Physiology of slow pathway conduction during sinus rhythm: evidence from high density mapping within the triangle of Koch.

Purpose: To evaluate nature of AV nodal activation in patients with AVNRT using high density electro-anatomic mapping (HD-EAM).

Methods: HD-EAM was created in 30 patients with AVNRT from the triangle of Koch (ToK) in sinus rhythm (SR). Isochronal late activation maps (ILAM) were created.

Utility of high resolution mapping to guide ablation of ventricular arrhythmias from the aortic sinuses of Valsalva.

Purpose: Left ventricular outflow tract (LVOT) arrhythmias are commonly targeted from the aortic sinuses of Valsalva (SOV). Both presystolic potentials during ventricular arrhythmia (VA) and late diastolic potentials during sinus rhythm have been recognized as markers of successful ablation sites. The study aimed to evaluate the utility of high resolution mapping (HRM) with small and closely spaced electrodes for guiding ablation of VA from the SOV.

Coronary Spasm and Polymorphic Ventricular Tachycardia One Year After Takotsubo.

Stress cardiomyopathy is typically considered to be a disease with a favorable long-term prognosis, with malignant arrhythmias accompanying only the acute phase. We describe a 51-year-old female who presented with palpitations one year after stress cardiomyopathy and complete recovery of apical left ventricular wall motion. Coronary spasm was strongly suspected based on transient ST-segment elevations followed by sustained polymorphic ventricular tachycardia captured on ambulatory Holter.

Air Entrapment Causing Inappropriate Shock From a Subcutaneous Implantable Cardioverter Defibrillator.

Subcutaneous implantable cardioverter defibrillator (S-ICD) is an accepted alternative to conventional transvenous devices. Their efficacy in arrhythmia management is comparable to ICDs. However, those devices also have limitations such as lack of anti-tachycardia pacing capability or higher occurrence of device oversensing associated with inappropriate shocks.

"2 for 1 Phenomenon" on Implantable Cardioverter Defibrillator Intracardiac Tracing.

"2 for 1 phenomenon" is simultaneous anterograde conduction over the fast and slow pathways of the atrioventricular (AV) nodal pathway, leading to a double ventricular response from each atrial beat. This phenomenon can initiate AV nodal reentrant tachycardia (AVNRT). The unique induction of AVNRT was observed in a patient with an implantable cardioverter defibrillator in our case.

Device therapy in the setting of long QT syndrome.

Congenital long QT syndrome (LQTS) is an inherited disorder of myocardial repolarization characterized by prolongation of the QT interval associated with life-threatening polymorphic ventricular tachycardia. The treatment of congenital LQTS involves antiadrenergic therapies: β-blockers and surgical left cardiac sympathetic denervation (LCSD) to decrease sympathetic input to the heart, cardiac pacing, and implantable cardioverter-defibrillator (ICDs). Although this article focuses on the role of device therapy for the treatment of LQTS, it also discusses the role of β-blockers and LCSD because they are concomitant with device therapy.

Ibandronate and ventricular arrhythmia risk.

Introduction: Bisphosphonates, including ibandronate, are used in the prevention and treatment of osteoporosis.

Methods And Results: We report a case of suspected ibandronate-associated arrhythmia, following a single dose of ibandronate in a 55-year-old female. ECG at presentation revealed frequent ectopy and QT/QTc interval prolongation; at follow-up 9 months later the QT/QTc intervals were normalized.

QTc compared to JTc for monitoring drug-induced repolarization changes in the setting of ventricular pacing.

Background: QT prolongation is a risk factor for proarrhythmia when beginning antiarrhythmic drug therapy (AAD). However, there are no data regarding monitoring repolarization changes during a ventricular paced (VP) rhythm.

Objective: The purpose of this study was to compare serial changes in corrected QT and JT intervals, during native conduction (NC) and VP rhythms when initiating Class III AADs.

Impact of international normalized ratio and activated clotting time on unfractionated heparin dosing during ablation of atrial fibrillation.

Background: For ablation of atrial fibrillation, it is unclear how baseline international normalized ratio (INR) affects the dosing of unfractionated heparin (UFH).

Methods And Results: A retrospective review of 170 consecutive patients undergoing atrial fibrillation ablation with baseline activated clotting time (ACT) and INR values was performed. Patients were grouped according to INR <2.

A rare case of permanent junctional reciprocating tachycardia ablated on the roof of the left atrium.

Left-sided anteroseptal accessory pathways that course through the aortomitral fibrous continuity are some of the rarest types of accessory pathways. At this region the atrium and ventricle are separated by their greatest distance because of the intervening aortic valve. These pathways often have a long circuitous course that may involve the root and cusps of the aortic valve.

The Management of Vasovagal Syncope in a Patient with Brugada Syndrome.

Vasovagal syncope is the most common cause of the neurally mediated reflex syncopes. A higher susceptibility to vasovagal syncope has been reported in patients with Brugada syndrome (BrS) and may be caused by associated autonomic dysfunction. It is unclear what risk vasovagal syncope confers to patients with BrS.

Management of sudden cardiac death risk in the very early postmyocardial infarction period.

Purpose Of Review: The purpose of this review is to summarize the numerous recent studies assessing the strategies to manage the increased risk of sudden cardiac death (SCD) early after a myocardial infarction (MI).

Recent Findings: Early after a MI, the risk of SCD is high. Several trials have been completed in attempt to identify and treat patients at increased risk for SCD early post-MI.

Cardiac potassium channel dysfunction in sudden infant death syndrome.

Life-threatening arrhythmias have been suspected as one cause of the sudden infant death syndrome (SIDS), and this hypothesis is supported by the observation that mutations in arrhythmia susceptibility genes occur in 5-10% of cases. However, the functional consequences of cardiac potassium channel gene mutations associated with SIDS and how these alleles might mechanistically predispose to sudden death are unknown. To address these questions, we studied four missense KCNH2 (encoding HERG) variants, one compound KCNH2 genotype, and a missense KCNQ1 mutation all previously identified in Norwegian SIDS cases.

Prevalence of long-QT syndrome gene variants in sudden infant death syndrome.

Background: The hypothesis that some cases of sudden infant death syndrome (SIDS) could be caused by long-QT syndrome (LQTS) has been supported by molecular studies. However, there are inadequate data regarding the true prevalence of mutations in arrhythmia-susceptibility genes among SIDS cases. Given the importance and potential implications of these observations, we performed a study to more accurately quantify the contribution to SIDS of LQTS gene mutations and rare variants.