Ageing,the autonomic nervous system and arrhythmia: From brain to heart

An ageing myocardium possesses significant electrophysiological alterations that predisposes the elderly patient to arrhythmic risk. Whilst these alterations are intrinsic to the cardiac myocytes, they are modulated by the cardiac autonomic nervous system (ANS) and consequently, ageing of the cardiac ANS is fundamental to the development of arrhythmias. A systems-based approach that incorporates the influence of the cardiac ANS could lead to better mechanistic understanding of how arrhythmogenic triggers and substrates interact spatially and temporally to produce sustained arrhythmia and why its incidence increases with age. Despite the existence of physiological oscillations of ANS activity on the heart, pathological oscillations can lead to defective activation and recovery properties of the myocardium. Such changes can be attributable to the decrease in functionality and structural alterations to ANS specific receptors in the myocardium with age. These altered ANS adaptive responses can occur either as a normal ageing process or accelerated in the presence of specific cardiac pathologies, such as genetic mutations or neurodegenerative conditions. Targeted intervention that seek to manipulate the ageing ANS influence on the myocardium may prove to be an efficacious approach for the management of arrhythmia in the ageing population.     

Atrial Fibrillation Clinics in Canada: A Nationwide Project Report

The increased prevalence of atrial fibrillation (AF) has led to specialized AF clinics (AFCs) to facilitate management of AF patients. In this article we report on outpatient AFCs in Canada, which is essential to health policies required to standardize the performance of existing AFCs and help design new AFCs. We surveyed 14 clinics in 5 provinces; 100% provided responses to a detailed questionnaire on clinic processes and care practices. Fourteen care maps were analyzed, and 5 models of care were identified; 4 were specific to AFCs. An online survey with 49 questions included items on: (1) process before visit; (2) process at visit; (3) patient education provided; (4) outreach; and (5) specific clinic information. Clinicians’ advice to patients on self-care items such as: (1) amount of alcohol and (2) caffeine intake; (3) exercise activity; (4) stressful events; (5) “when to go to the emergency department”; and (6) lifestyle changes, were evaluated to assess consistency in practice. There were moderate variances in clinicians’ advice to patients in 5 of 6 self-care items. The 1 item that had 100% consistent practice recommendation was when to go to the emergency department. A guideline-based clinical assessment checklist (CAC) was piloted to obtain feedback on its usability in real-world practice; revisions finalized the “simplified CAC” for AF care encompassing 35 data points with rationale. There was 100% positive feedback on its ability to provide baseline elements in AF care. When validated, a “simplified CAC” can facilitate a standardized clinical assessment tool in clinical practice.     

Hypertrophy of lymphoid organs is a possible phenotypic characteristic of R420W mutation of the cardiac ryanodine receptor gene: A study using a knock-in mouse model

Cardiac ryanodine receptor gene (RyR2) mutations sometimes result in sudden cardiac death due to fatal arrhythmias. N-terminal R420W mutation of RyR2 is known to show similar phenotypes to arrhythmogenic right ventricular cardiomyopathy and to cause juvenile sudden death. We previously reported two sudden death cases with the same R420W mutation. Interestingly, the cases showed hypertrophy of lymphoid organs such as the thymus and mesenteric lymph nodes. The present study examined whether R420W mutation of RYR2 causes hypertrophy of lymphoid organs by generating a mouse model carrying the mutation. Homozygous (RyR2^R420W/R420W) mice showed significant increases in thymus and spleen weights but not in kidney, heart, and brain weights compared with wild-type mice. The mice also showed remarkable hypertrophy of mesenteric lymph nodes. Immunohistochemical study revealed that RyR2 protein was prominently expressed in epithelial cells of the thymic medulla in the thymus. These findings show that mice with R420W mutation of RyR2 exhibit hypertrophy of lymphoid organs. Sudden unexplained death cases with the mutation may display such findings at autopsy.     

基于移动通讯技术的新型院外远程实时心电监测系统的临床研究

目的 评价一种自主研发的基于移动通讯技术的新型院外远程实时心电监测系统数据传输的实时性及对心律失常检测的敏感性.方法 通过测定心电信号传输的延时评估系统的实时性;通过与动态心电图对比评估远程监测对心律失常检测的敏感性.结果 远程监测时心电数据传输的最短延时为9s,最长延时为17s,平均延时为（13.4±4.5）s.在100例受试者中,远程监测和动态心电图分别检测到偶发房性期前收缩62例、57例,频发房性期前收缩22例、25例,心房颤动均为9例,非阵发性室性心动过速16例、12例,差异均无统计学意义（均P ＞0.05）.同时均发现二度Ⅱ型房室传导阻滞5例、三度房室传导阻滞2例.结论 该系统有较好的实时性,对心律失常检出的敏感性与动态心电图相仿.     

注射用磷酸肌酸钠对非体外循环下冠状动脉旁路移植术患者动脉血氧分压、心肌酶及心律失常的影响

目的：探讨注射用磷酸肌酸钠对冠状动脉旁路移植术(CABG)患者动脉血氧分压、心肌酶及心律失常的影响。方法：70例本院ASA分级Ⅱ～Ⅲ级，CABG预术患者，随机分成对照组和实验组，每组35例。麻醉完毕后，给予对照组患者常规药物及液体应用,而实验组则在对照组基础上给予磷酸肌酸钠1g静脉滴注。术毕时血气分析检测动脉血氧分压；术后24h检测心肌酶谱；术后24h记录Ⅱ导联心电图心律失常发生情况。结果: 相比对照组，实验组术毕动脉血氧分压提高显著（p<0.05）；两组心肌酶含量术后均升高，实验组上升较对照组明显减少(p<0.05)；实验组心律失常的发生率8.5%，明显低于对照组37.1%(p<0.05)。结论：磷酸肌酸钠能提高冠心病手术患者动脉血氧分压，改善心肌酶含量，降低心律失常发生率。