High Cholesterol and Blood Pressure
- Persistent high cholesterol can, indirectly, cause an increase in blood pressure
Atherosclerosis (arteriosclerosis, hardening of the arteries) can increase blood pressure
It is not the high level of cholesterol circulating in the blood, i.e. high LDL (bad) cholesterol levels, but the resulting atherosclerosis, often referred to as hardening of the arteries, that increases blood pressure.
Narrowed, less smooth arteries cause increased blood pressure
As atherosclerosis develops, a coating (plaque) starts to build up on the inside of arteries. When plaque first forms it usually contains a lot of cholesterol, in what are known as fatty streaks. Later, in the older parts of the plaque, there is often deposition of calcium (becomes calcified), which makes the plaque stiff and inflexible. As the plaque builds up, it both makes the artery narrower, and is a rigid barrier that disrupt the smooth flow of blood. Both the narrowing and less smooth flow result in an increase in blood pressure, since the heart starts to have a harder time pumping blood round the body. As described in the section on diabetes and blood pressure the narrowing of arteries is similar to the end of a garden hose being squeezed or restricted in some way, which causes the water to come out with higher pressure. Add a few barriers and lumps to the inside of the hose and and this will further increase the amount of pressure needed to force the water through the hose.
Stiffer arteries result in poorer control of blood pressure
Additionally, the hardening of the artery by the formation of calcified plaque means that the artery cannot expand or contract so easily. In a healthy artery, when the body senses that blood pressure is high, one of the responses is to increase the diameter (widen the inside) of the artery by expanding. So an artery stiffened by plaque will not be as flexible and able to assist in reducing high blood pressure by getting wider.
Note: Many drugs that decrease blood pressure do so by dilating (widening) arteries. If arteries are stiff and less able to dilate, these types of drugs are going to be less effective.
High blood pressure may increase atherosclerosis
It has been suggested that when blood vessels get an area that is damaged, that the area of damage may present a site where atherosclerosis can occur. Since high blood pressure keeps arteries under a constant stress, it is likely that damage to the arteries is more likely to occur. If this is correct, then high blood pressure, by damaging arteries, will increase the amount and/or rate of atherosclerosis that occurs.
High blood pressure and high cholesterol may make each other worse
So, high cholesterol, via atherosclerosis, probably causes an increase in blood pressure. High blood pressure by damaging arteries increases the level of atherosclerosis, which then increases blood pressure, which then increases the amount of atherosclerosis, which …….....