An abnormal heart rhythm characterized by very rapid contractions of the ventricles that results in the inability of the heart to pump blood is ventricular tachycardia.
Ventricular tachycardia is a heart rhythm disorder caused by abnormal electrical signals in the ventricles of the heart. This disorder causes the heart to beat faster than normal and as a consequence, the heart may not be able to pump enough blood to your body because the ventricles are beating so fast that they don't have time to fill properly.