Hypertension (High Blood Pressure)
Hypertension is the medical term for abnormally high arterial blood pressure.
There are between 72 and 103 million American adults with high blood pressure, depending on how we chose to define hypertension. As many as 1 in 5 adults with hypertension are not aware that they have it.
Hypertension is the primary or secondary cause of about 15% of all deaths in America.
It is linked to some 635,000 annual deaths due to heart disease, and 142,000 annual deaths due to stroke.
Symptoms & Diagnosis
What is blood pressure?
Blood pressure is measured as the force of blood pushing against the arterial wall as it flows from the heart to the body. A blood pressure reading consists of two values.
The top number is the systolic blood pressure, which is the pressure in the arterial wall generated from the contraction of the heart and expulsion of blood to the arterial circulation. The bottom number is the diastolic blood pressure, which is the lowest pressure in the arterial wall when the heart relaxes in order to fill with blood to begin the next cardiac cycle.
The difference between the systolic pressure and the diastolic pressure is known as the pulse pressure. For example, a 120/80 reading reflects a pulse pressure of 40, while a 140/80 reading reflects a pulse pressure of 60.
How is hypertension diagnosed?
A blood pressure cuff, also known as a sphygmomanometer, is used to measure blood pressure. When the cuff is put around the upper arm and inflated with air, the pressure eventually blocks the flow of blood down the arm past the cuff. The pressure in the cuff is then slowly released.
When the pressure of the cuff is less than the systolic pressure, the arterial blood will begin to flow past the cuff. This pulsation of arterial flow can be felt—or heard with a stethoscope—at that point. As the rest of the air is slowly let out of the blood pressure cuff, the pulse will become quiet again. This level of pressure at this point is the diastolic pressure.
The definition of high blood pressure or hypertension may be a little bit confusing, so let’s start with what is a normal blood pressure. A normal blood pressure is less than 120/80 mmHg. That means both the top number (systolic) and bottom number (diastolic) are below this cutoff value.
Traditionally a reading equal to or above 140/90 in an office setting was the definition of hypertension. What about readings between 120/80 and 140/90? That’s where some of the confusion ensues. Terms such as elevated blood pressure and prehypertension are sometimes used for readings between 120-129 systolic despite a normal diastolic reading. Recently, the American Heart Association lowered the cutoff for the diagnosis of hypertension to 130-139 systolic or 80-89 diastolic.
Are there common symptoms of hypertension?
Most patients have no symptoms related to high blood pressure, although especially with more severe elevation of blood pressure, some patients will experience headaches, chest pressure, shortness of breath, or visual changes.
Why does knowing your blood pressure matter?
Essential hypertension or high blood pressure is a common, treatable condition which is an important risk factor for heart attack, heart failure, stroke, and kidney failure. Hypertension is also implicated in earlier onset and worsening progression of Alzheimer’s disease and vascular dementia, erectile dysfunction, and many other health problems.
Because so often people experience no symptoms, hypertension has been called “the silent killer.” This is why a routine blood pressure check is recommended annually for all adults over age 40, and at least every three years for adults age 18-39.
Understanding Your Hypertension Diagnosis
Why does hypertension increase risk for cardiovascular disease? What is the underlying biology?
If left uncontrolled, hypertension can lead to a heart attack, an enlargement of the heart, and eventually heart failure. Blood vessels may develop bulges (aneurysms) and weak spots that make them more likely to clog and burst. The pressure in the blood vessels can also cause blood to leak out into the brain and cause a stroke. Hypertension can even lead to kidney failure, blindness, and cognitive impairment.
The underlying biology of hypertension is not fully understood. Blood pressure interacts with several important factors (including family history, race, older age, decreased physical activity, obesity, high-sodium diet, and excessive alcohol consumption) to create arterial stiffness. The actual risk for cardiac events is then greatly multiplied by the presence of several independent cardiac risk factors (e.g. smoking, diabetes, and hypercholesterolemia).
How long can people have high blood pressure before there are deleterious consequences?
The damage to arterial blood vessels and the consequent risk for vascular events is a function of both the duration and severity of high blood pressure. If blood pressure stays elevated above 140/90 for months or years, the muscular arterial walls become thickened and stiff due to loss of elastic tissue, which increases the likelihood of atherosclerosis and subsequent vascular blockages.
Similar to what we know about heavy smoking or uncontrolled diabetes, people who have untreated hypertension for many years are more likely to have irreversible vascular damage and worse cardiovascular disease than their peers.
Can you talk about the changing numbers for what “high” blood pressure is and how people should make sense of it?
As noted in the introduction of the diagnosis of hypertension, for many years, healthcare providers followed guidelines that defined hypertension as readings above 140/90, and the goal was to have patients achieve levels less than that value.
In 2015, a landmark study called the SPRINT trial was published, proving that tighter blood pressure control resulted in fewer cardiovascular events and decreased all-cause mortality. Based on this study, the American College of Cardiology and the American Heart Association redefined hypertension as anything greater than 130/80.
These new guidelines were highly controversial, as an additional 31 million Americans were now labelled as having hypertension. Two of the nation’s largest medical societies, the American Academy of Family Physicians (AAFP) and the American College of Physicians(ACP), rejected the guidelines, and the controversy over the definition of hypertension gathered national media attention.
The bottom line is that patients need to engage in a shared decision-making process with their healthcare provider to decide about when to initiate medical therapy and the goal they want to achieve. Factors such as family history, other medical conditions, and age would be important considerations in this discussion.
Are systolic (top number) and diastolic (bottom number) blood pressures equally important?
The cardiac cycle includes systole (the contraction of the heart pumping the blood from the heart to the arteries) and diastole (relaxation to fill the heart for the next cycle). Because about two-thirds of the entire cardiac cycle is spent in diastole, the “mean arterial pressure” is weighted more heavily towards diastole. In addition, the systolic reading varies much more in response to physiologic and emotional stresses due to the effects of adrenaline.
As a result, physicians were previously taught to be more concerned by elevations of diastolic pressure (e.g., a reading of 130/90 is somewhat worse than 140/80). Although this might make intuitive sense, research indicates that this is only true for younger patients.
While the diastolic pressure is a better predictor of mortality for people under age 50, the systolic pressure and the pulse pressure (the difference between the systolic and diastolic reading) are thought to be equally important predictors of mortality for patients aged 50-59. After age 60, the pulse pressure becomes the strongest predictor of coronary heart disease.
Causes
How important are genetics in hypertension?
Primary hypertension (also known as essential hypertension) refers to hypertension with no single identifiable cause. It is by far the most common type of high blood pressure, and it is thought to be mostly determined by lifestyle choices and environmental factors (smoking, high-salt diet, lack of exercise, inability to manage stress, etc.).
Hypertension is a complex polygenic disorder in which many genes or gene combinations influence blood pressure Primary hypertension is known to be about twice as common in people who have at least one hypertensive parent.
Secondary hypertension is hypertension that can be linked to a cause, typically various medications or medical conditions (among them, primary renal disease; obstructive sleep apnea; coarctation of the aorta; and numerous endocrine problems such as primary aldosteronism, Cushing’s syndrome, pheochromocytoma, and hyperthyroidism). Each of these secondary causes has its own mix of genetic and environmental factors.
What else influences who develops high blood pressure?
In addition to poor diet, lack of physical activity, and alcohol consumption, interpersonal factors can contribute to hypertension. For example, research has shown marital stress and work stress are important predictors of high blood pressure and subsequent cardiac events.
Are all people with high blood pressure at equal risk for heart disease and other long-term effects?
High blood pressure is a major risk factor for all forms of vascular disease, including heart attack, stroke, kidney disease, and peripheral vascular disease. Even Alzheimer’s disease and multi-infarct dementia will occur more frequently and progress more rapidly with uncontrolled hypertension.
However, the overall risk and prognosis for vascular disease depends greatly on several other factors. For instance, hypertension alone has a better prognosis than hypertension in combination with high cholesterol, diabetes, smoking, obesity, and sedentary lifestyle.
The American Heart Association has a validated cardiac risk predictor, which can be used to predict a person’s risk of a serious cardiovascular event—such as heart or stroke—within the next ten years.
Lifestyle-Based Hypertension Treatment
Can people reduce their blood pressure with non-medication interventions?
Yes, if you can improve your fitness, nutrition, and sleep, and if you control or eliminate stress in your life, your blood pressure will be significantly reduced. The Dean Ornish Program, a multidisciplinary rehab program that incorporates fitness, nutrition, and stress management techniques, has been proven to reduce blood pressure, and to thereby reduce cardiovascular disease and cardiovascular events. Mindfulness meditation has been shown to have similar effects.
Are there any supplements that have been connected to reducing blood pressure?
Many vitamins, nutritional supplements, and enzymes have been shown to reduce blood pressure. Among the most well known is coenzyme Q10 (CoQ10), with pressure reductions as great at 17/10 systolic/diastolic.
Next to CoQ10, magnesium is arguably the most promising supplement, with systolic pressure reduction of up to five points for the latter. To give a sense of what other options exist, a 2014 review article discussed the utility of a wide range of supplements including calcium, zinc, omega-3 and omega-9 fats, vitamin B6, vitamin C, vitamin E, vitamin D, garlic, and seaweed.
What’s the best kind of exercise for blood pressure improvement? Does research favor a particular exercise type or regimen over others?
Regular aerobic exercise has been proven to lower blood pressure. The American College of Sports Medicine (and almost all other major medical organizations) recommends getting 150 minutes per week of moderate intensity cardiovascular exercise.
In addition to this, many flexibility-based exercises, such as yoga (even when done at a low heart rate and low metabolic rate), are proven to reduce blood pressure.
Studies have also shown that a strength training program, done consistently for at least three months, will lower blood pressure for people with stage 1 hypertension (>140/90). People with stage 2 hypertension (>160/100), however, should have an exam and a diagnostic work up before they begin any heavy weightlifting.
What’s the best diet for hypertension?
Any plant-based diet that is low in sodium and saturated fat will improve hypertension. The DASH diet, the Ornish diet, and the Mediterranean diet are all good options, but the dietary changes need to be maintained over time. A low-sodium version of the DASH diet is particularly effective in reducing blood pressure.
Short-term and rapid weight loss diets, on the other hand, are notorious for causing a significant loss of lean muscle mass. Following the “25% rule,” if a person loses 40 pounds rapidly, about ten of those pounds will be lean muscle mass. Since it may take as long as a year to build ten pounds of real skeletal muscle, a 40-pound weight loss should therefore be attempted over the course of an entire year. The goal should be to lose weight at a rate of 1.0 pounds per week, while simultaneously engaging in a strength training program to build lean muscle mass.
What kinds of stress reduction techniques have evidence behind them?
Many stress reduction techniques have been used to reduce high blood pressure, including mindfulness-based stress reduction (MBSR), progressive muscle relaxation (PMR), biofeedback, deep breathing exercises, etc. The efficacy of PMR is well known, and a randomised controlled study showed MBSR to be slightly more effective than PMR at lowering blood pressure.
The Harmony Trial was unable to reproduce those results, but the observation was made that, in many studies, blood pressure reductions were at least achieved among the subset of hypertensive patients who were on medications, which suggests that MBSR may actually help to improve drug adherence.
Medication for Hypertension
Who needs medication?
After three-to-six months of lifestyle modifications, if blood pressure is still greater than 140/90, the usual recommendation is to start on a medication. Also, patients with readings over 160/100 may be started on medications right away and at the same time that efforts at lifestyle modification are started. The goal for blood pressure treatment is to achieve less than 130/80.
For adults over age 60 without other major risk factors, the AAFP and the ACP recently published guidelines that relaxed the threshold for pharmacologic hypertension treatment. In otherwise healthy patients, treatment initiation would begin at systolic pressure values above 150 mmHg with a goal to achieve a target systolic pressure below 150 mmHg.
What are the most common forms of medication and how do they aid in the treatment of hypertension?
The initial drug therapy may be a diuretic, an ACE inhibitor, ARB, or a calcium channel blocker, often in combination form, depending on age and other patient factors.
The American Heart Association has a nice summary of the commonly used blood pressure medications and their side effects. But in short, diuretics help your body get rid of salt and water, ACE and ARB medications improve blood flow to the kidneys, and calcium channel blockers help to relax blood vessels and decrease the force of cardiac contraction.
Once people are on medication, are they ever able to stop?
Yes, if they are successful in making significant progress toward the lifestyle changes described. Weight reduction for overweight and obese patients is associated with a blood pressure reduction of 5-20 mmHg per 20 pounds of weight loss. Other effective lifestyle changes include the DASH diet (8-14 mmHg decrease), sodium restriction (2-8 mmHg decrease), regular aerobic exercise (4-9 mmHg decrease), and moderation of alcohol consumption (2-4 mmHg decrease). The full evidence for all of these improvements is clearly summarized in the important JNC-7 report, and updated in JNC-8.
Adopting all five of these lifestyle changes together could reduce the systolic blood pressure by 20 mmHg or more and allow many formally hypertensive patients to become normotensive and no longer require medications.
For people who are on medication, is there anything they can do to lower their blood pressure and/or affect risk?
Yes. Blood pressure is best controlled with improved fitness and nutrition, better sleep, and better stress management. Medications are meant to be “in addition to,” not “instead of,” lifestyle changes.
If a person can achieve the recommended exercise goals of 30 minutes of moderate intensity cardiovascular exercise five times per week plus strength training three times per week, plus yoga/flexibility sessions three times per week, blood pressure typically will significantly decrease.
There is a lower risk of cardiovascular events for people who eat a plant-based diet and get at least seven hours of undisturbed sleep and achieve better stress management.
Sodium restriction is usually beneficial; studies have shown that 51% of hypertensive patients and 26% of normotensive patients are “salt sensitive.” Unfortunately, the testing methods to determine the extent of salt sensitivity are laborious and expensive.
Beyond Fitness and Nutrition: What about Stress, Sleep, Smoking, and other Substances?
How much does stress matter?
High blood pressure, job stress, and poor sleep patterns have recently been proven to be a deadly trio. Patients with these conditions are three times more likely to die of heart disease than normotensive people who get adequate sleep and have lower stress jobs.
What about sleep?
Inadequate sleep raises blood pressure. The Sleep Heart Health Study demonstrated a 19% increase in hypertension for people who slept six-to-seven hours, and a 66% increase in hypertension for people who slept less than six hours, as compared to those who got the recommended seven-to-eight hours of sleep. More recently, the CARDIA Study demonstrated a 37% increase in hypertension for each hour of sleep reduction.
One particular form of disturbed sleep, obstructive sleep apnea, can raise blood pressure to especially high levels. With obstructive sleep apnea, epinephrine (adrenaline) must be released in large bursts throughout the night in order to make the sleeping body move just enough to open the obstructed airway. The circulating epinephrine causes morning headaches and elevates blood pressure.
Does smoking affect blood pressure?
Smoking causes vasoconstriction, thereby raising blood pressure. Smoking also directly damages the lining of all the blood vessels, which contributes to vascular diseases and their consequences. These complications include heart attacks from coronary disease, strokes from cerebrovascular disease, toe-and-foot amputations from peripheral vascular disease, and kidney failure from kidney disease.
There is no cardiovascular benefit from smoking, and smokers can expect to lose at least one decade of life expectancy due to their smoking. Fortunately, many of the cardiovascular harms of smoking are reversible; tobacco cessation reduces the risk of death by about 90%.
Does alcohol or do other drugs affect blood pressure?
The cardiac and blood pressure effects of alcohol are a bit more complex. Alcohol is a known coronary vasodilator, and it is believed to be cardioprotective when taken in moderate amounts (defined as zero-to-one drink per day for women or one-to-two drinks per day for men).
However, while there may be some cardiovascular benefit to a small amount of alcohol, more is not better. Several studies and clinical trials have looked at the dose relationship between alcohol, blood pressure, and cardiovascular disease, and the observation is that high consumption of alcohol (more than 14 drinks per week) is associated with higher blood pressure. The CDC has put out some useful and comprehensive public health recommendations regarding alcohol consumption.
Cocaine is a potent stimulant and can cause very high blood pressure. Other stimulants such as methamphetamines and prescription medications such as Adderal can cause similar marked elevations in blood pressure. Nasal decongestants, some herbal supplements, prednisone, and non-steroidal anti-inflammatory drugs are also potential contributors to blood pressure elevation.
What are the most interesting new areas of research?
An enduring challenge is simply to make the diagnosis of hypertension, and to have an accurate assessment of blood pressure before medications are added or changed. For decades, this was done with sporadic pressure measurements in the physician’s office.
As home devices and wearables become more readily available, we enter a new era of information that will enhance clinical care, including ambulatory blood pressure measurement (e.g. pressures recorded automatically every 30 minutes over the course of 24 hours at home). By engaging more closely with patients, doctors will be able to achieve better blood pressure control and decrease cardiovascular morbidity and mortality.
Useful Links
Facts, Statistics, and Maps (CDC)
Global perspective and hypertension guidelines (The World Health Organization)
The American Heart Association’s perspective on hypertension (American Heart Association)
Connect with our physicians
V. Ted Leon, MD MPH and Andrew Cunningham, MD are both members of the Galileo Clinical Team. Connect with one of our physicians about Hypertension (High Blood Pressure) or any of the many other conditions we treat.