The word "mitral" is related to an important component of the heart, and the word "fibrillation" relates to an unsynchronized heart rhythm. Both words deal with the heart as a subject, but the phrase "mitral fibrillation" is a misnomer, because the mitral valve does not cause the heart to beat in rhythm. Irregular mitral conditions can include mitral valve prolapse, which leads to mitral regurgitation, and mitral stenosis. Fibrillation on the other hand can be divided into two types of disorders: atrial or ventricular. The phrase "mitral fibrillation" is sometimes mistakenly used to mean atrial fibrillation.
The mitral valve of the heart also is known as the left atrioventricular valve. It is located between the left atrium and left ventricle of the heart, and it helps control the flow of blood to the heart. When it is working properly, pressure from the left atrium opens the mitral valve, which fills with blood. The blood then is able to flow in the the left ventricle, whereupon the mitral valve closes to prevent blood flowing backward.
In mitral valve prolapse, the valve does not close properly after the left atrium of the heart fills with blood and empties into the left ventricle. This can cause blood to leak backward from the left ventricle into the left atrium again. This backward leak is known as mitral regurgitation, a condition that is not necessarily life threatening, and some patients do not even notice symptoms. Fibrillation can result from mitral valve prolapse, however.
Mitral stenosis is a heart condition that results in the mitral valve narrowing. This decreases the flood flow within the left atrium and ventricle of the heart. To compensate for the lack of blood, the size and pressure of the atrium increase, which results in an unsynchronized heart rhythm, or fibrillation.
In atrial fibrillation, the heart ventricles contract faster than normal. This means that the ventricles do not have enough time to completely fill with blood. This decreases the blood supply reaching the lungs and other parts of the body. Atrial fibrillation can lead to stroke or heart failure.
Ventricular fibrillation is a more serious condition than atrial fibrillation. In ventricular fibrillation, the lower chambers of the heart quiver in an unsynchronized rhythm. Little to no blood is pumped through the heart during this type of fibrillation, resulting in cardiac arrest, which requires immediate medical attention.