Rapid pacing-induced moderate myocardial dysfunction in dogs significantly prolonged propagated deflection-to-deflection intervals during VF compared with controls (125.5 vs 103.4 ms, p=0.009).
RCT
randomized
Does rapid pacing-induced moderate myocardial dysfunction alter electrophysiologic properties and ventricular fibrillation characteristics in mongrel dogs?
Moderate myocardial dysfunction induced by rapid pacing in dogs leads to significant electrophysiological abnormalities and altered ventricular fibrillation characteristics without structural changes in cell morphology or gap junctions.
Tasa de eventos absoluta: 125.5% vs 103.4%
valor p: p=0.009
This study tests the hypothesis that moderate myocardial dysfunction is associated with altered myocardial anisotropic properties and structurally altered ventricular fibrillation (VF). Mongrel dogs were randomized to either a control group or a group that was rapidly paced at 250 beats/min until the left ventricular ejection fraction was < or = 40%. Changes in anisotropic properties and the electrical characteristics of VF associated with the development of moderate myocardial dysfunction were assessed by microminiature epicardial mapping studies. In vivo conduction, refractory periods, and repolarization times were prolonged in both longitudinal and transverse directions in myopathic animals versus controls. VF was different in myopathic versus control animals. There were significantly more conducted deflections during VF in normal hearts compared with myopathic hearts. Propagated deflection-to-deflection intervals during VF were significantly longer in myopathic hearts compared with controls (125.5 +/- 49.06 versus 103.4 +/- 32.9 ms, p = 0.009). There were no abnormalities in cell size, cell shape, or the number of intercellular gap junctions and there was no detectable change in the expression of the gap junction proteins Cx43 and Cx45. Moderate myocardial dysfunction is associated with significant electrophysiological abnormalities in the absence of changes in myocardial cell morphology or intercellular connections, suggesting a functional abnormality in cell-to-cell communication.
Kavanagh et al. (Sun,) conducted a rct in Moderate myocardial dysfunction. Rapid pacing vs. Control was evaluated on Propagated deflection-to-deflection intervals during VF (p=0.009). Rapid pacing-induced moderate myocardial dysfunction in dogs significantly prolonged propagated deflection-to-deflection intervals during VF compared with controls (125.5 vs 103.4 ms, p=0.009).