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B-PO02-012 USE OF STORED DEFIBRILLATOR ELECTROGRAMS AND EXTRA STIMULUS MAPPING FOR IDENTIFICATION OF VENTRICULAR ECTOPY TRIGGERING VENTRICULAR FIBRILLATION

      Background

      Ablation using activation or pace mapping of PVCs from Purkinje tissue triggering VF; is associated with high success rates. However, sometimes PVCs are not observed during ablation.

      Objective

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      Methods

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      Results

      A 40 y/o female with a diagnosis of Idiopathic Ventricular Fibrillation, s/p ICD and bilateral sympathectomy presented with VF storm. Frequent short-coupled PVCs (LBB, left superior axis) localized to the RV papillary muscle (PM) as well as episodes of PVC induced VF (Fig 1A) were noted. The patient was stabilized with lidocaine and esmolol infusion and by pacing at a higher rate at 100 bpm. In the EP lab, despite administration of isoproterenol and calcium, clinical PVCs could not be induced. Pace mapping comparing the stored shock vector ICD EGM and surface ECG near the anterolateral and posteromedial PM of the RV and the moderator band was not good. However, extra stimulus pace mapping at an interval similar to the coupling interval of the PVC in these areas had a good match with the shock vector ICD EGM and the surface 12 lead ECG (Fig 1B) obtained during the procedure. Purkinje potentials in these sites were also targeted for radiofrequency ablation (Fig 1C). Ablation lesions were further consolidated. There was no recurrence of VF post ablation and during short-term follow up.

      Conclusion

      Successful ablation of short coupled PVC inducing VF can be obtained with extra stimulus pace mapping in areas known to have different exit sites due to preferential conduction like outflow tract, septum and PM. In the absence of clinical PVCs, careful analysis of stored ICD EGMs can be useful.
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