Diastolic pressure, the bottom number, occurs as the heart relaxes following a contraction. It represents the minimum pressure to which the arteries are exposed. High blood pressure accelerates the process that leads to hardening of the arteries. Unfortunately despite intensive research, the cause of hypertension is not found in a vast majority of cases. Genetic factors are considered to very important in the development of hypertension.
Hypertension often runs in families.
Cases of hypertension where some specific cause can be found are termed as secondary hypertension. In chronic kidney disease, excessive fluid accumulation in the body elevates blood pressure. Reduction of blood supply to the kidneys causes production of the hormone renin, which acts to constrict the arteries, thereby elevating blood pressure. This condition can be present for a long time , causing progressive unnoticed heart and blood vessel disease, before it is recognized. It is a common myth that people suffering from high blood pressure have symptoms like headache or are quick to anger.