High cholesterol can lead to atherosclerosis, a process in which the build up of plaque inside the artery walls leads to the hardening and narrowing of blood vessels. The blood flow through these narrowed arteries is reduced.
If the coronary arteries that supply the heart are affected, it can cause heart pain and feelings of constriction such as angina pectoris, especially in times of physical or psychological stress.
The buildup of atherosclerotic plaque buildup is a gradual process that takes decades. The process is caused primarily when oxidised low-density lipoprotein (LDL) particles, the "bad" cholesterol, is deposited inside the vessel walls.
Blood clots may form in the these blood vessels, completely blocking some of the arteries within minutes. If this happens in the coronary arteries, the parts of the heart muscle that are deprived of oxygen and nutrients may die, leading to a heart attack (= myocardial infarction). If this happens in arteries supplying the brain, it can lead to a stroke (apoplexy).
Atherosclerotic Plaque Can Trigger A Heart Attack
- In a healthy artery, the inside is surrounded by a thick, musculus artery wall. The innermost layer is called the endothel, and over a period of many years, excess cholesterol (especially oxidized LDL) is deposited in the endothel.
- Immune cells such as macrophages that attempt to eliminate oxidized LDL, only make the problem worse by becoming trapped in the newly formed plaque. These immobilised, lipid-filled immune cells are visible as "fatty streaks" under the microscope.
- Calcium may be deposited in the fatty streaks, and connective tissue may form inside the plaque. This can lead to a hardening of the arteries or atherosclerosis.
- The plaque now contains lipids, calcium, macrophages, connective tissue, some muscle cells and cell debris. You will see that a dark red blod clot has formed over a small rupture on the surface of the plaque. The blood clot may dissolve without causing any damage.
- However, this blood clot may also grow and block the entire artery within minutes. Another possibillity is that the blood clot breaks off and blocks other arteries further down the bloodstream. This can lead to a heart attack, stroke or pulmonary embolism.
Other Forms Of Heart Disease
Atheriosclerosis can also lead to other forms of cardiovascular disease (cardio = heart & vascular = blood vessels), apart from coronary artery disease which only affects the blood vessels directly supplying the heart muscle.
It may also lead to a widening of the aorta, the main artery leading from the heart and cause a life-threatening (= aortic aneurysm) if it tears.
Other vascular diseases caused by atherosclerosis include:
- Stroke and pulmonary embolism which can result from blood clots in the arteries of the brain and lung. Obstruction of a lung artery causing a pulmonary embolism can result in breathlessness (dyspnea), anxiety of suffocation or even death.
- Narrowing or even a complete blockage of the arteries in the legs, resulting in pain while walking or even death of the foot or leg tissue (gangrene), roughly comparable to "smoker's leg".
According to the WHO's 2002 World Health Report, cardiovascular disease is the world's leading cause of death, killing more than 12 million people every year. More than 4 million of those deaths are attributed to high cholesterol.