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A nurse takes your blood pressure at your annual physical. The numbers are recorded and the checkup continues. But do you know where on the blood pressure chart your levels are? Are they healthy? Too low? Too high, meaning you have hypertension? If you have high blood pressure or are heading in that direction, you should know that hypertension is among the primary enlarged heart causes, and a major risk factor for heart failure.
To better understand your blood pressure readings, you should understand what blood pressure is and what each number represents.
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What Is Blood Pressure?
Imagine a garden hose hooked up to a spigot. When the hose is flexible and there are no kinks in it, you can turn on the water full blast and it will flow easily through the hose. But if there’s a kink in the hose, the water doesn’t flow as well beyond the kink. And the pressure inside the hose builds up behind the kink. Or imagine there is gunk inside the hose blocking the path of the water. Your arteries are a lot like that garden hose.
Simply put, blood pressure is the force exerted by blood flow against the interior walls of your arteries. Ideally, your arteries are relaxed, open, and clear of any blockage. This allows blood to flow easily.
A variety of factors, however, can lead to narrowed arteries. Plaque buildup on the artery walls is a common problem and can sometimes result in total blockage. The arteries can also become less able to widen if you’re a smoker. Cold weather can temporarily constrict your arteries, too.
When your bloodstream is forced to move through tighter passageways, your blood pressure increases and your heart has to work harder. Over time, this leads to a weaker but enlarged heart. Causes of enlarged heart, other than hypertension, include a disease of the heart’s valves or a disease of the heart muscle itself, also known as cardiomyopathy.
This is why it’s important to know what measurements indicate high blood pressure. “Hypertension is a leading risk factor for death and disability worldwide,” says Paul Whelton, MD, a hypertension expert at Tulane University. “High blood pressure raises the risk of having a heart attack, heart failure, stroke, or kidney disease.”
Reading a Blood Pressure Chart
When your heart contracts and squeezes blood out into your network of arteries, the pressure inside those blood vessels is at its highest. This is called systolic pressure and it’s the top number on your blood pressure reading. In between beats, the heart relaxes and the pressure drops. This is your diastolic blood pressure, and it’s the reading’s bottom number.
Once you get your reading, you can see where on a blood pressure chart your levels place you.
- A healthy or normal blood pressure is considered less than 120/80 mm Hg (millimeters of mercury—which is still how the measurement is presented, even though most new blood pressure monitors don’t actually use mercury any more).
- A systolic pressure of 120 to 139 mm Hg or a diastolic pressure of 80 to 89 mm Hg is considered pre-hypertension—a precursor to high blood pressure.
- Stage 1 hypertension is considered any systolic pressure between 140 to 159 or diastolic pressure between 90 and 99.
- Stage 2 hypertension is considered any systolic pressure of 160 mm Hg or higher, or diastolic pressure of 100 mm Hg or higher.
If your numbers put you in the Stage 1 or Stage 2 areas of the blood pressure chart, you should definitely talk with your doctor about medications and lifestyle changes that can help bring it down. If you’ve been prescribed anti-hypertensive medications, you have to keep taking them even if you get your blood pressure to a healthy target.
Older adults may be able to live comfortably and in good health with a blood pressure in the 130/85 range. Such a reading may not necessitate any medical intervention. But complicating factors, such as diabetes or a history of heart attack or stroke, must be considered before you and your doctor work out the right target blood pressure for you.
“Every person has to be evaluated as an individual,” says Lynne Braun, PhD, CNP, a nurse practitioner with the Rush Heart Center for Women at Chicago’s Rush University Medical Center. “Realistically, we can’t get everybody down to 120, and trying to do so may create unintended problems.”
The definition of low blood pressure differs from one person to the next, but in general, a reading of less than 90/60 mm Hg is considered low. If you’re in that category, you may need medications to help you boost your blood pressure. As you might imagine, hypotension (low blood pressure) is much less common than hypertension.
Heed the Warnings
If your blood pressure remains high for a long period of time, you run the risk of damaging your blood vessels. Your stroke risk rises significantly, too. And because your heart is working harder to push blood through your system, that very valuable muscle can become overworked and grow thicker. An enlarged heart causes further complications, including heart failure. Medications and special implantable pumps can help boost heart function. But if you can manage your blood pressure before it gets too high and puts your heart at risk, you may be able to avoid a lot of complications down the road.
“We know we can prevent high blood pressure through diet, weight loss, and physical activity,” says Dr. Whelton. “We can also treat it, and we can treat it effectively.”
If you’ve seen your numbers on the hypertension part of the blood pressure chart, it’s time to be proactive. If your doctor isn’t giving you advice or treatment that seems right, don’t hesitate to get a second opinion.
Originally published in October 2016 and updated.