Ventricular tachycardia

Ventricular tachycardia is a rapid heart rhythm arising from the heart’s lower chambers. It can reduce effective blood flow and may deteriorate into ventricular fibrillation.

Reentry (cardiac electrophysiology): A circulating electrical wave repeatedly activates heart tissue because conduction and recovery times permit a loop. Reentry is a common mechanism sustaining ventricular tachycardia, especially around scar tissue.
Synchronized cardioversion: An electrical shock timed to the QRS complex to restore an organized heart rhythm. It is used for unstable tachycardia with a pulse to avoid shocking during ventricular repolarization.
Monomorphic ventricular tachycardia: Ventricular tachycardia with a consistent QRS shape from beat to beat on an electrocardiogram. Its stable electrical pattern often reflects a repeating circuit, particularly in scarred myocardium.
Ventricles of the heart: The two lower heart chambers that pump blood to the lungs and the rest of the body. The rhythm originates in these chambers, whose contractions generate systemic and pulmonary blood flow.
Supraventricular tachycardia: A rapid heart rhythm originating above the ventricles, usually in the atria or atrioventricular junction. Both rhythms are fast, but their sites of origin and typical electrocardiogram patterns differ.
Ectopic pacemaker: A focus outside the sinoatrial node generates impulses that can initiate or control a heart rhythm. An abnormal ventricular focus can trigger tachycardia without a circulating wave.
Defibrillation: An unsynchronized electrical shock used to terminate ventricular fibrillation or pulseless ventricular tachycardia. Pulseless ventricular tachycardia is treated as a shockable cardiac-arrest rhythm.
Polymorphic ventricular tachycardia: Ventricular tachycardia in which the QRS shape and electrical axis vary from beat to beat. Its changing pattern points to distinct mechanisms and urgent causes.
QRS complex: The electrocardiogram waveform representing ventricular depolarization. Its width and shape help distinguish ventricular rhythms from rhythms conducted from above.
Accelerated idioventricular rhythm: A ventricular rhythm faster than the usual escape rate but generally slower than ventricular tachycardia. Its slower rate and frequent spontaneous resolution distinguish it from typical ventricular tachycardia.

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