Irregular heart rhythms and heart failure
Damaged heart muscle can lead to irregular transmissions of electrical signals in your heart and cause the following abnormal heart rhythms.
Atrial fibrillation is an irregular heart rhythm (arrhythmia) in your atria, the smaller chambers on the top of your heart. During atrial fibrillation, your atria conduct electrical impulses erratically and do not efficiently pump the blood inside them into the larger heart chambers (ventricles).
Heart failure often causes your atria to enlarge (dilate) because of the increased blood pressure that is transmitted from the left ventricle. This expansion can damage the muscle that makes up the walls of the atrium and lead to impaired conduction of electrical impulses through the atrial muscle or the generation of electrical impulses from abnormal locations in the atria.
The irregular, rapid heartbeat that occurs with atrial fibrillation can cause you to have palpitations. It can also cause your heart failure to become significantly worse because the atrial contractions are no longer effective, which can further diminish the ability of your heart to pump properly. In addition, the lack of effective atrial contractions causes blood to pool in the dilated atrial chambers. This is very dangerous, because blood that pools in the atria is more likely to form blood clots, which can travel to the brain and other organs. These blood clots are an important cause of stroke. For this reason, if you have heart failure and atrial fibrillation, your doctor may suggest that you take a blood thinner (such as warfarin) to prevent stroke.
Ventricular fibrillation is an arrhythmia in one or both of your ventricles that makes it impossible for your heart to pump correctly. Your ventricles are the main pumping chambers of your heart that are responsible for delivering blood to your entire body. When your ventricles do not pump in a regular rhythm, blood cannot flow to the rest of your body, and your body tissues quickly become starved for oxygen. Ventricular fibrillation is the most dangerous complication of heart failure and commonly causes sudden death.
You may be at risk for ventricular fibrillation if:
- Your heart has thickened in response to heart failure. This thickening can interfere with your heart's electrical system.
- Either of your ventricles has enlarged in response to heart failure. This enlargement can interfere with your heart's electrical system.
- Your drug treatment for heart failure has left you with low blood levels of potassium or magnesium. Both minerals are needed for proper electrical function of your heart.
A particular cause of heart failure, a heart attack, may also cause ventricular fibrillation. Damaged and dying heart muscle does not conduct electricity properly, which can cause ventricular fibrillation.
| Author: | Robin Parks, MS | Last Updated: September 1, 2006 |
| Medical Review: | Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology | |
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