Mechanisms of ventricular arrhythmias induced by myocardial contusion - A high-resolution mapping study in left ventricular rabbit heart

Background The aims of the Langendorff-perfused rabbit heart study were to evaluate the arrhythmogenic consequences of myocardial contusion and to det ermine the mechanism of arrhythmia. Methods: Six hearts were in the control group, and 24 hearts (intact heart protocol) were submitted to one of four different contusion kinetic energie s (75, 100, 150, or 200 millijoules [mJ]; n = 6), Occurrence of arrhythmia, of an electrically silent area (i.e., area with no electrical activity), a nd of line of fixed conduction block were reported before and for 1 h after contusion. In 16 hearts (frozen hearts) submitted to cryoprocedure and con tusion impact of 100 or 200 mJ, ventricular conduction velocities, anisotro pic ratio, wavelengths, ventricular effective refractory period, and its di spersion were measured before and For 1 h after contusion. Using high-resol ution mapping, arrhythmias were recorded and analyzed. Results: The intact heart study showed that the number and seriousness of c ontusion-induced arrhythmias Increased with increasing contusion kinetic en ergy, as did the number of electrically silent areas (five of six ventricul ar fibrillations and five of six electrically silent areas at 200 mJ), In t he frozen heart study, immediately after contusion ventricular effective re fractory periods were shortened and dispersed, and wavelengths were also sh ortened. The arrhythmia analysis showed that all ventricular tachycardias b ut one were based on reentry developed around an electrically silent area o r a line of fixed conduction block. Conclusions: Myocardial contusion has direct arrhythmogenic effects, and th e seriousness of arrhythmia Increases with the level of contusion kinetic e nergy, The mechanism of arrhythmia was mainly based on reentrant circuit ar ound a fixed obstacle.