What is Supraventricular Tachycardia?
Tachycardia is an abnormally fast heart rate, over 100 beats per minute in adults. Supraventricular tachycardia is an abnormally fast heart rate caused by an abnormal electrical impulse from an area above the ventricles, the lower chambers of the heart.
Normally, the contraction of the heart is controlled by a serious of electrical impulses originating from the sinoatrial node (SA node). This node is like a tiny pacemaker located in the upper right chamber of the heart, the atrium. The electrical impulse travels through the heart muscle to the atrioventricular node (AV node), making the heart contract and pump blood round the body.
During supraventricular tachycardia, the electrical impulse from the SA node is over ridden or short circuited by another area of the heart with faster impulses. For example, a small area in one of the atria can become more 'excitable' than usual and start to produce its own electrical impulses. These faster impulses spread down to the ventricles, causing the heart to contract or beat faster than normal.
Supraventricular tachycardia is diagnosed following assessment with an electrocardiogram (ECG) carried out by a doctor or nurse.
Who can suffer from supraventricular tachycardia?
The first episode of supraventricular tachycardia often begins in childhood or early adulthood. Although an uncommon condition, it can however occur at any age.
What are the symptoms of supraventricular tachycardia?
An episode of supraventricular tachycardia can last for seconds, minutes or hours. Symptoms include palpitations, breathlessness, dizziness, chest pain, and in extreme cases loss of consciousness.
Most importantly the heart rate rapidly increases to 140-200 beats per minute.
How can supraventricular tachycardia be treated?
In many cases the episode of supraventricular tachycardia is short (lasting seconds to an hour) with symptoms stopping quickly. In these cases no treatment is necessary.
If symptoms last a long time or are very severe, medication can be administered to block the electrical impulses to the heart. This requires medical attention.
Medication, such as digoxin and beta blockers, may also be prescribed to prevent recurring episodes of supraventicular tachycardia.