ABNORMAL HEART RHYTHMS
WHAT YOU SHOULD KNOW
The number of times the heart beats each minute is called the heart rate. In an older child or teenager who’s resting the heart beats about 70 times a minute. It beats about 140 times a minute in a newborn. Usually the heart rhythm is regular which means that the time from one beat to the next is about the same. Exercise can make the heart speed up and during sleep the heart slows down. If the heart isn’t beating regularly, it has an arrhythmia. The most common but normal heart rhythm irregularity occurs during breathing. When a child breathes in, the heart rate speeds up for a few beats and when the child breathes out, the heart rate normally slows down again. This variation is called sinus arrhythmia and is normal. If a child continues to have arrhythmia which isn’t normal, a doctor may recommend a child be seen by a pediatric cardiologist who specializes in children’s heart problems.
A person’s heart when normal is slightly larger than that person’s clenched fist. The normal heart is strong and a hard working pump which is divided into right and left sides and a upper and lower chamber on each side. The right and left atria (upper chambers) receive blood from the body and the lungs. The right and left ventricles (lower chambers) are the muscular chambers. They pump blood out of the heart to the lungs and body. The blood travels through a series of valves which open and close to the let the blood flow in one direction only.
Arrhythmias can occur at any age and sometimes a child is not aware of the occurrence. A child’s family history or history of the problem can be very helpful in determining the severity of the possible heart problem. Questions such as:
· Is the child aware of unusual heartbeats?
· Does the child feel weak, lightheaded or dizzy?
· Has the child ever fainted?
Arrhythmias often occur with no symptoms, and some medicines may make the condition worse. It’s important to inform the child’s doctor if the child is prescribed other drugs or has taken an over-the-counter medicine.
The heart’s activity must be recorded on an electrocardiogram (ECG or EKG) to identify an arrhythmia. Each time the heart beats it sends out an electric-like signal that the ECG machine can record. To record the ECG, small patches or stickers called electrodes are placed on different parts of your chest to measure the heart’s electrical activity. This record is recorded permanently on paper or in a computer.
Three major waves of electric signals appear on the ECG. Each one shows a different part of the heart beat. P wave is the first wave and it records the electrical activity of the heart’s two upper chambers (atria). The second and largest wave is the QRS wave. This wave records the electrical activity of the heart’s two lower chambers (ventricles). T wave is the third wave and it records the heart’s return to the resting state. By studying the shape and size of the waves and the time between the waves, a doctor can learn the rate and regularity of the beats and therefore understand a person’s heart and its rhythm.
ABNORMAL HEART RHYTHMS
QUESTIONS
1. How many heart beats are normal for a teen that is resting? For a new born?
2. The normal sized heart is how big?
3. Define sinus node.
4. Define an ECG? How does it differ from an EKG?