Heart Education

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At Pediatric Cardiology Associates of Houston, we strive to keep our patients and their families updated with the latest clinical information. Please click on any topic below to learn more.

The heart has four separate chambers. The two upper chambers are called the right and left atria. The atria are receiving chambers for blood returning from the body and the lungs. The wall dividing the two atria is called the atrial septum. The lower two chambers are the right and left ventricles. The ventricles are muscular chambers responsible for pumping blood to the body and lungs. The wall dividing the two ventricles is called the ventricular septum. There are four separate valves in the heart: the tricuspid valve, pulmonary valve, mitral valve, and aortic valve. The valves open to allow bloodflow forward and close prevent any backflow. Finally, there are a number of veins and arteries attaching to the heart. The superior and inferior vena cava drain blood back from the heart to the right atrium (see Normal blood flow). The pulmonary veins drain blood back from the lungs to the left atrium. The pulmonary artery connects to the right ventricle and directs blood out to the lungs. The aorta connects to the left ventricle and directs blood out to the body.
Normal Heart Anatomy
The heart is in charge of pumping blood to the lungs and to the body. Normally, blue blood (eg deoxygenated blood, or blood without oxygen) returns from the body via the inferior and superior vena cava to the right atrium. (See Normal heart anatomy). From there, the blue blood passes into the right ventricle where it is then pumped out to the lungs to receive oxygen. The presence of oxygen in the blood turns the blood a more red color ("red" or oxygenated blood). Red blood returns from the lungs to the left atrium and then passed into the left ventricle. The left ventricle then pumps the red blood out the aorta to the body so that the oxygen can be delivered to the tissues.
Normal Blood Flow
The heart functions to pump blood to the lungs and the body. In order to pump, the heart requires an electrical impulse just like any other muscle in the body. The electricity for the heart originates from the sinus node in the upper right corner of the right atrium. Electricity then spreads across both atria before reaching the AV node where it momentarily pauses. From the AV node, electricity then rapidly passes through the right and left bundle branches to reach the ventricles. As electricity passes through the ventricles, the muscle is stimulated to contract.
Normal Electrical Conduction

Many people believe that the term heart murmur refers to a defect or abnormality with the heart. In reality, this is not the case. The term murmur simply means a noise or sound. Therefore, the term heart murmur simply means a noise or sound which is heard in the heart. It doesn't by any means imply that there is a problem with the heart.

There are many different types of heart murmurs. Some murmurs are sounds which are produced by defects or abnormalities with the heart. For example, a defective valve that doesn't open properly might produce a heart murmur as the blood flows past it. Likewise, a hole in one of the walls of the heart may produce a heart murmur as the blood flows through it.

On the other hand, many heart murmurs are termed “innocent” or “functional” murmurs. In this case, there is no problem or defect producing the heart murmur. Instead, the murmur or sound is simply being produced by the normal flow of blood through the heart. Fortunately, the majority of murmurs heard in young people are often innocent!

An easy way to think about an innocent murmur is to compare it to water that flows out of a faucet. Almost any faucet will make some noise as water flows from it. Some faucets make louder noises than others. However, just because one faucet is louder than another, this doesn't mean that there is a problem with that faucet! Likewise, when blood flows through the heart, in some children it may make a louder noise than in other children, despite the fact that the heart is perfectly normal.

When a heart murmur is heard, it is important to determine whether it is due to some type of defect or problem, or on the other hand, an innocent murmur. In many cases this can be determined simply by listening. In some cases a referral to a cardiologist may be necessary. More advanced testing, for example an ECG or echocardiogram, may also be necessary. An echocardiogram (an ultrasound) is used to evaluate the structure of the heart and look closely at the valves and walls of the heart.

If the heart murmur is determined to be innocent, then one can rest assured that the heart is completely normal. Since the heart is normal, no special restrictions or precautions are needed. Full activity is permitted. A person with an innocent heart murmur is not at any increased risk for heart related problems in the future.

Birth defects of the heart are called congenital heart defects. They are the most common type of birth defects and occur in about 1 in every 150 children. Some of the more common types of congenital heart defects are listed below.

The term arrhythmia refers to an electrical disorder of the heart. Listed below are some of the more common arrhythmias that occur in children.

Heart related symptoms can occur in children just as they can in adults. Click on any of the topics listed below to learn more about certain heart related symptoms.

What are cholesterol and triglycerides?

Cholesterol is a soft, waxy substance found in the bloodstream and in all your body's cells. Triglycerides are the most common type of fat in your body, and provide a major energy source. Both cholesterol and triglycerides are essential for the normal function of your body. They are both produced by the body, as well as found in the food that we eat. Unfortunately, high levels of cholesterol and triglycerides in the bloodstream can cause damage over long periods of time. They do this by depositing in the walls of the arteries causing plaque build-up. This process can start in childhood. However, it takes many, many years for it to get to the point that it can cause problems. Significant plaque build-up in the arteries feeding the heart muscle with blood can lead to a heart attack. Plaque build-up in the arteries in the brain can result in a stroke. The risk of a heart attack or stroke in a child is basically zero. However, if left uncorrected, high levels of cholesterol and triglycerides may cause problems forsomeone as early as in their late 30s or early 40s.

What causes high levels of cholesterol and triglycerides?

Cholesterol and triglycerides come from two sources: your body and food. Your liver and other cells in your body make about 75 percent of blood cholesterol. The other 25 percent comes from the foods you eat. There are two main types of cholesterol particles in the bloodstream. LDL cholesterol is the “bad” cholesterol - it directly contributes to plaque build-up. HDL cholesterol is the “good” cholesterol - high levels appear to protect against plaque build-up. Usually a high level of cholesterol in the bloodstream is caused by eating too much cholesterol and saturated fat, which stimulates the production of cholesterol and triglycerides in the liver. However, some individuals have a genetic defect that causes them to manufacture an excess amount of LDL cholesterol.

What are the current guidelines for lowering cholesterol and triglycerides in children/teenagers?

The current guidelines for cholesterol/triglyceride management were updated by the American Academy of Pediatrics in early 2008. In nearly all cases, dietary management is the first step. Medication is typically reserved only for severe cases that have not responded to dietary changes. It is important to point out that the guidelines for children and teenagers are much less strict than those for adults. To qualify for medication, a child should be over the age of 8 and have failed a trial of dietary therapy. In addition, the LDL should be above 190, or above 160 if there is a family history of early heart problems or other risk factors such as high blood pressure or obesity. Dietary changes include the following: Limiting cholesterol to less than 200 mg per day, and limiting saturated fat to less than 7% of total calories. Other products that can help lower cholesterol include soluble fiber and plant sterols/stanols.

Cholesterol and Lipid Problems