Atrial fibrillation

Atrial fibrillation
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Normal rhythmic contractions of the upper chambers of the heart (atria) are replaced by rapid irregular twitching of the muscular wall.
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The lower chambers of the heart (ventricles) respond irregularly causing an irregular and usually rapid heart rate. Atrial fibrillation may come and go (paroxysmal atrial fibrillation) or persist (chronic atrial fibrillation.
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Atrial fibrillation is common, especially in older people. The main causes of this disorder include mitral valve disease, high blood pressure, heart failure, excessive alcohol use, an overactive thyroid, stimulants (cocaine, methamphetamines), and stress from other illnesses.