fusion beats
ECG complexes resulting from simultaneous activation of ventricles by both supraventricular and ventricular impulses.
Full Definition
Electrocardiographic complexes that occur when supraventricular and ventricular impulses simultaneously activate different portions of the ventricular myocardium, creating a QRS morphology that represents a 'fusion' of both activation patterns. These beats typically have intermediate width and morphology between the patient's baseline QRS and the ventricular tachycardia complexes. Fusion beats are highly specific for ventricular tachycardia and support the diagnosis when present during wide complex tachycardia, as they demonstrate independent ventricular ectopic activity occurring alongside residual AV conduction.
Usage
Usage note: Distinguished from capture beats by intermediate rather than normal QRS morphology.
In Context
- "Several fusion beats were identified, supporting the diagnosis of ventricular tachycardia." — ECG interpretation report
- "The morphology of the fusion beats suggested partial capture during the ventricular arrhythmia." — Electrophysiology consultation