Ventricular tachycardia (VT) is a condition in which the lower chambers of the heart (ventricles) beat abnormally fast. This rapid heart rate is caused by electrical signals that arise from the ventricles themselves instead of following the normal pattern of arising in the upper chambers of the heart (atria) and spreading throughout the heart. Alternatively, ventricular tachycardias may be caused by electrical signals that do not follow the normal path through the heart's conduction system (e.g., reentrant signals).

Ventricular tachycardias may be sustained or nonsustained, and they may occur in either of the ventricles (left and right). There are several different kinds, and their severity ranges from mostly without symptoms to a life-threatening condition that must be treated immediately. The severity is often connected to the presence of underlying heart disease.

The most dangerous kinds of ventricular tachycardia may result in fainting (syncope) or even cardiac arrest. A patient who has collapsed and gone into cardiac arrest, needs to be treated with a defibrillator immediately to avoid sudden cardiac death.

Some patients with mild forms of VT do not require treatment. For example, their VT may permanently resolve after their medication has been changed. Other patients require more regular treatment. Treatment options include medications, catheter ablation, surgery and insertion of an implantable cardioverter defibrillator. The choice of therapy depends on the nature of the VT and the risk of more serious cardiac arrhythmias.

Ventricular tachycardia is an abnormal condition in which the ventricles of the heart beat abnormally fast. This rapid eartbeat is stimulated by electrical signals that arise from within specialized cardiac cells within the ventricles themselves, or it may be caused by electrical signals that do not follow the normal conduction system and stimulate more than one contraction. These are called reentrant signals.

In a normal heart, electrical signals arise from a specialized “natural pacemaker” in the upper right atrium called the sinoatrial node (SA node). These signals first spread through the atria, then into the ventricles. During ventricular tachycardia, however, additional signals arise from the ventricles themselves or are caused by a defect in the heart's conduction system.

Ventricular tachycardias are classified by their duration (e.g., sustained or nonsustained) and whether they occur without cause or because of an underlying condition, such as coronary artery disease. Short, unsustained episodes of ventricular tachycardia generally do not produce symptoms and do not require treatment. However, longer, sustained episodes of VT, in the presence of an underlying heart disease, may cause a medical emergency. Over time, VT can lead to heart failure or degenerate into ventricular fibrillation, which can result in cardiac arrest.

The specific types of VT include:

Ventricular tachycardia (VT) can sometimes develop even when a patient has no other underlying conditions. This type of VT is also known as idiopathic ventricular tachycardia and tends to be less dangerous than other causes of VT. These other causes include:

Progress in genetic research has led to the discovery of a gene that is involved in regulating the heart’s electrical activity. Finding ways to use gene therapy to correct this defect, researchers hope, will significantly lower the risk of ventricular tachycardia progressing to more serious cardiac problems.

Some patients with ventricular tachycardia (VT) have no symptoms. Others experience symptoms such as:

Physicians who examine a patient with VT may detect low blood pressure (hypotension). In the most severe cases, patients with VT will go into cardiac arrest and collapse. Defibrillation must occur immediately in order to save a patient’s life once he or she has gone into cardiac arrest.

Ventricular tachycardia may also be implicated when drivers lose consciousness or “fall asleep” behind the wheel. Other heart-related conditions that could lead to loss of consciousness while driving (or near-loss of consciousness and pulling off the road) include syncope, supraventricular tachycardia and/or advanced AV block.

The first steps that a physician takes when diagnosing ventricular tachycardia (VT) is to obtain a patient’s medical history and to give the patient a physical examination. Next, the physician may order blood tests and an electrocardiogram (EKG). The EKG is a sensitive test that measures the heart's electrical activity and displays it on a computer screen or printout for a physician to analyze. 

If the EKG is normal, but the physician still suspects an abnormal heart rhythm, then the patient may need to wear a portable EKG Holter monitor for 24 hours. This device monitors the heart rate for 24 hours, allowing physicians to diagnose nonsustained arrhythmias that occur outside of the physician's office. If the Holter monitor still doesn't record any arrhythmias, the patient may be given a different kind of event recorder that is activated by the patient only when the arrhythmia occurs. This will allow the physician to study the characteristics of their particular arrhythmia. 

Depending on the results of these tests, a more invasive test called an electrophysiology (EP) study may be performed. An EP study is a procedure in which a thin tube (catheter) is inserted into a vein or artery (e.g., in the groin) and guided to the heart, where it can perform specific measurements of the heart’s electrical activity and pathways. During the EP study, a physician may or may not be able to reproduce the patient’s VT. If it can be produced, the patient is at particularly high risk of going into cardiac arrest at some point in the future.

EP studies are also an important part of therapy for VT treatment. They are typically performed before surgery or catheter ablation. These precise studies can exactly locate the source of an abnormal rhythm, thus allowing physicians to exactly target the defective area.

In some cases (e.g. nonsustained ventricular tachycardia [VT] without underlying heart disease), no treatment may be necessary. If treatment is needed, the most common treatment is medication. The goal with medication is to stop the abnormal heart rhythm and prevent it from recurring. Medications used include antiarrhythmics, beta blockers and others.

In recent years, alternative methods have become increasingly common in the management of ventricular tachycardias. These alternative methods include catheter ablation, which is often recommended for patients without underlying heart disease or for patients with certain kinds of arrhythmias (e.g., reentrant ventricular tachycardia). In this procedure, a physician inserts a long, thin tube called a catheter into a blood vessel and guides it into the heart. The catheter is tipped with a special radiofrequency transmitter that is used to destroy selected cardiac cells that are causing the abnormal heart rhythm. So far, ablation has been shown to eliminate certain kinds of VT in between 80 and 100 percent of cases, and its use will likely increase.

Among patients with underlying heart disease, the use of implantable cardioverter defibrillators (ICD) has been steadily growing. This device senses abnormal heart rhythms and delivers a shock to the heart to restore a normal rhythm. In some cases, patients may be treated with medications, catheter ablation and implantation of an ICD.

Surgery is also an option, although to some extent it has become less common since the advent of the ICD. Before surgery for an arrhythmia, the patient's heart will be carefully mapped and areas identified where the abnormal beat is originating. During surgery, these areas are carefully removed. In heart attack patients, this surgery may be accompanied by the placement of bypass grafts to re-establish the flow of oxygen-rich blood. Surgery may also be recommended for patients in whom medications have failed or who are already undergoing surgery to remove a ventricular aneurysm or to repair a defective heart valve.

Because of the risk of fainting associated with ventricular tachycardia, patients may be advised against driving or operating heavy machinery until the condition is under control. American Heart Association has recommended that anyone who has experienced confusion, dizziness or other signs of altered consciousness during a VT episode wait several months before getting behind the wheel again. Once tests have confirmed that treatment has effectively controlled the arrhythmia, then people are generally free to start driving again.

In many cases, an initial episode of VT cannot be prevented. However, once diagnosed, treatment can help prevent future episodes. Furthermore, people can adopt heart-healthy strategies that decrease the likelihood of developing risk factors such as coronary artery disease.

Preparing questions in advance can help patients have more meaningful discussions with their doctor. Patients may wish to ask their physicians the following questions related to ventricular tachycardia:

1. Do I have ventricular tachycardia? How does this affect my heartbeat?
   
   
2. Does my condition require treatment? How severe is my condition?
   
   
3. Do I have any underlying conditions that caused ventricular tachycardia? What condition(s)?
   
   
4. What sort of symptoms can I expect with this condition? Are any of these dangerous?
   
   
5. Could one of the medications I am currently taking be complicating this condition? Would altering my medications improve my condition?
   
   
6. Are there any medications available that I could use to control this condition?
   
   
7. Are there any lifestyle changes I can make that would improve my condition?
   
   
8. Is it still safe for my to drive with this condition?
   
   
9. Could my ventricular tachycardia be caused by my pregnancy? Could the condition interfere with my pregnancy?