High Blood Pressure: The Silent Killer

By Zheng-Bo Huang, M.D.

     Attending physician, Director of Geriatric Consult Service
Section of Geriatrics, Department of Medicine
St. Vincents Hospital and Medical Center, New York
 Assistant Professor
New York Medical College, New York

Why Is It Important To Know About High Blood Pressure?

High blood pressure is also called hypertension. People with hypertension have increased chance of getting heart attack, heart failure, kidney disease, or of having a stroke. Do you know that heart disease is the number one killer and stroke the third common cause of death in the U.S.? In urban areas of China, stroke and heart disease are the first and the fourth killers, respectively. Hypertension is especially dangerous because it often gives no signs or symptoms.

About 1 in every 4 American adults have hypertension. In China about 12% of those older than 15 years had hypertension (nationwide survey in 1991). But when you are 65 years or older, the chance to have hypertension is more than 50%. Fortunately, though, you can easily to find out if you have hypertension by having your blood pressure checked regularly. If it is high, you can take steps to lower it. If it is normal, you should learn how to keep it from becoming high. In the following sections, I will give you more details about high blood pressure and the ways to treat or prevent it.

What Is High Blood Pressure ?

Blood pressure (Bp) is expressed as systolic pressure over diastolic pressure, for example, 130/80. Each time the heart contracts, it pumps out blood to arteries and creates the systolic pressure. When the heart relaxes in between beats, the blood pressure in the arteries falls. This is the diastolic pressure.

Blood pressure lower than 140/90 (systolic pressure <140 as well as diastolic pressure <90) is considered normal. However, your heart and blood vessels are even better off if your Bp is below 120/80. For a long time, people used to think that low Bp (for example, 104/64 in an adult) was unhealthy. We now know that this is not true, except for rare cases. 

What Happens When Your Blood Pressure Is High?

Depending on your activities Bp of a normal person goes up and down during the day. For example, when you run for a bus or have sex, your Bp goes up. When you sleep, your Bp goes down. These variations in Bp are normal.

People with hypertension have Bp that stays up all or most of the time (>140/90). If not controlled it can cause serious medical problems:

·        Arteriosclerosis (“hardening of the arteries”). This can speed the deposition of cholesterol in the vessels, reduce the blood flow, and lead to a heart attack or stroke.

·        Heart Attack. When the arteries supplying the heart become blocked, blood flow and oxygen reduce, which can cause chest pain. When the flow of an artery to the heart stops completely, it is called myocardial infarction or heart attack.

·        Heart Failure. High blood pressure makes the heart overwork and the heart becomes thicken and stretch. Eventually the heart fails to function properly. This is heart failure. Patients with heart failure have fluid back up in their lung or/and in their body.

·        Stoke. When arteriosclerosis occur in the arteries of the brain or in the arteries leading to the brain, blood clots can be formed in the damaged vassals or they can come from other places to block the arteries in the brain. This is a stroke (thrombotic or non-hemorrhagic stroke). A stroke can also happen when very high blood pressure breaks a weaken artery in the brain (hemorrhagic stroke)

·        Kidney Damage.  Long standing high blood pressure can narrow, thicken, and damage the arteries of the kidney. When kidneys fail altogether, dialysis or a kidney transplant may required.

·        Peripheral Vascular Disease. Arteriosclerosis can also occur in arteries supplying the extremities, causing pain in legs or feet due to poor circulation. In severe cases, gangrenes happen and amputation may be required to save the life.   

What Causes High Blood Pressure?

For most people with hypertension, no single cause is known. We call this type of hypertension “essential” or “primary” hypertension. However, we do know that over weight or obese persons or people who have a high salt intake in their diet have an increased chance of getting hypertension. Essential hypertension can not be cured, though in most cases it can be controlled.

In a few people, hypertension is caused by a known cause like chronic kidney disease, adrenal gland tumor, narrowing of kidney arteries, or pregnancy. We call this type of hypertension “ secondary” hypertension. Secondary hypertension usually can be cured if its cause is found and corrected.

“If Your Blood Pressure Is Not Lower Than 140/90, Ask Your Doctor Why”

Most patients with hypertension have no symptoms; and the damage from hypertension is a chronic process before disasters happen. Therefore, many people with hypertension do not know, or even know but do not treat or try to control their high blood pressure. The latest data (1991-1994) showed that 68% of hypertensive American were aware of having hypertension; 53% were treated; and 27% (about half of those treated) were under control. A survey in China in 1991 showed that only 26% of those with hypertension knew that they had hypertension; 12% were treated, and 3% (1 of every 4 who were treated) had their high blood pressure under control. No wonder that China is one the countries having the highest stroke rate.

For a long time doctors thought hypertension was systolic Bp > 160 or/and diastolic Bp > 95. Now we have changed our view. We knew antihypertensive drug treatment can reduce heart attack, heart failure, stroke, and death rate for those with a DBp > 90 and/or with SBp > 160. It is now also clear that there are benefits of treatment at lower pressures. Thus a Bp >140/90 is abnormal and bringing it below 140/90 and lower if tolerated is beneficial, particularly to prevent strokes, to prevent kidney failure, and to prevent or slow heart failure. So ask your doctor why if your Bp is not lower than 140/90.

We now consider Bp <120/80 as optimum; Bp <130/85 as normal; Bp within 130-139/85-89 as high normal. Those who have Bp 140/90 or higher are diagnosed as having hypertension. Stage 1 hypertension is defined as Bp140-159/90-99; Stage 2 as Bp 160-179/100-109; and Stage 3 as Bp > 180/110 (either systolic or diastolic fits the criteria).

How To Treat High Blood Pressure?

The goal of therapy for hypertension is based on patient’s risk factors and other related diseases. Following is the recommendation from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure:

Control blood pressure to below:

·        140/90 for patients with uncomplicated hypertension; set a lower goal for those with target organ damage or clinical cardiovascular disease.

·        130/85 for patients with diabetes.

·        125/75 for patients with kidney failure with urine protein loss >1 g/24 hours.

“When do I need to take medication?” This depends on

1.     The level of your Bp

2.     Whether you have major risk factors (smoking, high cholesterol, diabetes, older than 60, male gender, postmenopausal woman, family history of heart attack), or

3.     Whether you have target organ damage/clinical carediovascular diseases (heart disease, stroke, kidney disease, peripheral arterial disease, or hypertensive eye disease)

High-normal blood pressure (130-139/85-89): Lifestyle modification (see below) is probably the only thing you need to do if you do not have organ damage/cardiovascular diseases. The goal is to bring your Bp down to <130/85, optimally <120/80. If you have above organ diseases, you should not wait to see the effect of lifestyle modification but start antihypertensive drugs under the supervision of your doctor.

Stage 1 hypertension (140-159/90-99): If you do not have major risk factors nor organ damage/cardiovascular diseases, you can try modification of lifestyle up to 12 months to see if you can bring your Bp down to normal range. If you have multiple major risk factors or organ damage/ cardiovascular diseases, you need to start drug therapy as well as lifestyle modification.

Stage 2 and 3 (>160/>100):  You should start drug therapy and lifestyle modification and see your doctor regularly.

While you are taking antihypertensive drugs: Be compliant to your doctor’s instruction and report any possible adverse effects of the drug to your doctor. Do not stop or change dose of the drug without consulting your doctor. If your Bp has been under control for a long period, do not stop medication yourself, because your Bp may go up easily without warning or signs. Most of the patients on medication might need them for the rest of their life, although a few may successfully taper off their medications after they change their lifestyles.

How Can You Prevent High Blood Pressure? Lifestyle Modification.

The following lifestyle modifications can lower your blood pressure if your Bp is high or high-normal. They can also help you preventing from having hypertension:

1.     Maintain a healthy weight; lose weight if you are overweight or obese. Blood pressure rises as body weight increases. Overweight persons are 2 to 6 times more likely to develop hypertension. When they lose weight, their Bp goes down. Weight reduction also enhances the Bp-lowering effect of concurrent antihypertensive drugs and can reduce the risk for diabetes and hyperlipidemia.

Ideal body weight depends on the height. Doctors use a gauge, body mass index (BMI), to estimate the body weight status of a person. BMI is calculated as weight in kilogram divided by height in meter squared (BMI=kg/M²). To estimate BMI using pounds and inches, BMI=[lbs/inch²] x 704.5.

Normally a person’s BMI should be < 25. Overweight is defined as a BMI of 25 to 29.9 and obesity as a BMI of > 30.

A conversion table of heights and weights resulting in BMI units is provided in the following table.

Table. Conversion of Heights (lb.) and Weights (kg.) Resulting in BMI (kg/M²)