Blood Pressure – What Does it Mean?

Podcast Transcript

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Luke Laffin, MD:
My name's Luke Laffin and I'm a preventive cardiologist at the Cleveland Clinic. I'm actually co-director of the Center for Blood Pressure Disorders here on the main campus of the Cleveland Clinic. And it's great to speak with you today about a topic near and dear to my heart, which is blood pressure. And the question is, well, what does your blood pressure tell you? How high is too high? What about my blood pressure quote/unquote spiking? And what's too low? We'll talk about some of the basics over the next few minutes.

Luke Laffin, MD:
So when we think about what is too high, we have to remember that everyone's going to have some fluctuation in blood pressure over the course of the day, that's normal. Blood pressure isn't some straight line. And there's a variety of factors that can impact blood pressure, pain, stress, salty food, exercise, anxiety, all of these factors play a role. What we really worry about is sustained elevations in blood pressure. Another term for that is hypertension. Hypertension is chronically elevated blood pressures that increase one's risk for adverse events. Predominantly, heart failure, kidney disease, coronary artery disease, and then strokes.

Luke Laffin, MD:
So we're really trying to understand that more than anything else. If I went out there got myself on a treadmill and had someone check my blood pressure while I was running, guess what? It should go up, and that's physiologic. But it should return to a normal range or even below that following exercise, and that's going to be important more than anything else. So when we think about what is too high, there's not necessarily a consensus about where we actually term someone having hypertension. The guidelines changed within the United States back in 2017 with the American College of Cardiology/American Heart Association definition, which stated blood pressure greater than 130 over 80 is technically, at minimum, stage one hypertension. Greater than 140 over 90 is stage two hypertension.

Luke Laffin, MD:
This is a little bit different than the European guidelines, which were released the following year, which state hypertension diagnosis should start at 140 over 90. Either way, it oftentimes come down as semantics about how we use it. The rationale behind changing the numbers for the American guidelines was that there was a lot of provider or clinical inertia. Meaning, you're running in at 138 over 85, ah, you're going to be fine. Well, we know that that's probably too high, particularly for individuals at elevated cardiovascular risk. So that was one of the impetus behind the change in diagnosing or labeling patients with hypertension rather than some meaningless term like pre-hypertension, or... Actually, I'm not going to say meaningless term, but I'm going to say less instructive term than pre-hypertension or elevated blood pressure, so to speak.

Luke Laffin, MD:
What's too low? Well oftentimes we'll think about what's too low, there's not a specific number that I want to point to for individuals. However, if you're symptomatic, lightheaded, dizzy, et cetera, that blood pressure is probably too low for you. We definitely say less than 90 over 60 is hypotension. Certain patients, particularly patients with heart failure with reduced ejection fraction, we do push their blood pressure as low as possible to try and get medicines in their system, or at least in their regular medication routine that will help the heart contract more strongly and remodel and improve its pumping function. But for the vast majority of the people that we see, particularly in our Hypertension Clinic, that's too low.

Luke Laffin, MD:
I love to see most of my hypertension patients somewhere around 120 millimeters of mercury for their systolic blood pressure and under 80 millimeters of mercury for their diastolic blood pressure. Now systolic blood pressure is the top number of course, diastolic blood pressure is the bottom number. When we think about diastolic blood pressure, we also have to think about, well, what's too low for that. And there's different sets of data that we can draw upon, but typically we think less than 55 on average, now everyone's going to be up and down a little bit, above and below that, but less than 55 on average people are going to do worse from a cardiovascular perspective. And so sometimes if you have a wide pulse pressure, which is the difference between the top and the bottom numbers, we have to find a balance between lowering the systolic blood pressure but also maintaining a diastolic blood pressure above 55, if at all possible.

Luke Laffin, MD:
When we talk about blood pressure spikes, well, number one, I really dislike that term because it sort of means nothing more than anything else, and patients overuse it. One term that's also, I think, overused is this term of labile blood pressure. There actually is no formal definition, although people tend to throw it around, clinicians, patients, et cetera, all the time. So what it does that really mean? Well, it sort of depends who you ask. Everyone's going to have variations in blood pressure throughout the day, it's important to understand that these are based on things that we do, like I talked about earlier. But also they're based on the 24 hour cycle, the so-called circadian variation of blood pressure. What is normal is about a 10 to 20 percent decrease in blood pressure as we sleep at night. Then, starting around 3:00 AM. There's often a sharp, upward rise on blood pressure, technical term is called the early morning blood pressure surge, with blood pressure is typically peaking between 6:00 AM and noon. Then there's another dip middle of the day. Then another peak, usually not quite as high as the morning, but sometimes it can be. And that second peak typically takes place around dinner time or so.

Luke Laffin, MD:
So understanding that is also important, particularly if you're having problems with lower blood pressures in the middle of the day, maybe all it's going to take is moving your pressure medicines till later in the day, taking them at night. That's oftentimes we do that in individuals that are taking once a day blood pressure medicines, because most blood pressure medicines you only have to take once a day, they're active over a 24 hour period.

Luke Laffin, MD:
If you notice that your blood pressure is particularly erratic, a couple easy things do. And to make sure that you're doing is number one, make sure you're checking your blood pressure appropriately. It is not appropriate to just throw on some random blood pressure cuff and check your blood pressure when you're standing or feet are up or if you're not positioned appropriately. You need to be checking blood pressure in a regimented way. And what does that mean? Well, that means sitting for a full five minute before you check blood pressure feet flat on the floor arm supported at heart height and back supported and straight. Oftentimes we'll recommend taking two or three consecutive readings as well and newer machines, automatic blood pressure machines, tend to take two or three readings consecutively and give the average, this is going to be a better overall marker of your blood pressure because that's typically what's done in a clinical trial setting than just the one and done blood pressure measurement.

Luke Laffin, MD:
So keeping track of that is also important. In rare circumstances, we can see big swings in blood pressure. Really high blood pressures particularly when people are lying down and really low blood pressures when they're up and about or standing up. It's not often we see it, but we definitely do see, it can be an underlying problem called autonomic dysfunction and that you need specialized doctors for and different ways to think about how to treat blood pressure. Oftentimes we'll see that in patients with a history of radiation or surgery to their head and neck, the best example is people with any type of head and neck cancer that may have received radiation. What it does is it can impact the sensors in our neck, particularly the carotid baroreceptors so our body doesn't sense changes in position and doesn't react as appropriately as it normally would.

Luke Laffin, MD:
We can also see it in individuals with longstanding diabetes and it doesn't have to be longstanding, poorly controlled diabetes. We know that in certain individuals poorly controlled blood glucose can lead to neuropathies and problems with their autonomic nervous system. And then sometimes, and this is a little bit less often, but sometimes it can be a harbinger of an underlying neurological disease. Early Parkinson's disease, et cetera. Now I would say that's not the majority of individuals, I would say it's actually a small minority, but it's important to talk to your doctor if that's the case and seek some professional guidance, be it in our Center for Blood Pressure Disorders, our Center for Syncope, up with our electrophysiologists, there's all kinds of testing. And actually more so than testing, suggestions that we can give about lifestyle factors to prevent those lows in blood pressure, but also address those highs as well.

Luke Laffin, MD:
So that's a lot that I told you about blood pressure, we got a little bit of specific at the end, but I think it's important when people are thinking about labile blood pressure or changes in blood pressure that are significant to consider all those factors. Thank you very much for your time.

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