Interventional and Device-based Autonomic Modulation in Heart Failure

Heart failure is an increasingly prevalent disease with high mortality and public health burden. It is associated with autonomic imbalance characterized by sympathetic hyperactivity and parasympathetic hypoactivity. Evolving novel interventional and device-based therapy has sought to restore autonomic balance by neuromodulation. Results of preclinical animal studies and early clinical trials have demonstrated its safety and efficacy in heart failure. In this review article, we will discuss specific neuromodulatory treatment modalities individually—spinal cord stimulation, vagus nerve stimulation, baroreceptor activation therapy and renal sympathetic nerve denervation

Fast-slow asymptotic for semi-analytical ignition criteria in FitzHugh-Nagumo system

We study the problem of initiation of excitation waves in the FitzHugh-Nagumo model. Our approach follows earlier works and is based on the idea of approximating the boundary between basins of attraction of propagating waves and of the resting state as the stable manifold of a critical solution. Here, we obtain analytical expressions for the essential ingredients of the theory by singular perturbation using two small parameters, the separation of time scales of the activator and inhibitor, and the threshold in the activator's kinetics. This results in a closed analytical expression for the strength-duration curve.Comment: 10 pages, 5 figures, as accepted to Chaos on 2017/06/2

Double and triple sequential shocks reduce ventricular defibrillation threshold in dogs with and without myocardial infarction

The role of optimal placement of electrodes and mode of shock delivery from a defibrillator was examined in dogs with and without myocardial infarction. Single, double and triple truncated exponential shocks separated by 1 ms were delivered through various electrode combinations and cardiac vectors after electrical induction of ventricular fibrillation. A single shock through a pathway not incorporating the interventricular septum (catheter electrodes or epicardial patches between anterior and posterior left ventricle) required the highest total energy (22.6 and > 26.4 J, respectively) and peak voltage (1,004 and > 1,094 V, respectively) to terminate ventricular fibrillation. A single shock through a pathway including the interventricular septum required lower total energy and peak voltage to defibrillate.Combinations of two sequential shocks between an intracardiac catheter electrode and anterior left ventricular epicardial patch, between the catheter electrode and subcutaneous extrathoracic plate and between three ventricular epicardial patches all significantly reduced total energy (7.7, 8.7 and 7.8 J, respectively) and peak voltage (424, 436 and 424 V, respectively) needed to defibrillate. Three sequential shocks exerted no significant additional reduction in total energy of the defibrillation threshold than did two sequential shocks. In-farcted canine heart required less peak voltage but not total energy to terminate ventricular fibrillation than did noninfarcted heart. Therefore, two sequential shocks over different pathways reduce both total energy and peak voltage required to terminate ventricular fibrillation

Walks4work: Rationale and study design to investigate walking at lunchtime in the workplace setting

Background: Following recruitment of a private sector company, an 8week lunchtime walking intervention was implemented to examine the effect of the intervention on modifiable cardiovascular disease risk factors, and further to see if walking environment had any further effect on the cardiovascular disease risk factors. Methods. For phase 1 of the study participants were divided into three groups, two lunchtime walking intervention groups to walk around either an urban or natural environment twice a week during their lunch break over an 8week period. The third group was a waiting-list control who would be invited to join the walking groups after phase 1. In phase 2 all participants were encouraged to walk during their lunch break on self-selecting routes. Health checks were completed at baseline, end of phase 1 and end of phase 2 in order to measure the impact of the intervention on cardiovascular disease risk. The primary outcome variables of heart rate and heart rate variability were measured to assess autonomic function associated with cardiovascular disease. Secondary outcome variables (Body mass index, blood pressure, fitness, autonomic response to a stressor) related to cardiovascular disease were also measured. The efficacy of the intervention in increasing physical activity was objectively monitored throughout the 8-weeks using an accelerometer device. Discussion. The results of this study will help in developing interventions with low researcher input with high participant output that may be implemented in the workplace. If effective, this study will highlight the contribution that natural environments can make in the reduction of modifiable cardiovascular disease risk factors within the workplace. © 2012 Brown et al.; licensee BioMed Central Ltd

Reading and re-reading Shrek

This article presents the findings of a small-scale research project which aimed to enable young people to reflect on their childhood responses to the popular films, ‘Shrek’ and ‘Shrek 2’. During the project the participants develop new readings of the films in the light of their own recent experiences both of life and of other texts. The research draws on reader response theories to describe the complex readings of the films made by two young women from Rotherham. These readings include an engagement with an element of the films’ narrative structure, the relationship dilemma between the main characters. There was also clearly recollection of enjoyment of the animation style, the humour and the fairytale intertextuality of the film. However, the strongest response was based on more recent experiences and involved considerable empathy with the characters. This has important implications for both educational research and classroom practice. This paper argues for an increased recognition of the significance of children and young people’s engagements with popular children’s films as integral to their development as readers and creators of narrative texts

Recurrence of ventricular arrhythmias in ischaemic secondary prevention implantable cardioverter defibrillator recipients: long-term follow-up of the Leiden out-of-hospital cardiac arrest study (LOHCAT)

Aims to assess the long-term rate of mortality and the recurrence of potentially life-threatening ventricular arrhythmias in secondary prevention implantable cardioverter defibrillator (ICD) patients and to construct a model for baseline risk stratification.Methods and resultsSince 1996, all patients with ischaemic heart disease, receiving ICD therapy for secondary prevention of sudden death, were included in the current study. Patients were evaluated at implantation and during long-term follow-up. A total of 456 patients were included in the analysis and followed for 54 ± 35 months. During follow-up, 100 (22) patients died and ICD therapy was noted in 216 (47) patients, of which 138 (30) for fast, potentially life-threatening ventricular arrhythmia. Multivariate analysis revealed a history of atrial fibrillation or flutter (AF), ventricular tachycardia as presenting arrhythmia, and wide QRS and poor left ventricular ejection fraction as independent predictors of life-threatening ventricular arrhythmias. The strongest predictor was AF with a hazard ratio of 2.1 (95 confidence interval 1.3-3.2). On the basis of the available clinical data, it was not possible to identify a group which exhibited no risk on recurrence of potentially life-threatening ventricular arrhythmias.ConclusionIschaemic secondary prevention ICD recipients exhibit a high recurrence rate of potentially life-threatening ventricular arrhythmias. Factors that increase risk can be identified but, even with these factors, it was not possible to distinguish a recurrence-free group