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How do pacemakers and defibrillators work? A cardiologist explains how they interact with the electrical system of the heart

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How do pacemakers and defibrillators work? A cardiologist explains how they interact with the electrical system of the heart

Electrocardiograms, or ECGs, record the electrical activity of your heart.
Randy Faris/The Image Bank via Getty Images

Virginia Singla, University of Pittsburgh

Your heart’s job is to keep your pulse steady to pump blood throughout your body. Sometimes your heart rate is slower when you’re relaxing, and sometimes it’s faster when you’re exercising or stressed. If your heart’s ability to keep the beat starts to go awry, cardiac electrophysiologists like me look for outside from an implantable device.

There are two common implantable devices for the heart: artificial pacemakers and defibrillators. Artificial pacemakers keep blood and oxygen flowing during times of stress. Defibrillators are devices that detect dangerously fast heart rates and deliver shocks like those used during cardiopulmonary resuscitation, also known as CPR, to restart the heart.

Understanding how these devices work requires appreciating how the heart’s electrical system works and the weak links that cause malfunctions.

The heart’s natural pacemaker system

Abnormally slow heart rates result from breakdowns in two principal of the heart.

First, the sinoatrial, or SA, node sets your “resting” heart rate, usually somewhere between 60 and 100 beats per minute. This is the base effort needed to circulate enough blood to sustain normal bodily function. Elevated levels of certain hormones circulating in the body, such as adrenaline and serotonin, can increase heart rate above resting levels.

Trained athletes frequently have a lower resting heart rate due to extra physical conditioning. Like any other muscle, the heart becomes stronger with . Because their heart functions more efficiently, athletes require fewer heart beats overall to circulate blood.

Diagram of cross-section of heart showing the SA and AV nodes
Breakdowns in the sinoatrial and atrioventricular nodes can cause heart rate problems.
Rob Kreuger, medical illustrator/Wikimedia Commons, CC BY-SA

The atrioventricular, or AV, node is the second key area of the heart’s electrical wiring. The atrioventricular node takes information about how fast the heart is beating from the sinoatrial node and relays it to the ventricles, the muscular portions of the heart that allow it to pump blood to the rest of the body.

When the atrioventricular node breaks down, the ventricles don’t receive the electrical signal from the sinoatrial node instructing them to “pump,” or create a heartbeat. This causes heart rate to become dangerously slow.

When heart rate is too slow

If resting heart rate is abnormally low or fails to increase with hormonal changes, pacemakers can help keep blood and oxygen circulating at a healthy rate.

Both the SA node and the AV node naturally slow with age, but sometimes this happens at an accelerated pace and to abnormally slow heart rates. Slow heart rates can also be caused by other diseases, thyroid problems and Lyme disease. In these cases, slow rates are treatable without a pacemaker.

A common pacemaker system has a battery and two wires that can send and receive electrical signals. One wire rests near the sinoatrial node, and the second in one of the heart’s ventricles.

If the wire near the sinoatrial node doesn’t detect any electrical activity over a set time, the pacemaker’s battery will send an impulse to the ventricle to initiate an electrical signal. Within fractions of a second, the wire in the ventricle should detect that electrical activity. If an impulse is detected, this signifies that the AV node conducted the signal correctly to the rest of the heart, and the pacemaker does not activate. If the wire doesn’t receive this signal, the battery delivers an impulse through the wire directly to the ventricle, causing the muscle to contract and initiate a heartbeat.

The heart’s muscle will only contract in response to a pacemaker impulse if the muscle is otherwise healthy. Pacemakers do not keep patients alive if the heart shuts down, such as during a massive infection, blood clot or kidney failure. Pacemakers simply keep the heart rate in a comfortable range if the primary problem in the heart is electrical.

Diagram of cross-section of heart with implanted pacemaker
Pacemaker electrodes are implanted directly in the heart.
National Heart, Lung, and Blood Institute

program a pacemaker’s software so the resting pulse doesn’t drop below a certain rate, commonly 50 to 60 beats per minute. If the resting rate is set at 60 beats per minute, the pacemaker will wait exactly one second before initiating an electrical pulse. The heart’s pulse rate can be higher than this number if the sinoatrial node initiates a heartbeat naturally. If the pacemaker detects activity from the sinoatrial node, it will reset its timer for another full second.

Modern pacemakers also contain sensors to predict whether the heart may benefit from a faster heart rate under certain circumstances. For example, pacemaker batteries contain accelerometers like those used in pedometers to detect if a person is in motion. If these sensors activate, the pacemaker can raise its minimum rate like how the heart would normally respond to exercise. Sensors can also detect if a person begins to breathe more quickly or if the heart begins to contract more powerfully, all signs normally associated with increases in heart rate.

When heart rate is too fast

Like pacemakers, a cardiac defibrillator with a battery and wires that record the heart’s rate. But instead of treating slow heart rates, defibrillators are programmed to detect fast heart rates, usually in the range of 200 beats per minute. Heart rates in this range are often caused by ventricular tachycardia or ventricular fibrillation, which are potentially lethal heart rhythms resulting from the lower chamber of the heart beating too quickly or quivering.

Certain people are at elevated risk for these types of rhythm disturbances. Many cases of “sudden death” in athletes and other young people are either suspected or proved to be related to ventricular fibrillation.

Defibrillators deliver an electric charge to restart the heart.

Defibrillators deliver internal shocks to the heart when their sensors detect either ventricular tachycardia or ventricular fibrillation. These shocks stop the heart for a fraction of a second to give the sinoatrial node a to resume its normal activity. These shocks can be painful, so doctors usually also prescribe medications or other procedures to help prevent needing the shocks in the first place.

A defibrillator is like a seatbelt: It is reassuring to have, but ideally it never needs to be deployed.

Beyond the surgery

Pacemakers and defibrillators do require some maintenance. Certain settings, such as how low the pacemaker will allow the pulse to go, can be adjusted over time. Doctors have computers that can communicate with the devices and alter their programming. Some devices use Bluetooth technology.

The battery cannot be recharged and must be replaced, generally after six to 10 years. Battery life depends on how frequently the heart requires the pacemaker to initiate heartbeats. Pacemaker wires occasionally need to be replaced if they fracture or if the insulation wears down after years of bending with each heartbeat. On rare occasions, pacemaker parts are recalled. Usually these parts do not require replacement but may require special attention. More frequent checkups of the electrical “” of the devices are usually prescribed for early detection of any problems with battery or wire failures.

Pacemakers and defibrillators are always changing, in part to keep up with medical and nonmedical technologies.

With cloud-based management systems that make medical information available to doctors in real time, security has become a major focus of modern pacemaker software. Other medical technologies such as MRIs can change how pacemakers and defibrillators work if not handled carefully – MRIs create electromagnetic impulses that cardiac devices can misinterpret as heartbeats. Modern devices are engineered with these factors in mind, but still require careful programming for these special circumstances.

When used correctly, pacemakers and defibrillators improve both quality of life and life expectancy. While teams of engineers design these small machines, they rely on doctors knowing who will benefit from this technology and how to program the software to best serve each specific patient and scenario.The Conversation

Virginia Singla, Clinical Assistant Professor of Cardiology, University of Pittsburgh

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Election anxiety doesn’t need to win − here are 3 science-backed strategies from a clinical psychologist to rein in the stress

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theconversation.com – Shannon Sauer-Zavala, Associate Professor of Psychology & Licensed Clinical Psychologist, of Kentucky – 2024-11-01 15:46:00

The world won’t end if you stop scrolling.
georgeclerk/E+ via Getty Images

Shannon Sauer-Zavala, University of Kentucky

Uncertainty about the election getting to you? Is anxiety the dominant feature of your emotional landscape, maybe with a small sprinkling of impending doom?

You are not alone. A recent survey found 69% of American adults are seriously stressed about the 2024 presidential election.

It’s difficult not to be worked up about in today’s polarized climate. Regardless of which side of the political aisle you sit on, you may find yourself glued to your browser or TV, gobbling up every tiny tidbit of and feeling your stress levels skyrocket.

I’m a psychologist who develops and tests strategies for combating anxiety. As I constantly tell my stressed-out clients, when it comes to election news, there’s a fine line between being well informed and being oversaturated with information.

If you’re ready to short-circuit your stress spiral, here are three science-backed strategies for coping with anxiety in times of uncertainty.

Approach your emotions with mindfulness

Being mindful refers to the quality of awareness you bring to your experiences – specifically, nonjudgmental attention focused on what’s right now.

Mindfulness practices originated in Eastern spiritual traditions, Buddhism. Over the past several decades, mindfulness has gained popularity as a powerful tool for managing anxiety. For instance, meditation apps such as Headspace and Calm incorporate it. Even if meditation isn’t your thing, though, you can still apply nonjudgmental awareness, focused on the present, to election-related anxiety.

Be present. Anxiety can draw you into an uncomfortable spiral of “what-ifs” about the future. When you make a point to be present, you remind yourself what is actually happening right now, rather than letting hypothetical fears take over.

Although you may have serious concerns about the fate of the nation, those outcomes have not yet to bear. As I tell my patients, “We’ll cross that bridge if we come to it. For now, focus on the step right in front of you.”

If you notice yourself getting carried away by of the future, you can pull yourself back to the present by bringing awareness to simple sensations – the feel of your feet on the floor, the rhythm of your breath, or the sounds around you – and remind yourself that you are safe in the current moment.

Pay nonjudgmental attention. Many people are hard on themselves for feeling strong emotions. This critical mindset might look like telling yourself that you’re overreacting, or that it’s weak to let others see that you’re upset. You might even view that uncomfortable feeling in the pit of your stomach as evidence that negative outcomes are right around the corner.

Making judgments about your emotions only serves to make you feel worse. In fact, researchers find that pushing away emotions or beating yourself up for having them leads to more frequent and stronger anxiety.

Instead, try giving yourself a break. Tell yourself, “This election is high stakes, so it makes sense I’m anxious.” Then, notice if your anxiety is driven by a fear about the future, and bring yourself back to the present.

older woman comforts a younger woman who is looking off into distance
Pull your thoughts back to the here and now.
supersizer/E+ via Getty Images

Get flexible with your thinking

Cognitive flexibility is the ability to shift away from rigid, all-or-nothing thinking about the future.

When people are anxious, they tend to focus on the worst-case scenario. For example, you might be telling yourself, “With this candidate in office, things will be terrible and I won’t be able to cope.”

In this scenario, I encourage my patients to move past that initial thought of how awful it will be and instead consider exactly how they will respond to the inauguration, the next day, , month and so on.

Cognitive flexibility allows you to explore how you will cope, even in the face of a negative outcome, helping you feel a bit less out of control. If you’re experiencing a lot of anxiety about the election, try thinking through what you’d do if the undesirable candidate takes office – thoughts like “I’ll donate to causes that are important to me” and “I’ll attend protests.”

Choose your actions with intention

Another tool for managing your anxiety is to consider whether your behaviors are affecting how you feel.

Remember, for instance, the goal of 24-hour news networks is to increase ratings. It’s in their interest to keep you riveted to your screens by making it seem like important announcements are imminent. As a result, it may feel difficult to disconnect and take part in your usual self-care behavior.

Try telling yourself, “If something happens, someone will text me,” and go for a walk or, better yet, to bed. Keeping up with healthy habits can help reduce your vulnerability to uncontrolled anxiety.

woman faces away from camera, wearing a 'VOTE' t shirt
It’s not on your shoulders to solve every single problem in the world.
AP Photo/John Hanna

Post-Election Day, you may continue to feel drawn to the news and motivated to show up – whether that means donating, volunteering or protesting – for a variety of causes you think will be affected by the election results. Many people describe feeling guilty if they say no or disengage, leading them to overcommit and wind up overwhelmed.

If this sounds like you, try reminding yourself that taking a break from politics to cook, engage with your or friends, get some work done or go to the gym does not mean you don’t care. In fact, keeping up with the activities that fuel you will give you the energy to contribute to important causes more meaningfully.The Conversation

Shannon Sauer-ZavalaUniversity of Kentucky

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How to overcome your device dependency and manage a successful digital detox

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theconversation.com – Kelley Cours Anderson, Assistant Professor of Marketing, College of Charleston – 2024-11-01 07:39:00

Getting outside – without your phone – is one way to disconnect.
We Are/DigitalVision via Getty Images

Kelley Cours Anderson, College of Charleston and Karen Anne Wallach, University of Alabama in Huntsville

in the digital world can be rewarding. It’s convenient to order groceries for pickup, share photographs or music, and keep in touch with family and friends, no matter the distance. However, it can also be draining. The feeling of being constantly “on” and productive has driven people to reconsider their balance in the saturated digital world.

More than 70% of American adults are concerned about how technology affects their mental health and personal relationships. This worry is reinforced through media that point to people’s unhealthy habits with social media and phones.

What to do? There is a fuzzy line between healthy and unhealthy digital consumption. Some folks feel the need to fully disconnect from the digital world to understand this boundary. The idea of digital detoxing is gaining popularity. This practice involves intentionally unplugging from digital technologies in the pursuit of balance and digital well-being. Nearly half of Americans report that they are making a conscious effort to regularly step away from their screens.

But is this attempt enough? It’s no surprise that 62% of Americans confess to feeling addicted to their devices and the internet. Despite people’s best efforts to unplug and strike a balance, research indicates that digital detoxes often fall short.

two men in a park grin as one tosses a bean bag
Getting outside, being with someone else and fun are all good approaches to disconnecting from the digital world.
kali9/E+ via Getty Images

Digital well-being is subjective. We research technology and consumer behavior. Our recent research studied the digital detox journey, where people take a much-needed break from digital consumption, aiming to uncover what supports or sabotages those seeking digital well-being. Our findings highlighted four key strategies to improve the outcome of this journey toward achieving a healthier digital balance: replacement practices, social bonds, mindfulness and digital well-being as a journey.

1. Finding replacement practices

We found that feelings of withdrawal during a digital detox are quite common. For many, reaching for their phones and scrolling has become such a ritual that they often don’t realize they are doing it. Many turn to their devices when bored or stressed, much like an adult pacifier. As a result, finding an alternative to distract your mind and occupy your hands can be crucial during a digital detox.

These replacement practices often involve hobbies or activities that result in play. As adults, people sometimes forget what it feels like to have fun. By separating fun from your task list and engaging in play for its own sake, you can significantly reduce stress levels and boost your digital well-being.

2. Shoring up social bonds

Humans are inherently social creatures. Indeed, tools such as email, text messages and social media offer ways to enhance social connections. This innate desire for connection, however, combined with people’s reliance on technology, can lead to feelings of FOMO – fear of missing out – and anxiety during a digital detox.

The average adult now spends 70% less time with friends than they did two decades ago. Digital devices offer connection, but pieces of the experience are missing, such as the joy of in-person contact and trust in others that can be difficult to get online. So while we’re a more connected society, relationships suffer and people are more lonely than ever.

Therefore, during a digital detox it is vital to fill your cup with community, whether through existing friendships or by creating new ones. We recommend engaging in a digital detox alongside others, because FOMO may rear its ugly head if your friend pulls out their phone during a night out.

Taking a short digital detox with the Offline Club.

3. Emphasizing mindfulness

In ‘s fast-paced , finding a moment to pause can feel nearly impossible. Many experience solitude deprivation, meaning people often don’t have moments to be alone with their own . Yet, the ability to just be can allow time for reflection, helping you consider what makes you happy and healthy. Finding moments where you can step away – to be still and silent – can a much-needed recharge.

With adults spending about 90% of their time indoors, breaking the routine and outside can offer a more holistic perspective on both personal and global well-being. In our study, yoga and meditation were common ways that detoxers found moments to become more aware of their own thoughts, which helped foster more intentional behaviors.

4. Viewing digital well-being as an ongoing journey

Ultimately, digital well-being is a journey. It is not a checklist that, once completed, means you are fulfilled.

Unfortunately, a single detox isn’t enough to cure digital imbalance. Instead, a successful detox often leaves people feeling introspective and curious. Our research participants shared that relapses are common, especially if they don’t set and monitor ongoing goals. Importantly, your needs change and evolve over time. In other words, what works now might not be what you need in the future.

Willpower just isn’t enough. We recommend identifying specific goals for yourself related to your own digital well-being. These aren’t productivity goals but goals to be unproductive. The aim is to unplug in more fulfilling ways. Whether planning a weekly game night with friends or taking a 10-minute walk without your phone, making time to unplug is worth it in the long run.

Researchers still have more to learn to help digital wellness. We should remember, though, that individual differences play a crucial role in this equation, meaning that the journey to achieving digital harmony is uniquely personal. Thus, as people navigate their tech-saturated lives, it’s clear that finding the right balance is a complex, highly individualized .

The digital detox journey can be challenging, but many people discover it to be rewarding in the end. People are not machines, however, so recognizing your limits and finding ways to reconnect with yourself and others during a detox can significantly enhance your sense of humanity and digital well-being.The Conversation

Kelley Cours Anderson, Assistant Professor of Marketing, College of Charleston and Karen Anne Wallach, Assistant Professor of Marketing, University of Alabama in Huntsville

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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‘Safe route’ or ‘sushi route’ − 2 strategies to turn yuck to yum and convince people to eat unusual foods

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theconversation.com – Alexandra Plakias, Associate Professor of Philosophy, Hamilton College – 2024-11-01 07:39:00

By the 1980s, many New Yorkers were all in on sushi, a food that seemed weird just decades before.
Allan Tannenbaum/Getty Images

Alexandra Plakias, Hamilton College

What will the diets of the future look like? The answer depends in part on what foods Westerners can be persuaded to eat.

These consumers are increasingly being told their diets need to change. Current eating habits are unsustainable, and the global demand for meat is growing.

Recent years have seen increased interest and investment in what are called alternative proteins – products that can replace typical meats with more sustainable alternatives. One option is cultivated, or cultured, meat and seafood: muscle tissue grown in labs in bioreactors, using animal stem cells. Another approach involves replacing standard meat with such options as insects or plant-based imitation meats. All of these products promise a more sustainable alternative to factory-farmed meat. The question is, will consumers accept them?

I’m a philosopher who studies food and disgust, and I’m interested in how people react to new foods such as lab-grown meat, bugs and other so-called alternative proteins. Disgust and food neophobia – a fear of new foods – are often cited as obstacles to adopting new, more sustainable food choices, but I believe that recent history offers a more complicated picture. Past shifts in food habits suggest there are two paths to the adoption of new foods: One relies on familiarity and safety, the other on novelty and excitement.

Disgust and the yuck factor

Disgust is a strong feeling of revulsion in response to objects perceived to be contaminating, polluting or unclean. Scientists believe that it evolved to protect human beings from invisible contaminants such as pathogens and parasites. Some causes of disgust are widely shared, such as feces or vomit. Others, including foods, are more culturally variable.

So it’s not surprising that self-reported willingness to eat insects varies across nationalities. Insects have been an important part of traditional diets of cultures around the world for thousands of years, the ancient Greeks.

Many articles about the possibility of introducing insects to Western or American diners have emphasized the challenges posed by neophobia and “the yuck factor.” People won’t accept these new foods, the thinking goes, because they’re too different or even downright disgusting.

If that’s right, then the best approach to win on the plate for new foods might be to try to make them seem similar to familiar menu items.

The safe route to food acceptance

Poster from 1940s with photo of soldier and civilians saluting with heading 'Sure – We'll 'Share the Meat''
During World War II, the worked to make it seem patriotic to not pig out on the usual meat.
U.S. National Archives/Flickr, CC BY

During World War II, the United States government wanted to redirect its limited meat supply to troops on the front lines. So it needed to convince home cooks to give up their steaks, chops and roasts in favor of what it called variety meats: kidneys, liver, tongue and so on.

To figure out how to shift consumer habits, a team of psychologists and anthropologists was charged with studying how food habits and preferences were formed – and how they could be changed.

The Committee on Food Habits recommended stressing these organ meats’ similarity to available, familiar, existing foods. This approach – call it the “safe route” – focuses on individual attitudes and choices. It tries to psychological and practical barriers to individual choice and counteracts beliefs or values that might dissuade people from adopting new foods.

As the name suggests, the safe route tries to downplay novelty, using familiar forms and tastes. For example, it would incorporate unfamiliar cuts of meats into meatloaf or meatballs or grind crickets into flour for cookies or protein bars.

The sushi route

But more recent history suggests something different: Foods such as sushi, offal and even lobster became desirable not despite but because of their novelty and difference.

Sushi’s arrival in the postwar U.S. coincided with the rise of consumer culture. Dining out was gaining traction as a leisure activity, and people were increasingly open to new experiences as a sign of status and sophistication. Rather than appealing to the housewife preparing comfort foods, sushi gained popularity by appealing to the desire for new and exciting experiences.

By 1966, The New York Times reported that New Yorkers were dining on “raw fish dishes, sushi and sashimi, with a gusto once reserved for corn flakes.” Now, of course, sushi is widely consumed, available even in grocery stores nationwide. In fact, the grocery chain Kroger sells more than 40 million pieces of sushi a year. Whereas the safe route suggests sneaking new foods into our diets, the sushi route suggests embracing their novelty and using that as a selling point.

Sushi is just one example of a food adopted via this route. After the turn of the millennium, a new generation of diners rediscovered offal as high-end restaurants and chefs offered “nose to tail” dining. Rather than positioning foods like tongue and pigs’ ears as familiar and comforting, a willingness to embrace the yuck factor became a sign of adventurousness, even masculinity. This framing is the exact opposite of the safe route recommended by the Committee on Food Habits.

Chef displaying a plate of fried bugs with guacamole
Mexico is one place that has a centuries-old tradition of eating some insects.
AP Photo/Dario Lopez-Mills

The future of alternative proteins

What lessons can be drawn from these examples? For dietary shifts to last, they should be framed positively. Persuading customers that variety meats were a necessary wartime substitution worked temporarily but ultimately led to the perception that they were subpar choices. If cultivated meat and insects are pitched as necessary sacrifices, any gains they make may be temporary at best.

Instead, producers could appeal to consumers’ desire for healthier, more sustainable and more exciting foods.

Cultivated meat may be “safe-ly” marketed as nuggets and burgers, but, in principle, the options are endless: Curious consumers could sample lab-grown whale or turtle meat guilt-, or even find out what woolly mammoth tasted like.

Ultimately, the chefs, consumers and entrepreneurs seeking to remake our food don’t need to choose just one route. While we can grind insects into protein powders, we can also look to chefs cooking traditional cuisines that use insects to broaden our culinary horizons.The Conversation

Alexandra Plakias, Associate Professor of Philosophy, Hamilton College

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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