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.
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.