Heart Basics

What is heart attack?

 

Heart attacks result from blood vessel disease in the heart. Coronary heart disease (CHD), sometimes referred to as coronary artery disease (CAD), are general names for heart attack (and angina).

A heart attack, or myocardial infarction, occurs when the blood supply to part of the heart muscle itself (the myocardium) is severely reduced or stopped. This occurs when one of the coronary arteries (the arteries that supply blood to the heart muscle) is blocked by an obstruction, such as a blood clot that has formed on plaque due to atherosclerosis. Such an event is sometimes called a coronary thrombosis or coronary occlusion.

 

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What is angina?

Chest pain called angina pectoris is another result of coronary artery disease. Angina is a symptom of a condition called myocardial schema, which occurs when the heart muscle (myocardium) doesn't get as much blood (hence as much oxygen) as it needs for a given level of work. Lack of blood supply is called ischemia. 

 

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What is silent ischemia?

Some people have ischemia, which means not enough blood flows to a part of the body's tissue. This occurs when spasm or disease narrows the arteries bringing blood to the heart. As many as three to four million Americans may have ischemia episodes without knowing it. These people have silent ischemia. They may have a heart attack with no prior warning.

 

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What is the heart's collateral circulation?

Collateral circulation involves small arteries that connect two larger coronary arteries of different segments of the same artery. They provide an alternate route for blood flow to the heart muscle. Everyone has collateral vessels, at least in microscopic form. These vessels aren't open under normal conditions but grow and enlarge in some people with coronary heart disease. When a collateral vessel enlarges, it lets blood flow from an open artery to either adjacent artery or further downstream on the same artery. Myocardial ischemia stimulates the growth of collateral vessels, so they can form a kind of "detour"around a blockage and provide alternate routes of blood flow.

Research has shown that while everyone has collateral vessels, they don't open and become available in all people. People who have open collateral vessels can benefit, because collateral vessels help protect heart muscle from tissue death if the normal blood supply is cut off. 

 

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What are arrhythmias?

Normal cardiac rhythm results from electrical impulses that start in the sinoatrial (SA or sinus) node. They spread in a timely way through the atria to the atrioventricular (AV) node. From there each impulse travels over the many specialized fibers of the His-Purkinje system, distributing the electrical "ignition signal" to the ventricular muscle cells.

The transmission of impulses is delayed a fraction within the AV node. This allows time for the atrial contraction that helps fill the ventricles with blood.

The term arrhythmias refers to any change from this normal sequence of beginning and conducting impulses. Some arrhythmias are so brief (for example, a temporary pause or premature beat) that the overall heart rate isn't greatly affected. However, if arrhythmias last for some time, they may cause the heart rate to be too slow or too fast.

The term bradycardia is used to describe a rate of less than 60 beats per minute. Tachycardia usually refers to a heart rate of more than 100 beats per minute.

 

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What is sudden cardiac death (SCD)?

It's the sudden, abrupt loss of heart function (i.e. cardiac arrest) in a person who may or may not have diagnosed heart disease, but in whom the time and mode of death occur unexpectedly. The unexpected nature of the event is the key point in the definition.

 

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What is a stroke?

Stroke is a form of cardiovascular disease that affects the arteries of the central nervous system. A stroke (or "brain attack") occurs when a blood vessel bringing oxygen and nutrients to the brain bursts or is clogged by a blood clot or some other particle. Because of this rupture or blockage, part of the brain doesn't get the flow of blood it needs. Deprived of oxygen, nerve cells in the affected area of the brain can't function and die within minutes. And when nerve cells can't function, the part of the body controlled by these cells can't function either. The devastating effects of stroke are often permanent because dead brain cells aren't replaced.

 

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What is rheumatic heart disease?

Rheumatic heart disease is a condition in which the heart valves are damaged by a disease process that begins with a strep throat (streptococcal infection). If it's not treated, the streptoccocal infection can develop into acute rheumatic fever. Rheumatic fever is an inflammatory disease that can affect many connective tissues of the body especially those of the heart, the joints, the brain or the skin. When rheumatic fever permanently damages the heart, the damage is called rheumatic heart disease.

People of all ages can develop acute rheumatic fever, but it usually occurs in children 5 years to 15 years old. The resulting rheumatic heart disease can last for life.

 

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What is congestive heart failure?

Congestive heart failure is a condition that occurs because the heart muscle is damaged or overworked. This damage can result from high blood pressure, a heart attack, atherosclerosis, a congenital heart defect, heart muscle disease (called cardiomyopathy), rheumatic fever or high blood pressure in the lungs resulting from lung disease. Because it's damaged, the heart lacks the strength to keep blood circulating normally throughout the body. The "failing" heart keeps working but doesn't work as efficiently as it should.

 

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What is Kawasaki Disease?

Kawasaki disease (also known as Kawasaki syndrome or mucocutaneous lymph node syndrome) is a children's illness. It tends to strike most often under the age of 8. Boys are almost twice as likely to get it as girls; the disease also tends to appear more often among those of Asian ancestry.

Fever, rash, swollen hands and feet, redness of the whites of the eyes, swollen lymph glands in the neck, and irritation and inflammation of the mouth, lips and throat all characterize Kawasaki disease.

 

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What is bacterial endocarditis?

Bacterial endocarditis is a serious infection of the heart valves or the tissues lining the heart. It rarely occurs but is a real threat to people with structural abnormalities of heart, artificial (prosthetic) heart valves or people with rheumatic or other acquired heart valve dysfunction. Also, people who've previously had bacterial endocarditis are at risk for getting it again, even when they don't have heart disease

 

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Excerpts reproduced from American heart Association Fighting Heart Disease and Stroke Heart and Stroke Facts. Meat issue: Signals, Actions, and Symptoms of Heart Attack.