Hypertension - Blood pressure that is consistently (more than 6 months) above 140/90. Systolic blood pressure (The measurement of the contraction of the ventricles of the heart, which drives the blood through the aorta and pulmonary artery) is the top number. Diastolic blood pressure (determined during the dilatation of the heart cavities, during which these cavities fill with blood) is the bottom number. Hypertension may have no known cause (essential or idiopathic hypertension) or be associated with other primary diseases (secondary hypertension).