Recurrent ventricular tachycardia (VT) can be treated by substrate modification of the myocardial scar by catheter ablation during sinus rhythm without VT induction. Better defining this arrhythmic substrate could help improve outcome and reduce ablation burden.

BACKGROUND Three-dimensional (3D) mapping of the ventricular conduction system is challenging. OBJECTIVE The purpose of this study was to use ripple mapping to distinguish conduction system activation to that of adjacent myocardium in order to characterize the conduction system in the postinfarct left ventricle (LV). METHODS High-density mapping (PentaRay, CARTO) was performed during normal rhythm in patients undergoing ventricular tachycardia ablation. Ripple maps were viewed from the end of the P wave to QRS onset in 1-ms increments. Clusters of >3 ripple bars were interrogated for the presence of Purkinje potentials, which were tagged on the 3D geometry. Repeating this process allowed conduction system delineation. RESULTS Maps were reviewed in 24 patients (mean 3112 +/- 613 points). There were 150.9 +/- 24.5 Purkinje potentials per map, at the left posterior fascicle (LPF) in 22 patients (92%) and at the left anterior fascicle (LAF) in 15 patients (63%). The LAF was shorter (41.4 vs 68.8 mm; P = .0005) and activated for a shorter duration (40.6 vs 64.9 ms; P = .002) than the LPF. Fourteen of 24 patients had left bundle branch block (LBBB), with 11 of 14 (78%) having Purkinje potential-associated breakout. There were fewer breakouts from the conduction system during LBBB (1.8 vs 3.4; 1.6 +/- 0.6; P = .039) and an inverse correlation between breakout sites and QRS duration (P = .0035). CONCLUSION We applied ripple mapping to present a detailed electroanatomic characterization of the conduction system in the postinfarct LV. Patients with broader QRS had fewer LV breakout sites from the conduction system. However, there was 3D mapping evidence of LV breakout from an intact conduction system in the majority of patients with LBBB.

Electro-anatomical 3D mapping of the ventricular conduction system is challenging due to double potentials generated by fascicular/Purkinje (FP) tissue and adjacent ventricular myocardium. We used Ripple Mapping (RM) to distinguish these two wavefronts and systemically characterise the conduction system in the post-infarct left ventricle. High-density electrogram collection (PentaRay, CARTO) was performed during sinus rhythm or atrial pacing in patients undergoing ablation for ventricular tachycardia. Ripple maps were viewed, from P wave to the end of the QRS, in a forward sequence of 1ms step-by-step increments. Ripple bars activating in clusters of >3 were interrogated for the presence of split electrograms with a sharp, low amplitude (>0.03mV) FP deflection preceding a broader and higher amplitude ventricular deflection. FP potentials were tagged on the geometry with a yellow disc. Repeating this process allowed the entire conduction system to be highlighted on the endocardial geometry. RMs were reviewed in 24 pts with a mean point density of 3112 ± 613 points. There were 150.9 ± 24.5 FP potentials identified per map. FP potentials were identified on the septum in 22 pts (92%) at the location of the left posterior fascicle (LPF) and on the anterior LV in 15 pts (63%) at the location of the left anterior fascicle (LAF). The LAF was shorter than the LPF (41.4 vs 68.8mm, p= 0.0005) and activated for a shorter time period (40.6 vs 64.9ms, p=0.002). 14/24 pts had LBBB and 11/14 (79%) had FP potential associated LV breakout. The LAF and LPF, when active during LBBB, were shorter than in non-LBBB ((LAF:23.2 vs 49.1mm, p= 0.026), (LPF: 65.6 vs 76.1mm, p= 0.05)). There were fewer breakout sites from the conduction system during LBBB (1.8 vs 3.4 (1.6 ± 0.6, p=0.039)). There was an inverse correlation between the number of breakout sites and QRS duration (p=0.0035). We have applied Ripple Mapping to present a detailed electro-anatomic characterisation of conduction system in the post-infarct LV. Patients with broader QRS had fewer LV breakout sites from the conduction system and most patients with LBBB demonstrated evidence of LV breakout from the conduction system.

The article speaks about the need for training within the company; the company’s role in the provision of training; the measurement of training (its success, etc.); what its role is in training provision; and what might be the evolution of its training commitment after its provision has been established.

Recurrent implantable cardioverter-defibrillator (ICD) therapies for post-infarct ventricular tachycardia (VT) can cause significant morbidity. Substrate modification of the ventricular scar by targeting conduction channels has been proposed as a potential intervention.

Background Identification and elimination of nonpulmonary vein targets may improve clinical outcomes in patients with persistent atrial fibrillation (AF). We report on the use of a novel, noncontact imaging and mapping system that uses ultrasound to reconstruct atrial chamber anatomy and measures timing and density of dipolar, ionic activation (ie, charge density) across the myocardium to guide ablation of atrial arrhythmias. Methods The prospective, nonrandomized UNCOVER AF trial (Utilizing Novel Dipole Density Capabilities to Objectively Visualize the Etiology of Rhythms in Atrial Fibrillation) was conducted at 13 centers across Europe and Canada. Patients with persistent AF (>7 days, <1 year) aged 18 to 80 years, scheduled for de novo catheter ablation, were eligible. Before pulmonary vein isolation, AF was mapped and then iteratively remapped to guide each subsequent ablation of charge density-identified targets. AF recurrence was evaluated at 3, 6, 9, and 12 months using continuous 24-hour ECG monitors. The primary effectiveness outcome was freedom from AF >30 seconds at 12 months for a single procedure with a secondary outcome being acute procedural efficacy. The primary safety outcome was freedom from device/procedure-related major adverse events. Results Between October 2016 and April 2017, 129 patients were enrolled, and 127 underwent mapping and catheter ablation. Acute procedural efficacy was demonstrated in 125 patients (98%). At 12 months, single procedure freedom from AF on or off antiarrhythmic drugs was 72.5% (95% CI, 63.9%-80.3%). After 1 or 2 procedures, freedom from AF was 93.2% (95% CI, 87.1%-97.0%). A total of 29 (23%) retreatments because of arrhythmia recurrence were performed with average time from index procedure to first retreatment being 7 months. The primary safety outcome was 98% with no device-related major adverse events reported. Conclusions This novel ultrasound imaging and charge density mapping system safely guided ablation of nonpulmonary vein targets in persistent AF patients with 73% single procedure and 93% second procedure freedom from AF at 12 months. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT02825992 EU/NCT02462980 CN.

Star formation within dwarf galaxies is governed by several factors. Many of these factors are external, including ram-pressure stripping, tidal stripping, and heating by external UV radiation. The latter, in particular, may prevent star formation in the smallest systems. Internal factors include negative feedback in the form of UV radiation, winds and supernovae from massive stars. These act to reduce the star formation efficiency within dwarf systems, which may, in turn, solve several theoretical and observational problems associated with galaxy formation. In this contribution, we discuss our recent work to examine the importance of the many factors in the evolution of dwarf galaxies.