Attenuation of stretch-induced arrhythmias following chemical ablation of Purkinje fibres, in isolated rabbit hearts

Purkinje fibres (PFs) play an important role in some ventricular arrhythmias and acute ventricular stretch can evoke mechanically-induced arrhythmias. We tested whether Purkinje fibres, play a role in these arrhythmias. Pseudo-ECGs were recorded in isolated, Langendorff-perfused, rabbit hearts in which the left ventricular endocardial surface was also irrigated with Tyrode, via an indwelling catheter placed in the left ventricular lumen. The number and period of ectopic activations was measured during left ventricular lumen inflation via an indwelling fluid-filled balloon (500 μL added over 2 s and maintained for 15 s in total). Mechanically-induced arrhythmias occurred in 70% of balloon inflations: they were maximal in the first 5 s and ceased within 15 s. Brief, (10 s) irrigation of the left ventricular lumen with Lugol solution (IK/I2), via the indwelling catheter, reduced inflation-induced ectopics by 98% (p < 0.05). Ablation of endocardial PFs by Lugol was confirmed by Triphenyltetrazolium Chloride staining. Optical mapping revealed the left ventricular epicardial activation patterns of ectopics could have PF-mediated and focal sources. In silico modelling predicted ectopic sources originating in the endocardial region propagate to and through the Purkinje fibres network. Acute distention-induced ectopics are multi-focal, their attenuation by Lugol, their activation patterns and in silico modelling indicate a participation of Purkinje fibres in these arrhythmias

The Spectrum of Idiopathic Ventricular Fibrillation and J-Wave Syndromes: Novel Mapping Insights

KEY POINTS Idiopathic ventricular fibrillation (IVF) is defined as unexplained sudden cardiac death due to ven-tricular fibrillation (VF) without any identifiable structural or electrical cause after extensive investigations (no phenotype). Recent data show that the use of high-density electrophysiologic mapping may ultimately offer sub-clinical diagnoses of cardiac disease in about 90% of individuals with IVF. Two major conditions underlie the occurrence of VF: the presence of either depolarization abnormalities due to micro-structural myocardial alteration or Purkinje abnormalities manifesting as triggering ectopy or reentry in the peripheral network. J-wave syndromes are defined as a distinct electrocardiographic phenotype (slurring/notch) affecting the junction between the QRS complex and the ST segment in inferolateral leads. Recent data provide evidence for heterogeneous substrates, related to either delayed depolarization due to microstructural alterations or early repolarization abnormalities. IVF and J-wave syndromes are the result of a wide spectrum of pathophysiologic processes. The individual phenotypic characterization is essential given its implications in therapy, genetic testing, and risk stratification

Malignant Purkinje Ectopy induced by Sodium-channel Blocker

International audienc