The many forms of heart disease
Heart disease and cardiovascular disease (CVD) are catch-all terms for several conditions that affect the heart, the blood vessels that nourish the heart (the coronary arteries), and the arteries that distribute blood to the brain, legs, and everywhere in-between. Two harmful internal processes underlie most forms of heart disease:
- Atherosclerosis: atherosclerosis is the accumulation of cholesterol-filled plaque in the inner walls of an artery. It is usually accompanied by low-grade inflammation. Atherosclerosis is a slow-growing, generally silent condition that plays a key role in many types of heart disease. It can begin during teenage years, or even earlier. Atherosclerosis first appears as whitish streaks on the inner lining of artery walls. As more and more cholesterol enters the artery wall, these fatty streaks turn into plaques—pockets of cholesterol, white blood cells, and more. Plaque can bulge outward into the bloodstream, or inward away from the bloodstream. Large plaques can narrow the opening available for blood flow, causing chest pain, or angina, during physical exertion or stress. Large and small plaques can rupture, creating a blood clot that, if too large, can completely block blood flow in the vessels, causing a heart attack or stroke.
- Endothelial dysfunction: the endothelium is the layer of tissue that lines the inside of arteries. A healthy endothelium works to keep an artery free from plaque or blood clots. It also allows the artery to easily widen and narrow to regulate blood flow. Smoking, high blood pressure, and other “insults” can cause the endothelium to malfunction. Endothelial dysfunction harms health directly and also contributes to atherosclerosis.
Atherosclerosis and endothelial dysfunction can be prevented. Halting them once they’ve started, or reversing them, is possible too, but is much harder to achieve. Atherosclerosis and endothelial dysfunction can lead to a variety of conditions:
- Coronary artery disease: atherosclerosis in one or more arteries that nourish the heart muscle. Coronary artery disease underlies:
- Angina: chest pain or discomfort with exertion or stress. Angina occurs when the heart’s demand for oxygen (because it is working harder) outstrips the coronary arteries’ abilities to supply part of the heart with enough oxygenated blood.
- Heart attack: the complete blockage of blood flow through an artery, which prevents part of the heart muscle from receiving any oxygenated blood. Such blockages occur when a plaque ruptures and a clot forms to seal the break. If the clot is large enough, it can completely block the blood vessel. A clot can also break away and lodge in a smaller artery.
- Stroke: essentially a brain attack. Most strokes occur when a clot blocks an artery feeding part of the brain (these are called ischemic strokes). Without a constant supply of oxygen, brain cells rapidly die. About 20% of strokes occur when a blood vessel bursts and bleeds into the brain (these are called hemorrhagic strokes).
- Heart failure: the inability of the heart to pump blood through the body as efficiently as it should. This prevents other organs from getting as much oxygenated blood as they need to carry out their functions
- Heart arrhythmias: potentially harmful changes in the rhythm of the heartbeat. They include ventricular fibrillation, which nearly always causes death, and atrial fibrillation, which causes fatigue and increases the risk of stroke.
- Valve disorders: four valves inside the heart ensure a one-way flow of blood through the heart and around the body. Corrosion of a valve can cause it to leak, which makes the heart work harder. This can cause symptoms such as shortness of breath or lead to heart failure.
- Peripheral artery disease: atherosclerosis-induced reductions in circulation to the arms, legs, kidneys, digestive system, and other parts of the body.
- Cognitive decline: age-related memory loss and decline in thinking abilities. Although it is usually blamed on Alzheimer’s disease, a common cause is poor blood flow to the brain through atherosclerosis-narrowed arteries.
The American Heart Association estimates that more than 85 million Americans have some form of heart disease.  It is the leading cause of death in the United States  and most countries.
- Mozaffarian D, Benjamin EJ, Go AS, et al. Heart Disease and Stroke Statistics-2016 Update: A Report From the American Heart Association. Circulation. 2016;133:e38-360.
- Hoyert D, Xu J. Deaths: Preliminary data for 2011. Hyattsville, MD: National Center for Health Statistics; 2012.
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