What is ventricular tachycardia?
Ventricular tachycardia is a type of fast heart rhythm that starts in the lower part of the heart (ventricles). The heart might beat more than 100 beats per minute.
Some forms of ventricular tachycardia may get worse and lead to ventricular fibrillation, which can be life-threatening. With ventricular fibrillation, the heartbeats are very fast and irregular. Ventricular fibrillation may cause cardiac arrest. In cardiac arrest, the heart stops pumping blood to the body. Cardiac arrest can cause sudden cardiac death.
What causes it?
Sometimes it is not known what causes ventricular tachycardia, especially when it occurs in young people. But in most cases ventricular tachycardia is caused by heart disease, such as a previous heart attack, a congenital heart defect, hypertrophic cardiomyopathy, dilated cardiomyopathy, or myocarditis. Sometimes ventricular tachycardia occurs after heart surgery. Inherited heart rhythm problems, such as long QT syndrome or Brugada syndrome, are rare causes of ventricular tachycardia.
Some medicines can cause ventricular tachycardia. These include antiarrhythmic medicines, other heart medicines, and antibiotics. Less common causes include blood imbalances, such as low potassium levels and other electrolyte imbalances.
Natural health products that contain a banned substance called ephedra, also known as ma huang, can trigger ventricular tachycardia. Illegal drugs (such as stimulants, like cocaine) also may cause ventricular tachycardia.
What are the symptoms?
In ventricular tachycardia, the heart beats too rapidly and the ventricles cannot effectively pump oxygen-rich blood to the rest of the body.
- Palpitations, an uncomfortable awareness of the heart beating rapidly or irregularly.
- Dizziness or light-headedness.
- Shortness of breath.
- Chest pain or pressure.
- Near-fainting or fainting (syncope).
Ventricular tachycardia can be life-threatening. Some types of ventricular tachycardia can turn into ventricular fibrillation, which can cause sudden death.
How is it diagnosed?
If an electrocardiogram (EKG, ECG) can be done while ventricular tachycardia is occurring, it often provides the most useful information. An electrocardiogram is a tracing of the electrical activity of your heart. It is usually done along with a history and physical examination, lab tests, and a chest X-ray.
Because ventricular tachycardia can occur intermittently and may not always be captured by an EKG at the doctor's office, you may be asked to use a portable EKG to record your heart rhythm on a continuous basis. This is referred to by several names, including ambulatory electrocardiography, ambulatory EKG, Holter monitoring, 24-hour EKG, or cardiac event monitoring.
Your doctor may recommend further tests, including an echocardiogram to evaluate your heart's function, a stress test or coronary angiogram to determine whether a part of the heart is not getting enough blood, and/or an electrophysiology (EP) study. An EP study can locate specific areas of heart tissue that give rise to abnormal electrical impulses, which may be causing the ventricular tachycardia. This information is used to determine the best treatment.
Genetic tests may be done if you might have a heart problem that runs in families. The tests look for heart problems that can cause ventricular tachycardia. If you have one of these heart problems, a genetic test may be recommended for your close relatives.
How is ventricular tachycardia treated?
Goals of treatment are to:
- Prevent an abnormal heartbeat.
- Improve your symptoms.
- Prevent cardiac arrest (the heart stops pumping blood) and sudden death.
To prevent VT and relieve symptoms, you may take heart rhythm medicines.
Some people may have a catheter ablation. This procedure destroys small areas of heart tissue that cause the irregular heartbeat. It may make VT happen less often. Or it may stop VT from happening again.
Your doctor may recommend a device that can detect a life-threatening abnormal heartbeat and help restore a normal rhythm. This device might be implanted (ICD, or implantable cardioverter-defibrillator) or worn as a vest.
If you have VT that is not stopping, it is a medical emergency. You may need a shock to try to get your heart back into a normal rhythm. This can be from an automated external defibrillator (AED), by paramedics, or through treatment in an emergency room. A doctor may give you medicines if your condition is stable.