Box Lesion Isolation of the Left Atrial Posterior Wall with Radiofrequency Ablation Restricted in Predetermined Lines for the Treatment of Persistent Atrial Fibrillation: The Prognostic Role of Acute Interventional Outcome and Trigger Identification.

The left atrial posterior wall (PW) is known to be a critical substrate for the initiation and perpetuation of atrial fibrillation (AF) and has been explored as a target for catheter ablation, particularly in persistent AF (PerAF). In this retrospective study, we investigate the clinical outcome of patients with PerAF who underwent PW isolation (PWI) restricted in predetermined lines in addition to pulmonary vein isolation (PVI). One hundred consecutive patients (64 ± 9.1 years, 66% male, 20% with previous PVI ablation) underwent PWI in a box lesion setting for PerAF lasting >3 months (34% long-standing PerAF). PW triggers were defined as either foci from the PW that repeatedly induced AF or as isolated AF or atrial tachycardia (AT) within the PW. After a mean follow-up period of 25.6 ± 6.7 months, 61% of the patients remained in sinus rhythm after the last procedure. In 79 patients, the PW was successfully isolated, while, in 21 patients, complete isolation was not possible due to failure in completion of the roof line (n = 16), the floor line (n = 7), or both (n = 2). Patients with incomplete isolation had similar AF/AT recurrence rates compared to those with complete PWI. In 12 patients, PW triggers were identified, and PWI in these patients was shown to have a significantly better prognosis in terms of sinus rhythm maintenance (P = .031). Failure of complete PWI does not predispose a patient to an inferior outcome nor is it responsible for iatrogenic ATs. The presence of AF triggers within the PW leads to a particularly favorable result after box lesion isolation.

The Electrophysiology of Atrial Fibrillation: From Basic Mechanisms to Catheter Ablation.

The electrophysiology of atrial fibrillation (AF) has always been a deep mystery in understanding this complex arrhythmia. The pathophysiological mechanisms of AF are complex and often remain unclear despite extensive research. Therefore, the implementation of basic science knowledge to clinical practice is challenging. After more than 20 years, pulmonary vein isolation (PVI) remains the cornerstone ablation strategy for maintaining the sinus rhythm (SR). However, there is no doubt that, in many cases, especially in persistent and long-standing persistent AF, PVI is not enough, and eventually, the restoration of SR occurs after additional intervention in the rest of the atrial myocardium. Substrate mapping is a modern challenge as it can reveal focal sources or rotational activities that may be responsible for maintaining AF. Whether these areas are actually the cause of the AF maintenance is unknown. If this really happens, then the targeted ablation may be the solution; otherwise, more rough techniques such as atrial compartmentalization may prove to be more effective. In this article, we attempt a broad review of the known pathophysiological mechanisms of AF, and we present the recent efforts of advanced technology initially to reveal the electrical impulse during AF and then to intervene effectively with ablation.

Incidence, electrophysiological characteristics, and long-term follow-up of perimitral atrial flutter in patients with previously confirmed mitral isthmus block.

INTRODUCTION: After mitral isthmus (ΜΙ) catheter ablation, perimitral atrial flutter (PMF) circuits can be maintained due to the preservation of residual myocardial connections, even if conventional pacing criteria for complete MI block are apparently met (MI pseudo-block). We aimed to study the incidence, the electrophysiological characteristics, and the long-term outcome of these patients. METHODS: Seventy-two consecutive patients (mean age 62.4 ± 10.2, 62.5% male) underwent MI ablation, either as part of an atrial fibrillation (AF) ablation strategy (n = 35), or to treat clinical reentrant atrial tachycardia (AT) (n = 32), or to treat AT that occurred during ablation for AF (n = 5). Ιn all patients, the electrophysiological characteristics of PMF circuits were studied by high-density mapping. RESULTS: Mitral isthmus block was successfully achieved in 69/72 patients (95.6%). Five patients developed PMF after confirming MI block. In these patients, high-density mapping during the PMF showed a breakthrough in MI with extremely low impulse conduction velocity (CV). In contrast, in usual PMF circuits that occurred after AF ablation, the lowest CV of the reentrant circuit was of significantly higher value (0.07 ± 0.02 m/s vs 0.25 ± 0.07 m/s, respectively; P < .001). Patients presented with clinical AT had better prognosis in maintaining sinus rhythm after MI ablation compared with patients presented with AF. CONCLUSION: Perimitral atrial flutter with MI pseudo-block may be present after MI ablation and has specific electrophysiological features characterized by remarkably slow CV in the MI. Thus, even after MI block is achieved, a more detailed mapping in the boundaries of the ablation line or reinduction attempts may be needed to exclude residual conduction.

Ventricular ectopy from the non-coronary cusp: Pathophysiological and anatomical considerations.

Non-coronary cusp (NCC) is a rare site for ventricular arrhythmias because it does not come into direct contact with the ventricular myocardium. Instead, the NCC comes in contact with the membranous septum near the His region. We describe a case of a young man with a ventricular ectopy who was successfully ablated in the NCC. In our case the much greater prematurity in the NCC than in the His region suggests that the arrhythmic site of origin is not in the peri-His area but most likely a myocardial extension adjoining the aortic root.

Safety of smartwatches and their chargers in patients with cardiac implantable electronic devices.

AIMS: Cardiac implantable electronic devices (CIEDs) are susceptible to electromagnetic interference (EMI). Smartwatches and their chargers could be a possible source of EMI. We sought to assess whether the latest generation smartwatches and their chargers interfere with proper CIED function. METHODS AND RESULTS: We included consecutive CIED recipients in two centres. We tested two latest generation smartwatches (Apple Watch and Samsung Galaxy Watch) and their charging cables for potential EMI. The testing was performed under continuous electrocardiogram recording and real-time device telemetry, with nominal and 'worst-case' settings. In vitro magnetic field measurements were performed to assess the emissions from the tested devices, initially in contact with the probe and then at a distance of 10 cm and 20 cm. In total, 171 patients with CIEDs (71.3% pacemakers-28.7% implantable cardioverter-defibrillators) from five manufacturers were enrolled (63.2% males, 74.8 ± 11.4 years), resulting in 684 EMI tests. No EMI was identified in any patient either under nominal or 'worst-case scenario' programming. The peak magnetic flux density emitted by the smartwatches was similar to the background noise level (0.81 µT) even when in contact with the measuring probe. The respective values for the chargers were 4.696 µΤ and 4.299 µΤ for the Samsung and Apple chargers, respectively, which fell at the background noise level when placed at 20 cm and 10 cm, respectively. CONCLUSION: Two latest generation smartwatches and their chargers resulted in no EMI in CIED recipients. The absence of EMI in conjunction with the extremely low intensity of magnetic fields emitted by these devices support the safety of their use by CIED patients.

Regular tachycardia terminated by ventricular anti-tachycardia pacing in an ICD recipient. What is the mechanism?

This is the case of a misdiagnosed atrioventricular nodal reentry tachycardia (AVNRT) with occasionally 2:1 atrioventricular block terminated by delivery of an inappropriate ventricular antitachycardia pacing scheme, in an ICD recipient. The detailed analysis of stored electrograms facilitated the revelation of the arrhythmic mechanism.

Does a bed rail system of alcohol-based handrub antiseptic improve compliance of health care workers with hand hygiene? Results from a pilot study.

BACKGROUND: Hand hygiene is the cornerstone of prevention of nosocomial infections and a challenge for infection-control teams. METHODS: Bed-rail dispensers of alcohol-based hand rub antiseptic (AHRA) were first initiated only in department A (period I), followed by department B (period II). Opportunities for hand hygiene (OHH) were recorded during periods I, II, and III (post-trial follow-up). Only application of AHRA before and after contacting each patient was considered as appropriate. Comparative evaluation between periods I and II, as well as II and III, was performed. Predictors of AHRA compliance were also assessed by regression analysis. RESULTS: HCWs' compliance was improved after the initiation of the bed-rail approach in department B (51.5%, vs 36.4% P = .005). In department A, where this system already existed, no changes were observed. The bed-rail AHRA system (P = .007 [OR 1.8(1.2-3.0)]) and nurses (P < .0001[OR 5.6 (3.1-9.9)]) were predictors of hand hygiene in department B. HCWs' compliance declined in department B (26.5% vs 51.5%, P < .0001) and department A (27.5% vs 35.9%, P = .1) during period III. CONCLUSIONS: The bed-rail approach initially improved HCWs' compliance with AHRA but did not radically influence behavior in internal medicine settings. Multidisciplinary strategies are required to establish hand hygiene recommendations.

Irregular ventricular tachycardia underdetected by implantable cardioverter defibrillator device.

A case of sustained monomorphic ventricular tachycardia underdetected by a single chamber implantable cardioverter defibrillator because of RR interval irregularity is presented. The programmed stability criterion is responsible for the underdetection. Special attention must be paid when it comes to programming this detection parameter.