Bachmann's Bundle's Unique Physiology: Reviewing How it Made an Atypical Flutter Even More Atypical.

A 69-year-old man with a history of previous ablation and cardiac surgery was found on cardiac electrophysiology study to have a macro-re-entrant left atrial flutter initially misdiagnosed as a micro-re-entrant right atrial tachycardia resulting from the unique conduction properties of Bachmann's bundle. ().

Metabolic heterogeneous zone assessed by FDG-PET is predictive of postablation mortality in patients with ventricular tachycardia.

Purpose: We sought to study the predictive value of the metabolic heterogeneous zone (HZ) as determined by Fluorodeoxyglucose ( FDG) positron emission tomography (PET) viability studies in ventricular tachycardia (VT) patients.

Methods: PET studies utilizing Rubidium ( Rb) tracer for perfusion and FDG tracer for viability were analyzed using PMOD (PMOD Technologies) and further analyzed using 684-segment plots. FDG uptake was normalized to the area with maximal perfusion on the rest Rb study.

Metabolic Scar Assessment withF-FDG PET: Correlation to Ischemic Ventricular Tachycardia Substrate and Successful Ablation Sites.

The functional and molecular imaging characteristics of ischemic ventricular tachycardia (VT) substrate are incompletely understood. Our objective was to compare regional F-FDG PET tracer uptake with detailed electroanatomic maps (EAMs) in a more extensive series of postinfarction VT patients to define the metabolic properties of VT substrate and successful ablation sites. Three-dimensional (3D) metabolic left ventricular reconstructions were created from perfusion-normalized F-FDG PET images in consecutive patients undergoing VT ablation.

Dominant vector changes during early wavebreak/spiral wave (Wiggers stage 1) in ventricular fibrillation: insights from the analysis of 100 electrophysiology studies.

Purpose: To describe electrocardiographic vector patterns during early VF transition (Wiggers stage 1).

Methods: In 100 electrophysiology studies with VF induction, the first 3 beats of VF were analyzed in lead I for left/right axis (LA/RA), V1 for left/right bundle (LB/RB), and aVF for superior/inferior axis (SA/IA). Correlation with demographic/clinical factors was performed using regression analyses and mixed effect modeling.

Ventricular arrhythmia ablation lesions detectability and temporal changes on cardiac magnetic resonance.

Background: Cardiac magnetic resonance (CMR) characteristics of ventricular radiofrequency ablation (RFA) lesions have only been incompletely defined.

Aim: To determine the detectability and imaging characteristics of ventricular RFA lesions in an unselected patient cohort undergoing ventricular arrhythmia ablation.

Methods And Results: A retrospective chart review (n = 249) identified 36 patients with either pre-/postablation CMR (n = 14) or only postablation CMR (n = 22).

A Tale of 2 Hearts: Simultaneous Dual Tachycardias Occurring 22 Years After Orthotopic Heart Transplantation.

At 22 years following heart transplantation, a patient presented with incessant atrial flutter. During electrophysiologic study, 2 simultaneous atrial arrhythmias were mapped, 1 from the donor and 1 from the recipient's heart. High-density mapping allowed for rapid identification of electrically abnormal areas, which were successfully ablated, thus restoring sinus rhythm.

Ventricular Tachycardia (VT) Substrate Characteristics: Insights from Multimodality Structural and Functional Imaging of the VT Substrate Using Cardiac MRI Scar, I-Metaiodobenzylguanidine SPECT Innervation, and Bipolar Voltage.

Postischemic adaptation results in characteristic myocardial structural and functional changes in the ventricular tachycardia (VT) substrate. The aim of this study was to compare myocardial structural and functional adaptations (late gadolinium enhancement/abnormal innervation) with detailed VT mapping data to identify regional heterogeneities in postischemic changes. Fifteen patients with ischemic cardiomyopathy and drug-refractory VT underwent late gadolinium enhancement cardiac MRI (CMR), I-metaiodobenzylguanidine SPECT, and high-resolution bipolar voltage mapping to assess fibrosis (>3 SDs), abnormal innervation (<50% tracer uptake), and low-voltage area (<1.

Proof of concept study of a novel pacemapping algorithm as a basis to guide ablation of ventricular arrhythmias.

Aims: To determine if a software algorithm can use an individualized distance-morphology difference model, built from three initial pacemaps, to prospectively locate the exit site (ES) of ventricular arrhythmias (VA).

Methods And Results: Consecutive patients undergoing ablation of VA from a single centre were recruited. During mapping, three initial pacing points were collected in the chamber of interest and the navigation algorithm applied to predict the ES, which was corroborated by conventional mapping techniques.

Validation of a novel CARTOSEG™ segmentation module software for contrast-enhanced computed tomography-guided radiofrequency ablation in patients with atrial fibrillation.

Introduction: Visualization of left atrial (LA) anatomy using image integration modules has been associated with decreased radiation exposure and improved procedural outcome when used for guidance of pulmonary vein isolation (PVI) in atrial fibrillation (AF) ablation. We evaluated the CARTOSEG™ CT Segmentation Module (Biosense Webster, Inc.) that offers a new CT-specific semiautomatic reconstruction of the atrial endocardium.

Location, variations, and predictors of epicardial fat mapping using multidetector computed tomography to assist epicardial ventricular tachycardia ablation.

Background: A significant number of ventricular tachycardia circuits are located close to the epicardial surface and are amendable to epicardial ablation. Epicardial fat often interferes with substrate mapping and ablation, though little is known regarding the distribution of fat and its fluctuation with the cardiac cycle.

Methods: We studied 40 patients who underwent a 64-slice multidetector computed tomography in order to describe patterns of epicardial fat distribution, variation during cardiac cycle, and clinical predictors of epicardial fat.

Hibernating substrate of ventricular tachycardia: a three-dimensional metabolic and electro-anatomic assessment.

Purpose: Hibernating myocardium (HM) is associated with sudden cardiac death (SCD). Little is known about the electrophysiological properties of HM and the basis of its association with SCD. We aimed to electrophysiologically characterize HM in patients with ventricular tachycardia (VT).

Relationship Between Distance and Change in Surface ECG Morphology During Pacemapping as a Guide to Ablation of Ventricular Arrhythmias: Implications for the Spatial Resolution of Pacemapping.

Background: Pacemapping is used to localize the exit site of ventricular arrhythmia. Although the relationship between distance and change in QRS morphology is its basis, this relationship has not been systematically quantified.

Methods And Results: Patients (n=68) undergoing ventricular arrhythmia ablation between March 2012 and July 2013 were recruited.

Global and Regional Myocardial Innervation Before and After Ablation of Drug-Refractory Ventricular Tachycardia Assessed with 123I-MIBG.

Unlabelled: Cardiac innervation is a critical component of ventricular arrhythmogenesis that can be noninvasively assessed with (123)I-MIBG. However, the effect of ventricular tachycardia (VT) ablation on global and regional left ventricular sympathetic innervation and clinical outcomes has not been previously assessed.

Methods: In this prospective, single-center feasibility study, 13 patients with cardiomyopathy (n = 9 ischemic, n = 4 nonischemic) who were scheduled to undergo ablation of drug-refractory VT underwent 15-min and 4-h (123)I-MIBG scans before and 6 mo after the ablation procedure.

Three-dimensional 123I-meta-iodobenzylguanidine cardiac innervation maps to assess substrate and successful ablation sites for ventricular tachycardia: feasibility study for a novel paradigm of innervation imaging.

Background: Innervation is a critical component of arrhythmogenesis and may present an important trigger/substrate modifier not used in current ventricular tachycardia (VT) ablation strategies.

Methods And Results: Fifteen patients referred for ischemic VT ablation underwent preprocedural cardiac (123)I- meta-iodobenzylguanidine ((123)I-mIBG) imaging, which was used to create 3-dimensional (3D) innervation models and registered to high-density voltage maps. 3D (123)I-mIBG innervation maps demonstrated areas of complete denervation and (123)I-mIBG transition zone in all patients, which corresponded to 0% to 31% and 32% to 52% uptake.

Differences in quantitative assessment of myocardial scar and gray zone by LGE-CMR imaging using established gray zone protocols.

Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging is the gold standard for myocardial scar evaluation. Heterogeneous areas of scar ('gray zone'), may serve as arrhythmogenic substrate. Various gray zone protocols have been correlated to clinical outcomes and ventricular tachycardia channels.

Impact of ICD artifact burden on late gadolinium enhancement cardiac MR imaging in patients undergoing ventricular tachycardia ablation.

Background: Cardiac magnetic resonance imaging (CMRI) is the gold standard for myocardial scar evaluation. Although ideal for substrate assessment in ventricular tachycardia (VT), most patients have an implantable cardioverter-defibrillator (ICD) at presentation for ablation. This study evaluates the ICD artifact burden during standard late gadolinium enhancement CMRI (LGE-CMRI) evaluation of myocardial scar in VT patients with ICDs.

Safety of computed tomography in patients with cardiac rhythm management devices: assessment of the U.S. Food and Drug Administration advisory in clinical practice.

Objectives: To assess the safety of computed tomography (CT) imaging in patients with cardiac rhythm management (CRM) devices, which was subject to an advisory from the U.S. Food and Drug Administration (FDA) in 2008.

Prospective assessment of the CryoMaze procedure with continuous outpatient telemetry in 136 patients.

Background: Only 40% of patients with atrial fibrillation (AF) undergoing cardiac surgery are treated with surgical AF correction. We prospectively studied endocardial cryoablation of the Cox-maze III lesion set following prespecified rhythm assessment with outpatient telemetry.

Methods: Between 2007 and 2011, 136 patients underwent surgical AF correction using an argon-powered cryoablation device.

Cardiac sarcoidosis: electrophysiological outcomes on long-term follow-up and the role of the implantable cardioverter-defibrillator.

Objectives: The objectives of this study were to identify the predictors of life-threatening ventricular arrhythmias in patients with cardiac sarcoidosis (CS) and to evaluate the role of the implantable cardioverter-defibrillator (ICD) in this patient population.

Background: ICD implantation is a class IIA recommendation for patients with CS. However, some indications for ICD implantation in CS patients are still unclear and not enough data are available to establish predictors of malignant ventricular tachyarrhythmias in this group of patients.

Assessment of ventricular tachycardia scar substrate by intracardiac echocardiography.

Background: Intracardiac echocardiography (ICE) is increasingly used to guide complex ablation procedures. This study aimed to assess the scar substrate of ventricular tachycardia (VT) by ICE in patients undergoing VT ablation.

Methods: In 22 patients undergoing VT ablation (10 ischemic, 12 nonischemic), the Biosense CARTOSOUND module (Biosense Webster, Diamond Bar, CA, USA) was used for three-dimensional reconstruction of the ventricles.

A multicenter study of shock pathways for subcutaneous implantable defibrillators.

Introduction: A purely subcutaneous implantable cardioverter defibrillator (ICD) requires higher energy but may be an effective alternative to transvenous ICDs to deliver lifesaving therapies.

Objective: To identify combinations of anteroposterior subcutaneous shock pathways and waveforms with defibrillation efficacy comparable to transvenous ICDs.

Methods: Defibrillation testing was performed in 141 patients temporarily implanted with an active can emulator and subcutaneous coil electrodes.

Impact of fluoroscopy unit on the accuracy of a magnet-based electroanatomic mapping and navigation system: an in vitro and in vivo validation study.

Introduction: During mapping and ablation procedures, the movement of large ferromagnetic items (i.e., fluoroscopic equipment) introduce heterogeneities in the electromagnetic field, which may affect the accuracy of electromagnet-based navigation.