Ventricular tachycardia (VT) is a very fast heartbeat caused by a malfunction in one of the heart’s ventricles. It is a pulse of more than 100 beats per minute with at least three irregular heartbeats in a row.
VT can occur with or without heart disease. It can make you feel like your heart is racing. You may tire easily or feel faint.
Treatment depends on the symptoms and the cause. In some cases, no treatment is required. In others, a device might be implanted to stop tachycardia when it occurs. The condition may exist without symptoms, or it can cause sudden cardiac arrest.
Classification of VT is based on:
- duration (how long an episode lasts)
- morphology (the shape on an ECG)
- hemodynamic effect (effect on the blood pumping in the heart)
The types of VT are as follows:
- nonsustained VT stops spontaneously without causing problems with blood flow
- sustained VT lasts longer than 30 seconds and/or requires help for stopping or produces severe blood flow problems which can lead to fainting
- monomorphic VT is VT in which each heartbeat resembles the next on an ECG
- polymorphic VT is VT in which heartbeats vary in appearance on an ECG
Risk factors for VT include:
- coronary artery disease: hardening and narrowing of the arteries that supply blood to the heart
- previous heart attack
- family history of VT
Many factors can cause VT. Sometimes there is no apparent cause. The most common causes of VT are heart related.
Known causes of VT include:
- structural heart disease (can be the result of scarring from a previous heart attack)
- ischemic heart disease (caused by reduced blood supply to the heart)
- acute coronary ischemia (most common cause of out-of-hospital sudden cardiac death)
Certain forms of VT are inherited (passed down through families). These include:
- catecholaminergic polymorphic VT: Exercising causes a fast heart rate, which varies from beat to beat and can cause fainting and even death.
- arrhythmogenic right ventricular dysplasia (ARVD): causes either polymorphic or monomorphic VT
VT may make you feel like your heart is going to burst from beating so fast. Symptoms include:
- syncope (fainting)
- fatigue (your body feels like it has exercised, but your heart is just running too fast)
- tachycardia (very fast heart rate)
A diagnosis of VT is made by listening to and observing the heart. Tests used to make a diagnosis include:
- electrocardiogram (ECG): provides a readout of your heartbeat, allowing doctors to spot abnormalities
- transesophageal echocardiograph: a procedure in which an ultrasound probe is put down your esophagus to allow for clearer pictures and to hear the heart better
- cardiac magnetic resonance imaging (CMRI): an MRI scan of the heart
The goal of treatment is to immediately correct your heart rhythm and prevent future episodes. In an emergency, treatment may include:
- electrical defibrillation
- electric shock
- antiarrythmic medication given through a vein
Long-term treatment may include oral antiarrythmic medication. However, these are frequently avoided because of severe side effects. Other long-term treatments include:
- cardioverter defibrillator: a device implanted in the body to interrupt tachycardia when it occurs
- radio-frequency (RF) ablation: destroys abnormal pathways that are causing the heart to beat incorrectly
- cardiac-resynchronization therapy (CRT): a type of pacemaker implanted to regulate your heartbeat
Untreated VT puts a patient at greater risk for sudden cardiac death. Patients with implanted devices have a good outlook. Once in place, these devices can prevent sudden cardiac death and keep a patient’s heart working properly. Complications from an implanted pacemaker or damage from ablation are uncommon.