The Silent Killer: High Blood Pressure

September 01, 2019

"This is important because there are over 75 million adults in the United States with high blood pressure."

Today's Inside Health will be the first in a two-part series with Dr. Keller Wortham, MD, on a condition so subtle that it's sometimes known as the silent killer: high blood pressure. Today, we'll talk about what blood pressure is, how it's measured, and what factors can nudge it out of the normal range. Then stay tuned for tomorrow's part two, where Dr. Keller will provide some natural steps anyone can do at home to get blood pressure back to where it needs to be.

Video Highlights

  • 02:03: What is Blood Pressure?
  • 03:17: What do the Two Numbers Mean?
  • 05:05: How Do We Measure Blood Pressure?
  • 07:47: What Influences Blood Pressure
  • 08:51: Three Blood Pressure Factors
  • 12:53: High Blood Pressure
  • 15:52: Why You Need to Get Your Blood Pressure Checked

The silent killer we’re talking about today isn’t the type you see in the movies. It’s much scarier in a way, because it's already coursing through your veins — actually, really it's more pressurizing your veins. We’re talking about high blood pressure, and it’s pretty serious stuff.  

In the health world it seems like we're obsessed with blood pressure.  It's the first thing they check when you go to the doctor's appointment. A lot of people check it at home. Some people get really nervous when they come in to have their blood pressure checked, because they feel like there's so much importance on that number that their concern about it actually sends their blood pressure up. But even people whose blood pressure is in the normal range may not really know what’s up with blood pressure (pun intended). So that’s what we’re talking about today.

What Is Blood Pressure?  

Basically, it is the pressure that your blood is exerting on the walls of your veins and arteries.  So, you can think of the blood pressure as a complicated plumbing system inside your house. We've got a heart, and we've got it pumping blood through our veins, and it needs to get stuff where it needs to go. It’s similar to water pressure in a building — if it's too high you might burst the pipe, but if it's too low you might not have enough pressure to take a shower. So, we've got this pressure going through our system because of our heart and blood vessels, and it needs to find a sweet spot to keep in the right place so it’s neither too high nor too low. In the body, the stakes are very high — it's not just about whether you have a shower or whether you have a flood. It's about getting the right amount of oxygen and nutrients to your brain and all your organs without causing damage to them by the pressure being too high.  So, it's very important that we keep our blood pressure in a normal range.

What do the Two Numbers Mean?

What is the sweet spot for blood pressure?  You may have heard the magic number is 120/80, and that's true. That is a very good blood pressure. But you might ask why is that a sweet spot? Why are there two numbers and what do they really mean?  So we’re going to talk right now about why there are two numbers and why they matter, and then we'll go on to explore the influences on blood pressure and what happens when that blood pressure goes too high.  In order to understand those two numbers, you need to keep in mind that the blood pressure, is really about the heart. 

Systolic Pressure

Our heart is the pump that keeps blood coursing through our arteries and veins and when the heart beats, it increases the pressure within the system. And that increase in pressure is what gives us the top number, the highest amount of pressure in our body, which is known as systolic pressure.  

Diastolic Pressure

Then the heart relaxes and as the pressure drops in the system, it reaches the lowest point right before the heart beats again. That lowest point right before the heart beats again is diastolic pressure

So, the heart is constantly beating and the blood pressure fluctuating between these two levels — the highest is going to be right when the heart's beating and the lowest it's going to be right before the heart beats again, when it's relaxed. That is what gives us those two numbers: systolic and diastolic blood pressure.

How Do We Measure Blood Pressure?

How do we know what our blood pressure is? Well, there are many ways to measure blood pressure, but the most common is using a blood pressure cuff, which you can get at the pharmacy so you can do it at home, or your doctor might do it with a cuff there at the office.  To take a good blood pressure you need to be relaxed. You should be seated, and keep your arm pretty much at the level of your heart. Don't have your blood pressure taken if you just ran into the medical office — you need to relax for a few minutes, and then once you are relaxed, you can get a cuff.  You slide that cuff over your arm (most of the time over your biceps) and then that cuff is going to inflate, creating a pressure within that cuff that will keep going and keep going until it occludes, or blocks the blood flow down your arm. Then, once it has blocked that blood flow, it's going to start to deflate and continue deflating until it gets to a point where your own pressure is able to overcome the restricted pressure in the cuff. 

So, the first thing that's going to happen as that blood pressure drops is that every time your heart beats, when your blood pressure gets to its highest, it’ll be able to overcome the pressure in the cuff and get your blood down the arm just during those beats. Then eventually, as the pressure in the cuff continues to lower, your blood pressure is going to be able to get through all the time, because there's enough pressure both when the heart is beating and when it's relaxed. So, that's what gives you both the upper number and the lower number as the cuff deflates. 

Now, blood pressure is measured in millimeters of mercury. That’s because a long time ago, when basically as the cuff inflated, we needed to know how much pressure was in that, and it was measured by how much force that pressure was exerting on a column of mercury in a device. Some doctors’ offices still have a column of that silver liquid, but most of the time we've got something like an automatic cuff that doesn't have mercury in it. But those numbers, the 120/80, comes basically from how much pressure it was exerting on this column of mercury in the days of the original blood pressure cuffs.

What Influences Blood Pressure

Let’s talk about some of the influences that play a part in your blood pressure. Your blood pressure is one of the most important homeostatic processes in your body. Homeostasis is just a fancy word that means keeping things balanced and in equilibrium, and blood pressure is so important to keep in that regulated sweet spot. It can be influenced by many different things, including changes in your body position, whether you're running, whether you're sleeping, sitting or standing, whether you're hot or cold, whether you're dehydrated, and many other things. And it's trying to deal with all these different changes in your atmosphere and the environment in your body, and keeping that blood pressure in a normal range. So, it has a lot of ways that it's testing what's going out in your body and environment, and responding to it.

Three Blood Pressure Factors

When it comes to like blood pressure basics, there are three main things that influence your blood pressure directly.  

  • Peripheral Resistance. This basically means how tight your blood vessels are.
  • Cardiac Output. That's basically how strong your heart is beating.  
  • Blood volume. This refers to how much liquid you have in the system.  

So, your blood pressure is determined, at least directly, by how hard your arteries are squeezing, how hard your heart is pumping and how much blood you have on board. But it's not quite as simple as that, because there are so many other influences that are coming in, that are more complex. Your blood pressure is influenced by your kidneys and how they're filtering your electrolytes. It's influenced by your adrenal glands, which are glands that sit on top of the kidneys that release hormones which tell the kidneys how much water or liquid to get rid of, and what electrolytes to get rid of. It sends messages back to other systems that can clamp down your blood pressure. It's influenced by your nervous system — both your sympathetic and parasympathetic nervous systems — which are kind of the gas and the brakes of your nervous system, telling your heart to speed up or slow down, or telling your blood vessels to clamp or relax.

It's influenced by your brain and what you're thinking, whether you're stressed and the effect that stress might have on the other parts of your body. It's also influenced by other chemicals that you put in your body, including nicotine, caffeine, or alcohol. So, there are so many things that are influencing your blood pressure, and many of these influences are things that you actually have control over.

High Blood Pressure

So, we talked about the sweet spot being about 120/80. If you’re just a little over that, it could be due to a number of temporary factors — caffeine, traffic, mild stress, etc., so you don’t necessarily need to worry if it’s not exactly 120/80. But if it gets too high, the medical term for that is hypertension.

Hypertension is defined as blood pressure over 140 in the top number and over 90 in the bottom number. So, if you’re at 130/85, it’s not perfect but you don’t have hypertension. High blood pressure is measured in stages, but in general if you're over 140 and over 90 you are falling into the hypertensive category. So, why is that important? Well, high blood pressure, or hypertension, puts you at risk for a lot of different health issues including: heart attack, stroke, kidney disease, retinal disease, and erectile dysfunction, just to name a few. A lot of things can happen just from having high blood pressure, and a lot of times you can have high blood pressure and not even know that you have it. That is why it's called the silent killer. So it's very important for you to evaluate your blood pressure either with your doctor or at home, and find out if it's high.

So, why is it that high blood pressure causes all these problems? Well, let’s go back to the plumbing analogy. You've got this pump and these pipes coursing through your body, and if the pressure gets too high in them you can actually start to get too much of a flow of blood to the fragile little arteries called capillaries in all of the organs, and as the blood courses through them, it can actually start to damage those little arteries. Unlike the metal pipes which you would have in a house, your arteries are more flexible — more like hoses. And if you've ever seen a garden hose start to get a little weak spot and start to swell from too much water pressure, that’s what can happen in the tiny arteries or even the larger arteries of your body. If that happens, you risk having a blowout.  

Another issue is that over time, blood pressure that is too high can reduce the flexibility and cause inflammation of the lining of your pipes. Using the hose analogy, you can think of it like a rusting or corrosion of the pipes. So, if you have high cholesterol, or if you have a very inflammatory diet, these things can start to kind of reduce the flexibility of those hoses and their ability to deal with the changes in blood pressure in your body.

Why You Need to Get Your Blood Pressure Checked

This is important because there are over 75 million adults in the United States with high blood pressure. That is one out of every three people, and many of these people might not even know they have it. So they're sitting on this ticking time bomb, with a risk for stroke or heart attack or kidney disease or retinal disease or erectile dysfunction. It affects 33% of white women and 37% of white men, and in the black community it's affecting 43% of black men and 47% of black women. It’s different also in Asian communities. Basically, it affects different races differently, and different sexes differently. You don’t have control over your race or gender, but it's also very tied into your lifestyle, your diet and a lot of other factors that you do have some control over. So, when it comes to blood pressure the bottom-line is, you should know what your blood pressure is. Get it tested. You can get a cuff to check at home, or get it checked at your physical exam. It's important to have regular visits to your doctor. You can just walk into a pharmacy, where there are usually cuffs you can use. If you don’t want to buy one, and aren't going to a doctor, you can just go in there and check.  

Again, you want to hit that sweet spot of having your blood pressure be under 140 and under 90. There are other populations with additional risk factors as well. If you have diabetes, or if you have had a heart attack or stroke, there are stricter requirements. Again, everybody's different, so talk to your doctor about where your blood pressure should be. If it is high, then stay tuned because in the next video, we're going to talk about some things that you can do to bring it down, many of them without medications — just utilizing the resources available in your own home, diet, and lifestyle.

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