When you think about aging, do you think about your aging heart as well? We all know the years are creeping (or flying) by. We all hope we’ll be able to resist the effects of age and work really hard to make sure our minds and bodies stay strong despite the passing of time.
Today, I’d like to focus on maintaining the health and strength on one part of your body in particular: your heart!
Why does your heart deserve some special attention?
It is the organ most likely to wear out on you first! So, it’s most important that you understand how your heart and cardiovascular system work, and how aging affects them so that you have the tools you need to minimize these effects.
Before we get into the effects of age, let’s get started with the basics of how your heart works.
Heart Beat-sics… I Mean Basics
Your heart’s main responsibility is supplying your entire body with blood. According to the American Heart Association blood flows through the following cycle: “body – heart – lungs – heart – body.” Blood, with the help of the heart, carries oxygen and nutrients to cells and tissues throughout your body. It also takes carbon dioxide and other waste products away from your tissues so they can be removed from your lungs, kidneys, and liver. By the time it gets back to your heart, the oxygen is all used up and the blood begins the cycle again with another fresh supply of oxygen. Each beat indicates your blood is moving from one location to the next.
Figure 1: Circulation of Blood through the Heart (left) and Body (right).
Aging Heart: When Age Takes Its Toll
As the years roll by, your heart can start losing its ability to carry out these critical jobs.
Well, the short answer is: cellular damage.
Throughout your entire life (womb to tomb) your cells are dividing and dividing, making more cells. When this process is working perfectly, old or dead cells are replaced with new cells, keeping your whole body healthy.
While this process is essential for letting you grow and thrive it, ultimately, also promotes aging. See, as your cells divide, they make copies of your DNA to be passed on to the newer cells. Each time this happens, there’s a risk for errors to occur in the copying. There’s also a risk that mutations will occur as a result of mutagens (which are anything that changes your DNA) and be passed on to your new cells, making all of their offspring full of errors, too.
Since DNA tells your cells how to do their jobs, when these DNA errors occur in the cells that make up your heart or those that line your arteries, it gets harder and harder for them to do their jobs properly. This can lead to multiple serious diseases including:
- heart attack
- heart failure
Let’s take a closer look at how aging and poor cell function contribute to each of these diseases.
Heart Disease (Cardiovascular Disease/CVD)
The term “heart disease” can refer to many things, but the root of nearly all forms of heart disease is atherosclerosis. As you’ll see later, atherosclerosis can lead to heart attacks, strokes, and congestive heart failure. (You could think of it as the canary in the coalmine, warning you of possible dangers ahead.)
Atherosclerosis is the process of plaque building up in the walls of your veins or arteries. Plaque is formed from a combination of fatty substances, cholesterol, cellular waste, and blood clotting components.
What causes atherosclerosis?
It all starts with changes in the function of the cells lining your arteries. See, cells on the inside of your arteries are supposed to form a perfectly organized single layer of cells — this is absolutely required for them to do their jobs correctly. When they stop working properly, however, due to DNA errors, the cells start piling up, leading to a condition called arterial thickening.
Actually, your arterial cells are so sensitive that changes in cell function can lead to atrial thickening starting in infancy! Though atrial thickening in and of itself is not necessarily dangerous, it lays the foundation for plaque buildup.
So, what decides if this thickening leads to atherosclerosis and becomes dangerous?
The most important determining factor is: high blood cholesterol.
Blood Cholesterol and Atherosclerosis
Let’s pause for a quick, informative intermission. Cholesterol gets a bad rap. I think this is mostly because we only hear about it when it’s causing atherosclerosis (like right now)! In reality, it’s needed for many normal functions in your body. For example, cholesterol is necessary for hormone production and is a component of all cell membranes. In fact, cholesterol is so important to your health that your body has a complicated self-regulating process to make sure that you always have just the right amount in your body. If you eat more cholesterol, your body produces less. (Yes! Your body makes cholesterol!) If you eat less, your body produces more. Normally, this system works great and cholesterol is not dangerous for you at all. Now back to your regularly scheduled programming.
How is high blood cholesterol important in causing atherosclerosis?
Well, it turns out that, when your artery walls are thickened and there is lots of cholesterol around, cholesterol molecules can wiggle in between the cells (that aren’t organized the way they are supposed to be). Since cholesterol isn’t supposed to be in your artery wall, this triggers your immune system to go investigate the intrusion. And now you have a problem.
Cholesterol, Immune Cells and Atherosclerosis
Once your immune system notices the cholesterol in your arteries, it works to quarantine it, walling off the area of your artery wall and working to digest the fatty build-up. The chemicals your immune system releases in this process, though, damage the walls of your arteries. This damage opens up gaps in your artery wall, letting more cholesterol in and drawing more immune cells. You’ve now got a vicious cycle on your hands.
This cycle can become more vicious, more quickly if the type of cholesterol in your blood is something called “LDL cholesterol.” LDL cholesterol (LDL stands for low-density lipoproteins) tends to just hang out in your bloodstream, rather than heading back to your liver when it’s not needed, like your HDL cholesterol (tightly packaged cholesterol) does. This makes it far more likely to eek its way into the lining of your arteries and contribute to atherosclerosis.
Regardless of the type of packaging the cholesterol had before it got into your artery wall, once it does (and your immune cells follow), you have an atherosclerotic plaque. This plaque thickens and stiffens your artery walls and narrows the passageway inside your artery.
Narrower-than-normal passageways are not your friend! Arteries that are narrow and stiff can’t expand and contract the way they’re supposed to when your blood pressure changes. Increased pressure in your arteries, because they’re too stiff and narrow, can cause chunks of that plaque to break off and cause even more problems!
Making Atherosclerosis Worse: Non-cholesterol Factors
High cholesterol levels, particularly high LDL cholesterol levels, in your blood may be the most important risk factor for developing atherosclerosis, but they’re not the only ones. Any medical condition or environmental exposure that can damage your arteries and let more cholesterol get into artery walls can make atherosclerosis worse. These include things like:
- High triglycerides
- High blood pressure
Additionally, you can have genetic differences in the way the walls of your arteries are constructed, how your immune system responds to cholesterol in your artery walls and how stable plaque in your artery walls are. These natural differences can make it more likely that you will develop altherosclerosis and/or its complications as you age. A good tip off that you might have genes that aren’t great for your arterial health is if atherosclerosis runs in your family.
Ok, take a deep breath. You’ve made it through the long part! Now that you know about atherosclerosis, the other complications associated with an aging heart will be easier to understand, because atherosclerosis is often at the heart of them.
Remember when I mentioned that the increased blood pressure associated with stiff and narrow arteries can cause pieces of plaque to break off? That is an important tidbit to keep in mind to understand both heart attacks and strokes!
The pieces of plaque that sometimes break off end up floating along in the bloodstream. In a normal width artery that might not be a big deal. If your arteries are narrow, however, and too stiff to expand because of atherosclerosis, there is an increased chance that plaque will get stuck and block the flow of blood to different parts of your body. Without blood flow, those parts of your body are cut off from their oxygen supply. Without oxygen, those body parts start to die off.
If the blood/oxygen supply is cut to your heart muscles, you have a heart attack. Your heart muscles start dying and cannot beat properly. If blood and oxygen flow aren’t restored to allow your heart to beat normally again, this can easily become fatal because without a properly beating heart, your entire body is being deprived of blood and oxygen.
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Similar to a heart attack, a stroke can be the result of plaque cutting off blood supply. In this case, however, the blood supply is cut off to the brain. This causes damage to the cells of the brain. Of course, just like damage to your heart, damage to your brain has consequences for your whole body.
After all, your brain is your body’s command center. When damage occurs, your brain may not be able to command your body as it should, or once could. Motor skills like moving your arms or swallowing can be lost. You may lose the ability to talk all together, or to have your sentences make sense. In some cases, your brain can stop functioning altogether, which is fatal.
The severity of stroke symptoms depend on which area of the brain is affected by the blood and oxygen loss, and how long the loss lasts.
Congestive Heart Failure (CHF)
Congestive heart failure sounds pretty scary to me – the heart is failing?? Yikes! One piece of good news, I suppose, is that this doesn’t mean the heart has failed, but that it is in the process of failing. Maybe I’m just really trying to find the silver lining here.
While heart attack and stroke are pretty closely related to atherosclerosis, CHF can develop a little differently. It is a result of damage to heart muscles rather than directly related to blockages. Though this damage can come from a lack of oxygen to your heart muscles stemming from a blockage, it can also be the consequence of the aging heart muscle cells themselves.
Aging and cell dysfunction of heart muscle cells causes your heart muscles to be unable to contract the way they should. This leads to stiff heart muscles, poor or weak heartbeats, and a decrease in blood flow to the rest of your body.
As you can imagine, this is a real problem for your whole body health, just as heart attacks and strokes are. Organs throughout your whole body can start struggling to function without enough blood flow and oxygen. If the lack of blood flow reaches your kidneys, things can become very serious.
Without enough blood flow, your kidneys can’t filter your blood into urine properly, letting too much fluid stay in your body. This fluid then builds up in your legs, abdomen and lungs, making it even harder for your heart to pump blood (the blood needs extra force to get through the fluid) and it makes it harder for your lungs to get oxygen into the blood your heart is managing to pump. You have a vicious cycle on your hands that, again, can end up being fatal.
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Take Home Message
Your heart is an amazing organ, capable of providing your entire body with the oxygen and nutrients it needs to keep you moving! It is, however, not immune to the effects of age. It’s important that you know all the threats of aging on your heart — including CHF, atherosclerosis, heart attacks, and strokes — so that you can keep your ticker ticking well for many years to come!