Ventricular Tachycardia (VT)
Ventricular tachycardia (VT) arises in ventricular myocardium below the His bundle, so activation spreads slowly cell to cell, widening the QRS complex and desynchronising ventricular contraction.
Definition
Ventricular tachycardia is three or more consecutive ventricular beats at a rate above 100 per minute, arising in the ventricles independently of atrial and atrioventricular nodal conduction. It is non-sustained when it lasts under 30 seconds, and sustained when it runs for 30 seconds or longer or needs earlier termination. Monomorphic VT keeps the same QRS shape beat to beat; polymorphic VT changes continually, and torsades de pointes is the polymorphic subtype occurring with QT prolongation.
First principles
The pulse decides which algorithm you are on
The same broad-complex rhythm can give a tolerable blood pressure, profound compromise, or no output at all. Pulseless VT is a shockable cardiac arrest, managed exactly as ventricular fibrillation (VF). With a pulse, VT sits on the peri-arrest tachyarrhythmia algorithm, where five life-threatening features decide the route. They are shock, syncope with severe or ongoing hypotension, myocardial ischaemia, severe heart failure with pulmonary oedema, and an arrhythmia occurring immediately after return of spontaneous circulation (ROSC).
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