Understanding the causes of atherosclerosis and blocked arteries is essential to reversing the condition and preventing any further problems.
Atherosclerosis is a contributing factor in cardiovascular disease or coronary heart disease (CHD) which is the most common cause of death in the UK, the USA and most industrialized countries.
Atherosclerosis is a disease of the arteries in which fatty deposits called plaques or atheroma collect on the insides of the artery walls, leading to narrowing and obstruction of blood flow.
This condition can affect all the arteries in the body.
The coronary arteries (that is, arteries that supply the heart) can become blocked in various ways: by plaques forming around the walls, plaque can rupture and release fatty deposits that can block the arteries, or a blood clot can attach to the plaque.
If any of the above happens, the heart muscle will be starved for oxygen and an individual will suffer a heart attack (also called myocardial infarction or MI) or coronary occlusion (a coronary).
Before this occurs, many people are diagnosed with angina pectoris, which occurs when blood flow to the heart is severely restricted, causing chest pain, most classically on exertion or when under stress.
Atherosclerosis can also occur in the carotid and vertebral arteries leading to the head and brain and if a blockage occurs there it may lead to a stroke.
If it happens in the lungs, it leads to a pulmonary embolism (an embolus is a mobile clot that may partially or completely block a vessel).
Peripheral atherosclerosis affects the limbs, causing aching muscles, fatigue and cramping pains in the ankle and legs.
Pain in the leg brought on by walking and quickly relieved by rest is called intermittent claudication.
Risk factors contributing to the causes of atherosclerosis are many and they include high blood pressure (hypertension), cigarette smoking, obesity, diabetes, and elevated cholesterol in the blood.
Physical inactivity and family predisposition are also risk factors.
There's nothing you can do about some risk factors, such as family history, age, or genetic abnormalities, but others are entirely within your power to control, such as diet, obesity, smoking and physical activity.
Atherosclerosis is the most common form of arteriosclerosis, which refers to any hardening of the arteries with loss of elasticity.
Atherosclerosis is a hardening of an artery specifically due to an atheromatous plaque which narrows the lumen of the arteries.
Healthy blood vessel should be flexible and strong, capable of containing the pulsating pressure of rushing blood, heartbeat after heartbeat, for a lifetime. But they are also delicate and vulnerable and can easily get damaged.
Things like smoking, high blood pressure and oxidized cholesterol can all cause damage to artery walls and be amongst the causes of atherosclerosis.
Cholesterol is essential to the body as it is part of all cell membranes, myelin sheath that surrounds and protects nerves and it's used to make vitamin D, bile and some hormones.
Cholesterol is carried in the blood where it's needed only if it's attached to low-density lipoprotein molecules or LDLs.
The presence of LDLs in the body therefore should not constitute a problem, in fact is essential to health. It only becomes a problem if not enough high-density lipoproteins or HDLs are present. HDLs are the lipoprotein particles that remove unwanted cholesterol from tissues and carry it back to the liver.
Another problem for cholesterol is the presence of free radicals. When not enough antioxidants are present in the diet, free radicals can get out of control and oxidize cholesterol and it's this oxidized cholesterol that causes damage to the artery walls.
The damage caused by this oxidized LDLs sets in motion a series of reactions with the ultimate purpose of repairing the damage but become part of the causes of atherosclerosis.
The body's immune system sends in specialized white blood cells (macrophages and T-lymphocytes) to repair the damage and to absorb the oxidized-LDL forming foam cells.
These white blood cells, though, are not able to process the oxidized-LDL, and ultimately grow then rupture, depositing a greater amount of oxidized cholesterol into the artery wall.
This triggers more white blood cells to rush to the site, continuing the cycle. So the immune system becomes part of the causes of atherosclerosis.
Eventually, the artery becomes inflamed. The cholesterol plaque causes the muscle cells to enlarge and form a hard cover over the affected area, where calcium and other substances accumulate that make the plaque hard and brittle.
This hard cover is what causes a narrowing of the artery, reduces the blood flow and increases blood pressure.
In addition, the brittle plaque can break off, travel through the blood stream and form a clot anywhere in the body.
Also, blood clots can form on the plaque and cause obstruction of the artery.
Or the plaque may weaken the artery wall so that it balloons out, forming an aneurism, which may burst and cause an haemorrhage or bleeding.
Although cholesterol in itself is not one of the main causes of atherosclerosis, the higher your LDL cholesterol, the greater your risk of developing life-threatening plaque and blocked arteries.
This is why your LDL cholesterol should be low.
According to the National Institute of Health (NIH), the optimal level of LDL cholesterol should be below 100 mg/dL. High LDL cholesterol is defined as 160 mg/dL and higher - but anything above 130 is worth treating.
HDL cholesterol, on the other hand, is like nature's plaque vacuum cleaner, because it picks up the vessel-clogging cholesterol and carries it away to the liver to be disposed of in the form of bile.
The higher your HDL levels, the cleaner your blood vessels will be. So you want your HDL to be high.
According to the NIH, people with HDL of 60 mg/dL. or higher have a lower risk of heart disease, whereas HDL below 40 mg/dL. is considered too low.
Because HDL is so important to the health of blood vessels, some physicians prefer to talk about the cholesterol ratio - your total cholesterol divided by your HDL cholesterol.
For example, if your total cholesterol number is 250 and your HDL is 50, your ratio is 250/50 or 5. A ratio of 3.5 is considered optimal and people are urged to aim for a ratio of 5 of less.
Amongst the causes of atherosclerosis is high blood pressure.
Although high blood pressure can cause atherosclerosis, atherosclerosis can also cause high blood pressure, a bit of a catch 22 situation.
Calcium-based and fatty deposits typically form in areas of the arteries weakened by high blood pressure or strain.
The consequent narrowing of the arteries means that your heart has to pump that much harder to squeeze blood through them, which leads to increased blood pressure.
As the arteries become less pliable and less flexible, cells may experience ischaemia (oxygen deprivation) due to decreased blood supply to the tissues, with all the bad consequences that we've already discussed.
Older adults are at a greater risk for high blood pressure and atherosclerosis, but anyone can suffer from it even without knowing it.
Atherosclerosis generally begins during adolescence but it doesn't become symptomatic until much damage has already been done.
For most people, often the first sign of any problem is a heart attack or a stroke. Restriction to blood flow to the coronary arteries may bring on symptoms of angina (chest pain) on exertion.
This is why it's never too early to start working at the causes of atherosclerosis; if you wait until you get some symptoms, it might be too late.
So what can you do about it? Now that you understand the causes of atherosclerosis, you know that it's not just an inevitable disease of old age, but there's much you can do about it.
Obviously regular exercise is important, as is staying away from cigarettes or quitting smoking if you've picked up the habit.
But perhaps the most important of all strategies is having a healthy diet.
Reaching for the right foods is the most effective way to work on the causes of atherosclerosis, and it can help you lower cholesterol and high blood pressure.
So what are some of the best and the worst foods that can affect the progression of atherosclerosis?
Read the next articles to find out.
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