As our population ages and prevention increasingly becomes the watchword in medicine, I often see patients concerned about their risk of suffering a heart attack or stroke. Hypertension (high blood pressure) is the single greatest contributor to both of these devastating events. Sadly, it is estimated that only 50% of the 60 million Americans with hypertension are aware of their condition because it is most often a condition without symptoms. Hypertension has thus aptly been labeled a "silent killer."
Of those with known high blood pressure, only 50% are optimally treated. Since hypertension becomes more common with advancing age, the magnitude of this condition may increase over the next decade. The good news is that, unlike many of the conditions I encounter, hypertension is entirely treatable.
What does "Hypertension" mean?
With each heartbeat, the heart contracts and blood is pumped throughout the body. With each heart contraction, blood is pulsed (pushed) into the blood vessels leading away from the heart (called arteries). This pressure of the blood in the arteries increases when the heart contracts and decreases as the heart refills with blood between contractions.
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The maximum pressure in the arteries during contraction of the heart is called the systolic blood pressure and is the top number of a blood pressure reading. The minimum pressure in between heartbeats is called the diastolic blood pressure and is the bottom number of a blood pressure measurement. For example if you have normal blood pressure, your reading might be 120/80 (which is said as "120 over 80"), with 120 being your systolic pressure and 80 being your diastolic pressure. Hypertension is an abnormal elevation in either the systolic or diastolic pressure. There is no precise dividing line between normal and elevated blood pressure, but a blood pressure in excess of 140/90 is generally considered the point at which you can be considered hypertensive.
How is Hypertension Diagnosed?
A single elevated blood pressure measurement does not clinch the diagnosis of hypertension because your blood pressure can vary depending on when and how it's taken. It is important to realize that blood pressure can vary throughout the day and from one day to the next. In general, multiple measurements (usually three or more) over a period of weeks to months are required to make a diagnosis of hypertension and initiate therapy.
When I evaluate a patient with known hypertension, I make a number of simple assessments. These include an electrocardiogram (EKG), which evaluates the heart's electrical system and can determine if there has been thickening of the heart muscle, and an examination of the blood vessels in the eye. These evaluations allow me to determine if there has been organ damage due to sustained high blood pressure and can provide me with clues as to how long the blood pressure has been elevated. Evidence of organ damage calls for more aggressive and earlier initiation of therapy.
What Is White Coat or Office Hypertension?
As many as 20% of patients with mildly to moderately elevated blood pressure in a doctor's office may have normal blood pressure when measured at home or at work. This has been attributed to the anxiety and stress that a visit to the doctor can provoke in someone and is referred to as "white coat hypertension" or "office hypertension." This condition is important to identify because white coat hypertension does not require specific treatment since it has not been found to be associated with the risks (heart attack, stroke, and organ damage) of sustained hypertension. However, white coat hypertension is not an entirely normal response to being in a physician's office and may predict the future development of essential hypertension.
Should I Monitor My Blood Pressure at Home?
I encourage my patients to measure their blood pressure at home several times throughout the day. Most experts now believe that home blood pressure measurements are more predictive of adverse outcomes than office measurements. (Home monitoring is one of the best ways to identify white coat hypertension.) I also instruct my patients to bring their home blood pressure machine to the office to verify its accuracy. Home blood pressure monitoring has two other advantages. It allows me to better assess the effectiveness of the blood pressure medications I have prescribed, and it improves compliance by giving my patients a sense of responsibility and partnership in management decisions.