Notches in sinusoidal phase
Established VF was characterized by large amplitude sinusoidal complexes and traces with an appearance of notches.
We should not confuse the presence of notches with ECG VF that generally have low amplitude waves in advanced stages, not analyzed in this study, which corresponds to what is known in the literature as “fine course” VF compared to “ large course” VF16.
Notches in the sinusoidal complexes appeared in sustained but not in non sustained VF, therefore, notches in the sinusoidal traces of ventricular fibrillation could be a predictor of sustained VF and may also be the electrocardiographic pattern of activation of essential structures in the VF maintenance. This hypothesis is reinforced with the observation of a case with delayed end after shock (Fig 5).
Krummen determined that sustained but not self-limiting VF was characterized by greater rotor stability . In addition, rotor exhibited greater surface ECG variation during VF than focal sourced due to wavebreak, secondary rotors and meander17.
This variability in the amplitude of ECG waves could be due to the presence of higher amplitude waves over which others of lower amplitude are superimposed, producing the appearance of notches described in our study.
At an experimental level, Li et al 18proved the following: long-duration ventricular fibrillation exhibits 2 distinct organized states, one potentially arising focally in the Purkinje system and the other potentially arising from a stable re-entrant circuit near the apical left ventricular endocardium. Could notches be the electrocardiographic manifestation of these components? . In this way, in figures presented by Masuda19, sustained and non-sustained VF is shown ; the Purkinje firing may be responsable for the morphologies of notches in sustained VF , which is not present in non sustained VF.