What Causes Heart Disease?

Heart disease is the most common cause of death in the U.S. Maybe that’s because there are so many facets of heart disease. The heart and its accompanying circulatory system can be injured or damaged — not only by trauma, but also by genetic predisposition, viruses, and lifestyle choices.

Deaths from heart disease usually are attributed to heart attacks, but heart attacks can be caused by many factors:

  • Atherosclerosis (blockages in the arteries)

  • Ischemia (lack of oxygen)

  • Thromboembolism (blood clots that travel through the bloodstream and block blood vessels elsewhere in the body)

  • Hypertension (high blood pressure)

Atherosclerosis occurs when fats, especially cholesterol, accumulate in the lining of the arteries. Cholesterol is part of the fat transport system through the bloodstream, and it is needed as the precursor of steroid synthesis. But, when there is too much cholesterol is in the body, it starts to stick to the vessels, rather than pass through them. The fatty deposits are called plaques. As the plaques increase in size, they fill more and more of the artery, eventually affecting blood flow.

If arteries are partially blocked, ischemic heart disease may occur. People with ischemic heart disease have difficulty breathing during exercise or times of stress because the blocked arteries slow the blood flow, which prevents enough oxygen from being delivered to the heart muscle tissues. The lack of oxygen can cause a pain in the chest that radiates to the left arm. This pain is called angina pectoris (pectoris refers to the chest, as in the pectoral muscles).

If an artery is blocked by a plaque, blood cells can stick to the plaque, eventually forming a blood clot. A blood clot stuck in a blood vessel is called a thrombus. If the thrombus breaks free and moves around the bloodstream, it is called an embolism. A thromboembolism is a blood clot that breaks free from where it was formed, travels through the bloodstream, and blocks another spot in a blood vessel.

Although the heart fills with blood to pump to the rest of the body, it also must have nutrients and oxygen supplied to the tissues that form it. Because your heart is made of living cells and tissues, it needs to have blood vessels running through it so that nutrients and oxygen can be delivered to the cells within the heart. Arteries that bring blood to the tissues and cells of the heart are called coronary arteries.

If a clot or plaque blocks a coronary artery, oxygen cannot be delivered to the muscle tissue, and a heart attack occurs. The tissue in the area of the heart where the attack occurs often dies because of the lack of oxygen. The technical term for a heart attack is a myocardial infarction. Myo- means muscle, cardi- means heart, and an infarct refers to dead tissue.

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