Heart: Ventricular Tachycardia
Ventricular tachycardia is a fast heart rate — anything over the normal 100 beats per minute — which starts in the lower chambers of the heart, the ventricles. It causes the ventricles to contract before they have had a chance to completely fill with blood, impairing blood flow to the body.
Ventricular tachycardia occurs in people with underlying heart abnormalities. In those who have had a heart attack, for example, the scar from the heart attack causes the electrical abnormalities that create the tachycardia.
This is a serious disorder and requires prompt treatment. It poses a serious danger in that it may evolve into the more serious ventricular fibrillation. In this life-threatening condition, the ventricles quiver, pumping very little blood out of the heart. Ventricular fibrillation is the primary cause of sudden cardiac death. If normal rhythm is not restored within three to five minutes, the heart and brain will be damaged, and it could be life threatening.
Severe ventricular tachycardia and ventricular fibrillation can be converted into normal rhythm with a controlled electrical shock from a defibrillator.