Changes in the propagation pattern within the conduction channel during sinus rhythm and ventricular tachycardia demonstrated by non-contact mapping: role of late potential activity.

Sustained monomorphic ventricular tachycardia (VT) in patients with a previous myocardial infarction is due to re-entry mechanism in areas of slow conduction. The recognition of the pathogenic mechanism and the characterization of the activation pathway are usually obtained by indirect measures with entrainment mapping and pacing manoeuvres. We studied a 61-years-old patient with a history of previous inferior myocardial infarction and we provided the in vivo direct visualization of the critical components of re-entry circuit by non-contact mapping. VT circuit entrance, central pathway, and exit were characterized during the same beat by virtual electrodes and visualized on a three-dimensional map both during sinus rhythm, ongoing VT, and pacemapping. The analysis demonstrated an activation of the conductive channel in opposite directions during the sinus rhythm and ventricular tachycardia. Late potentials during sinus rhythm turned into mid-diastolic activity during VT; non-contact mapping allowed the ablation procedure to be performed in sinus rhythm, targeting the central pathway of the conducting channel and the abolition of VT inducibility.