Ventricular Tachycardia

Ventricular tachycardia is a rhythm disorder in which the ventricles (the lower chambers of the heart) beat fast on their own signals, usually more than 100 times per minute and often much faster. Normally, the ventricles wait for a signal from the upper chambers. In ventricular tachycardia, signals arise or circle inside the ventricles, so the heart's contractions become less coordinated and less blood is pumped. On an ECG, the waves can look uniform (monomorphic) or keep changing (polymorphic), and this difference helps your doctor look for the cause.

Brief or Sustained

Doctors distinguish nonsustained ventricular tachycardia, which stops on its own in less than 30 seconds, from sustained ventricular tachycardia, which lasts longer or causes blood pressure to drop. The brief form often causes no symptoms and is found on a Holter recording, but its cause still needs to be looked for. The sustained form is an emergency because it can turn into ventricular fibrillation, a chaotic rhythm that makes the heart stop pumping. That condition is covered on the Ventricular Fibrillation page.

Causes to Look For

A common cause is scar tissue in the heart muscle after a heart attack. This scar tissue forms pathways where signals can circle. Cardiomyopathy, inflammation of the heart muscle, and inherited abnormalities of the electrical system, such as long QT syndrome or Brugada syndrome, can also be causes. Low potassium or magnesium levels and certain medicines can trigger episodes. In some people with a healthy heart, ventricular tachycardia comes from a single spot in the outflow tract of a ventricle; this type is usually not life-threatening and can be treated with medicines or ablation.

Long-Term Treatment

After an episode is controlled, your doctor looks for the cause and assesses the heart's pumping strength. Treatment may include medicines, catheter ablation to deactivate the source of the signals, and an implantable cardioverter defibrillator (ICD), which can stop dangerous episodes automatically. The underlying disease, such as coronary artery disease or heart failure, is also treated. If someone in your family died suddenly at a young age, tell your doctor, because this may point to an inherited abnormality.

During an episode, an ECG shows a fast rhythm with wide ventricular waves, because the signal spreads through the ventricles without using the normal pathway. This recording is important for distinguishing ventricular tachycardia from other types of tachycardia. If episodes are infrequent, a Holter monitor, a long-term recorder, or data from an ICD helps capture them. Blood tests check electrolytes and signs of heart muscle damage.

Once your condition is stable, echocardiography assesses the heart's pumping strength, which helps decide whether an ICD is needed. Cardiac MRI can show scar tissue or inflammation in the heart muscle. Coronary angiography or coronary CT looks for narrowing of the heart's blood vessels. In certain situations, your doctor recommends a treadmill test, genetic testing, or an electrophysiology study to map the source of the signals before ablation.

Ventricular tachycardia always needs to be evaluated by a cardiologist, including the brief form that causes no symptoms. Make an appointment soon if your Holter or ECG results show a rhythm from the ventricles, or if you have heart disease and start having frequent palpitations. For danger signs, do not wait.

• A fast heartbeat with dizziness or nearly fainting
• Holter or ECG results showing ventricular tachycardia, even if brief
• A past heart attack or heart failure, and palpitations that have become frequent
• A family member who died suddenly at a young age
• Fainting, chest pain, severe shortness of breath, or repeated ICD shocks: go to the emergency room right away