Your heart normally beats in a regular rhythm and rate that is just right for the work your body is doing at any moment. The usual resting heart rate for adults is between 50 to 100 beats per minute. Children have naturally higher normal heart rates than adults.
The heart is a pump made up of four chambers: two upper chambers (atria) and two lower chambers (ventricles). It is powered by an electrical system that puts out pulses in a regular rhythm. These pulses keep the heart pumping and keep blood flowing to the lungs and body.
When the heart beats too fast, too slow, or with a skipping (irregular) rhythm, a person is said to have an arrhythmia. A change in the heart's rhythm may feel like an extra-strong heartbeat (palpitation) or a fluttering in your chest. Premature ventricular contractions (PVCs) often cause this feeling.
A heartbeat that is occasionally irregular usually is not a concern if it does not cause other symptoms, such as dizziness, light-headedness, or shortness of breath. It is not uncommon for children to have extra heartbeats. In healthy children, an extra heartbeat is not a cause for concern.
When heart rate or rhythm changes are minor
Many changes in heart rate or rhythm are minor and do not require medical treatment if you do not have other symptoms or a history of heart disease. Smoking, drinking alcohol or caffeine, or taking other stimulants such as diet pills or cough and cold medicines may cause your heart to beat faster or skip a beat. Your heart rate or rhythm can change when you are under stress or having pain. Your heart may beat faster when you have an illness or a fever. Hard physical exercise usually increases your heart rate, which can sometimes cause changes in your heart rhythm.
Natural health products, such as goldenseal, oleander, motherwort, or ephedra (also called ma huang), may cause irregular heartbeats.
It is not uncommon for pregnant women to have minor heart rate or rhythm changes. These changes usually are not a cause for concern for women who do not have a history of heart disease.
Well-trained athletes usually have slow heart rates with occasional pauses in the normal rhythm. Evaluation is usually not needed unless other symptoms are present, such as light-headedness or fainting (syncope), or there is a family history of heart problems.
When heart rate or rhythm changes are more serious
Irregular heartbeats change the amount of blood that flows to the lungs and other parts of the body. The amount of blood that the heart pumps may be decreased when the heart pumps too slow or too fast.
Changes such as atrial fibrillation that start in the upper chambers of the heart can be serious, because they increase your risk of forming blood clots in your heart. This in turn can increase your risk for having a stroke or a blood clot in your lungs (pulmonary embolism). People who have heart disease, heart failure, or a history of heart attack should be more concerned with any changes in their usual heart rhythm or rate.
Fast heart rhythms that begin in the lower chambers of the heart are called ventricular arrhythmias. They include ventricular tachycardia and ventricular fibrillation. These types of heart rhythms make it hard for the heart to pump enough blood to the brain or the rest of the body and can be life-threatening. Ventricular arrhythmias may be caused by heart disease such as heart valve problems, impaired blood flow to the heart muscle (ischemia or a heart attack), a weakened heart muscle (cardiomyopathy), or heart failure.
Symptoms of ventricular tachycardia include palpitations, feeling dizzy or light-headed, shortness of breath, chest pain or pressure, and fainting or near-fainting. Ventricular fibrillation may cause fainting within seconds and causes death if not treated. Emergency medical treatment may include medicines and electrical shock (defibrillation).
Taking illegal drugs (such as stimulants, like cocaine or methamphetamine) or misusing prescription and non-prescription medicines can cause serious heart rhythm or rate changes and may be life-threatening.
The use of ephedra, a stimulant sold for weight loss and sports performance, is restricted in Canada, and the U.S. Food and Drug Administration (FDA) has banned the sale of ephedra because of concerns about safety. Ephedra has been linked to heart attacks, strokes, and some sudden deaths.