its most basic form, your heart rate is just the number of times per minute that your heart is sending an electrical signal through the heart muscle, leading to a mechanical contraction that pumps blood out to the body. For most folks, the kind of normal heart rate range is somewhere between 60 to 100 beats per minute. And that can vary through the day, patient to patient, based on lots of different things, your level of activity, whether or not you're feeling well or perhaps under the weather, if you're well rested, any medications or supplements, things like that, that maybe you've ingested. Again, at its most simple form, the heart rate is just how often your heart's beating and how many times per minute it's pumping blood out to the body.

Melanie Cole, MS: So, we're looking at between 60 and 100 for basically the range. There are things though, Dr. Wallace, that can make our heart rates go up or go down. People say, "Oh, you know, a flutter when they're excited or when they're exercising." So many things. Tell us about how the heart can really change and sometimes it's a positive thing and sometimes not so much.

Grant Wallace, MD: Yeah. I mean, I would say, heart rate variations are a normal thing and that is something that you want. That is a marker of a healthy cardiac electrical system, but also a marker of normal physiologic function of the body.

So, when you're at rest, say you're sound asleep in the middle of the night, your heart rates are going to be lower. At that point, you're not particularly metabolically active, so your body doesn't need or isn't demanding high levels of oxygen to perform cellular functions. It doesn't have a bunch of waste products from the cellular function that it needs to ship out, so your heart rates go down.

Once you get up in the morning, that number starts to climb up a little bit. And again, it varies throughout the day based on your activity. You know, I mentioned 60 to 100 is kind of the "normal range." That is all kind of in context. It is certainly not abnormal for your heart rates to be above 100 if you're working in the yard, or walking the dog, or carrying in groceries from the car. And we want your heart rate to go up to meet the demands of whatever you're asking your body to do. But there are also situations when elevated heart rates can be abnormal. Certainly, if you're relaxing in the evening, you know, watching TV and you start to feel a palpitation or fluttering in the chest and you check your heart rate and it's 125 beats a minute, that's probably inappropriately high for the level of activity that you're performing and could be a marker of some sort of irregular rhythm or some sort of marker of something not so good.

So, the heart rate is just a single kind of metric in the bigger picture of what we look at when we're taking care of folks, but it can be a valuable one to help us tease out what's really going on.

Melanie Cole, MS: Dr. Wallace, you said when you're sitting there and you take your heart rate, would you please tell listeners how to take their heart rate? Because they go up to their neck, they can't find it. They go to the wrist with their two fingers, they're not really sure what they're supposed to be feeling.

Grant Wallace, MD: Sure. The most straightforward way to check your heart rate is just to grab a watch, or if you've got a clock on the wall with a seconds hand, start with that and then find your pulse. And like you said, it can be in the wrist, at the base of the thumb is where the radial artery sits. When I'm seeing patients in the clinic and I just want to check something real quick, that's where I go to. The artery in the neck, the carotid artery is a bigger vessel. So, sometimes the pulse there is easier to identify, but you got to find it somewhere. And again, for some folks that can be easier than others. But if you hunt around a little bit, usually you can find it. And then, once you've gotten your position locked down and can feel your pulse, then you just wait until that second hand hits one of the big numbers and you start counting. And count for 30 seconds, count every heartbeat and times it by two or count for a minute and just count every heartbeat, and that's the beats per minute that your heart is beating at. But the heart rate is defined by beats per minute. So, some way to get to a total number of beats in that minute, that's the most basic way.

There are now, and have been for a while, different technological tools that will help you do that perhaps more easily or more efficiently. And those could range anywhere from most blood pressure cuffs have a way to monitor the heart rate. Pulse oximeters which are the little clips you put on your finger that test your blood oxygen, those also will measure your heart rate usually. And then, things like smartwatches or other more kind of high tech devices have different ways of measuring your heart rate as well. So, any of them are suitable, as long as if you're doing it yourself, again, counting, feel your pulse and count it appropriately in that time span.

Melanie Cole, MS: Well, I'm glad you mentioned some of the technology that's available, you know, outside of blood pressure cuffs and oximeters, pulse oximeter, those things. But smartwatches, wearable technology. People are wearing these things everywhere. Does it sometimes make people a little hyperaware and we can trust what we see on there?

Grant Wallace, MD: To answer the first question, it certainly can. The advent of wearable monitors certainly give folks I think the opportunity to have more understanding of their health day to day. But with that, it comes with lots of information and sometimes, the ability to interpret that information or kind of wrap your head around it can be challenging and can lead to perhaps more anxiety or maybe create more problems than it's really helping. But certainly, in folks that have a good understanding of what they're looking for or what they're using that tool for, I think they can be very helpful.

For the most part, smartwatches or smart devices that are measuring your heart rate do it through a function called photoplasmography. So, if you've had a smartwatch, you may have noticed as it kind of rocks off your wrist a little bit, you see red or green or blue lights that are kind of flashing on the underside of that device. What's happening there is that device is shining these specific wavelengths of light through the skin, and those beams of light are bouncing off of red blood cells as they flow through the capillaries or the very small blood vessels in your skin. And with each heartbeat, the flow and amount of blood increases in those vessels. And then, in between each heartbeat, it slows down and so that device is able to measure the frequency of those changes in flow, more or less, and that's how it arrives at a number for beats per minute. Many of them are doing that constantly, some of them do it intermittently, take little burst readings and then shut down. But they all kind of work more or less through that same light-based sensor mechanism.

Melanie Cole, MS: What an excellent explanation, Dr. Wallace. Thank you for that. So, when do we get concerned? And if we get concerned, whether or not we've taken our own heart rate, or we've learned about it on one of our smart devices, what if we get concerned? What would be concerning and what do we do about it?

Grant Wallace, MD: First off, I always tell my patients that you know your body better than anybody. So if you're concerned for whatever reason, I don't want you to just ignore it. You give us a call, if you're really concerned, having dramatic symptoms, crushing chest pain, can't breathe, lightheaded, dizzy, passing out, those are all things that should be seen in the emergency department, you know, right away.

Let's say you're otherwise feeling well, and maybe you just got a new smartwatch and you're sitting down watching TV and it gives you an alert and says, "Heart rate low" and you look down and it says your heart rate is 52 beats per minute. And you're like, "Oh, my gosh. It's alarming. My watch is telling me something bad's going on." But if it's evening time, you had dinner you're finally able to relax from the day and you otherwise feel fine, then it probably isn't something that's an absolute emergency.

I also tell a lot of my patients that heart rate number is just that. It's a number. Certainly, there are numbers that are more concerning to us than others. I mean, you know, heart rates in the teens, 20s, 30s usually are outside the kind of bounds of normal physiology. But for a lot of folks, overnight or at times of pretty significant rest, it's not uncommon to see their heart rates dip down into the 50s or sometimes even the high 40s. And if you feel fine, if you're not feeling lightheaded, short of breath, really fatigued, really drowsy, then that probably is just a marker of your normal physiology and your body's just in a deeper state of calm and isn't needing to have those higher heart rates to meet the metabolic demands.

But certainly, if you are having symptoms again, the most common symptoms that come with slow heart rates are things like shortness of breath with activity, lightheadedness or dizziness with activity or position changes, just a global sense of fatigue, if that is happening in conjunction with heart rates that are low at rest or more concerningly usually low with activity, then that can certainly be a marker of some problems going on with the electrical system that need to be further looked into and potentially addressed with either medical therapy, or even sometimes device-based therapy. So, that's kind of on the low end, on the slow end.

On the high end, a little bit of a different story. Going back to our conversation a little bit earlier, I said, it's normal for your heart rate to go up with activity. And that is absolutely true. When you're exercising or doing vigorous work, it's expected that your heart rate climbs up. And it certainly could get up over a hundred depending on the level of activity. But at rest, sitting down watching TV at the end of the day, I wouldn't necessarily expect your heart rate to be elevated, say above the hundred range, 105, 115, 125. That would be probably a little bit abnormal based on the level of activity you're performing. And there certainly can be a variety of reasons as to why your heart rate is elevated. Some of them heart-related specifically, some of them outside the heart that are just leading to increased levels of kind of adrenaline or whatnot in the body that result in higher heart rates. But either way, those situations usually are something that, at a minimum, you want to have some reassurance to say, "No, that's okay." And certainly, if there's something more going on, we want to figure it out and get on top of it to make sure that folks are protected.

Melanie Cole, MS: Yeah, I certainly think that a high heart rate can be more alarming. And certainly, there's so many things that can affect your heart rate. Tell us what you do, Dr. Wallace, to help people if somebody has very fast or slow. What do you do for them?

Grant Wallace, MD: Yeah. The first step in all of this is, when I have a patient who I'm seeing for evaluation of either fast or slow rhythms, is to get the whole story. The context oftentimes matters a lot in these situations. And so, I want to figure out, "All right. What are you feeling? When are you feeling it? What kind of things bring it on? What kind of things seem to help it go away?" So, making sure we've got the full comprehensive history is always step one.

Then, step two is kind of the diagnostic portion. If you have a smartwatch that does record these things we go through and look at the heart rate graphs and distribution. And you know, you pull it up, you see it's 8:00. And 7:00, my heart rate was 65. And here at 8:00, it jumps up and it's 120. And then by 9:00, it's back down to 65. Well, you weren't just sitting there watching TV, that's probably abnormal, which can either be with external monitors that basically sit there and watch every single heartbeat and are programmed to record tracings of heart rhythms when they fall out of whatever parameters we set. Too fast, too slow, irregular, you name it.

And then, once we've been able to hopefully make a diagnosis, atrial fibrillation, atrial flutter, SVT, sinus bradycardia, heart block, whatever it may be, then we talk about, "All right, what do you have? What are the implications of that diagnosis? And what are the treatment options that are available?" whether it's medical therapy, device-based therapy, interventions with ablation procedures, what have you.

So, that's kind of the other half of my job, obviously a big part of it is making the diagnosis, but then we've got multiple tools in the toolkit to provide interventions that can help folks get back to their best selves living their life to the fullest with the highest degree of ability and quality. And in the setting of slow heart rates, bradycardia. So whether that's sinus bradycardia, meaning your natural pacemaker is just wearing out a little bit and can't keep up with the demands or things like heart block where the wiring that carries signals from the top chambers to the bottom chambers, if they're starting to break down and you're dropping beats or missing beats going top to bottom, those are typically conditions that are best managed with the implantation of a pacemaker device.

Conversely, if we're talking about fast heart rhythms, pacemakers don't really do a whole lot to help fast heart rhythms. Those are things that we typically treat either with medical therapy, medications that slow down conduction and signals in the heart, or with ablation therapy. If you're someone who has SVT due to an abnormal extra circuit in the heart, we can go in through a procedure, find that extra circuit and find a critical portion of that circuit and deliver just little bit of millimeters of energy cautery to interrupt that circuit so it's no longer able to get activated.

So obviously, depending on the diagnosis, depending on the patient, depending on their values and their goals, that kind of determines what we do or when we do it.

Melanie Cole, MS: Well, thank you so much, Dr. Wallace, for joining us. And really what a great educator you are. Thank you for sharing your incredible expertise for listeners today. And thank you to our Bryan Foundation partner – US Bank. And for more information or to listen to more podcasts from our experts, you can visit bryanhealth.org/podcasts.

That concludes this episode of Bryan Health Podcast. Please always remember to subscribe, rate, and review Bryan Health Podcast on Apple Podcasts, Spotify, iHeart, and Pandora. Until next time, I'm Melanie Cole.