Improved Ablation Efficiency in PVI Guided by Contact Force and Local Impedance: Chronic Canine Model.

The purpose of this study was to assess the effect local impedance (LI) has on an ablation workflow when combined with a contact force (CF) ablation catheter. Left pulmonary vein isolation was performed in an canine model ( = 8) using a nominal (30 W) or an elevated (50 W) power strategy with a CF catheter. The catheter was enabled to measure LI prior to and during ablation.

Long-term performance of a novel communicating antitachycardia pacing-enabled leadless pacemaker and subcutaneous implantable cardioverter-defibrillator system: A comprehensive preclinical study.

Background: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) and leadless pacemakers (LPs) are intended to diminish transvenous lead-related complications. However, S-ICDs do not deliver antibradycardia pacing or antitachycardia pacing, and currently, there is no commercially available coordinated leadless option for patients with defibrillator and (expected) pacing needs.

Objective: We evaluated the performance, safety, and potential replacement strategies of a novel modular cardiac rhythm management (mCRM) system, a wirelessly communicating antitachycardia pacing-enabled LP and S-ICD in a preclinical model.

Time-Averaged Wavefront Analysis Demonstrates Preferential Pathways of Atrial Fibrillation, Predicting Pulmonary Vein Isolation Acute Response.

Electrical activation during atrial fibrillation (AF) appears chaotic and disorganised, which impedes characterisation of the underlying substrate and treatment planning. While globally chaotic, there may be local preferential activation pathways that represent potential ablation targets. This study aimed to identify preferential activation pathways during AF and predict the acute ablation response when these are targeted by pulmonary vein isolation (PVI).

Local impedance-guided radiofrequency ablation with standard and high power: Results of a preclinical investigation.

Background: Local impedance (LI) drop measured with microfidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15-30 Ω LI drops created successful lesions, while more than 40 Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI-guided ablation using standard (30 W) and high-power (50 W) in a preclinical model.

Unraveling the Underlying Arrhythmia Mechanism in Persistent Atrial Fibrillation: Results From the STARLIGHT Study.

Background: The mechanisms that initiate and sustain persistent atrial fibrillation are not well characterized. Ablation results remain significantly worse than in paroxysmal atrial fibrillation in which the mechanism is better understood and subsequent targeted therapy has been developed. The aim of this study was to characterize and quantify patterns of activation during atrial fibrillation using contact mapping.

Acute and 3-Month Performance of a Communicating Leadless Antitachycardia Pacemaker and Subcutaneous Implantable Defibrillator.

Objectives: The primary objective was to assess the acute and 3-month performance of the modular antitachycardia pacing (ATP)-enabled leadless pacemaker (LP) and subcutaneous implantable cardioverter-defibrillator (S-ICD) system, particularly device-device communication and ATP delivery.

Background: Transvenous pacemakers and implantable cardioverter-defibrillators (ICDs) have considerable rates of lead complications. We examined the next step in multicomponent leadless cardiac rhythm management: feasibility of pacing (including ATP) by a LP, commanded by an implanted S-ICD through wireless, intrabody, device-device communication.

Novel Measure of Local Impedance Predicts Catheter-Tissue Contact and Lesion Formation.

Background: Coupling between the ablation catheter and myocardium is critical to resistively heat tissue with radiofrequency ablation. The objective of this study was to evaluate whether a novel local impedance (LI) measurement on an ablation catheter identifies catheter-tissue coupling and is predictive of lesion formation.

Methods And Results: LI was studied in explanted hearts (n=10 swine) and in vivo (n=10; 50-70 kg swine) using an investigational electroanatomic mapping system that measures impedance from an ablation catheter with mini-electrodes incorporated in the distal electrode (Rhythmia and IntellaNav MiFi OI, Boston Scientific).

Practical Considerations of Mapping Persistent Atrial Fibrillation With Whole-Chamber Basket Catheters.

Objectives: This study sought to evaluate basket catheter deployment, catheter-tissue contact, and time-space stability of unipolar atrial electrograms (aEGMs) recorded in persistent atrial fibrillation (AF) patients.

Background: Panoramic mapping of human AF using multiple-electrode basket catheters may identify AF sources. Although clinical results using this technique are provocative, questions remain about its effectiveness.

Ventricular preexcitation modulates strain and attenuates cardiac remodeling in a swine model of myocardial infarction.

Background: Myocardial infarction modifies the distribution of stress within the heart, increasing wall stress in ischemic and surrounding tissue, which often leads to adverse left ventricular remodeling. Electrical preexcitation pacing with appropriate timing of high-stress regions can reduce local strain and may attenuate global remodeling.

Methods And Results: Myocardial infarction was induced in 24 swine to study the short-term (n=12) and long-term (n=12) effects of therapy.

Long-term caspase inhibition ameliorates apoptosis, reduces myocardial troponin-I cleavage, protects left ventricular function, and attenuates remodeling in rats with myocardial infarction.

Objectives: This study was designed to evaluate whether in vivo caspase inhibition can prevent myocardial contractile protein degradation, improve myocardial function, and attenuate ventricular remodeling.

Background: Apoptosis is thought to play an important role in the development and progression of heart failure (HF) after a myocardial infarction (MI). However, it is not known whether inhibiting apoptosis can attenuate left ventricular (LV) remodeling and minimize systolic dysfunction.