A very fast heart rate is called Tachycardia meaning the heart beats faster than 100 beats per minute. A fast uncoordinated heart rate is called Fibrillation. Fibrillation is the most serious form of arrhythmia are contractions of individual heart muscle fibers. Arrhythmias cause nearly 250,000 deaths each year. Supraventricular Arrhythmia A very common long term arrhythmia is atrial fibrillation.
Atrial fibrillation is very abnormal.
A normal heart beats between 60 and 100 times a minute. In response to this, the ventricles usually beat irregularly at a rate of 170 to 200 times per minute. So in Atrial Fibrillation, the upper part of the heart may beat up to 8 times as much as a normal heart. Ventricular arrhythmia One of the most serious arrhythmias is sustained ventricular tachycardia. In sustained ventricular tachycardia, there are consecutive impulses that arise from the ventricles at a heart rate of 100 beats or more per minute until stopped by drug treatment or electrical conversion.