1,720,971 research outputs found
Right ventricular outflow tract pacing: an alternative, safe, and effective pacing site
No full textThe right ventricular apex (RVA) has traditionally been preferred for the insertion of permanent cardiac pacemaker leads because of vast experience with their use, their ease of implantation, and the stability of passive fixation leads in the RVA trabeculae. However, prolonged RVA pacing is associated with progressive left ventricular dysfunction due to dysynchronous ventricular activation, and often results in substantial functional, hemodynamic, electrical, and structural changes, as previously demonstrated in many studies. Only in recent years has interest in the use of alternate pacing sites developed. The right ventricular outflow tract (RVOT) is now the preferred site of pacing because of potential advantages such as ease of application, better hemodynamics, synchronous activation, fewer myocardial perfusion defects, and a narrower QRS complex compared with RVA pacing. This review article comprehensively discusses this novel technique in terms of its beneficial effects, long-term safety, and performance measures compared with RVA pacing, and as an alternative method for biventricular pacing
The Impact of Precordial ECG Lead Positions and Leaning Forward in Unmasking J-wave Patterns
No full textPrevalence of Brugada-type electrocardiogram pattern by recording right precordial leads at higher intercostal spaces
No full textRecording electrocardiograms (ECGs) by placing the right precordial leads at higher intercostal spaces (ICSs) increases the sensitivity for detecting Brugada-type ECG pattern (BTEP). Published studies unfortunately used standard lead positions for recording ECGs and underestimated the true prevalence of BTEP. Therefore, by placing right precordial leads at higher ICS, we aimed to find out the true prevalence of BTEP in our population. Healthy male volunteers (n 504) between 18 and 55 years of age (37.3 10.7 years) without known cardiac or metabolic disorders were enrolled into the study. After the standard ECG recording, two other recordings were obtained by placing the right precordial leads to the third and second ICS. Electrocardiograms were stratified by two independent reviewers for the presence of BTEP. There were 15 subjects (3) who displayed BTEP on their standard ECG recordings. Number of cases displaying BTEP increased to 25 (5) and 38 (7.5) when the right precordial leads were moved to third and second ICS, respectively. Although none of the subjects displayed type 1 BTEP on their standard ECGs, three subjects displayed type 1 BTEP on the third and four subjects displayed type 1 BTEP on the second ICS. Our study revealed that the prevalence of BTEP in healthy male subjects was 7.5 by placing the right precordial leads to higher ICS. Instead of standard lead locations that are not sensitive enough for detection of BTEP we recommend high right ICS recording in further prevalence studies
Increase in QRS amplitudes is better than N-terminal pro-B-type natriuretic peptide to predict clinical improvement in decompensated heart failure
No full textBackground: We aimed to investigate the correlation between ECG QRS voltage changes, N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and clinical improvement in decompensated heart failure (DHF). Methods and results: DHF patients (n = 56) with a mean age of 67.5 +/- 12.6 years showed limb QRS amplitude increase and NT-proBNP level decrease with clinical improvement (p < 0.001). Significant correlation was found between percent changes (Delta%) in body weight and Delta% in QRS voltages of aVR, aVF, DII, Sigma QRSI + II and Sigma QRS (all limb-leads) (r = -0.40; r = -0.35; r = -0.32; r = -0.30; r = -0.30 respectively, p < 0.05). No correlation was found between Delta% in NT-proBNP and body weight (r = -0.23, p = 0.09). Delta% NT-proBNP was correlated with Delta% QRS voltage only in aVR (r = -0.312, p = 0.019). In ROC analysis, >= 0.5 mm increase in aVR QRS Voltage was found to predict >= 5 kg weight loss with a sensitivity of 74% and specificity of 62% (p = 0.013, AUC: 0.699). Conclusions: Increase in QRS voltages especially in aVR was found to be more sensitive than NT-proBNP to predict clinical improvement in DHF. (C) 2014 Elsevier Inc. All rights reserved
Pulmonary vasoreactivity testing in diagnosis and prognosis of pulmonary hypertension
No full textRight heart catheterization (RHC) is required for confirmation of the diagnosis of pulmonary hypertension (PH) and to asses the prognosis and etiology. Pulmonary vasoreactivity testing (PVT) is one of the most crucial parts of RHC especially in the suitable patient subsets of pulmonary arterial hypertension (PAH) defined by the most recent guidelines. PVT has substantial importance in defining the most appropriate treatment modality. The aim of this review is to provide a comprehensive review of the literature about PVT and the agents used in PVT, to emphasize the importance of this procedure when done with correct indications with a correct technique and to contribute in the accurate management of PH patients. (Anadolu Kardiyol Derg 2010; 10: Suppl 1; 43-9
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
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