High Blood Pressure

You have no doubt heard high blood pressure referred to as the silent killer. That's because most people cannot feel their blood pressure. They don't know when it is elevated and they are unaware of the damage going on inside the body. Symptoms do not show up until health problems have progressed. Uncontrolled hypertension takes a toll on blood vessels. That in turn increases the risk of heart attcks, strokes and aneurysms. That's when a weak spot in a blood vessel (like the aorta) bulges. If an aneurysm starts leaking blood or blows, it can be fatal. Other complications of hypertension include kidney disease, heart failure, eye damage and dementia. 

Everyone agrees that getting hypertension under control reduces the likelihood of experiencing such catastrophes. But there is controversy about:

  • When blood pressure should be considered a problem? 
  • How best should it be treated?
  • What are the pros and cons of drug therapy?
  • Are there nondrug ways to help control hypertension?

Do You Have High Blood Pressure?

There is a very good chance that you do. That's because the latest guidelines from the the American Heart Association (AHA) and the American College of Cardiology (ACC) have lowered the diagnostic bar. If you have systolic blood pressure over 130 or diastolic blood pressure over 80 you are now defined as hypertensive. That means that roughly half of all adults in the United States (100 million people) have high blood pressure. It wasn't always so. 

Dr. Charles Friedberg was a prominent cardiologist during the mid 20th century. In his well regarded textbook of the day he wrote that mild benign hypertension (defined then as blood pressure up to 200/100) did not require treatment (Journal of Clinical Hypertension, Suppl. 8, Aug., 2006). Another highly regarded cardiologist of the day, Dr. W. Evans, considered blood pressure elevated when it was greater than 180/110. Given what we now know, such numbers were far too lenient. 

During the 1960s and 1970s data collected from the Framingham Heart Study encouraged doctors to get blood pressure down from such high levels. Doing so could reduce a patient's risk for stroke, heart failure and kidney damage. The first guideline was published by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure in 1977. It recommended treatment if diastolic blood pressure (the second and lower number) reached 105.

By 2003, the official guideline was that hypertension started at a blood pressure of 140/90. Blood pressure greater than 120/80 was considered prehypertension. It did not require drug treatment, though many physicians did precribe medications for this "condition." At the annual meeting of the American Heart Association on November 13, 2017 new guidelines were introduced (Hypertension, June, 2018). Under the new criteria, blood pressure at or above 130/80 was defined as hypertension. Some blood pressure monitors will tell you that if your blood pressure is 132/80 you have Stage 1 hypertension. 

What Causes Hypertension?

At the danger of oversimplification, it may be helpful to think about blood pressure in terms of plumbing. Think of the heart as a pump with hoses connected to it. In actuality, there is one main outflow hose (the aorta) that connects to lots of smaller branching hoses (arteries) throughout the body. Each time the heart contracts to push blood through the system, pressure in the outflow hoses reaches a peak, called the systolic pressure. As the heart relaxes, the pressure lets up. That’s called diastolic pressure. Because early pressure-measuring devices used a column of mercury, blood pressure is expressed in units of milimeters of mercury (mm Hg). The systolic is first and the diastolic second: 120/80, etc.

Now, think about a garden hose and imagine that the water is just pouring out without much pressure. If you held the hose in your hand the water might only reach a few feet. To get a strong flow, you need a nozzle to narrow the opening. The smaller the nozzle, the farther and harder the water will shoot. 

Blood vessels operate in a somewhat similar manner. Healthy blood vessels are flexible and can change their diameter by contracting or relaxing. When the diameter narrows, as it does under stress or excitement or as a consequence of atherosclerosis, the pressure inside the vessel increases. Atherosclerosis (aka hardening of the arteries) makes the vessels stiff so they cannot dilate and lower blood pressure. 

If pressure inside the circulatory system gets too high, organs such as the brain, the heart, or the kidneys may suffer. Equally, if blood pressure drops too low, not enough blood carrying oxygen or nutrients can get to vital organs. When people go into septic shock because of a serious blood infection, their blood pressure drops dramatically. Without adequate blood flow, kidneys and other organs can fail. 

Blood pressure can vary significantly throughout a normal day or week—by as much as 50 points over the course of 24 hours. Exercise or agitation makes it rise; meditation, deep breathing or sleeping usually makes it drop. The levels at which a doctor decides that blood pressure requires treatment are somewhat arbitrary, and may be different from one doctor to the next.

White Coat Hypertension

White coat hypertension is the medical term for a reaction some people have to the approach of a doctor or nurse with a blood pressure cuff. The pulse may quicken and blood pressure soar 20 or more points right in the doctor’s office.

The best study of this was done some years ago in Italy with equipment that took extremely accurate, continuous blood pressure measurements on 48 hospitalized people (Lancet, Sept. 24, 1983). The researchers actually placed a catheter in the radial artery of the arm to directly measure blood pressure. When a physician entered the room, 47 out of 48 patients experienced a dramatic increase in BP within one to four minutes. The average systolic rise was 27 points, but one reading spiked 75 mm. Even people with normal blood pressure had substantial elevations when a doctor entered the room.

Many physicians find the phenomenon of white coat hypertension hard to handle. They think of themselves as healers. How could a doctor's presence provoke such a dramatic alarm reaction in a patient? It's challenging for health professionals to contemplate that they are scaring their patients. 

White coat hypertension is controversial. Some physicians believe that it should be treated aggressively, on the grounds that any stress may make blood pressure rise excessively in someone who experiences it. They reason that if a person has hypertension in the doctor’s office, he or she may respond in a similar way to a disagreement with the boss, an argument with a spouse, or a close call in traffic.

Other doctors fear that white coat hypertension may lead to false diagnoses of disease, as our blood pressure is constantly changing throughout the day and week. Being labeled “hypertensive” is enough to affect self-image, work productivity, and general well being. It may also result in unnecessary medication.

A systematic review of studies of white coat hypertension in the Annals of Internal Medicine (June 18, 2019) concluded that untreated white coat hypertension was associated with increased risk of cardiovascular events. Another review reported that blood sugar may be a confounding factor (Clinical and Experimental Pharmacology & Physiology, Jan. 2014): "In conclusion, management of a patient with WCHT [white-coat hypertension] should focus on cardiovascular risk factors, particularly glucose intolerance, not blood pressure alone."

How many people are affected by white coat hypertension? We have been disappointed to discover that this important question has not been studied as rigorously as you might imagine. Some experts estimate that 15 to 30 percent of patients diagnosed with high blood pressure may have a problem only in the doctor’s office. One study titled "How Common Is White Coat Hypertension?" was published in JAMA (Jan. 8, 1988). It concluded that 21% of clinic patients with white coat hypertension had normal blood pressure outside the clinic. 

We encourage people to acquire an easy-to-use home blood pressure monitor and to keep a diary of readings that can be shared with a health care provider. This way, people can measure their blood pressure under a variety of conditions (work, stress, relaxation, etc.), which can help determine the most appropriate treatment strategy. There are also accurate home devices that can send blood pressure readings to a home computer or a smart phone or directly to a doctor's office.

blood pressure measurement

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Published on: October 31st, 2019 | Last Updated: May 24th, 2021
Publisher: The People's Pharmacy

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