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.
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 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 usually are fast and regular, such as
ventricular tachycardia, or fast and irregular, such as 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
Ventricular tachycardia is a life-threatening arrhythmia
that can quickly lead to ventricular fibrillation, which causes death if not
treated. Both usually cause fainting (syncope) within seconds, and you may have
symptoms of a heart attack. Emergency medical
treatment is needed, such as medicines and electrical shock
When you have a change in your heart rhythm or
rate, you also may have other symptoms, such as chest pain, shortness of
breath, lightheadedness, fainting, confusion, or weakness. Changes in your
heart rate or rhythm with other symptoms can be caused by a serious heart
Taking illegal drugs (such as stimulants, like cocaine or methamphetamine)
or misusing prescription and nonprescription
medicines can cause serious heart rhythm or rate
changes and may be life-threatening.
The U.S. Food and Drug
Administration (FDA) has banned the sale of ephedra, a stimulant sold for
weight loss and sports performance, because of concerns about safety. Ephedra
has been linked to
strokes, and some sudden deaths.
Check your symptoms to decide if and when
you should see a doctor.