arrhythmia, ventricular

arrhythmia, ventricular An abnormally rapid heart rhythm that originates in the lower chambers of the heart (ventricles). Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation. Both are life-threatening arrhythmias, and they are most commonly associated with heart attacks or scarring of the heart muscle from previous heart attacks.