What is Ventricular Tachycardia (VT)?
Ventricular tachycardia is an abnormal heart rhythm arising in the bottom chambers of the heart (the ventricles).
What causes VT?
In most cases VT is caused by a disease of the heart muscle. For example, VT can occur during or after a heart attack or in conditions such as cardiomyopathy or in those with congenital heart disease. Rarely, VT occurs in patients whose heart appears normal.
What are the symptoms of VT?
VT can cause a racing of the heart or palpitations. It may also cause fainting or, in some cases, sudden death.
How is VT diagnosed?
VT may be suspected in patients who have heart disease and have black-outs or faints or palpitations. The diagnosis is usually made by electrocardiogram (ECG). In many cases it is necessary to perform a test known as an electrophysiological study or EPS to confirm the presence of VT. An EPS is performed in hospital. During this test wires or tubes are placed in the veins in the groin and are passed into the heart. The doctor is able to record electrical signals from these wires which will aid in the diagnosis of VT.
What treatments are available for VT?
The treatment for VT depends on the cause. In many patients the first-line treatment is an implantable defibrillator (see elsewhere on this site for an explanation of implantable defibrillator). In short, implantable defibrillators are a special kind of pacemaker which terminates abnormal heart rhythms such as VT, either with small pulses of electricity (this is known as overdrive pacing) or with an electric shock. Medications may also be useful in reducing or preventing VT. Sometimes VT is treated with a technique known as catheter ablation. This procedure is performed in hospital. Catheter ablation involves passing wires into the heart via small incisions into the groin. Then radiofrequency current (like cautery) is used to destroy the short-circuits causing the VT.
Is catheter ablation successful and what are the risks of catheter ablation?
The success rate of catheter ablation depends on the condition causing the VT. Catheter ablation of VT occurring in an otherwise normal heart has a high success rate. The success rate in patients who have had a previous heart attack or have cardiomyopathy is lower, but still quite good.
The risks of this procedure depend very much on the presence of other heart conditions which might cause the VT. Overall the risks of catheter ablation include a 1 in 500-2000 risk of death, a 1 in 500-2000 risk of heart attack or stroke and 1-2 chances in 100 of problems such as bleeding, the formation of blood clots or damage to blood vessels.
© Dr Mark McGuire 5/1/2016 (version 1.0)