Douglas L. Packer

Mechanisms of phrenic nerve injury during radiofrequency ablation at the pulmonary vein orifice.

Background: The phrenic nerve can be injured with radiofrequency energy delivery. Nevertheless, the mechanisms of injury are unknown. This study was undertaken to examine phrenic nerve tissue temperatures during ablation at the pulmonary vein (PV) orifice, assess the temperature dependence of injury, and to delineate the possible mechanisms of untoward nerve effects.

A Systematical Analysis of In Vivo Contact Forces on Virtual Catheter Tip/Tissue Surface Contact during Cardiac Mapping and Intervention

Introduction: While catheter tip/tissue contact has been shown to be an important determinant of ablative lesions in in vitro studies, the impact of contact on the outcomes of mapping and ablation in the intact heart has not been evaluated.

Long-term outcome of atrial fibrillation ablation: Impact and predictors of very late recurrence

Long‐Term Outcome of AF Ablation. Introduction: Ablation eliminates atrial fibrillation (AF) in studies with 1 year follow‐up, but very late recurrences may compromise long‐term efficacy. In a large cohort, we sought to describe the determinants of delayed recurrence after AF ablation.

Outcomes After Cardiac Perforation During Radiofrequency Ablation of the Atrium

Background: Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter‐based radiofrequency ablation procedures in the left atrium.

Percutaneous epicardial left atrial appendage closure: preliminary results of an electrogram guided approach.

Background: Pharmacologic therapies to prevent stroke in atrial fibrillation (AF) have numerous limitations, prompting the development of device‐based therapies. We investigated whether an electrogram‐based approach using a novel hollow suture can safely capture and ligate the left atrial appendage (LAA).

Intra‐Atrial Conduction Block Along the Mitral Valve Annulus During Accessory Pathway Ablation: Evidence for a Left Atrial “Isthmus”

Left Atrial Isthmus. Introduction: We observed a change in the atrial activation sequence during radiofrequency (RF) energy application in patients undergoing left accessory pathway (AP) ablation. This occurred without damage to the AP and in the absence of a second AP or alternative arrhythmia mechanism. We hypothesized that block in a left atrial “isthmus” of tissue between the mitral annulus and a left inferior pulmonary vein was responsible for these findings.

Electrophysiological anatomy of typical atrial flutter: The posterior boundary and causes for difficulty with ablation

Electrophysiological Anatomy of Typical Atrial Flutter. Background: The electrophysiological anatomy of cavotricuspid isthmus‐dependent atrial flutter (CVTI‐AFL) has not been fully elucidated.

Distortion of right superior pulmonary vein anatomy by balloon catheters as a contributor to phrenic nerve injury

Introduction: Cryothermal, HIFU, and laser catheter‐based balloon technologies have been developed to simplify ablation for AF. Initial enthusiasm for their widespread use has been dampened by phrenic nerve (PN) injury. The interaction between PN and pulmonary vein (PV) geometry contributing to PN injury is unclear.

Mechanism of Tissue Heating During High Intensity Focused Ultrasound Pulmonary Vein Isolation: Implications for Atrial Fibrillation Ablation Efficacy and Phrenic Nerve Protection

Introduction: The purpose of this study was to examine tissue temperatures around pulmonary veins (PVs) during high intensity focused ultrasound (HIFU) balloon ablation for atrial fibrillation. The thermodynamics and extent of PV and phrenic nerve (PN) heating during HIFU ablation have not been established.

Synchronous Ventricular Pacing without Crossing the Tricuspid Valve or Entering the Coronary Sinus—Preliminary Results

Background: Right ventricular apical (RVA) pacing promotes tricuspid regurgitation (TR), electromechanical dyssynchrony, and ventricular dysfunction. We tested a novel intramyocardial bipolar lead to assess whether stimulation of the atrioventricular septum (AVS) produces synchronous ventricular activation without crossing the tricuspid valve (TV).