Sustained ventricular tachycardias

ECG findings for sustained ventricular tachycardia (VT) include wide QRS complex (duration >120 milliseconds) at a rate greater than 100 bpm.

Patients may have a normal cardiac output or may be haemodynamically compromised during episodes of VT. Presence or absence of symptoms does not reliably differentiate VT from supraventricular tachycardia.

Torsades de pointes is a polymorphic VT with a characteristic twisting morphology occurring in the setting of QT interval prolongation.

Sustained VT is usually observed in ischaemic and non-ischaemic cardiomyopathy, but idiopathic VT may also be observed in patients without structural heart disease.

Among patients with prior myocardial infarction or non-ischaemic cardiomyopathy, VT is usually due to re-entry involving regions of slowed conduction adjacent to scar.

Due to the unpredictable and life-threatening nature of most aetiologies of sustained VT, prophylactic implantable cardioverter defibrillator implantation is recommended in high-risk patients.

Sustained VT is a ventricular rhythm faster than 100 bpm typically lasting at least 30 seconds or requiring termination earlier due to haemodynamic instability. VT is defined as a wide complex tachycardia (QRS 120 milliseconds or greater) that originates from one of the ventricles, and is not due to aberrant conduction (e.g., from bundle branch block), at a rate of 100 bpm or greater. 'Idiopathic' VT occurs in the absence of apparent structural heart disease (e.g., prior myocardial infarction, active ischaemia, cardiomyopathy, valvular disease, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoid, left ventricular non-compaction, or other disorders of the myocardium), known channelopathy (e.g., long QT syndrome, Brugada syndrome, catecholaminergic polymorphic VT, short QT syndrome), drug toxicity, or electrolyte imbalance. VT can be described as monomorphic or polymorphic. Torsades de pointes is a polymorphic VT with a characteristic twisting morphology occurring in the setting of QT interval prolongation. Sustained VT often results in hypotension and symptoms of weakness, syncope, or palpitations; however, the arrhythmia may be present in patients who are asymptomatic and normotensive.[Figure caption and citation for the preceding image starts]: Sustained (monomorphic) ventricular tachycardiaFrom the collection of Prof Sei Iwai; used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Torsades de pointesFrom the collections of Dr Kenneth Stein and Dr Richard Keating; used with permission [Citation ends].