Ventricular tachycardia is a type of heart rhythm disorder (arrhythmia) in which the lower chambers of your heart (ventricles) beat very quickly because of a problem in your heart's electrical system.
In ventricular tachycardia, your heart may not be able to pump enough blood to your body and lungs because the chambers are beating so fast that they don't have time to properly fill. Ventricular tachycardia may be brief — lasting for just seconds and often not causing symptoms — or it can last for much longer, and you can develop symptoms such as dizziness or lightheadedness, or you can even pass out. This condition usually occurs in people with other heart conditions, such as coronary artery disease, cardiomyopathy and some types of valvular heart disease.
Ventricular tachycardia may lead to a condition in which your lower heart chambers quiver (ventricular fibrillation), which may cause your heart to stop (sudden cardiac arrest) and lead to death if not treated immediately. Ventricular tachycardia can also cause your heart to stop, especially if the heart is beating very quickly, if it's lasting for a long period, and if you have an underlying heart condition.