What is svt

Understanding Supraventricular Tachycardia

Supraventricular Tachycardia (SVT) is a condition characterized by a rapid heartbeat that originates above the ventricles, the heart's lower chambers. In SVT, electrical signals in the atria or atrioventricular node cause the heart to beat much faster than normal, often between 150-250 beats per minute. While a normal resting heart rate is 60-100 beats per minute, episodes of SVT can be alarming and uncomfortable for those experiencing them.

How the Heart's Electrical System Works

The heart's electrical system normally generates impulses in the sinoatrial (SA) node, which initiate heartbeats. These impulses travel through the atria to the atrioventricular (AV) node and then to the ventricles, producing a coordinated heartbeat. In SVT, an abnormal electrical pathway or a reentrant circuit allows electrical impulses to loop abnormally, causing rapid repetitive firing and a racing heartbeat. This disruption of the normal electrical rhythm is what distinguishes SVT from other arrhythmias.

Symptoms of SVT

During an SVT episode, people typically experience a racing or pounding heartbeat, chest discomfort or pain, shortness of breath, dizziness or lightheadedness, and fatigue. Episodes can last from a few seconds to several hours. Some people also experience sweating, anxiety, or a sensation of impending doom during episodes. Between episodes, many people with SVT feel completely normal with no symptoms whatsoever.

Types of SVT

• AVNRT: Atrioventricular nodal reentrant tachycardia accounts for about 60% of SVT cases and is caused by dual pathways in the AV node.
• AVRT: Atrioventricular reentrant tachycardia is caused by an abnormal extra pathway between the atria and ventricles, often associated with Wolff-Parkinson-White syndrome.
• Atrial Tachycardia: Caused by rapid firing of cells in the atrium, separate from the normal pacemaker.
• Atrial Flutter: A regular rapid rhythm in the atrium that often leads to a fast ventricular rate.

Treatment Options

Treatment for SVT depends on the frequency and severity of episodes. Initial approaches include vagal maneuvers such as coughing, bearing down, or ice water immersion, which can sometimes terminate an episode. Medications like beta-blockers, calcium channel blockers, or antiarrhythmic drugs can prevent or manage episodes. For more permanent solutions, radiofrequency catheter ablation is highly effective, curing SVT in 85-95% of cases by destroying the abnormal electrical pathways causing the arrhythmia.

When to Seek Medical Care

If you experience symptoms of SVT for the first time, you should seek medical evaluation. While SVT is generally not immediately life-threatening, a healthcare provider can confirm the diagnosis through an ECG or cardiac monitoring and recommend appropriate treatment. Seek emergency care if you experience severe chest pain, loss of consciousness, or persistent symptoms that do not respond to vagal maneuvers.