Introduction and objectives: The ventricular myocardium consists of a continuous muscular band. This anatomy would
provide the interpretation for two fundamental aspects of left ventricular dynamics: the mechanism of left ventricular twist and
rapid diastolic filling due to the suction effect. The aim of this study was to investigate the electrical activation of the endocardial
and epicardial bands to understand ventricular twist and the mechanism of active suction during the diastolic isovolumic phase.
Methods: Five patients underwent three-dimensional endoepicardial electro anatomic mapping during ablation of lone atrial
fibrilation or concealed epicardial accessory pathways.
Results: Three-dimensional endo-epicardial mapping demonstrates an electrical activation sequence in the area of the apex
loop in agreement with the synchronic contraction of the descending and ascending band segments. The simultaneous and opposing
radial activation of the ascending band segment, starting in the descending band segment, in the area in which both band segments
intertwine, is consistent with the mechanism of ventricular twist. The late activation of the ascending band segment is consistent
with its persistent contraction during the initial period of the isovolumic diastolic phase (the basis of the suction mechanism).
Conclusion: This study could explain the process of ventricular twist during systole and the active diastolic suction.