Dr. Mike Smith (Host): This is MD Cast by Tampa General Hospital, a go-to listening location for specialized physician to physician content and a valuable learning tool for world-class healthcare. I'm Dr. Mike. And with me is Dr. Suketa Shah from Tampa General Hospital. Today, we'll be talking about the impacts of obstructive sleep apnea on cardiovascular health and what clinicians need to know at the bedside and in the clinic. Dr. Shah, welcome to the show.

Dr. Suketa Shah: Thank you, Dr. Mike.

Host: Can you start by explaining how obstructive sleep apnea physiologically contributes to cardiovascular disease?

Dr. Suketa Shah: So, obstructive sleep apnea, just as a kind of quick overview, it's basically a repetitive obstruction or occlusion of one's airway when you're sleeping at night. And so, essentially, when your airway is closing down, these repetitive airway closures lead to essentially what we call a sympathomimetic response. Basically, your body gets this kind of microadrenaline release every time your airway closes down. And so, that puts a stress on your body and impacts the cardiovascular system for that reason.

Host: Yeah. And so, that surge of the sympathetic nervous system, that adrenaline that's being released, that's just going to add to nighttime high blood pressure. If somebody already has atherosclerosis, that's not going to be a good thing. That's kind of how it all happens, huh?

Dr. Suketa Shah: That's correct. So basically, those microadrenaline releases, like you said, you're going to start seeing those repetitive spikes are going to lead to kind of spikes in blood pressure through the night. Those spikes in blood pressure are going to affect your vessel walls in your body. It's going to increase your risk of coronary artery disease. It's going to increase your risk of carotid artery disease. And then, it's also going to increase your arrhythmia risks that can occur with that. So, you kind of increase your heart attack risk, you increase your stroke risk, you increase your heart arrhythmia risk, you increase your recurrent atrial fibrillation or recurrent arrhythmia risks.

Host: And so, when this kind of stuff is happening, those short hypoxic events, does that also right then and there increase the risk of an acute event to happen?

Dr. Suketa Shah: So, it can. So when your airway closes, not all of the events are always associated with hypoxia and a drop in oxygen. But frequently, you see these drops in oxygen. Sometimes we see drops in oxygen dropping to the 50s and 60s percentage-wise when we actually do studies on people.

And those acute drops in the oxygenation also add a lot of risk, can lead to that acute heart attack. You always hear about people at 2:00 a.m. in the morning waking up because of heart attack risk. And most people, you know, why are you waking up from a dead sleep, you know, and having a heart attack when you're not exerting or doing anything else differently? And the general thought is that for many of these individuals, it's because of untreated sleep apnea.

Host: Now, from your experience, which cardiovascular patient populations are most likely to have undiagnosed sleep apnea? And what clinical red flags should prompt providers to screen for that?

Dr. Suketa Shah: So, I think because screening has become so relatively easy generally with home sleep studies that are performed these days, I think when you look from a cardiovascular risk, I think really just even anyone who is on three blood pressure medications or three blood pressure medicine equivalent, those individuals should probably already start to get screened. Some would even argue even at two blood pressure medicines, that somebody should start to get screened even with a home sleep study.

And by screening, you know, with that, you can ask them, "Do you snore at all?" You can look at the size of their neck. Is their body mass index elevated? Even asking any of those questions will help you increase that risk and worry with that. Not everybody complains of being sleepy or fatigued. Some people just think this is how you live and not actually realize that they are actually fatigued, so it's kind of built up slowly over a lot of years for these individuals. And then, anybody who actually has a cardiac risk, right? If you've already had a heart attack, if you've already had a stroke, if you have a cardiac stent in place, if you've had an arrhythmia, all of those individuals really should be tested.

Host: You mentioned that it's easier these days to get screened. You mentioned home tests. How confident are we that those home tests are going to provide the same rigorous results of going into a sleep clinic?

Dr. Suketa Shah: Depending on which home sleep study you do, right? There's different types of home sleep tests. There's the more thorough ones where you have different belts measuring the respiratory effort your body is taking, along with looking at nasal airflow and airflow that's going on, besides looking at your pulse oximeter and heart rate changes, versus the simpler ones that are measuring more wrist activity and then sensing how your pulse rate is changing to make estimates.

But all of them have generally been shown to be adequate, at least as a good screening tool. On top of that, if you have a high suspicion, then yes, the in-lab studies are the most accurate studies. But sometimes you have individuals who just don't fall asleep in a sleep lab where you're hooked up to all the different wires, sleeping in a different location versus your home.

So although it's the more accurate study, sometimes patients may not fall asleep as easily in the sleep lab. But from a screening perspective, it's probably a worthwhile thing to screen most anyone with that and then decide who needs to kind of go further if the screening test is negative.

Host: Now, how does things like smoking and alcohol, even obesity, how do they affect sleep apnea?

Dr. Suketa Shah: So from a smoking perspective, so cigarette smoking, you know, inhaling anything that is hot into the back of your throat is going to inflame your throat. It's going to inflame your nasal passage. So, you're definitely going to start to occlude the airway because of that. So, anyone who is a cigarette smoker, we're going to just see an increased risk in the snoring sound, and just make the assumption that the sleep apnea goes up just because with snoring and airway inflammation becoming worse, that back of the throat and nasal area is going to be more occluded.

When we look at alcohol and any sedative or sedative medications even, those will increase the risk of obstructive sleep apnea because as your body is more relaxed, those muscles are going to relax in the back of your throat. Your tongue is going to relax. That's going to increase your occlusion and your obstruction in the back of the throat.

And then, the same thing goes from an obesity perspective. Generally, if your body mass index is over 30, and there's lots of online calculators for body mass index based on your height and your weight. But if you're over 30, chances are that you're going to have a higher risk factor for sleep apnea, or if your neck size is larger. So, men with neck sizes that are over 16 and a half inches, women with neck sizes that are 14 and a half inches or higher have a higher incidence of having obstructive sleep apnea because everything gets occluded. But not everyone has to be obese. Thin individuals can have sleep apnea if the back of your airway is more crowded because either your tonsils are prominent or because your jaw sits a little further backwards. So, that kind of pushes your tongue backwards, or if for some reason you have a large tongue. So, there are different things that could occlude the back of the throat with that side, besides just being obese.

Host: So when we think about obstructive sleep apnea, what are we talking about the most here? What's obstructing the airway the most? Is it the tongue? Is it the adenoid tissue? What's really causing the obstruction?

Dr. Suketa Shah: Yeah. So, the obstruction's going to be in a few different areas, when you're looking at your airway, right, how is air going to get down all the way into our trachea and go down to our lungs? And so, where can it be occluded up top, right? So, you first have your nasal passage. And so, I'm in the University of South Florida Department of Otolaryngology, Head and Neck Surgery.

So, I'm in the ENT department. I'm not an ENT surgeon myself. I'm a sleep pulmonary critical care physician, who now just focuses purely on sleep apnea, but within the otolaryngology department. So, we kind of start with the nasal passage. Those with markedly deviated nasal septums, very prominent turbinates, things that block up the nasal passage will start to reduce airflow, and so start to lead to issues that can kind of develop into the sleep apnea side. And then, the adenoids are kind of tissues in the way back area. From a nasal perspective, generally that would be an issue more in children. Most of us, our adenoids do shrink down a little bit as we get older.

But from the adult perspective, we have our palatine tonsils, which are the ones that you can see when you look in the back of the throat, and they're kind of blocking the throat from the side area. You have your soft palate, and the uvula or velum area. So, that's the area that kind of flops down and that punching bag that you see in the back of your throat. So, the more that that area can kind of block up things, and then you can have a tongue that's enlarged, so that can also be an area that's kind of blocking up. And as we gain weight, just the neck itself and the fattier tissues in the neck itself can lead to issues. Even as we gain weight, there's some fatty tissue that actually even increases within the tongue itself. So, the tongue itself can get a little bit bigger size-wise. So, all of those different areas can occlude things.

And then, we even have some individuals where it's the epiglottis even lower down, the kind of trapdoor that's supposed to close over your windpipe when you're eating or swallowing. Sometimes that epiglottis actually gets floppier over time, and it's actually flopping closed much quicker. And that's actually occluding things. So, a lot of different areas. But for most people, it's more often than not the weight, that as you've gained weight, that's kind of narrowing the sides along the soft palate that's hanging down lower in the back of the throat

Host: I want to back up for a second and go back to the sleep studies. Whether it's at home or in a sleep clinic, can you review for general practitioners listening to this podcast what are the main things you're measuring and looking at?

Dr. Suketa Shah: So, it depends on which type of study is being done. So, the best home sleep studies are the ones that kind of have a belt across your chest, a belt across your abdomen, a nasal flow monitor, and then looking at the pulse ox and heart rate variability. So basically, when we're doing kind of the top line home sleep study, that one basically is we're looking to see is the chest and the abdomen, are you making an effort to breathe?

But when we're looking at the flow monitor, we're not seeing any flow occurring. So, that's a little monitor that's below your nose. So, we're not seeing airflow, but we can actually tell that the chest and the abdomen are trying to do the process to bring in airflow, yet there is no airflow occurring. So, that kind of would meet the criteria of an apnea, or what we call a hypopnea, where there might be a slight amount of flow or reduction in flow. And then, at the same time, we correlate that with what's happening to your oxygen levels. Are the oxygen levels dipping with that episode? Is your heart rate changing or varying with that episode? So, all of those things get looked at together to see if this meets the criteria of a sleep apnea event.

Some of the less cumbersome devices than that, you have ones that are kind of a wristwatch. There's even the rings that people can wear that are used for sleep apnea diagnosis. And those work more on a process of the heart rate variability, and they kind of make estimates. If your heart rate is varying, it's probably because of that sympathetic response that your body's having from these sleep apnea events. And so, it's making the estimates of sleep apnea based on that and correlating that to where the oxygen is dropping. But that's not doing respiratory measurements.

So, home studies, all of them can generally underestimate sleep apnea, if anything, because they're making an estimate that you're sleeping based on the fact you're not moving. But it's not as exact as in the lab. So, home studies will underestimate, if anything.

Host: If somebody wants to do a home study and that's just what they want to do, they're just not going to go to a sleep clinic, at least maybe do the more advanced at-home ones that are looking at the respiratory. Like, you're trying to breathe, but there's no airflow. Like maybe at least do that more advanced type

Dr. Suketa Shah: I think that would definitely be the more accurate of it. That's correct. So, that would be the better one if one is the choice or the option to be able to do that would be the better one to order.

Host: But I guess at the end of the day with the home studies, at least people are getting the studies done more often, right?

Dr. Suketa Shah: That's correct. We've been able to get access. And patients have gotten the chance to get access so much more to be able to get looked at and screened. And that's why we're able to address what is a large health problem. About a third of middle-aged men are felt to have sleep apnea. Think just under about 20% of middle-aged women are felt to have sleep apnea. And so, think of the population of the US, it's a lot of people. And so, the home studies have really gotten us to be able to get so many more individuals tested and looked at from a health perspective.

Host: Bringing this back to the cardiovascular effects of sleep apnea. When somebody gets a sleep study done, you're all on board. This is sleep apnea, obstructive sleep apnea. We got to get you treated. You start treating that. Let's not worry about the treatment yet, just you're just treating it, most likely with CPAP probably.

What kind of impact does that have, that early detection, getting them treated early? What does that impact have on like hypertension, heart failure, AFib?

Dr. Suketa Shah: We've definitely seen, you know, with studies that individuals who have atrial fibrillation, it reduces the recurrence of AFib. So after patients have been treated for AFib, many of them pop back into atrial fibrillation. But if you're treating the underlying sleep apnea, then the recurrence of atrial fibrillation is much improved.

And most of the data is very, very clear for those who have moderate to severe sleep apnea, and is likely for most of the individuals with mild sleep apnea, though the data is not as robust in the mild sleep apnea population. But generally speaking, we see a reduction in the number of recurrent heart attacks. We see an improvement or control of those individuals who have low ejection fractions or heart failure to help protect the cardiovascular risk and improve that ejection fraction, or at least a lot of medicines that are being given to help people who have cardiomyopathies and low ejection fractions to be more successful, and then to kind of reduce, you know, stroke risk. And if you're keeping oxygen levels better, hopefully reduce dementia risk for individuals over time also.

Host: So, CPAP is the first-line therapy, right?

Dr. Suketa Shah: Yeah. So, just because positive airway pressure, basically just working as a pneumatic splint to keep your airway open, generally will treat all levels of sleep apnea, mild, moderate, or severe. And there are different technologies in PAP therapy, some that are smarter technologies that some patients need.

So, CPAP is kind of the standard across the board initially, but there's bi-level PAP adaptive servo-ventilators, so even more complicated technology machines with that. But that works for everyone. But only about 80% of people, really enjoy using their CPAPs. Then, we kind of look at what do for the other 20% of individuals.

Host: Yeah. I, like, I guess that was really my question is, like, compliance with CPAP is, from what I understand, not all that great.

Dr. Suketa Shah: So, compliance with CPAP, one of the issues is CPAP machines are ordered as a wide range machine for everyone, a wide pressure range. But these are machines, and machine algorithms are not perfect. They're kind of built on perfect airway model, entities, and not everyone has a perfect airway.

And so, sometimes the algorithms don't work perfectly. So, the wide range models become uncomfortable because they're blowing too hard at times, and they don't feel as great for patients. So, the issue that most people have with compliance is most people who start on CPAP should generally be seen back within about two weeks. The physician should be downloading the data, talking to the patient how they're feeling, looking at the data, and then adjusting the machine down relatively quickly to improve the compliance rates with that. And so, that's if the data's been shown pretty clearly, getting patients in within about two weeks after being on their CPAP really improves compliance if you make those adjustments.

Host: Now, current alternative treatments, you see commercials for mouthpieces, muscle stimulation. What do you think about all those?

Dr. Suketa Shah: All this stuff works very, very well in different ways, right? So, we know that the surgical options, that we do here in our otolaryngology department here at USF, includes what we call hypoglossal nerve stimulators. So, these are implantable devices that hook to the nerve that goes to your tongue, and then you turn on a remote at night that keeps your tongue pushed forward.

And so, that works very well. But the surgical options, we generally look more often than not for people who have moderate to severe disease, not usually very mild disease group of individuals. And you have to be the correct candidate, right? It has to really be mostly the tongue kind of falling backwards in the back of your throat. It shouldn't be the issue about just weight and obesity kind of narrowing the sides. So, you have to have the correct patient, or whether it's cutting out tissue or tightening up tissue in the back of the throat. So, you have to be very picky about who is the appropriate patient for that. Dental appliances, what we call mandibular advancement devices, frequently made by specialty dentists who really just focus on sleep dentistry.

They make devices that are fitted to your mouth, and they pull your lower jaw or your mandible forward, and that opens up the space in the back of the throat. So again, better in the correct individual when you look at them anatomically. If they have a relatively open back of the throat and their jaw sits back a little bit, those patients do even better. But you can try it on just about anyone to have it made. It generally works best for mild sleep apnea to kind of the early moderate group. But in the individual who's thin with an open back of the throat, but their jaw just sits very far back, even severe disease patients do really well with those.

And then, you talk about kind of the muscle stimulators. They do have tongue-stimulating devices that it's kind of daytime treatment that about 20 minutes to 30 minutes during the daytime. You actually put something on your tongue that does an electric shock to your tongue for about 20 to 30 minutes. That strengthens your tongue muscle, so it doesn't fall into the back of your throat, generally best for mild sleep apnea. And so, different treatments definitely work. They've been shown study-wise to work and different things are covered by insurance also in different ways. But they all work in different levels. It's just knowing what's most appropriate for each patient's anatomy.

Host: Last question I'm going to ask you, Dr. Shah. How important is it for a patient to be involved in a multidisciplinary sleep cardiovascular care model?

Dr. Suketa Shah: I think it makes a great difference, where the physicians are able to communicate with each other quickly and easily. So when you have the cardiologists who are concerned about something that just doesn't look right, they're seeing these arrhythmias when they're doing these internal loop recorders, and they're doing their Holter monitors, and they want to figure out why these arrhythmias are occurring, it's very easy if you have a very easy kind of seamless conversation between that and sleep physicians who can look at the data that's going on with that to correlate, is it related to the sleep apnea events? Is it not related to the sleep apnea events? So, I do think the multidisciplinary group is really helpful.

We see that over here at USF/TGH, with us being able to be in these portals and being able to see each other and stuff in the hallways, just to be able to talk or be able to discuss patient care to further optimize and really pinpoint where we can improve anything for any patient.

Host: Dr. Shah, this has been fantastic. Thank you for a very thorough interview

Dr. Suketa Shah: Thank you very much, Dr. Mike.

Host: For more information, you can go to tgh.org/definingmedicine and visit cme.tgh.org for other CME opportunities, including live webinars, on-demand videos, and local events offered by Tampa General Hospital. If you enjoyed this podcast, please share it on your social channels and check out the entire MD Cast library for topics of interest to you. This is MD Cast by Tampa General Hospital. I'm Dr. Mike. Thanks for listening.