In Heart Disease, Women and Men Are Not Created Equal

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It may seem as if heart disease affects mostly men, but in fact it’s the No. 1 cause of death for both genders—more people die from heart disease than all cancers combined. Perhaps even more surprising is that more women than men will develop heart failure or die within a year of a heart attack.

Medical professionals don’t completely understand why women have worse outcomes than men when it comes to heart disease. One factor, however, is that heart attack symptoms are often very different in women and in some cases aren’t as obvious. Like men, women may experience classic chest pain, but they may also have a variety of more general symptoms, including:

  • nausea or vomiting,
  • indigestion,
  • shortness of breath,
  • pain in the upper back or arm,
  • neck and jaw pain, or
  • unusual fatigue.

Sometimes these symptoms may fade and reappear.

Men and women often have different types of artery disease. This may be a key to why symptoms are not the same. Men are more likely to have significant blockage of a major artery whereas many women have no evidence of arterial blockage. Women are more likely to have microvascular disease, which affects the heart’s smaller blood vessels.

Because many people believe that women are less likely to have a heart attack—combined with the differences in symptoms—may be why women don’t always realize they are having one. As a result, they may not seek treatment immediately. In one study, women did not get medical treatment for an average of 50 hours, compared to fewer than 16 hours for men. A delay in treatment contributes to a greater chance of dying from a heart attack.

In the emergency room, the lack of classic heart attack symptoms can lead to misdiagnosis, resulting in a delay in treatment. Studies show that women are less likely to receive appropriate treatment for heart attack compared to men. Even when they are treated appropriately, women often experience a higher risk of complications.

Although there have been tremendous improvements in the treatment of heart disease in women, more still needs to be done. Increased education and improved training will help the general public and medical professionals recognize the differences between men’s and women’s symptoms. In addition, more clinical research is needed to understand the reason for these gender-related differences and to better personalize the management of heart disease in women.

February is American Heart Month. Visit the American Heart Association’s website to learn more about heart disease in women.

 

John ChathamJohn Chatham, DPhil, is a professor of pathology and director of the Division of Molecular and Cellular Pathology at the University of Alabama at Birmingham.

 

Why Marriage Is Good for Your Heart

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Valentine’s Day is a time when many of us reflect on the importance of our closest relationships. Whether they include family, friends or a significant other, science is not silent on the impact these relationships have on our health. A review of 148 studies reveals that strong social relationships are associated with a 50 percent increased likelihood of survival, regardless of medical condition. Other studies link low social support to an increased risk and incidence of heart disease. The newest research, however, explores the effect our most intimate relationships—with a romantic partner—have on heart health.

A study that looked at more than 6,000 people reports that being single is associated with heart disease. Specifically, people who were single had a 45 percent higher rate of death from heart disease than those who were married. A striking finding in this study was that even though the reason for being unmarried varied among the participants—some people had never married, others were divorced, separated or widowed—the risks were consistently lower in married people. From these results, the overall benefit of the spousal relationship on heart health seems clear.

Many factors may account for the positive effect of marriage on heart health, including:

  • improved social support,
  • a less sedentary lifestyle, and
  • increased motivation to make healthy lifestyle changes.

The quality of marital relationships over time also influences heart disease risk factors. Men who described their relationships as “improving” had a lowering of risk factors compared to those in marriages categorized as “consistently good” or “deteriorating.”

In other words, marriage is generally good for your heart health and even better when you work to improve that relationship over time. So as you think about those closest to your heart on Valentine’s Day, do your heart a favor and take your sweetheart on a date.

Shawn Bender, PhD

Shawn Bender, PhD, is an assistant professor at the University of Missouri and a research health scientist at the Harry S. Truman Memorial Veterans’ Hospital.

In Hot Water

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This week, the I Spy Physiology blog answers a reader question: Why do we get dizzy when getting out of a hot tub?

There may not be a better way to chase away the winter “blahs” than soaking in the hot tub or standing under a steaming shower. However, sometimes, after a lengthy soak or steam you may feel lightheaded when you stand up. You may start to feel woozy and your balance may waver. You may even see stars for a moment or faint. Why does this happen?

When body temperature rises due to hot water, hot weather or fever, the body activates mechanisms to cool down toward normal temperature (97–99°F). The blood coursing through the body must rise to the surface of the skin, releasing heat, to reduce core temperature. This happens through a process called vasodilation. During vasodilation, blood vessels carrying blood away from the heart (arteries) open up to allow a larger volume of blood to flow through them. Blood flowing through the arteries near the skin’s surface releases heat into the environment and cools the body. However, when many arteries open up at the same time (while a person is standing up), gravity pulls the blood into the legs and away from the brain and heart. Pooling of blood in the legs can cause dizziness or lightheadedness because the brain and heart aren’t getting enough blood.

Lightheadedness and even fainting are the body’s way of “fixing” the lack of blood in the brain and heart. Once the brain, heart and legs are at the same level (when a person is lying down), blood flows into each organ more easily because gravity no longer pulls so much blood into the legs. Flexing the muscles is another way to return more blood to the brain and heart. Muscle contraction works against gravity and forces blood back to the heart and ultimately the brain. This provides the brain with enough blood volume to eliminate wooziness.

The next time you are enjoying a dip in a hot tub or a steaming shower, pause, flex your muscles and steady yourself before stepping out.

Jessica Taylor 2017Jessica C. Taylor, PhD, is the Senior Manager of Higher Education Programs at the American Physiological Society. She is a cardiovascular physiologist, exercise enthusiast and firm believer in warming up in hot water.

Relieve Stress and Anxiety with Exercise in the New Year

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If getting more exercise is one of your New Year’s resolutions, here is another reason to stick with it: daily exercise—which is known to lower blood pressure—has also been shown to reduce stress and anxiety. I am not the first to notice that physical activity improves my ability to respond to stressful situations, but as a physiologist, I naturally wonder about the biological basis of this observation.

The hippocampus—one of the brain regions that regulates anxiety levels—becomes activated during both exercise and stress. Research suggests that exercise can calm some of the nerve cells in the hippocampus that become overstimulated during times of stress. While we don’t fully understand the mechanisms, we do know that certain chemical signals in the brain inhibit nerve cell activity, and some of these signals are likely responsible for the observed reduction in stress and anxiety.

Reduced anxiety and stress immediately after physical activity is not the only benefit of exercise. Blood pressure also declines to healthier levels within minutes after exercising. Studies suggest that exercise causes vasodilation, or widening of the blood vessels. When blood vessels open wider, it allows the blood to flow more easily, thereby lowering the pressure of the blood inside the vessels. Activation of histamine receptors is one mechanism that contributes to the reduction in blood pressure following exercise.

While there are many other benefits to regular exercise, the reductions in stress and blood pressure occur immediately and last for many hours. So, consider engaging in a physically active lifestyle that includes daily exercise, and encourage family and friends to join in. The result could be less stress, less anxiety, and lower blood pressure. What better way to start 2018?

william-farquharWilliam B. Farquhar, PhD, is a professor in the department of kinesiology and applied physiology at the University of Delaware. In addition to being a member of the American Physiological Society, he is a Fellow of the American College of Sports Medicine.

 

Keeping the Juices Flowing with Beets

Beetroot Juice

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With the new year upon us, many people are setting new goals for themselves related to improving their health or focusing on career-related goals. If establishing better exercise and nutrition habits are part of your quest to attain optimal health and productivity in 2018, you are not alone. New gym memberships are likely to rise in the coming months, and some may try nutritional products such as fruit and vegetable juice concoctions touted to enhance performance and overall health. The global juicing industry has gained a lot of traction in the last several years due to a wider health awareness among consumers. Emerging evidence suggests that casting beets in the starring role of your juice habit—along with aerobic exercise—may be one potential route to improving your cardiovascular health, and more recently shown, brain health.

Beets are a good source of antioxidants, minerals and nitrates. The nitrate-rich properties of beets have caught the attention of researchers, particularly those in the field of vascular medicine. Nitrates in food are converted to nitric oxide in the body. Nitric oxide relaxes the walls of the arteries, lowering blood pressure and increasing blood flow to muscles. That is one of the reasons why the nitrates in beetroot juice have been shown to enhance exercise performance in high-performing athletes, as well as in less elite exercisers.

In addition to the cardiovascular and performance benefits of consuming beets, recent studies suggest that the root vegetable may also be linked to brain health. One study found that older adults who performed aerobic exercise for six weeks and drank beetroot juice daily had greater improvements in brain activity related to movement than the participants who exercised without drinking beetroot juice. The brain networks of the juicing group more closely resembled the brains of younger adults, suggesting that when combined with exercise, beets can enhance the brain’s ability to make new connections between brain cells. Another study showed that young adults who drank a single dose of beetroot juice had increased blood flow to the area of the brain involved in higher-order thinking. The study participants also fared better in cognitive tasks such as basic math.

So, before you lace up your running shoes or settle back into your office chair, consider topping off with a dose of beetroot to keep the juices flowing.

 

Yasina Somani cropYasina Somani, MS, is a PhD student in the Cardiovascular Aging and Exercise Lab at Penn State. She is interested in studying the effects of novel exercise and nutritional therapies on cardiovascular outcomes in both healthy and clinical populations.

 

2017’s 10 Most-read Posts

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Another physiology-filled year on the I Spy Physiology blog is almost over. This year, we’ve explored dozens of topics, ranging from skin cancer, gut health and spinal cord injury to the mystery of how hibernating animals’ muscles remain strong. We’ve celebrated women in science and smiled at the thought of turkeys running on treadmills. Today, we’re highlighting the 10 most-read posts of 2017.

Scholarly articles highlight the need for more research about women’s responses to illness and disease risk. In that vein, our most popular post this year looked at the relationship between sex-specific hormones and asthma. Posts about the danger of e-cigs—especially in the under-21 set—and how muscle rebuilds during the daunting feat of cycling the 500-mile Colorado Trail rounded out the top three. Take a look at this year’s top 10:

  1. When Hormones Take Your Breath Away
  2. The Trouble with E-Cigs: Why They May Pose More Harm than Good
  3. Muscle Rebuilding on the Colorado Trail
  4. Beer Does a Body Good?
  5. Meet Karyn Hamilton, Health and Exercise Science Professor
  6. Dog Gazing: Bond between Hound and Human
  7. Why Does Air Pollution Affect More Women than Men?
  8. When Vampires Attack: How Your Body Reacts to Extreme Blood Loss
  9. Microvesicles and Blood Vessels and Exercise, Oh My!
  10. The Hispanic Paradox: Why Are Some Ethnic Groups Living Longer than Others?

We’d love to hear what you’d like us to feature next year. Share your thoughts in the comments or send us an email. And don’t forget to follow our blog in 2018.

Erica Roth 

Exploring Causes and New Treatments for Sickle Cell Disease

genemarker

Shaina Willen, MD, of Vanderbilt University Medical Center, presents her poster at the Physiological and Pathophysiological Consequences of Sickle Cell Disease conference.

Sickle cell disease (SCD) is a lifelong disorder of the red blood cells. It’s caused by a mutation in a single gene and affects about 100,000 people in the U.S. Normal red blood cells are round, a shape that helps the cells carry oxygen around the body. But red blood cells in people with SCD can become abnormally shaped like a crescent (sickle), which can cause blood cells to get stuck in blood vessels and interfere with blood flow, leading to severe pain.

Scientists and medical doctors who specialize in SCD gathered last month in Washington, D.C., for the American Physiological Society conference “Physiological and Pathophysiological Consequences of Sickle Cell Disease.” They discussed new research into the causes of the disease and new therapies that can treat and even prevent SCD-related pain episodes. Read on to learn more about their findings.

Certain patients with SCD may have a higher risk than others of developing complications—such as increased pain, stroke, eye problems and kidney disease—but finding out which patients have a higher risk is challenging. New research from Vanderbilt University Medical Center has uncovered a genetic marker that may be able to identify which patients are more likely to have these complications.

Emotional stress is known to trigger or worsen physical symptoms of disease, including some types of pain. A group of researchers from California found that stress and the anticipation of pain causes blood vessels to become narrower (vasoconstriction). In people with SCD, vasoconstriction can be dangerous because abnormally shaped (sickled) cells may be more likely to get stuck in the blood vessels and block blood flow.

A healthy digestive system is typically filled with various types of bacteria that aid in digestion. However, researchers from Howard University found that people with SCD are more likely to have higher levels of one specific bacterium, Veillonella. Veillonella link together to form a film in the digestive tract, which can attract red blood cells. When red blood cells stick to the film, it can block blood flow to the rest of the body, which causes increased pain. This discovery may help scientists find a way to rebalance gut bacteria levels and reduce symptoms.

These studies are just a few examples of the high-caliber SCD research being done. Read more highlights from this year’s conference:

Alzheimer’s drugs may improve red blood cell function and quality of life

Scientists explore ways to create red blood cells outside the body and prevent sickling

Erica Roth 

When Vampires Attack: How Your Body Reacts to Extreme Blood Loss

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It’s Halloween and the number of vampire attacks in your neighborhood may be on the rise! What would happen to your body if you were unlucky enough to be the victim of a blood-sucking vampire?

The average adult has about 1 to 1.5 gallons of blood circulating in their body. Maintaining this amount of blood is very important—proper blood volume helps keep your blood pressure at a steady level and moves the right amount of blood around your body. As your heart pumps blood through your blood vessels, the blood carries nutrients and oxygen to your organs so that they have energy to do their jobs. The blood also takes away the waste that your organs produce.

When you lose a large amount of blood very rapidly (such as during a vampire attack) your blood pressure drops quickly. This is similar to having a punctured bicycle tire. As the air escapes through the hole, there is less pressure in your tire. During an episode of significant blood loss, your body starts to take action to increase blood volume and blood pressure:

  • Sensors called baroreceptors detect the decrease in blood pressure and cause your heart to pump faster and your blood vessels to narrow (constrict).
  • Your body releases chemicals called catecholamines, which also cause your heart to pump faster and your blood vessels to constrict.
  • Your pituitary gland releases a chemical called vasopressin. Vasopressin constricts blood vessels and helps your body hold on to as much water as possible by decreasing the amount of urine you produce.

When blood vessels constrict, the blood inside the vessels push against the sides of the vessel more, causing blood pressure to increase. Increased blood pressure reduces the amount of blood needed to fill your vessels.

If these actions are unable to restore your blood pressure, you can go into shock. Shock occurs when your blood pressure is so low that not enough blood is getting to your organs. In a state of shock, your heart, liver, kidneys and brain can’t function properly and they start to die from lack of oxygen and nutrients. You’ll eventually lose consciousness if you don’t get urgent medical attention—typically with intravenous fluids—to raise your blood pressure and increase circulation.

If you choose to trick or treat this Halloween, stay safe. Carry some garlic with you to ward off those pesky vampires and dial 911 ASAP if you have a run-in with a fanged stranger.

Dao Ho, PhD

Dao H. Ho, PhD, is a biomedical research physiologist at Tripler Army Medical Center. The views expressed in this blog post are those of the author and do not reflect the official policy or position of the U.S. Department of the Army, U.S. Department of Defense or the U.S. government.

Yoga + Deep Breathing = A Calmer You

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“I’m not flexible enough to do yoga!” In my 12 years as a yoga instructor, this is the excuse I have heard most often for why people aren’t practicing yoga. My initial response is usually, “That’s exactly why you should be practicing yoga!” However, I am also an assistant professor of physiology, and I know that the benefits of yoga go far beyond flexibility. Participating in yoga regularly imparts a number of benefits— from weight management to stress reduction—to our physical and mental health.

One very important side benefit of yoga that is linked to both physical and mental health is breath control. Slow, deep, conscious abdominal (belly) breathing, especially during difficult poses, trains us to use the same type of breathing in challenging scenarios off the mat, such as giving a presentation, taking an exam or performing a difficult task.

Why do deep, yogic belly breaths help us through stressful situations? Recent studies suggest that this type of breathing can decrease firing of the sympathetic nervous system while increasing activity of the parasympathetic nervous system. The spike in heart rate and blood pressure, sweaty palms and voice tremors you might experience when you speak in front of an audience, for example, are due to activation of your sympathetic nervous system—the “fight-or-flight” response. This nervous response is great if you are running from a bear in the woods. But in real life these changes can lead to short-term memory problems and high anxiety levels that may interfere with giving a presentation or taking a test.

If you approach stressful situations with abdominal breaths, however, you help shut down the fight-or-flight reaction and increase the parasympathetic nervous response. Called a relaxation response, your heart rate slows down and your blood pressure returns to normal. Once you’re relaxed, you can approach the task at hand in a calm, collected way.

Many types of yoga incorporate physical movements with deep abdominal breathing. The physical demands of these movements have the potential to cause the fight-or-flight response, but by combining these poses with yogic breathing, we learn how to control our breath in seemingly stressful situations. So the next time someone tells me they are not flexible enough to do yoga I will ask them if they can take a deep breath. If they say yes, then I know they are ready to go!

September is National Yoga Month. Check out a yoga class or festival near you.

Audrey Vasauskas

Putting Out Fires Hurts Firefighters’ Hearts

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As the temperature outside rises, our bodies make adjustments to keep our internal temperature constant to prevent us from overheating through a process called thermoregulation. This includes bodily functions such as sweating and widening of the blood vessels (vasodilation). When we sweat, perspiration evaporates from our skin to cool us down. When the blood vessels under our skin widen, our heart pumps more blood to our skin, which releases more heat from our inner body.

Our bodies are constantly working to hold a steady core temperature around 98-100 degrees Fahrenheit (F). This allows our organs to function properly. But when the temperature outside is extremely hot, our temperature can start to rise. A person with a body temperature above 104 degrees can develop heat stroke. This can cause dizziness, difficulty breathing, confusion, seizures or loss of consciousness. Brain and heart damage—sometimes permanent—can occur when body temperature climbs above 107 degrees F.

Too much summer heat can be unhealthy for everyone, but it can be especially dangerous to firefighters. The incidence of fires increases in the U. S. during the summer months. Firefighters fight almost twice as many fires in the summer compared to the rest of the year. On top of dealing with the extreme heat (sometimes over 700 degrees F!), these first responders face extreme physical exertion, mental stress and smoke inhalation on the job. All of these factors together can place firefighters in immediate danger of heat exhaustion, heatstroke and heart problems. In fact, firefighters are up to 136 times more likely to die from coronary artery or heart disease during or soon after they suppress a fire.

In a study published in Circulation last month, researchers may have uncovered several reasons why putting out fires puts firefighters at risk for heart disease. They discovered that a single, 20-minute session of fire simulation training—where healthy firefighters were exposed to physical activity in the extreme heat (about 755 degrees F)—was enough to injure their blood vessels, even though the firefighters’ core body temperature never reached above 101 degrees F. The problem: Although the firefighters’ bodies did keep their core temperature within a healthy range, their blood vessels did not relax properly immediately after the training. Also, as a result of the training, the firefighters’ blood clotted more easily. Damaged blood vessels and increased clotting of the blood can be very harmful to the heart and sometimes can lead to a heart attack.

This research shows us that even when we are able to keep our body temperature from getting too high, there are hidden dangers of being physically active in extremely hot temperatures. So keep your heart healthy this summer and don’t overexert yourself while outdoors!

Dao Ho, PhD

Dao H. Ho, PhD, is a biomedical research physiologist at Tripler Army Medical Center. The views expressed in this blog post are those of the author and do not reflect the official policy or position of the U.S. Department of the Army, U.S. Department of Defense or the U.S. government.