Most people with hypertension do not have a specified or diagnosable cause. We know that the risk of hypertension increases as patients age. The variables that contribute to blood pressure include the amount of blood pumped per beat from the heart, the rate at which the heart generates the delivery of that blood flow, and the resistance in the arteries to accepting that volume.

After age 50, the peripheral arteries become less elastic and less able to accommodate increases in flow. Younger people have more elastic arteries that expand to accept increases in volume. This expansion in turn lowers the pressure required to move the blood through the vessels. If the vessels remain contracted, as in older patients, a higher pressure is required to force the increased amount of fluid through the smaller pipe. In other words, the heart is responsible for expelling blood. However, high blood pressure arises mostly from the resistance of the peripheral arteries. Therefore, the heart is affected by, rather than the cause of, hypertension.

EKG showing hypertensive hypertrophy.

While we may not always know the ultimate cause of hypertension, we do know that certain factors can increase the risk of developing high blood pressure. Excessive amounts of alcohol, thyroid abnormalities, certain toxins, and drug abuse (in particular, cocaine and crack) are all known contributors to high blood pressure. Although a controversy currently exists over the role of salt, some evidence does suggest an association between increased salt intake and higher blood pressure.