1,721,077 research outputs found
Cardiac resynchronization therapy during rest and exercise: comparison of two optimization methods.
No full textOptimal exercise programming of cardiac resynchronization therapy (CRT) devices is unknown. We aimed to: (i) investigate variations in optimal atrioventricular (AV) and interventricular (VV) delays from rest to exercise, assessed by both echocardiography and an automated intracardiac electrogram (IEGM) method; (ii) evaluate the acute haemodynamic impact of CRT optimization performed during exercise
Effects of cardiac resynchronization therapy on myocardial contractile reserve during exercise.
No full textAimsMyocardial contractile reserve (MCR) is a marker of myocardial viability. The impact of cardiac resynchronization therapy (CRT) on MCR during exercise has been little studied. Our aim was to investigate the effects of CRT on global and regional MCR by exercise echocardiography.Methods and resultsTwenty-seven CRT responders (56 ischaemic) were assessed by echocardiography during rest and bicycle exercise. Images were acquired during spontaneous rhythm ('off) and active CRT ('on). Global MCR was expressed as the change (Δ) in left ventricular ejection fraction (LVEF) and aortic velocity-time integral (VTI) from rest to exercise. Regional MCR was expressed as the change in peak systolic tissue velocity (Sm) of the septum and lateral wall. Left ventricular ejection fraction and aortic VTI increased at 'on during rest and exercise, and the increase in global MCR during exercise was higher during 'on than 'off (Δ LVEF 6 ± 6 vs. 3 ± 3; P 0.009). Septum Sm increased during 'on at rest, and it was still higher during exercise (P≤ 0.01), although the absolute change from rest to exercise was similar during 'on and 'off. Lateral wall Sm did not change at rest during 'on, but basal lateral wall MCR during exercise was higher at 'on than 'off (P 0.036).ConclusionIn CRT responders, there is a pacing-dependent increase in global MCR during exercise. The changes in regional MCR of the septum and lateral wall show different patterns. These factors may help to understand the determinants of improved exercise tolerance in CRT responder
Changes in global longitudinal strain during rest and exercise in patients treated with cardiac resynchronization therapy.
No full textRelatively few data have been reported on prospective changes in global longitudinal strain (GLS) following cardiac resynchronization therapy (CRT), and none are available on GLS during physical exercise. We investigated the effects of CRT on GLS, assessed by speckle tracking two-dimensional (2D) echocardiography, at rest and during exercise after a mid-term follow-up. Twenty consecutive CRT patients (45% ischaemic) were assessed prospectively by speckle tracking 2D echocardiography before implant (at rest) and at mid-term follow-up (during rest and bicycle exercise). GLS, septum and lateral wall longitudinal strain, left ventricular ejection fraction (LVEF), and conventional functional variables were evaluated at baseline and follow-up. All patients completed the study protocol at rest. Exercise images were available in 90% of the patients. At follow-up, GLS improved at rest from -7·1 ± 2·6% to -9·1 ± 4·5% (P<0·01), with a further increase to -11 ± 5·1% during exercise (P<0·001). Longitudinal strain increased at rest both in the septum and in the lateral wall, with an additional increase during exercise in the lateral wall (P<0·05). GLS correlated with LVEF both at rest (r = -0·55 and r = -0·91 at baseline and 3 months, respectively; P<0·05) and during exercise (r = -0·89, P<0·05). Improvement in GLS during rest and exercise can be observed in CRT patients at mid-term follow-up and seems to correlate with changes in LVEF. GLS may be a valuable method to assess left ventricular function during rest and exercise
Short QT syndrome and arrhythmogenic cardiac diseases in the young: the challenge of implantable cardioverter-defibrillator therapy for children.
No full textnot availabl
Automatic verification of ventricular stimulation: fusion management algorithm
No full textVentricular stimulation with automatic control and back-up pulse warrants maximum safety for the patient and increases device longevity. Fusion phenomenon may hinder evoked response (ER) detection and cause unnecessary back-up stimulation. We evaluated an automatic fusion beat management algorithm and its relationship with atrioventricular (AV) interval programming in a DDD/R pacemaker
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
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