How the heart works and courses of heart problems

 

How the heart works

Chambers and the valves of the heart

Your heart is a pump. It's a muscular organ about the size of your fist, located slightly left of center in your chest. Your heart is divided into the right and the left sides.

  • The right side of the heart includes the right atrium and ventricle. It collects and pumps blood to the lungs through the pulmonary arteries.
  • The lungs give the blood a new supply of oxygen. The lungs also breathe out carbon dioxide, a waste product.
  • Oxygen-rich blood then enters the left side of the heart, including the left atrium and ventricle.
  • The left side of the heart pumps blood through the largest artery in the body (aorta) to supply tissues throughout the body with oxygen and nutrients.

Heart valves

Four heart valves keep your blood moving the right way by opening only one way and only when they need to. To work properly, the valves must be formed properly, must open all the way and must close tightly so there's no leakage. The four valves are:

  • Tricuspid
  • Mitral
  • Pulmonary
  • Aortic

Heartbeats

A beating heart squeezes (contracts) and relaxes in a continuous cycle.

  • During contraction (systole), your ventricles squeeze tight, forcing blood into the vessels to your lungs and body.
  • During relaxation (diastole), the ventricles are filled with blood coming from the upper chambers (left and right atria).

Electrical system

Your heart's electrical wiring keeps it beating. Your heartbeat controls the continuous exchange of oxygen-rich blood with oxygen-poor blood. This exchange keeps you alive.

  • Electrical signals begin high in the upper right chamber (right atrium) and travel through specialized pathways to the ventricles, delivering the signal for the heart to pump.
  • The system keeps your heart beating in a coordinated and normal rhythm, which keeps blood flowing.

Causes of coronary artery disease

A buildup of fatty plaques in your arteries (atherosclerosis) is the most common cause of coronary artery disease. Unhealthy lifestyle habits, such as a poor diet, lack of exercise, being overweight and smoking, can lead to atherosclerosis.

Causes of heart arrhythmia

Common causes of arrhythmias or conditions that can lead to arrhythmias include:

  • Coronary artery disease
  • Diabetes
  • Drug abuse
  • Excessive use of alcohol or caffeine
  • Heart defects you're born with (congenital heart defects)
  • High blood pressure
  • Smoking
  • Some over-the-counter medications, prescription medications, dietary supplements and herbal remedies
  • Stress
  • Valvular heart disease

In a healthy person with a normal, healthy heart, it's unlikely for a deadly arrhythmia to develop without some outside trigger, such as an electrical shock or the use of illegal drugs. However, in a heart that's diseased or deformed, the heart's electrical signals may not properly start or travel through the heart, making arrhythmias more likely to develop.

Causes of congenital heart defects

Congenital heart defects usually develop while a baby is in the womb. Heart defects can develop as the heart develops, about a month after conception, changing the flow of blood in the heart. Some medical conditions, medications and genes may play a role in causing heart defects.

Heart defects can also develop in adults. As you age, your heart's structure can change, causing a heart defect.

Causes of cardiomyopathy

The cause of cardiomyopathy, a thickening or enlarging of the heart muscle, may depend on the type:

  • Dilated cardiomyopathy. The cause of this most common type of cardiomyopathy often is unknown. The condition usually causes the left ventricle to widen. Dilated cardiomyopathy may be caused by reduced blood flow to the heart (ischemic heart disease) resulting from damage after a heart attack, infections, toxins and certain drugs, including those used to treat cancer. It may also be inherited from a parent.
  • Hypertrophic cardiomyopathy. This type usually is passed down through families (inherited). It can also develop over time because of high blood pressure or aging.
  • Restrictive cardiomyopathy. This least common type of cardiomyopathy, which causes the heart muscle to become rigid and less elastic, can occur for no known reason. Or it may be caused by diseases, such as connective tissue disorders or the buildup of abnormal proteins (amyloidosis).

Causes of heart infection

A heart infection, such as endocarditis, is caused when germs reach your heart muscle. The most common causes of heart infection include:

  • Bacteria
  • Viruses
  • Parasites

Causes of valvular heart disease

Many things can cause diseases of your heart valves. You may be born with valvular disease, or the valves may be damaged by conditions such as:

  • Rheumatic fever
  • Infections (infectious endocarditis)
  • Connective tissue disorder
Risk factors

Risk factors for developing heart disease include:

  • Age. Growing older increases your risk of damaged and narrowed arteries and a weakened or thickened heart muscle.
  • Sex. Men are generally at greater risk of heart disease. The risk for women increases after menopause.
  • Family history. A family history of heart disease increases your risk of coronary artery disease, especially if a parent developed it at an early age (before age 55 for a male relative, such as your brother or father, and 65 for a female relative, such as your mother or sister).
  • Smoking. Nicotine tightens your blood vessels, and carbon monoxide can damage their inner lining, making them more susceptible to atherosclerosis. Heart attacks are more common in smokers than in nonsmokers.
  • Poor diet. A diet that's high in fat, salt, sugar and cholesterol can contribute to the development of heart disease.
  • High blood pressure. Uncontrolled high blood pressure can result in hardening and thickening of your arteries, narrowing the vessels through which blood flows.
  • High blood cholesterol levels. High levels of cholesterol in your blood can increase the risk of plaque formation and atherosclerosis.
  • Diabetes. Diabetes increases your risk of heart disease. Both conditions share similar risk factors, such as obesity and high blood pressure.
  • Obesity. Excess weight typically worsens other heart disease risk factors.
  • Physical inactivity. Lack of exercise also is associated with many forms of heart disease and some of its other risk factors as well.
  • Stress. Unrelieved stress may damage your arteries and worsen other risk factors for heart disease.
  • Poor dental health. It's important to brush and floss your teeth and gums often, and have regular dental checkups. If your teeth and gums aren't healthy, germs can enter your bloodstream and travel to your heart, causing endocarditis.

Complications

Complications of heart disease include:

  • Heart failure. One of the most common complications of heart disease, heart failure occurs when your heart can't pump enough blood to meet your body's needs. Heart failure can result from many forms of heart disease, including heart defects, cardiovascular disease, valvular heart disease, heart infections or cardiomyopathy.
  • Heart attack. A blood clot blocking the blood flow through a blood vessel that feeds the heart causes a heart attack, possibly damaging or destroying a part of the heart muscle. Atherosclerosis can cause a heart attack.
  • Stroke. The risk factors that lead to cardiovascular disease can also lead to an ischemic stroke, which happens when the arteries to your brain are narrowed or blocked so that too little blood reaches your brain. A stroke is a medical emergency — brain tissue begins to die within just a few minutes of a stroke.
  • Aneurysm. A serious complication that can occur anywhere in your body, an aneurysm is a bulge in the wall of your artery. If an aneurysm bursts, you may face life-threatening internal bleeding.
  • Peripheral artery disease. When you develop peripheral artery disease, your extremities — usually your legs — don't receive enough blood flow. This causes symptoms, most notably leg pain when walking (claudication). Atherosclerosis also can lead to peripheral artery disease.
  • Sudden cardiac arrest. Sudden cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness, often caused by an arrhythmia. Sudden cardiac arrest is a medical emergency. If not treated immediately, it results in sudden cardiac death.


Causes 


Certain types of heart disease, such as heart defects, can't be prevented. However, the same lifestyle changes that can improve your heart disease can help you prevent it, including:

  • Don't smoke.
  • Control other health conditions, such as high blood pressure, high cholesterol and diabetes.
  • Exercise at least 30 minutes a day on most days of the week.
  • Eat a diet that's low in salt and saturated fat.
  • Maintain a healthy weight.
  • Reduce and manage stress.
  • Practice good hygiene.

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