Fusion Beat

• beat in which the depolerization of the ventricle (or the atria) is induced simultaneously from two seperate sites. In either case, a second activation waveform initiates depolerisation of part of the myocardium before an antecedant depolerisation has completed it's spread.
• Thus with atrial fusion beats the atria are activated from two different sites and with Ventricular fusion beats, the ventricles are activated from two different sites.
• Morphology of the fusion wave is an intermediate between the two pacemakers.