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Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical atrioventricular node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.

PURPOSE Inadequate anticoagulation among elderly individuals with atrial fibrillation (AF) is a common problem. This synthesis of the literature review describes the pathophysiology of AF, explains the mechanism of action of warfarin (Coumadin), identifies factors that contribute to warfarin (Coumadin)-associated bleeding in the elderly population, and explores alternatives to warfarin (Coumadin) therapy. Implications for advanced practice nurse practice, education, and research will be discussed. METHODS A literature search was conducted using Academic Search Premier, CINAHL Plus with Full Text, and Medline from 1999 to 2012. Search terms included warfarin (Coumadin), warfarin (Coumadin) genetics, diet, interactions, bleeding, atrial fibrillation, genetics, anticoagulation clinic, dabigatran, apixaban, rivaroxaban, and elderly. RESULTS The literature indicates that the potential bleeding risk associated with warfarin (Coumadin) therapy limits its use in the elderly population. However, some studies have found warfarin (Coumadin) to be more effective than aspirin in preventing stroke. The safety profiles of both medications were comparable; also, effective alternatives to warfarin (Coumadin) that do not require routine testing are now available. CONCLUSIONS Atrial fibrillation increases the probability of an embolic stroke, especially for the elderly population. Stroke risk and bleeding risk tools, in conjunction with patient preference, determine the best stroke prevention treatment. Anticoagulant clinics manage long-term warfarin (Coumadin) therapy effectively. Newer anticoagulants offer effective alternatives to warfarin (Coumadin) therapy.

A 53-year-old man with a dual-chamber implantable cardioverter-defibrillator presented to the electrophysiology (EP) lab for an EP study in evaluation of supraventricular tachycardia despite medical therapy. Fluoroscopic imaging during placement of diagnostic catheters demonstrated insulation failure with an externalized conductor on the right ventricular defibrillator lead just distal to the proximal defibrillator coil. Device interrogation revealed normal pacing, and shock impedances, normal sensing, and stable pacing thresholds.

Background— Although cardiac resynchronization therapy (CRT) can improve left ventricular ejection fraction (LVEF), it is not known whether a specific level of improvement will predict future implantable cardioverter defibrillator (ICD) therapy. Methods and Results— CRT-defibrillator (CRT-D) was implanted in 423 patients at 1 institution between October 2, 2001 and January 19, 2007. A retrospective analysis was performed to evaluate the relationship between post–CRT-D LVEF and ICD therapy for ventricular tachyarrhythmias. A landmark population of 270 patients, with post–CRT-D LVEF measured and no ICD therapy within 1 year of device implantation, was followed for subsequent outcomes. Of these, 22 patients (8.2%) had subsequent appropriate ICD therapy over a median follow-up of 1.5 years. The estimated 2-year risk of appropriate ICD therapy is 3.0% (95% confidence interval [95% CI], 0%–6.3%), 2.1% (95% CI, 0%–5.0%), and 1.5% (95% CI, 0%–3.9%) for post–CRT-D LVEF of 45%, 50%, and 55%, respectively. In patients with a primary prevention indication for CRT-D, the estimated 2-year risk is 3.3% (95% CI, 0%–7.3%), 2.5% (95% CI, 0%–6.1%), and 1.9% (95% CI, 0%–5.1%) for post–CRT-D LVEF of 45%, 50%, and 55%, respectively. Conclusions— When a CRT responder demonstrates near normalization in LVEF to ≥45%, the incidence of ICD therapy for ventricular arrhythmias becomes low. Future studies are needed to determine whether an ICD is still needed in some of these patients at the time of generator replacement.

Insulation Failure with Externalized Conductor A 53-year-old man with a dual-chamber implantable cardioverter-defibrillator presented to the electrophysiology (EP) lab for an EP study in evaluation of supraventricular tachycardia despite medical therapy. Fluoroscopic imaging during placement of diagnostic catheters demonstrated insulation failure with an externalized conductor on the right ventricular defibrillator lead just distal to the proximal defibrillator coil. Device interrogation revealed normal pacing, and shock impedances, normal sensing, and stable pacing thresholds.

Management of systemic right ventricular (RV) failure can be challenging. Anatomical abnormality due to congenital heart disease adds to the complexity when interventions are performed. We report a patient with acute systemic RV failure who was successfully managed with cardiac resynchronization therapy.