Exposure to passive smoking among bar staff

The median saliva cotinine concentration in 42 non-smoking bar staff in central London and Birmingham was 7.95 ng/ml, indicating a nicotine intake of about 0.6 mg per day. Pubs appear to give rise to exceptionally heavy exposure to environmental tobacco smoke. Passive smoking in pubs is of concern for its impact both on customers and on those for whom the pub is a place of work.     

Renal Denervation for Treatment of Cardiac Arrhythmias: State of the Art and Future Directions

Renal Denervation for Treatment of Cardiac Arrhythmias . It has now been more than a quarter of a century since modulation of the sympathetic nervous system was proposed for the treatment of cardiac arrhythmias of different origins. But it has also been some time since some of the early surgical attempts have been abandoned. With the development of ablation techniques, however, new approaches and targets have been recently introduced that have revolutionized our way of thinking about sympathetic modulation. Renal nerve ablation technology is now being successfully used for the treatment of resistant hypertension, but the indication spectrum might broaden and new therapeutic options might arise in the near future. This review focuses on the possible impact of renal sympathetic system modulation on cardiac arrhythmias, the current evidence supporting this approach, and the ongoing trials of this method in electrophysiological laboratories. We will discuss the potential roles that sympathetic modulation may play in the future.     

Modelling the macrophage invasion of tumours: Effects on growth and composition

E-mail: owen{at}maths.warwick.ac.uk E-mail: jas{at}maths.warwick.ac.uk Even in the early stages of their development, tumours are notsimply a homogeneous grouping of mutant cells; rather, theydevelop in tandem with normal tissue cells, and also recruitother cell types including lymphatic cells and the endothelialcells required for the development of a blood supply. It hasbeen repeatedly seen that macrophages form a significant proportionof the tumour mass, and that they can have a variety of effectsupon the tumour, leading to a delicate balance between growthpromotion and inhibition. This paper develops a model for theearly, avascular growth of a tumour, concentrating on the inhibitoryeffect of macrophages due to their cytolytic activity. It isshown that such an immune response is not sufficient to preventgrowth, due to it being a second-order process with respectto the density of the tumour cells present However, the presenceof macrophages does have important effects on the tumour composition,and the authors perform a detailed bifurcation analysis of theirmodel to clarify this. An extended model is also consideredwhich incorporates addition of exogenous chemical regulators.In this case, the model admits the possibility of tumour regression,and the therapeutic implications of this are discussed.     

Sudden and Fatal Malfunction of a Durata Defibrillator Lead due to External Insulation Failure

Defibrillator lead malfunction can be a disastrous complication, leading to loss of protection from sudden cardiac death in a high‐risk patient population. Recognition of lead‐specific risk for failure can assist in development of focused screening or surveillance, as in the case of the Riata lead (St. Jude Medical, St. Paul, MN, USA) or the Sprint Fidelis lead (Medtronic Inc., Minneapolis, MN, USA). A case of defibrillation failure secondary to a Durata lead insulation failure is presented. A brief review of the literature and current St. Jude Medical implantable cardiac defibrillator lead design is presented. Identification of arcing is identified as a potential sign of catastrophic insulation failure.     

Titration of Power Output During Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia

Radiofrequency lesions in the anterior, superior aspect of the tricuspid annulus result in selective elimination of fast pathway function in patients with typical atrioventricular (AV) nodal reentry tachycardia. This technique is simple and effective, but has been associated with a significant risk of inadvertent complete AV block. The purpose of this study was to compare the safety and effectiveness of two different techniques for radiofrequency catheter ablation of the fast AV nodal pathway. Initially, a fixed power output was used at each target site. This method was compared retrospectively to a newer technique where power output was gradually incremented at each site. Radiofrequency power was initially applied at 10 watts for 10–15 seconds. If no junctional ectopy or a change in PR intervoi was seen, power output was incremented by 2 to 4 watts every 10 to 15 seconds up to a maximum of 30 watts. Thirty seven of 38 (96%) patients treated using this incremental power output were cured of their AV nodal reentry tachycardia. None of these patients developed inadvertent complete AV block. In contrast, 92% of historic controls treated with a fixed power output between 20 and 30 watts achieved a primary success and nine of these 89 (10%) historic controls developed inadvertent complete AV block (P = 0.04). There was no difference in the amplitudes of atrial, His, or ventricular electrograms at the effective sites between the two groups. Conclusions: (1) the anterior approach to radiofrequency catheter ablation of typical AV nodal reentry is associated with a significant risk of inadvertent complete AV block if a fixed power output is used; (2) starting at low power and gradually incrementing the output during radiofrequency energy application reduces the risk of complete AV block; (3) this incremental technique does not compromise efficacy.