Radionuclide Evaluation of Dual Chamber Pacing: Comparison Between Variable AV Intervals and Ventricular Pacing

We prospectively evaluated changes in left ventricular ejection fraction, end diastolic volume, and stroke volume via radionuclide multigated acquisition study, Comparison was made between ventricular pacing and dual chamber pacing with varying AV intervals. The volumes and changes in ejection fraction were determined at rest, at set increased pacing rates, and during physiological stress. AV sequential pacing shows overall improvement in cardiac function in the majority of patients regardless of left ventricular function. The shorter AV interval would be appropriate for the majority of patients who have an atrial tracking mechanism (adequate intrinsic sensed atrial activity followed by ventricular pacing) and who undergo significant physiological stress.     

高血压病人左房收缩时间间期测定

为研究高血压病人之左室舒张功能，我们采用脉冲多普勒超声心动图技术测量分析了６６例高血压病人及４３例正常人的左房收缩时间间期。高血压组按有无第四心音分为两组。１８例高血压病人应用卡托普利治疗１周后分析左房收缩时间间期指标。高血压病人的心房射血前期及校正心房射血前期缩短，心房射血时间延长。高血压伴第四心音组与无第四心音组比较心房射血前期及校正心房射血前期缩短，心房射血时间延长。１８例高血压病人应用卡托普利治疗１周后左房收缩时间间期指标有明显改善。     

健康成年人血浆肌酐生物参考区间调查

目的通过测定广州市健康成年人群的肝素锂抗凝血浆肌酐值,建立该实验室血浆肌酐的生物参考区间。方法采用碱性苦味酸速率法对959例健康成年人(年龄>18 y,其中男442例,女517例)进行血浆肌酐的测定,并按性别和年龄组分别比较。结果血浆肌酐结果呈对数正态分布,成年人肌酐值男女间差异有统计学意义(P<0.01),成年健康男性年龄组肌酐值差异无显著性(P>0.05),其95%可信限的生物参考区间为57.3~111.3μm o l/L;女性61 y以上的年龄组与其他成年女性年龄组之间肌酐值差异有显著性(P<0.05),年龄18~60 y健康女性95%可信限的参考区间为43.8~83μm o l/L,年龄61 y以上健康女性95%可信限的参考区间为45~97μm o l/L。结论生物参考区间对疾病的预防、诊断、疗效及预后都有重要的指导意义,应依据标本类型、检测方法和检测人群制定适合各实验室的生物参考区间。     

Bayesian consensus-based sample size criteria for binomial proportions

Many sample size criteria exist. These include power calculations and methods based on confidence interval widths from a frequentist viewpoint, and Bayesian methods based on credible interval widths or decision theory. Bayesian methods account for the inherent uncertainty of inputs to sample size calculations through the use of prior information rather than the point estimates typically used by frequentist methods. However, the choice of prior density can be problematic because there will almost always be different appreciations of the past evidence. Such differences can be accommodated a priori by robust methods for Bayesian design, for example, using mixtures or ϵ-contaminated priors. This would then ensure that the prior class includes divergent opinions. However, one may prefer to report several posterior densities arising from a “community of priors,” which cover the range of plausible prior densities, rather than forming a single class of priors. To date, however, there are no corresponding sample size methods that specifically account for a community of prior densities in the sense of ensuring a large-enough sample size for the data to sufficiently overwhelm the priors to ensure consensus across widely divergent prior views. In this paper, we develop methods that account for the variability in prior opinions by providing the sample size required to induce posterior agreement to a prespecified degree. Prototypic examples to one- and two-sample binomial outcomes are included. We compare sample sizes from criteria that consider a family of priors to those that would result from previous interval-based Bayesian criteria.     

Accelerometer-derived time intervals during various pacing modes in patients with biventricular pacemakers: comparison with normals

INTRODUCTION: Changes due to biventricular pacing have been documented by shortening of QRS duration and echocardiography. Compared to normal ventricular activation, the presence of left bundle branch block (LBBB) results in a significant change in cardiac cycle time intervals.Some of these have been used to quantify the underlying cardiac dyssynchrony, assess the effects of biventricular pacing, and guide programming of ventricular pacing devices. This study evaluates a simple noninvasive method using accelerometers attached to the skin to measure cardiac time intervals in biventricularly paced patients. METHODS: Ten patients with biventricular pacemakers previously implanted for congestive heart failure were paced in the AAI mode, then in atrioventricular (AV) sequential mode from the right and left ventricles followed by biventricular pacing. Simultaneous recordings were obtained by 2D, Doppler echocardiography as well as by accelerometers. Similar recordings were obtained from 10 gender, aged matched, normal controls during sinus rhythm. RESULTS: Compared to normals, heart failure patients paced in AAI mode had prolonged isovolumetric contraction time (IVCT), shorter ventricular ejection time (LVET), and prolonged isovolumetric relaxation (IVRT). With biventricular pacing the IVCT decreased, but the LVET and IVRT did not change significantly. There was excellent correlation between the echo and accelerometer-measured intervals. CONCLUSIONS: Shortening of the IVCT measured by an accelerometer is a consistent time interval change due to biventricular pacing that probably reflects more rapid acceleration of left ventricular ejection. The accelerometer may be useful to assess immediate efficacy of biventricular pacing during device implantation and optimize programmable time intervals such as AV and interventricular (VV) delays.     

参照C28-A2确定胱抑素C的参考值范围

目的建立本实验室胱抑素C（胱氨酸蛋白酶抑制剂,Cytatin C,Cys-C）免疫透射比浊法测定试剂盒的参考值范围。方法随机抽取240例健康人员的新鲜血清,利用市售胱抑素C测定试剂盒（免疫透射比浊法）进行测定,测定结果按CLSIC28-A2（临床实验室参考值范围的定义和确认．第2版）进行统计处理。结果本实验室1～49岁健康人群胱抑素C参考值范围为0．59—1．06mg／L,50-88岁健康人群胱抑素C参考值范围为0．48～1．32mg／L。结论实验室有．必要根据CLSIC28-A2文件的规定建立自己的参考值范围。     

肌氨酸氧化酶法测定绍兴地区儿童及成人血清肌酐参考值的建立

目的建立肌氨酸氧化酶法测定绍兴地区儿童及成人血清肌酐参考范围。方法选择2011年5～9月在笔者医院健康体检儿童和住院患儿(男性2269例,女性1542例),按年龄分组:出生3～12个月(组1),1～3岁(组2),4～6岁(组3),7～11岁(组4),12～18岁(组5)。成人组选择在笔者医院健康体检者(男、女性各500例,组6),年龄25～48岁。以上各组研究对象均排除肾脏系统、泌尿系统、贫血、甲亢、尿崩症等疾病和营养不良。结果组1～组6各组血清肌酐测定值皆呈正态分布。随年龄的增长(组1～组6)血清肌酐呈趋势性增加,并且男女之间的差异也有增加趋势。结论不同年龄阶段应采用不同的血清肌酐参考范围。不同实验室应建立自己实验室的血清肌酐参考范围。