What defines supraventricular tachycardia (SVT)?

Supraventricular tachycardia (SVT) is characterized by a rapid heart rate that originates above the ventricles, specifically from the atria or the junctional tissue. This means that the irregular and often fast heartbeat is due to electrical impulses that start in areas other than the ventricles, such as the atria or the atrioventricular (AV) node.

The definition emphasizes that SVT typically involves heart rates exceeding 100 beats per minute and is often a result of reentrant circuits, enhanced automaticity, or triggered activity in the aforementioned regions. Consequently, this type of tachycardia will not involve the ventricles as the primary source of the rapid rhythm, which reinforces the uniqueness of SVT in distinguishing it from other forms of tachycardia originating lower down in the heart.

Understanding this definition is crucial for recognizing SVT on an electrocardiogram (ECG) and implementing the appropriate management strategies. The other options either describe conditions or arrhythmias that do not fit the specific criteria of SVT, making the correct answer about the origin and nature of the heart rate definitive.