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Clinical Electrophysiology: Ventricular Tachycardia
Ventricular tachycardia is a rapid heart rhythm (100 beats per minute or more) that starts in the lower chambers of the heart, the ventricles.
If the abnormal heartbeats last less than 30 seconds, it is called non-sustained ventricular tachycardia. If an episode of ventricular tachycardia lasts more than 30 seconds, it is called sustained ventricular tachycardia.
Symptoms of Ventricular Tachycardia
In some cases ventricular tachycardia occurs with no symptoms other than rapid heartbeat. A patient experiencing ventricular tachycardia will sometimes feel heart palpitations. Whether 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 in turn may cause the 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 of Ventricular Tachycardia
Ventricular tachycardia can be caused by a structural abnormality in the heart, with or without a heart attack, or may occur in patients with one of the following:
- Prior heart attack or coronary artery disease
- Heart failure
- Heart surgery
- Valvular heart disease
Ventricular tachycardia also can be caused by:
- Anti-arrhythmic medications
- Changes in blood chemistry or pH
- Lack of oxygen
Treatment for Ventricular Tachycardia
If ventricular tachycardia causes episodes that last more than 30 seconds or if the condition causes blood pressure to dramatically fall, an electric shock needs to be immediately applied to the heart to reset the electrical rhythm to normal (cardioversion). Drugs also may be given intravenously to help return the heart rate to normal.
If other approaches fail, it may be necessary to implant an implantable defibrillator that delivers an electrical impulse to the heart whenever it detects an abnormal heart rhythm. The procedure to implant a defibrillator is similar to that used to implant a pacemaker.