Table 1: Types of broad complex tachycardia
Ventricular origin | Supraventricular origin |
Monomorphic VT | Tachycardia with aberrant conduction or pre-existing bundle branch block |
Polymorphic VT | |
Fascicular tachycardia | |
Right ventricular outflow tract tachycardia |
In clinical practice the vast majority of broad complex tachycardia (BCT) will be ventricular in origin, as shown in the table.
Ventricular tachycardia (VT) most frequently results from damage to the myocardium secondary to ischaemia, cardiomyopathy or myocarditis, or may result from the effects of drugs such as flecainide or quinidine.
VT is defined as three or more ventricular extra systoles in succession at a rate of more than 120 bpm. The term ‘accelerated idioventricular rhythm’ refers to ventricular rhythms with rates of less than 120 bpm.
BCT may be ventricular or supraventricular (SVT) in origin and the range of arrhythmias manifesting as BCT are shown in the table. (Refer to the Supraventricular Tachycardia Learning Zone session for further information).