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Nodo- and fasciculoventricular pathways: Electrophysiological features and a proposed diagnostic algorithm for preexcitation variants
Fasciculoventricular and nodoventricular pathways (FVP and NVP) are uncommon preexcitation variants that can be misleading during electrophysiology studies (EPSs), and differentiating them could be challenging.1–3 In this article, we describe 2 representative cases and then we present various electrophysiological features and phenomenon encountered in patients with these particular accessory pathways (APs).Pulmonary vein signal interpretation during cryoballoon ablation for atrial fibrillation
The recognition that paroxysmal atrial fibrillation (AF) is predominantly triggered by ectopic beats arising from the vicinity of pulmonary veins (PVs) has spurred the establishment of percutaneous procedures specifically designed to electrically sequestrate the arrhythmogenic PV from the vulnerable left atrium (LA) substrate.1 Recently, the procedure has evolved with the development of purpose-built pulmonary vein isolation (PVI) tools, such as the cryoballoon catheter. This article discusses the anatomic and electrophysiologic bases for the interpretation of pulmonary vein potentials (PVPs) using a small-caliber circular mapping catheter (CMC) and provides an expanded discussion on the pacing maneuvers relevant to cryoballoon-based PVI procedures.Prevention of phrenic nerve injury during interventional electrophysiologic procedures
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The advent of innovative, potent ablative technologies and the adoption of endo–epicardial approaches to treat various arrhythmias have engendered a need for developing strategies to prevent collateral damage to critical structures such as the phrenic nerve (PN) and the esophagus during percutaneous electrophysiologic interventions. Here we detail phrenic nerve injury (PNI) prevention strategies during atrial fibrillation (AF), atrial tachycardia (AT), and ventricular tachycardia (VT) ablation. PNI is more common on the right side because of the anatomic course of the nerve and the greater preponderance of AF and AT ablations.Safety and prevention of complications during percutaneous epicardial access for the ablation of cardiac arrhythmias
Since its introduction, percutaneous epicardial access is increasingly being performed to facilitate catheter ablation of ventricular tachycardias (VTs) with epicardial circuits, difficult cases of idiopathic VTs, focal atrial tachycardia, and accessory pathways that cannot be successfully targeted endocardially.1 A thorough understanding of the clinical anatomy and potential complications is vital in order to perform a safe procedure.2 In this article, we present the clinical anatomy related to epicardial access, the technique of performing a subxiphoid epicardial puncture, and various measures to prevent complications.A straightforward, reliable technique for retaining vascular access during lead replacement
During the removal or replacement of device leads, it is often desirable to retain vascular access, which removes any risk of complications from venous cannulation techniques. In this article, I describe a rapid, safe, and flexible technique for the replacement of a nonadherent device lead while preserving vascular access.Catheter ablation of atrial fibrillation originating from extrapulmonary vein areas: Taipei approach
The pulmonary veins (PVs) are a dominant source of ectopic activity initiating atrial fibrillation (AF).1,2 We and others have demonstrated that extra-PV ectopic activity could initiate AF, and elimination of ectopic activity can cure this specific group of patients with AF.3-6 The Bordeaux group demonstrated that extensive ablation of extra-PV areas after isolation of all four PVs can convert chronic AF to focal or macroreentrant atrial tachycardias, and further elimination of these atrial tachycardias could maintain sinus rhythm in approximately 90% of patients with chronic AF.How to perform ablation of the parasympathetic ganglia of the left atrium
Catheter ablation of atrial fibrillation (AF) has generally consisted of eliminating pulmonary vein (PV) triggers initiating AF1 or modifying the adjacent atrial substrate to isolate the PVs.2 Mapping and ablation of complex fractionated atrial electrograms, thought to be responsible for maintaining AF, also have been reported.3 However, all of these strategies likely are associated with varying degrees of denervation, as suggested by experimental,4 clinical, and systematic analysis of the effects of modification of autonomic tone on the outcome of AF ablation.How to manage the patient with a high defibrillation threshold
Defibrillation threshold (DFT) testing is an integral part of implantable cardioverter-defibrillator (ICD) placement and follow-up. Unfortunately, the DFT can vary widely from day to day, influenced by many factors including electrolytes, sympathetic tone, antiarrhythmic drugs, and other medications. For this reason, a 10-J safety margin between the lowest successful defibrillation energy during testing and the maximal device output has been widely adapted as standard practice.1How to perform noncontact mapping
The anatomic and electrophysiologic complexity of arrhythmias subject to evaluation and catheter-based therapy has increased over the past several years. Use of advanced mapping systems, capable of three-dimensional rendering of cardiac chambers and superimposition of electrical information, are not designed to replace conventional mapping techniques but to be used as an adjunctive tool in the analysis and treatment of complex arrhythmias. EnSite 3000 (Endocardial Solutions, Minneapolis, MN) was the first component of the EnSite mapping system capable of advanced electroanatomic evaluation through novel catheter design and capabilities.How to manage patients with inappropriate sinus tachycardia
The objective of this review is to provide an overview of current understanding of inappropriate sinus tachycardia, with a brief discussion on diagnosis, mechanisms, and therapy. I propose a broad and multidisciplinary management approach for the majority of patients with inappropriate sinus tachycardia.Locating focal atrial tachycardias from P-wave morphology
Atrial tachycardia (AT) foci tend to cluster at characteristic anatomic locations that can be gleaned from careful analysis of the P wave.Para-Hisian pacing: Useful clinical technique to differentiate retrograde conduction between accessory atrioventricular pathways and atrioventricular nodal pathways
Para-Hisian pacing is a useful tool to differentiate between retrograde conduction over an accessory pathway and retrograde conduction over the fast or slow atrioventricular (AV) nodal pathways.1–3 Para-Hisian pacing uses right ventricular (RV) pacing close to the His bundle or proximal right bundle branch (RBB). As the position of the ventricular pacing catheter changes subtly during respiration (or by changing pacing output), the pacing stimulus changes capture among (1) basal anteroseptal RV plus His bundle or proximal RBB (His bundle-RBB capture); (2) capture of basal anteroseptal RV alone; and (3) His bundle-RBB capture alone.Determining inferior vena cava-tricuspid isthmus block after typical atrial flutter ablation
In typical atrial flutter, circular activation around the tricuspid ring is possible because the terminal crest prevents short-circuiting on the posterior wall, and the myocardium between the inferior vena cava (IVC) and the lower rim of the tricuspid ring is the obligatory pathway to close the circuit in the low right atrium (RA) (Figure 1). This IVC-tricuspid ring isthmus (cavotricuspid isthmus) has become the preferred target for ablation because it is the narrowest point of the circuit, it is easily accessible, and it is located far from the AV junction.
