Hypertension (High Blood Pressure)

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.