The Medical Minute: Hypertension often silent, always deadly

May 11, 2005

By John Messmer
Penn State Family & Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

May is National High Blood Pressure Education month. High blood pressure or hypertension ranks just after smoking and lack of exercise as a cause of cardiovascular disease. What is hypertension?

To circulate blood through the body, the heart works as a pump, squeezing blood with enough pressure to fill the arteries that carry it to the organs and back. The pressure needed to push the blood out of the heart is called the systolic pressure. As the heart relaxes and refills for the next pumping action, the pressure in the arteries drops back to a baseline level called the diastolic pressure. Diastolic pressure is maintained by the tightness off the arteries themselves and the volume of blood in the circulation. Arterial tension and blood volume are regulated by other organs and the chemicals they produce.

If either systolic or diastolic pressure is too high, it causes the heart to work too hard, increasing the chance of failure. Plus, high blood pressure stresses all other organs. Under high pressure, arteries stretch too much, damaging their inner lining. Once injured, artery walls get thicker, making it harder to pump blood through them, and cholesterol deposits on the inner surface, clogging the flow of blood. This is called atherosclerosis. When the arteries in organs such as the brain, kidneys and eyes develop atherosclerosis, they do not get enough oxygen and nutrition, so they slowly fail. Sometimes a small artery in an organ will burst from the pressure or clog from atherosclerosis. This is how strokes, heart attacks, kidney failure and hemorrhages on the retina of the eye occur -- all complications of high blood pressure.

It's worse when other diseases exist at the same time. Diabetes, smoking and high cholesterol cause damage also, but in conjunction with high blood pressure, the damage is multiplied rather than added together.

People often think they can tell when their blood pressure is high by how they feel. While some may have a general idea that their blood pressure is high when they are stressed, tired, upset and so on, studies have shown that these feelings are not reliable or accurate. For most people, high blood pressure causes no symptoms whatsoever until damage has occurred. Then the symptoms are from the injured organs, not the blood pressure itself. Only extraordinarily high blood pressure readings cause symptoms, such as headache, blurred vision, confusion or nose bleed.

The only way to know if a person has high blood pressure is to measure it. Doctors typically will measure blood pressure during every visit and many community organizations hold blood pressure screenings from time to time. Pharmacies often have free automated blood pressure equipment available, and people can consider buying their own sphygmomanometer (the device used to measure blood pressure). Authorities recommend an upper-arm cuff rather than a wrist or finger cuff, because the measurement should take place at heart level and there are too many sources of interference with accuracy of wrist or finger cuffs. Another good idea is to get a self-inflating cuff since manually pumping the cuff raises blood pressure.

Before taking the pressure, sit quietly for five minutes, at least. It's normal for blood pressure to go up with activity. Decisions about blood pressure are made on resting readings. Sit in a chair with your feet on the floor and arm relaxed, bent at the elbow and resting on a table or armrest. The cuff itself should have a width just about half the circumference of the arm. So, small people need a smaller cuff and large people need a bigger one. Readings should be taken several times, preferably on different days. They should be written down and shown to a doctor.

What reading is normal? It depends. For the average, healthy, non-pregnant adult with no other health problems, the systolic should be about 120 or less and the diastolic about 80 -- written as 120/80. Lower is better to a point, but that's a decision for the doctor. Systolic from 120-139 and diastolic from 80-89 is borderline or prehypertension. A systolic from 140-159 or diastolic 90-99 is high and is called stage 1 hypertension. Systolic 160 and higher or diastolic 100 or more is stage 2. The recommendations are different for children.

Blood pressure varies from day to day so having a blood pressure of 140/85 one day and 115/70 another day is not unusual. A list of all measured readings can help the doctor decide if treatment is needed. A small fraction of high blood pressure results from malfunctioning of other organs. This is called "secondary" hypertension. Most people have no identifiable cause for their hypertension -- so-called essential hypertension.

Many people can lower their pressure by five to 10 points by regular exercise, a five to 10 pound weight reduction and a better diet. Cutting back on sodium from the salt added in cooking and at the table and by avoiding packaged foods with added salt, such as soups and prepared meals, will help in many cases. Adding fresh fruits and vegetables and low-fat dairy and grain products has shown benefit. See http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf for details.

There are many types of medication available for high blood pressure, but designing treatment is a complex process. Physicians must consider a person's age, gender, other medical history, medications and lifestyle in choosing one or more blood pressure treatments. Certain types of drugs have special benefits in diabetes, some should be avoided if pregnancy might occur, others are more dangerous in the elderly or do not mix with other medications the person already may be using. Most people who require drug therapy will need two or more medications to do the best job of reducing long-term damage from hypertension.

It is very important to take blood pressure medications as prescribed. Intermittent use does not prevent long-term damage and may cause a stroke or heart attack. Regular monitoring by the doctor is necessary to evaluate the cardiovascular system and to prevent or treat other health conditions that compound the damage from high blood pressure. Some people's blood pressure is higher in the doctor's office, the so-called white coat hypertension, so taking home readings from time to time gives a better picture of average blood pressure over time.

Untreated or inadequately treated blood pressure is deadly. Starting from 115/75, risk of cardiovascular disease doubles for every 20/10 increase in blood pressure. The good news is treatment is possible, and risk returns to normal when blood pressure is normal.

For extensive information on high blood pressure, go to http://www.nhlbi.nih.gov/health/public/heart/index.htm online.

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Last Updated March 19, 2009