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.