Supraventricular tachycardia

Supraventricular tachycardia (SVT) is an abnormally fast heart rhythm arising above the ventricles, often involving the atria or atrioventricular conduction system. Its episodes commonly begin and end abruptly.

Atrioventricular nodal reentrant tachycardia: A reentrant tachycardia in which electrical impulses circulate through functionally distinct pathways in or near the atrioventricular node. This common SVT uses a loop near the AV node to sustain a rapid rhythm.
Electrocardiography: The recording and interpretation of the heart's electrical activity using electrodes on the skin. An ECG can reveal the rhythm and help distinguish SVT subtypes.
Ventricular tachycardia: A rapid heart rhythm arising in the ventricles, with potentially life-threatening effects on circulation. Unlike SVT, this rhythm originates in the ventricles and is generally treated as more dangerous.
Palpitations: The subjective sensation of an unusually forceful, rapid, fluttering, or irregular heartbeat. Palpitations are a common symptom during an SVT episode.
Atrioventricular reentrant tachycardia: A tachycardia sustained by an electrical circuit connecting the atria and ventricles through the AV node and an accessory pathway. An accessory pathway completes the circuit that drives this SVT subtype.
Valsalva maneuver: A forced exhalation against a closed airway that changes pressure in the chest and activates autonomic reflexes. A modified Valsalva maneuver can terminate some stable, regular SVT episodes.
Atrial fibrillation: An irregular heart rhythm caused by disorganized electrical activity in the atria. Its irregular rhythm distinguishes it from the typically regular paroxysmal SVT.
Syncope: A brief loss of consciousness caused by transiently reduced blood flow to the brain. A very rapid or prolonged episode can reduce cerebral blood flow and cause fainting.
Accessory pathway: An abnormal electrical connection between the atria and ventricles that bypasses the atrioventricular node. Some SVT circuits use this route to conduct impulses between chambers.
Adenosine: A short-acting medication that briefly slows or blocks conduction through the atrioventricular node. Its transient AV-node block can stop AV-node-dependent SVT or clarify the rhythm.

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