Q. At my last checkup, my blood pressure was 130/85. I'd like to have a better understanding of what those numbers mean.
A. Your heart is a pump, pushing blood throughout your body 60 to 80 times a minute. After each pump it relaxes, fills up with more blood and then pumps again. The heart pumps blood out through blood vessels called arteries, and collects blood returning from the body in blood vessels called veins.
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One way to think about the pressure in the arteries as the heart pumps is to visualize a garden hose. You turn on the faucet a little and feel the water coming out the end of the hose, striking your finger. Now you open up the faucet a little more, and the water hits your finger more forcefully. That's what happens in your arteries every time the heart pumps. It's like opening up the faucet for a few seconds, then closing the faucet a little and then opening it up again.
The top number in your blood pressure is the systolic pressure. It reflects the amount of pressure in your arteries when your heart pumps.
The bottom number is the diastolic pressure. It represents the pressure in between heartbeats, when the heart is relaxing.
Blood pressure is measured in millimeters of mercury (mm Hg). Hypertension, or high blood pressure, is defined as having a systolic reading of at least 140 mm Hg or a diastolic reading of at least 90 mm Hg, or both.
Why do doctors measure your blood pressure every time you come for a visit? Because nothing could be more important. A lot of people have high blood pressure. In my opinion, undiagnosed and untreated high blood pressure is one of the biggest threats to our health in the United States. High blood pressure greatly increases a person's risk for heart disease, stroke, kidney failure and blindness.
Why does high blood pressure weaken the heart? Because it makes the heart work harder, beat after beat. It also injures the arteries and increases the tendency for plaques of atherosclerosis to form in them. Sometimes it causes the arteries to rupture. President Franklin Roosevelt, for example, died when his high blood pressure caused a hemorrhage in his brain.
What makes high blood pressure so dangerous is that it can be really high without causing any symptoms -- until it suddenly causes big symptoms, such as the pain of a heart attack or the paralysis of a stroke. That's why measuring it regularly is so important.
Today we have simple machines that let us measure our own high blood pressure at home. I have high blood pressure, and I regularly make sure my medicines are keeping it in check.
We also have much more powerful blood pressure medicines today than ever before. President Roosevelt's doctors had nothing more to offer him during his time, even though he was the most powerful person in the world.
Q. I'm a single, postmenopausal woman in my 50s. Do I still need to worry about "safe" sex?
A. I'm surprised by how often my patients ask me the same question. "Safe" sex means using what doctors call "barrier protection" -- male or female condoms.
It is true that menopause brings freedom from worries about pregnancy (if your doctor is sure you have entered menopause). But menopause doesn't change at all your need to practice safe sex. That's particularly true if you're entering into a new relationship or have multiple sexual partners. Even postmenopausal women need to worry about sexually transmitted infections (STIs). STIs include particularly HIV, herpes, chlamydia, gonorrhea, syphilis, the papillomaviruses that can cause cervical cancer, chancroid (a bacterial infection), hepatitis and trichomonas.
That's right: There are a lot of them. STIs can be passed between women and their partners of either sex through vaginal, oral or anal sex.
Male condoms have been studied for many years. There is no doubt that they decrease the risk of transmitting all of the STIs. Some of the STIs -- particularly syphilis, chancroid, herpes and papillomavirus -- can affect the skin of the genitals that is not covered by condoms. So the protection against these infections from condoms is not quite as good as with the other STIs. But still, there is no doubt that male condoms greatly reduce the risk of STIs.
Female condoms also reduce the risk of STIs, although there are fewer studies of their effectiveness than there are with male condoms.
Does a woman who has entered menopause really need to worry about STIs? You sure do. In fact, postmenopausal women are more vulnerable to STIs than younger women. After menopause, the vaginal and cervical tissues get thinner. This makes the vaginal lining vulnerable to developing small tears and scratches, providing places for STIs to enter the body. Also, your immune response declines with age, making it harder to fight off an STI.
As a result, using a condom to prevent STIs continues to be important, even after menopause.
If you're starting a new relationship, consider the following suggestions. You may have heard them back in your teens or 20s, but they still apply today.
First, if there's any chance you might have sex with someone you've just met, carry condoms with you. Don't have sex if your partner refuses to use a condom.
Second, if you've recently met someone you think you might want to have sex with someday, talk to your potential partner about your views on safe sex. It may feel awkward, but it's important to discuss the issue of safe sex well before you're about to have sex.
Many of my patients get a thorough medical exam, including formal tests for STIs, before they start a new sexual relationship. Sometimes they ask me to write them a letter stating that the testing shows that they have no sexually transmissible diseases. Once an older male patient, a widower, invited me to his wedding. He said, "You ought to be there, doctor, because there wouldn't be a wedding without your letter."
• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.