This sends out electrical impulses through the atrial muscle to another clump of cells called the atrioventricular (AV) node, found between the atria and ventricles. The control of the heartbeat starts with a small clump of cells in the right atrium, called the sinoatrial node (the heart's natural pacemaker). A heartbeat happens when this muscle suddenly contracts (tightens) so that the chambers become smaller and the blood inside is squeezed out. The atria and ventricles have walls of muscle. The heart has two upper chambers (the left and right atria) and two lower chambers (the left and right ventricles).

drinking large amounts of caffeine or alcohol.some medications, including asthma medications, herbal supplements and cold remedies.SVT is usually triggered by extra heartbeats (ectopic beats), which occur in all of us but may also be triggered by: This produces a short circuit, which causes the fast heartbeat. People with Wolff-Parkinson-White syndrome are born with a strand of extra muscle tissue between these chambers. PSVT is usually caused by a short circuit in the electrical system of the heart, which causes an electrical signal to travel rapidly and continuously around in a circle, forcing the heart to beat each time it completes the circuit.Īnother type of SVT is called Wolff-Parkinson-White syndrome, where an abnormal electrical connection occurs between the atria (upper heart chambers) and ventricles (lower heart chambers). Paroxysm means a sudden temporary disturbance of heart rhythm. SVT is sometimes called paroxysmal supraventricular tachycardia (PSVT). It can also be permanently treated with a very effective surgical procedure called catheter ablation, which interrupts the abnormal electrical circuits.Īn episode of supraventricular tachycardia (SVT) occurs when abnormal electrical impulses suddenly start in the upper chambers of the heart, and override the heart's natural rhythm. If necessary, SVT can be treated with drugs that correct the abnormal heart rate. In the vast majority of cases, attacks of SVT are harmless, do not last long and settle on their own without treatment. SVT can occur in anyone at any age, but it often occurs for the first time in children or young adults. However, they may be triggered by a change in posture, exertion, emotional upset, coffee or alcohol. SVT attacks often happen for no obvious reason. Each time the signal completes the circuit, the impulse spreads out to the rest of your heart, forcing it to beat rapidly. The short circuit causes an electrical signal to travel continuously around in a circle. It is often a short circuit in the electrical system of your heart that causes these spontaneous impulses. These impulses override your heart's natural rhythm. SVT is caused by abnormal electrical impulses that start suddenly in the upper chambers of your heart (the atria). You usually feel heart palpitations (noticeable heartbeats) and a fast pulse. This reduces the amount of blood being pumped around the body, which can make you feel dizzy and short of breath.

In SVT, the heart muscle is contracting so fast that it cannot relax between contractions.

This process is repeated for every heartbeat. They then relax, so the heart can fill with blood again. When the heart beats normally, its muscular walls contract (tighten and squeeze) to force blood out and around the body. 'Tachycardia' means an abnormally rapid heart rhythm.'Supraventricular' means that the problem occurs in the upper chambers (atria) of the heart.The heart rate may be as high as 250 beats per minute, but is usually between 140 and 180 (a normal heartbeat should be 60-100 beats per minute at rest). They may occur regularly, several times a day, or very infrequently, once or twice a year. The heart will suddenly start racing, then stop racing or slow down abruptly.Įpisodes can last for seconds, minutes, hours or (in rare cases) days. Supraventricular tachycardia (SVT) is a heart condition featuring episodes of an abnormally fast heart rate.

Normal pulse rate