Supraventricular tachycardia (SVT) is a type of abnormally fast heart rhythm originating in the upper chambers of the heart (the atria). It's a specific type of arrhythmia, where the heart beats much faster than normal.
Understanding SVT
SVT is characterized by a rapid heart rate, typically exceeding 100 beats per minute and often ranging from 150 to 250 beats per minute. The "supraventricular" part of the name indicates that the issue arises above the ventricles (the heart's lower chambers).
Key Features of SVT
- Rapid Heart Rate: A hallmark symptom is a very fast heartbeat, often described as a racing or pounding sensation.
- Origin Above the Ventricles: The electrical signals causing the rapid heart rate originate in the atria or the atrioventricular (AV) node.
- Irregular Heartbeat (Arrhythmia): While SVT can sometimes present as a regular fast rhythm, it is classified as an arrhythmia because it deviates from the normal heart rhythm.
Types of SVT
There are several types of SVT, including:
- Atrioventricular Nodal Reentrant Tachycardia (AVNRT): This is the most common type of SVT, involving a re-entry circuit within the AV node.
- Atrioventricular Reciprocating Tachycardia (AVRT): This involves an accessory pathway between the atria and ventricles. Wolff-Parkinson-White (WPW) syndrome is a common example of AVRT.
- Atrial Tachycardia: This originates from a single location in the atria.
- Atrial Flutter: While technically a type of SVT, it involves a rapid, regular atrial rate (typically 250-350 beats per minute) with a characteristic "sawtooth" pattern on an electrocardiogram (ECG).
- Atrial Fibrillation: Although technically an SVT, it's usually classified separately because of its irregular and chaotic nature.
Symptoms of SVT
Symptoms can vary, but common ones include:
- Palpitations (feeling your heart racing or pounding)
- Dizziness or lightheadedness
- Shortness of breath
- Chest pain
- Anxiety
- Fainting (syncope)
Diagnosis and Treatment
SVT is usually diagnosed with an electrocardiogram (ECG) to monitor the heart's electrical activity. Treatment options range from vagal maneuvers (like bearing down or coughing) to medications (like adenosine or beta-blockers) and, in some cases, catheter ablation to eliminate the abnormal electrical pathway.
