People almost always have palpitations and other symptoms of heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more
(for example, breathlessness, chest discomfort, and/or fainting).Electrocardiography is used to make the diagnosis.
Drugs and procedures to destroy abnormal areas of the ventricles may be used, but usually an automatic implantable defibrillator is required.
(See also Overview of Abnormal Heart Rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more 
.)
Ventricular tachycardia may be thought of as a sequence of consecutive ventricular premature beats Ventricular Premature Beats A ventricular premature beat is an extra heartbeat resulting from abnormal electrical activation originating in the ventricles (the lower chambers of the heart) before a normal heartbeat would... read more . Sometimes only a few such beats occur together, and then the heart returns to a normal rhythm. Ventricular tachycardia that lasts more than 30 seconds is called sustained ventricular tachycardia.
Sustained ventricular tachycardia usually occurs in people with a structural heart disorder such as a heart attack Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or heart attack (myocardial infarction), depending on the location and amount... read more 
, heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more , or a cardiomyopathy Overview of Cardiomyopathy Cardiomyopathy refers to progressive impairment of the structure and function of the muscular walls of the heart chambers. There are three main types of cardiomyopathy: Dilated cardiomyopathy... read more 
. It is more common among older people. However, rarely, ventricular tachycardia develops in young people who do not have a structural heart disorder. Such young people may have a heart disorder called long QT syndrome Long QT Syndrome and Torsades de Pointes Ventricular Tachycardia Torsades de pointes ventricular tachycardia is a specific type of ventricular tachycardia that occurs in people who have a particular disorder of the heart's electrical activity called long... read more , which can be inherited or caused by certain drugs. It can also be due to other rare inherited disorders such as the Brugada syndrome (a cardiac channelopathy Cardiac Channelopathies Cardiac channelopathies are genetic abnormalities in heart cell proteins that control heart electrical activity and thus can cause heart rhythm disturbances. (See also Overview of Abnormal Heart... read more ).
Symptoms of Ventricular Tachycardia
People with ventricular tachycardia almost always have awareness of heart beats (palpitations). They may have weakness, light-headedness, and/or chest discomfort.
Sustained ventricular tachycardia can be dangerous because the ventricles cannot fill adequately or pump blood normally. Blood pressure tends to fall, and heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more follows. Sustained ventricular tachycardia is also dangerous because it can worsen until it becomes ventricular fibrillation Ventricular Fibrillation Ventricular fibrillation is a potentially fatal, uncoordinated series of very rapid, ineffective contractions of the ventricles (lower chambers of the heart) caused by many chaotic electrical... read more 
—a form of cardiac arrest. Sometimes ventricular tachycardia causes few symptoms, even at rates of up to 200 beats per minute, but it may still be extremely dangerous.
Diagnosis of Ventricular Tachycardia
Electrocardiography
Electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more 
(ECG) is used to diagnose ventricular tachycardia and to help determine whether treatment is required.
Treatment of Ventricular Tachycardia
Converting heartbeat to normal rhythm
Preventing further episodes
Immediate treatment
Ventricular tachycardia is treated when it causes symptoms or when episodes last more than 30 seconds even without causing symptoms.
People who have symptoms, particularly if blood pressure is too low, require immediate cardioversion Restoring normal rhythm Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more (an electrical shock to convert the heart to normal rhythm).
People who have no symptoms but who have had ventricular tachycardia for more than 30 seconds should be treated either with cardioversion or intravenous drugs.
Cardioversion is painful, so sedation is required, but cardioversion is almost always effective and aside from the discomfort has few side effects.
Drugs are not uncomfortable but are not as effective as cardioversion in stopping the abnormal heart rhythm (arrhythmia) and are more likely to cause side effects. The most commonly used drugs are amiodarone, lidocaine, and procainamide (see table Some Drugs Used to Treat Arrhythmias Some Drugs Used to Treat Arrhythmias 
).
Long-term treatment
The long-term goal is to prevent sudden death, rather than simply stopping the abnormal rhythm. In people with ventricular tachycardia who have an underlying heart disorder, particularly if their heart does not pump well, an implantable cardioverter-defibrillator Restoring normal rhythm (ICD, a small device that can detect an arrhythmia and deliver a shock to correct it) is often used. This procedure is similar to implantation of an artificial pacemaker Artificial pacemakers Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more .
Certain procedures may be used to destroy the small abnormal area in the ventricles, identified by ECG, that is usually responsible for sustained ventricular tachycardia. They include catheter ablation Restoring normal rhythm Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more (delivery of energy of a specific frequency or cold through a catheter inserted in the heart) and open-heart surgery.
More Information
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Heart Association: Arrhythmia: Information to help people understand their risks of arrhythmias as well as information on diagnosis and treatment
