1,720,974 research outputs found
Feasibility of a left atrial electrical disconnection procedure for atrial fibrillation using transcatheter radiofrequency ablation
No full textINTRODUCTION:
Transcatheter Left Atrial Electrical Disconnection. An effective, catheter-based treatment for persistent atrial fibrillation (AF) remains elusive. This study assessed the feasibility of transcatheter left atrial (LA) electrical disconnection and its effect on AF inducibility. METHOD AND RESULTS:
Thirteen anesthetized swine underwent noncontact mapping of the right atrium (RA) during coronary sinus (CS) pacing. Sites of earliest RA activation were identified using isopotential maps. An ablation catheter was navigated to these sites and a cluster of radiofrequency (RF) lesions applied until earliest activation shifted to a new site. The procedure was repeated until the atria were electrically disconnected. AF induction was attempted before and after ablation. Earliest RA activation was the CS os during proximal CS pacing and Bachmann's bundle during distal CS pacing. These two sites were successfully ablated in all 13 animals. Earliest activation then shifted to the fossa ovalis. RF energy was applied at a median of 2.5 sites (range 1 to 5) around the fossa, then at sites in the triangle of Koch, septum, cavotricuspid isthmus, and posterior wall. Atrial electrical disconnection was achieved in 10 of 13 animals (5 LA electrical disconnection, 3 RA electrical disconnection, 2 biatrial electrical disconnection with complete heart block). After atrial electrical disconnection, the LA became electrically silent. Before ablation, AF was inducible in every animal. After atrial electrical disconnection, AF was inducible in 3 of 10 animals. CONCLUSION:
Atrial electrical disconnection is feasible using noncontact mapping and RF ablation. Successful electrical disconnection of the atria reduces AF inducibility. This approach is worthy of further evaluation as a management strategy for persistent AF, combined with device therapies
Evaluation of body weight as a predictive factor for transvenous ventricular defibrillation characteristics
No full textAimsTo investigate the correlation between body weight and defibrillation threshold (DFT) for transvenous lead systems using a porcine model.Methods and resultsTwenty-eight pigs were anaesthetised and DFTs assessed in single and dual coil configurations using a four-reversal binary search method. DFT was correlated with body weight in the RV ? Can and RV ? SVC + Can configurations. A Pearson correlation coefficient and a two-sided p-value were calculated. A positive correlation exists between body weight and DFT in RV ? Can (, ) and RV ? SVC + Can (, ).ConclusionThere is a significant correlation between body weight and DFT in swine. This tends to be greater in the two-electrode than in the three-electrode configuration. With these and previous human observations, one may predict a higher DFT in heavy individuals and make appropriate procedural adjustments
Implantable loop recorders detect tachyarrhythmias in symptomatic patients with negative electrophysiological studies
No full textBACKGROUND: Implantable loop recorders (ILR) are a valuable tool in the investigation of syncope and compare favourably with non-invasive and intracardiac electrophysiological assessment of bradycardia. They are known to detect tachyarrhythmias but have not been shown to add to the diagnostic yield of electrophysiological testing in symptomatic patients. METHODS: We prospectively studied the first 41 patients (aged 48+/-19 years) in whom ILR were used at our institution after negative electrophysiological studies (EPS). All patients were symptomatic with palpitations (11), syncope (22) or both (8). Nine patients had known structural heart disease (two ischaemic, four cardiomyopathy, two valvular and one congenital). Patients were assessed according to demographic factors, symptoms and investigations. Loop recordings were analysed and assessed according to conventional criteria. RESULTS: Among 41 patients in whom electrophysiological studies had failed to demonstrate arrhythmias, six were found to have clinically significant tachyarrhythmias (four ventricular and two supraventricular). CONCLUSION: ILR diagnose prognostically significant tachyarrhythmias in symptomatic patients with negative electrophysiological studies
Letter to the Editor. Percutaneous coronary venous stenting to facilitate placement of a left ventricular lead
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Case series of sudden cardiac death
No full textObjective: The objective of this study was to establish whether Sudden Cardiac Death (SCD) victims could have been identified prior to their event and potentially considered for an implantable cardioverter defibrillator (ICD) on the basis of previous cardiac history recorded within healthcare records.Methods: A case series of SCD in the UK (Southampton). Consecutive cases of adult SCDs presumed to be primarily caused by a ventricular arrhythmia as determined by an experienced pathologist with special interest in heart disease were identified over a 12-month period. SCD cases with clear evidence of acute myocardial infarction or coronary thrombosis were excluded from this study. Data were extracted from pathology and police reports. Hospital and GP notes provided information on previous symptoms, investigations and cardiac disease history. Two experts (Consultant Cardiologists, Electrophysiologists) judged the appropriateness of each case against pre-defined criteria.Results: 975 Coroner’s post-mortems were undertaken, 366 of these cases were SCDs (38%). There was no clinical/pathological evidence of an acute myocardial infarction or thrombus in 232 of these cases (63% of all SCDs). Two hundred and fifteen of these cases lived within the catchment area and were included in this study. Sixty-four percent of cases were male and median age was 75 years. Thirty-seven percent of events were witnessed. Agreement between experts on appropriateness for an ICD was very good (kappa score of 0.64). One case (<1%) was considered appropriate for an ICD. Forty-one percent of cases had no evidence of confirmed or suspected heart disease. Fifty-eight percent of cases were considered to have required further cardiac investigations to determine appropriateness.Conclusion: Two fifths of SCD victims had no recorded health service contact in relation to cardiac abnormalities or possible arrhythmia symptoms within their lifetime. A large number of patients suffered previous cardiac events or symptoms suggestive of a ventricular arrhythmia but were not referred for further investigations
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