Anaphylaxis is a potentially life-threatening allergic reaction. Common causes of anaphylaxis are allergies to penicillin, bee stings, aspirin, eggs, peanuts, and nuts. In this video, you'll find out other possible causes, what preventive steps you can take to avoid anaphylaxis, and why emergency treatment is needed.

Atherosclerosis refers to the hardening and narrowing of arteries caused by a slow buildup of plaque on the artery walls. Narrowed arteries restrict blood flow, and small clots can form and partially or completely block an artery. In this video, you'll find out how atherosclerosis develops and what you can do to prevent it.

Fibrillation is a type of abnormal muscle contraction. A fibrillating heart muscle looks as if it is wiggling rather than squeezing and does not move blood the way a normal contraction does. This video discusses what happens when the fibrillation is in the atrium, one of the upper chambers of the heart.

The beating of your heart is very organized, taking its cue from a built-in electrical system. A normal heart rate is regular, at 60 to 100 beats per minute. An arrhythmia is any kind of abnormal heartbeat—too fast, too slow, or irregular. This video explains different arrhythmias and what you should do if you have one.

Cardiac catheterization procedure can diagnose a variety of heart conditions and determine the health of your coronary arteries, heart valves, and heart muscle. View this video to learn what happens during this procedure and various treatment options.

Physical activity is healthy for your heart—even after you've had a heart attack or bypass surgery. It's important to start out slowly, under the supervision of cardiac rehab specialists. In this video, you'll learn what's involved in cardiac rehab and how it can benefit your health in the long term.

A cardiac stress test may be ordered if you have or are suspected of having coronary artery disease. This test evaluates your heart’s response to stress or exercise. Watch this video and learn what to expect before, during, and after this procedure. Other types of stress tests will also be presented.

Your body needs cholesterol to make hormones and to keep your cells healthy. Cholesterol comes from two sources: your liver and your diet. However, if your diet exceeds the body’s need for cholesterol or saturated fats, your cholesterol level in your blood will increase. This video discusses treatments and lifestyle changes that may be prescribed by your doctor.

Normal blood pressure is essential for a healthy pregnancy. If you have high blood pressure before you become pregnant, you are at higher risk for developing certain problems during pregnancy. This video explains how chronic high blood pressure can affect you and your growing baby and why special monitoring is important.

Claudication refers to leg pain brought on by exertion and relieved with rest. The primary cause of claudication is atherosclerosis, or narrowing of the arteries that feed the leg muscles. This video explains who is at risk for this condition and what you can do to help prevent it.

This procedure, a common type of open heart surgery, is one way to treat blockages in the arteries of the heart. Watch the video and learn about the surgery and what you can expect during recovery and rehabilitation.

Coronary artery disease (CAD) is the most common type of heart disease in the United States. CAD develops when the arteries that supply blood to the heart muscle harden and narrow with a buildup of plaque. This video discusses who's at risk for CAD and what you can do to help prevent it.

Coronary artery disease (CAD) develops when the arteries that supply blood to the heart muscle harden and narrow with a buildup of plaque. Treatment is primarily through lifestyle changes and medication. This video examines the goals of treatment.

The ribs are connected to the breastbone by cartilage. This connection is called the "costochondral junction." Costochondritis is chest pain and tenderness in this region of the chest. In this video, you'll find out the different types of this condition and the treatments available.

Millions of Americans suffer heart attacks every year. Half of these are fatal, and some of the rest cause severe damage to heart's function. This video explains what happens during a heart attack and what can be done to minimize the damage.

Heart failure is a condition in which your heart cannot pump enough oxygenated blood to meet your body’s needs. This video explains the different types of heart failure, and the treatments that can help you manage your condition and live a healthy life.

Blood flowing through the heart is usually silent. A heart murmur is blood flow that makes a noise. Turbulent blood flow in or near the heart creates extra heart sounds, which can be heard with a stethoscope. This video explains how a heart murmur occurs and when it is a cause for concern.

Hemochromatosis is a condition in which a person's body is overloaded with iron. The excess iron accumulates in various organs and can cause health problems. This video discusses the possible causes of hemochromatosis, typical symptoms, and what treatments are available.

Even though most women with hypertension have healthy babies, they do have a higher risk of developing certain problems during pregnancy. Hypertension can damage the mother’s heart, kidneys and other organs. It can cause low-birth weight and early delivery of the baby. Early diagnosis and special monitoring of you and your baby by your healthcare provider are important.

Your heart is a pump that is responsible for delivering blood to all parts of your body. Arteries carry oxygen-rich blood from the lungs to nourish the cells, and veins transport oxygen-poor blood on its way back to the heart and lungs. This animation shows how the heart and circulatory system work.

Hypertension is the medical term for high blood pressure. Blood pressure is the force at which blood flows through the large blood vessels from the heart. When blood pressure is high over a period of time, it can lead to health problems, including stroke. This video offers details about blood pressure, its importance to health, and what you can do to keep yours normal.

People who have serious arrhythmias or who have experienced sudden cardiac death may benefit with an implantable cardioverter defibrillator (ICD). The device can deliver a shock when it senses that an abnormal rhythm is present. This video offers detailed information about these implantable devices.

Lyme disease is an illness spread by the bite of an infected tick. A bull's-eye rash is a typical symptom that identifies this illness, which untreated can affect many parts of the body. This video explains how the illness develops and what you can do to protect yourself against tick bites.

The mitral valve has two flaps between the upper left atrium and lower left ventricle of the heart. When your heart beats, this valve opens and closes in a rhythmic pattern. Mitral valve prolapse occurs when the valve doesn't close properly. Watch this video to learn more about MVP and how it can affect your health.

Obstructive sleep apnea (OSA) is a common problem that affects more people than diabetes or asthma. Untreated, OSA can lead to serious health problems, including high blood pressure and heart failure. This video gives an overview of OSA and how it is treated.

You may need a pacemaker if you have an abnormal heartbeat. To understand how a pacemaker works, watch this video. It will also help you learn how to care for and live with your pacemaker.

Normal blood pressure is important to good health. Some women develop high blood pressure during their pregnancy. Why this occurs isn't known, but certain factors put you at higher risk. This video explains the risk factors and symptoms, and how this condition is managed.

As the name suggests, premature ventricular contractions are contractions in the lower chambers of the heart that occur too early in the rhythm sequence. These contractions, also called Paces, are common, particularly in older adults. This video discusses what effect these contractions can have on your health.

Raynaud's phenomenon causes temporary decreased blood flow to the fingers, toes, and ears. It typically occurs in cold weather, when blood flow decreases in the fingers and toes. This video describes the common symptoms of this condition and the recommended treatment.

The main blood vessels that bring clean blood to your kidneys are called the renal arteries. With age, these arteries can become blocked and may cause high blood pressure. In this video, you'll find out how the blockage develops and what treatments are available to minimize symptoms.

A relapse happens when you return to smoking after a period of quitting—usually after the first three months. Most people experience several relapses before quitting for good. This video discusses situations that can trigger a relapse and offers a range of coping skills and behavior changes to get you back on track.

Cigarette smoking is the single leading cause of preventable death and disease in the United States. But because of the physical and psychological addiction to nicotine, smokers find it quite difficult to quit. This video offers important reasons to stop smoking and a framework of change to help you achieve your goal.

A transient ischemic attack (TIA), also called a ministroke stroke, causes symptoms similar to those of a stroke. The difference is that TIAs don’t cause permanent brain damage. This video explains what happens during a TIA, what you should do if you have symptoms, and what treatment is available.

A varicose vein is an abnormal dilation of the vessels that carry blood back to the heart. Although veins are located throughout the body, varicose veins are most commonly seen in the legs. This video looks at who's at risk for this condition, typical symptoms, and available treatments.