Diastolic blood pressure is the amount of force blood exerts on the vessels when the heart is at rest. It is generally displayed as the bottom number of the reading when blood pressure is taken. Systolic pressure is displayed as the top number, and it is the pressure put on the vessels when the heart beats.
Both diastolic and systolic blood pressure are taken at the same time using a cuff which is attached to a gauge. Air is pumped into the cuff and slowly released, and the blood pressure reading shows on the gauge. Sometimes this is done manually, although most doctors now use mechanical versions with digital readings. Blood pressure is usually written as a fraction with systolic on top and diastolic listed on the bottom.
In terms of risk factors for heart disease and other complications of hypertension, systolic is much more important than diastolic blood pressure readings. This is due in part because diastolic readings are much lower than systolic ones since the heart is relaxed when this measurement is taken. Between beats, not as much pressure is put on the veins, and health complications usually arise when too much stress is exerted on blood vessels.
This does not mean that diastolic blood pressure is unimportant. High blood pressure of either type is indicative of a problem. Dietary changes and medication can be used to treat hypertension. There is some indication that lower levels of diastolic blood pressure combined with elevated levels of systolic blood pressure may put patients at a higher risk of heart attack.
High blood pressure usually has no symptoms until it is very severe. When symptoms do occur, they can include dizziness, blurred vision, headache, nausea, vomiting, chest pain, and eventually heart attack or stroke. Since symptoms can be vague and generally do not occur until the condition is progressed, it is important to visit the doctor annually to ensure that levels are normal.
Diastolic blood pressure can be impacted by several things, and readings often change several times per day. Smoking, stress, and physical activity can all temporarily elevate blood pressure. Having high cholesterol and eating foods high in fat can cause full-blown hypertension. Avoiding cigarette smoke, exercising, and eating a proper diet can help prevent high blood pressure.