Blood pressure is the force of blood against the walls of the arteries. Diastolic blood pressure is the measure of this force as the heart rests between beats. High diastolic pressure is considered any reading higher than 90. Often, people who have high diastolic blood pressure have narrowed, hardened arteries.
Blood pressure comes from two forces. One is the force with which the heart pumps blood. The second is the arteries as they resist the blood flow.
Blood pressure is typically measured with a sphygmomanometer, which is made of an inflatable arm cuff and a measuring instrument. Originally, pressure was measured with mercury, which is why blood pressure measurements are given in millimeters of mercury (mmHG). Manual sphygmomanometers are used along with a stethoscope, but many blood pressure machines are automatic.
In a blood pressure measurement, the diastolic measurement is the second, lower, and the higher number represents systolic pressure — the pressure as the heart pumps blood. For example, in a typical blood pressure reading of 120/70 mmHg, the systolic blood pressure is 120, and the diastolic blood pressure is 70. If a person’s second number is regularly more than 90, that indicates that he or she has high diastolic blood pressure, a type of hypertension. A diastolic number between 80 and 90 is considered to be a sign of prehypertension. People who have high diastolic blood pressure often have a high systolic measurement as well.
Diastolic blood pressure can change throughout the day based on posture, exercise, stress level, use of nicotine and other factors. One high diastolic blood pressure reading is not necessarily an indicator of overall high diastolic blood pressure. It’s best for several blood pressure readings to be used to get an average blood pressure.
Hypertension usually causes no symptoms, but symptoms related to extremely high blood pressure might include drowsiness, nausea, confusion, headaches, vision problems and difficulty breathing. High diastolic blood pressure is a risk factor for heart attacks, strokes and kidney failure. This is especially true in young adults.
Doctors often recommend for patients to make lifestyle changes to lower blood pressure. These changes usually include exercising; quitting smoking, if the patient smokes; and drinking less alcohol. Doctors also frequently suggest changing diet to include more fruits and vegetables and less fats and sodium. If these changes do not lower the patient's diastolic blood pressure, medication may be prescribed.