Ventricular Tachycardia

The heart muscle is responsible for circulating blood throughout the body and uses electrical signals from within the heart to control the heartbeat. When the electrical system of the heart does not operate as it is supposed to, ventricular tachycardia can develop.

Ventricular tachycardia occurs when a patient experiences a rapid heart rhythm (100 beats or more per minute) that starts in the lower chambers of the heart (the ventricles). If the abnormal heartbeat lasts less than 30 seconds, the patient has nonsustained ventricular tachycardia. If the episode lasts more than 30 seconds, the patient has sustained ventricular tachycardia.

Symptoms

In some cases, ventricular tachycardia occurs with no symptoms other than rapid heartbeat. When symptoms are present, the patient may experience:

  • Fainting
  • Angina
  • Lightheadedness
  • Dizziness
  • Palpitations
  • Shortness of breath

Whether a patient is exhibiting symptoms or not, a rapid heart rate should be checked by a physician. The longer the episode lasts the more dangerous it is, because the heart's lower chambers cannot fill adequately with blood or pump normally. This condition, in turn, may cause blood pressure to fall. In extreme cases, heart failure can occur. Sustained ventricular tachycardia can lead to ventricular fibrillation, which can be life threatening.


Causes and Risk Factors

Ventricular tachycardia can be caused by a structural abnormality in the heart, with or without a heart attack, or it may occur in patients with one of the following:

Ventricular tachycardia also can be caused by:

Diagnosis

Diagnosis of ventricular tachycardia will generally begin with the physician taking a medical history and performing a physical exam. During the physical exam, the physician will listen to the patient’s heart and look for the following:

  • Rapid pulse
  • Low blood pressure
  • Loss of consciousness
  • Absent pulse

The physician will also ask the patient for a detailed description of symptoms, which may suggest the presence of an abnormal heart rhythm.

The physician may order diagnostic tests to determine the cause of the ventricular tachycardia. These tests can examine the heart muscle, the blood flow through the heart, and any potential leaking within the heart valves. An electrocardiogram (EKG) is a painless procedure that provides a picture of the electrical activity of the heart and how the heart is working. A similar test is an echocardiogram, a noninvasive procedure that uses ultrasound to create a moving picture of the heart as it works.

Additional imaging tests such as a cardiac MRI or chest X-ray may be used to see if the heart is enlarged — if the echocardiogram is inconclusive. An angiogram may be used to view the blood vessels around the heart.

Other diagnostic tests may include electrophysiology studies to look at the electrical system of the heart.

Treatments

Treatment for ventricular tachycardia will depend on the cause and severity of the condition. In some cases the event can be a medical emergency, such as when episodes last more than 30 seconds or if the condition causes blood pressure to fall dramatically.

In an emergency medical situation involving ventricular tachycardia, cardiopulmonary resuscitation (CPR) must be started as soon as possible — within a few minutes. As soon as possible, defibrillation (an electrical shock to the chest) should be administered. Antiarrhythmic drugs may then be given to help maintain a normal heart rhythm.

An electrical shock to the heart can restore normal heart rhythms if the ventricular tachycardia occurs within hours of a heart attack in patients who are not in shock and do not have heart failure. If shock and heart failure are present, it is likely that there is major damage to the ventricles. Defibrillation is not as successful in these cases.

Once the emergency situation has been addressed, the patient may be at an increased risk of having another episode. Treatment will address an underlying disorder if it is reversible and a cause of the ventricular tachycardia. Medication may also be given to prevent reoccurrences.

Surgery to implant a defibrillator in the chest can also be performed. The defibrillator identifies abnormal heart rhythms and sends an electric shock to the heart to correct the problem.

The knowledgeable and highly trained staff at the Cedars-Sinai Heart Institute will work with each patient to determine the best treatment option.

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