Cardiac pacemakers. When clinical evaluation lags behind technological progress

OBJECTIVE: The rise in the number of implantations of cardiac pacemakers is of some concern to decision makers in the health sector. We assessed the intrinsic and relative clinical efficacy of cardiac pacemakers in current clinical indications to find out whether scientific or clinical arguments might justify differences in market prices. METHODS: We retrieved papers on cardiac pacing (January 1993-April 1998) from five databases (MEDLINE, HealthSTAR, EMBASE, Cochrane Library, and PASCAL). The citations in these papers were used to seek further articles. We selected the articles that met the criteria of evidence-based medicine (EBM) (randomized and nonrandomized controlled trials) and classified them according to clinical indication and type of evaluation (either of the intrinsic efficacy of a pacemaker versus a control or of the relative efficacy of different pacing modes). RESULTS: A total of 542 references were retrieved, but under 10% met our EBM criteria. Very few were comparative studies versus controls; most were recent and tended to use endpoints other than survival. Clinical efficacy was not proven on the basis of EBM criteria, even in common indications (e.g., sick sinus syndrome). Studies comparing different pacing modes were rarely randomized and did not provide consistent evidence for the superiority of any pacing mode in a given indication. CONCLUSIONS: Knowledge of the natural history of the diseases for which cardiac pacing is indicated is scarce. There is an approximately 20-year gap between technological progress and clinical evaluation that cannot be easily bridged because of methodologic difficulties and ethical issues. Current guidelines on pacemaker use either rely on expert opinion or highlight present inadequacies and make recommendations for future work. Available clinical efficacy data do not justify the wide differences in the price of cardiac pacemakers.     

人工心脏起博器置入术并发症的预防及护理

目的 探讨人工心脏起博器置人术并发症的护理及有效预防措施.方法 对2010-2011年期间心内科收治的562例因病态窦房结综合征而进行人工心脏起博器置入术患者的临床资料进行回顾分析.结果 成功置入人工心脏起博器562例,其中VVI427例,DDD117例,ICD18例.24例出现了并发症,其发生率为4.27％,包括起博器综合症7例,囊袋出血6例,囊袋感染5例,心律失常2例,电极脱位2例,右室电极穿孔1例,气胸1例.结论 人工心脏起博器置入术后并发症的发生率虽然较低,但后果严重.术前采用有效的健康教育,术中医护密切配合,术后细心、恰当的护理有助于预防心脏起博器置人术并发症的发生.     

An analysis of symptoms in patients with permanent ventricular pacemakers.

The prevalence and severity of symptoms of the "pacemaker syndrome" were investigated in 64 patients with VVI pacemakers and compared, in the same patients, to a series of control symptoms, unrelated to pacemaker function. Symptoms were also compared in patient groups unlikely to have the "pacemaker syndrome" (atrial fibrillation), most likely to have such symptoms (retrograde atrial activation) and in an intermediate group (competitive paced and sinus rhythms). There was a linear relationship between the frequency and severity of "pacemaker" symptoms and control questions in all groups and no preponderance of "pacemaker" symptoms in any group. The study provides an estimate of the number and severity of symptoms in patients with VVI pacemakers, demonstrates the non-specificity of the "pacemaker syndrome" and shows no evidence of a sub-clinical "pacemaker syndrome" in the patients observed.     

心脏起搏器类高值医用耗材省级带量采购现状分析

目的:分析心脏起搏器类高值医用耗材省级带量采购实践情况,为完善高值医用耗材带量采购工作提供建议。方法:收集2019—2023年省级(包括省级联盟)心脏起搏器类耗材带量采购政策文件,运用文献分析法和专家咨询法对采购规则进行分析。结果:心脏起搏器采购品种均为双腔类产品,分组依据以市场份额为主,多数样本并未选取代表品报价,评标规则主要采用最低价拟中选结合其他拟中选方式。结论:各地在组织心脏起搏器带量采购时应扩大联盟范围,完善分组规则,制定符合产品特点的评标规则。     

Pacemaker in MR: absolute contraindication?

Due to developments in pacemaker technology, implanted pacemakers do not mean an absolute contraindication for MRI examination. However, there are several aspects of MRI examinations that should be considered for safety reasons in pacemaker patients. Based on literature data and own experiments, the safety protocol of MRI examination in pacemaker-implanted patients is described. The interaction of pacemakers--frequently implanted in Hungary--with MR scanners of 0,35 and 1,5 T was studied in vitro. In addition, the cardiac MRI examination of two pacemaker patients is presented. -ICD pacemakers showed strong interaction with static and changing magnetic field that affected pacemaker performance significantly. MRI examination can be safely performed in pacemaker-independent patients. Based on our in vitro and in vivo measurements, MRI examination is still contraindicated in pacemaker-dependent patients. In pacemaker-independent patients blood pressure, ECG monitoring and pulsoximetry are absolutely necessary, in addition, equipment for resuscitation should be available. Pacemaker should be specifically programmed before MRI examination and parameters and functionality should be checked in details afterwards.     

Risk of severe cardiac arrhythmia in male utility workers: a nationwide danish cohort study

To address concern about the potential cardiovascular effects of occupational exposure to electromagnetic fields in the 50- to 60-Hz frequency band, the authors launched an epidemiologic study of the incidence of severe cardiac arrhythmia, as indicated by the need for a pacemaker, in a nationwide cohort of Danish utility workers. The cohort of 24,056 men employed at utility companies between 1900 and 1993 was linked to the nationwide, population-based Danish Pacemaker Register, and the numbers of persons who had undergone pacemaker implantation between 1982 and 2000 were compared with corresponding numbers in the general population. In addition, the data on the utility workers were fitted to a multiplicative Poisson regression model in relation to estimated levels of exposure to 50-Hz electromagnetic fields. Overall, based on 135 men with pacemakers (140 expected), there was no increased risk of severe cardiac arrhythmia among the utility employees; the risk estimate was 0.96 (95% confidence interval: 0.81, 1.14). No clear dose-response pattern emerged with increasing levels of exposure to electromagnetic fields or with duration of employment. These results are largely reassuring, since they do not support the hypothesis of a link between occupational exposure to electromagnetic fields and an excess risk of severe cardiovascular arrhythmia leading to permanent implantation of a pacemaker.     

206例植入永久心脏起博器患者随访分析

[目的]了解患者植入起搏器后的心功能状态、症状改善情况、手术后起搏器工作状态以及并发症,并对随访结果进行比较分析,提高患者的预后效果. [方法]选取2000年1月～2010年4月于某院进行治疗的206例植入永久心脏起博器患者为研究对象,后将患者植入起搏器后的心功能状态、症状改善情况、手术后起搏器工作状态以及并发症进行统计及比较.[结果]头晕改善明显优于其他症状的改善情况,在并发症中血肿的发生明显高于其他并发症,P均＜ 0.05,差异有统计学意义.[结论]临床工作中应该掌握起搏器术后对患者的影响和较常发的并发症,能够做到早期预防,使患者能有一个更好的预后.     

Do doctors read forms? A one-year audit of medical certificates submitted to a crematorium.

To determine the thoroughness and accuracy with which medical certificates for cremation are completed, a record was made, during normal processing of the documents, of the number of questions that were not answered or answered wrongly, or in which clarification was required. Of 835 sets of forms only 346 (41%) were completed sufficiently accurately for the cremation to proceed without further enquiry. Junior doctors contributed the most errors but general practitioners and consultants also contributed large numbers of errors. Doctors ought to be far more accurate and thorough in completing cremation certificates than were those audited here. The results cast doubt on the reliability of information supplied on other forms. In view of the high frequency of poorly completed forms, review by a medical referee remains essential.     

Experience of a small British pacing centre between 1994 and 2000: some answers to the problem of low UK implantation rates

Raigmore is a district general hospital offering a permanent pacemaker service to its catchment population of 233,500. This report reviews the pacemaker practice over a seven year period (1994 to 2000) and makes a comparison with the national database and other hospitals in the UK. The records of all patients receiving new implantions for the period under observation were reviewed retrospectively. Data collected included number of patients paced each year, age, sex, indications and complications. In the 84 months studied 3/71 patients received new permanent pacemakers (the mean age was 74 years and 51% were male). The most common presenting symptoms were syncope (62%), dizzy spells (24%), and heart failure (11.5%). The most common indication for permanent pacemaker insertion was complete atrioventricular block (58%) followed by sick sinus syndrome (20%). The implantation rate was 419.3/million population/year in 2000. Pacemaker modes used were appropriate and the early and late complication rates were low (2.7%). This current audit demonstrates continued growth of the service with low-complication rates and implantation rates which approach those in Western Europe and North America.     

The epidemiology of pacemaker implantation in the United States.

Data on pacemaker implantation were obtained from the Medical Device Implant Supplement to the 1988 National Health Interview Survey, a nationally representative, population-based survey of 47,485 households (122,310 persons). The survey yielded an estimate of 456,482 noninstitutionalized adults with pacemakers (prevalence, 2.6 per 1,000). Prevalence rose significantly with age, from 0.4 per 1,000 among persons ages 18-64 to 26 per 1,000 among those ages 75 or older. Age-adjusted prevalence in males was 1.5 times that in females, and in whites 1.6 times that in nonwhites, although these differences were of borderline statistical significance. Prevalence did not vary significantly by region of residence, educational level, or income, but was significantly increased (more than threefold) in those reporting any activity limitation compared with those with no limitation. Fifteen percent of pacemakers in use were replacements; about one-fifth of these had been replaced more than twice. Sixty percent of previous pacemakers had been in place for at least 5 years. These data provide the first nationwide, population-based estimates of the epidemiology of pacemaker implantation, focusing particularly on the demographics of U.S. pacemaker recipients.     

分析探讨双腔心脏起搏器治疗慢性心律失常患者的临床效果

目的:探讨双腔心脏起搏器治疗慢性心律失常患者的临床效果。方法:本文纳入本院2015年3月~2019年3月收治的80例慢性心律失常患者,采用计算机程序生成随机数的方法分为对照组与观察组,每组40例;对照组患者植入单腔心脏起搏器;观察组患者植入双腔心脏起搏器,比较两组患者心功能治疗效果和不良反应情况。结果:从临床总有效率看,观察组患者明显高于对照组,差异有统计学意义(P<0.05);从不良反应发生情况看,观察组出现囊袋血肿2例(5.00%),对照组患者不良反应囊袋血肿4例,气胸2例,感染1例,发生率为17.50%,观察组显著低于对照组,差异有统计学意义(P<0.05)。结论:对慢性心律失常患者采用双腔心脏起搏器治疗疗效显著,可有效缓解改善心功能,减少不良反应。     

Used pacemakers: who's keeping track?

When a medical device salesman was indicted for selling mislabeled and used cardiac pacemakers as new, no one said how he obtained the devices. The incident raises concerns about the standard procedures used by hospitals for the disposal of pacemakers that may be removed from patients. While each hospital has its own rules for disposals, the Safe Medical Devices Act is changing that by requiring the tracking of pacemakers and other medical devices.     

Effects of high-intensity power-frequency electric fields on implanted modern multiprogrammable cardiac pacemakers

The effect on an implanted, multiprogrammable pacemaker of power-frequency (50 Hz) electric fields up to an intensity (unperturbed value measured at 1.7 m) of 20 kV/m were assessed in ten paced patients. Radiotelemetric monitoring of the electrocardiogram allowed supervision of the electrocardiogram throughout exposure to the alternating electric field. Displacement body currents of up to 300μA were achieved depending on the position and height of the patient. None of the pacemakers was inhibited, triggered or reverted to fixed rate operation during the exposure. The programmable functions, programmability or output characteristics were not affected. Small changes in cardiac rate and rhythm elicited the correct pacemaker responses. Unlike earlier models of pacemaker, this modern implanted pacemaker, which represents `the state of the art', is not affected by 50 Hz electric fields likely to be encountered when standing underneath power lines.     

Employment rehabilitation schemes for people with mental health problems

Although work and employment are important elements in the lives of people recovering from psychiatric illness, their access to meaningful occupation and paid employment is limited. A number of state and voluntary vocational rehabilitation schemes provide training or retraining for open employment but whether this is a realistic aim in the current economic climate has been questioned. This study, using direct observation and informal interviewing, explored the interaction between the staff and trainees of one such rehabilitation workshop. It sought to elicit information about the role of the workshop from both the trainer and trainee perspectives. The results indicate a number of differences between the staff and trainee models and illustrate the problems faced by the workshop in balancing its smooth operation against the needs and expectations of its staff and trainees. In particular, its organization around a relaxed interpretation of the ‘through-put’ concept of rehabilitation did not meet the requirements of all the trainees. We consider how employment rehabilitation schemes can achieve the dual role of both helping service users move into employment or other forms of meaningful occupation, and providing work and work substitutes for long-term users.     

Countershock and Pacemaking in Cardiac Arrhythmias

Application of electric current to the management of cardiac arrhythmias is the single most important factor in today's vastly improved survival of patients with acute myocardial infarction. But although defibrillators and pacemakers have become more sophisticated, problems still remain. Discussed here are the development of the devices, indications for their use, and pacemaker complications such as wire breakage.     

Chaotic dynamics in arrhythmias

The paper proposes the systematization of cardiac arrhythmias in accordance with a generalized scheme of transition from regular conditions to random changes, which makes it possible to conclude that the occurrence of more menacing arrhythmias in patients with implantable pacemakers may suggest that there is a risk for random disorders, as well as to recommend to change pacing parameters and even to replace the pacemaker. At present the authors are conducting computer-aided studies of the proposed approach in the Matlab medium. The algorithm of search for the facts of complication of the dynamic behavior of the system is based on the odd set theory which is presently most promising for designing cardiological monitoring systems. The new approach suggests that there are changes in the dynamics of arrhythmias and hence it will be of practical value in treating all cardiological patients.     

永久起搏电极植入途径及起搏类型的探讨

目的评价起搏电极的植入途径及永久起搏器的类型。方法选择1987年至1999年安置的80例永久起搏器患者。结果经颈外静脉植入电极6例,手术时间(256±75)min,经头静脉植入电极48例,手术时间(247±65)min,P>0.05;经锁骨下静脉途径植入电极26例,手术时间(118±35)min,P均<0.01。其中,AAI型3例(4%),DDD型5例(6%),VVI型72例(90%)。结论经锁骨下静脉植入起搏电极方法简单、组织损伤小、手术时间短,优于其他途径;VVI型起搏器在我国仍然是主要使用的起搏器。     

VVI起搏器右室不同起搏部位临床疗效观察

目的：观察右室间隔部（RVS）和右室心尖部（RVA）起搏对起搏参数、QRS波宽度、心脏功能的影响。方法：23例置入VVI起搏器患者,随机分为两组,一组患者行右室间隔起搏（11例）,一组行右室心尖部起搏（12例）。分别于术前、术后1周及随访6个月通过心电图及心脏超声检查患者QRS波时间、左心室射血分数（LVEF）、二尖瓣血流E峰和A峰最大充盈速度比值（E/A）等相关指标进行观察随访。结果：右室间隔部起搏和心尖部起搏比较,起搏阈值、电极阻抗、感知差异无统计学意义,术后右室心尖部起搏QRS波明显增宽,LVEF、E/A值明显降低,右室间隔部起搏无显著变化,6个月随访RVS组QRS波增宽程度小,LVEF、E/A均显著高于RVA组（P〈0.05）。结论：VVI起搏器选择RVS起搏优于RVA起搏。     

Psychometric properties of Aquarel. a disease-specific quality of life questionnaire for pacemaker patients

In cardiac pacing current clinical practice permits the use of ventricular or atrioventricular-synchronous pacemakers. However, it is not known which type of pacemaker results in superior clinical and patient outcomes. To date, there is no feasible and validated disease-specific questionnaire for pacemaker patients to assess quality of life (QoL) available. The Aquarel questionnaire was developed as a disease-specific extension to the Short-Form-36 (SF-36). A cross-sectional study was carried out in 74 pacemaker patients to evaluate validity and reliability of this instrument. Items were selected and scales constructed based on factorial analysis. Internal consistency, content validity and test-retest reliability were moderate to excellent. Correlations with the SF-36 scales, pacing mode and functional tests were as hypothesized, demonstrating the individual value and distinctiveness of the Aquarel subscales. The results support the feasibility and usefulness of evaluating QoL in pacemaker patients when using Aquarel as an extension to the SF-36.     

Interference between mobile phones and pacemakers: a look inside

In this study we analyzed the problem of electromagnetic interference (EMI) between mobile telephones and cardiac pacemakers (PM), by looking at the mechanisms by which the radiated radio frequency (RF) GSM signal may affect the pacemaker function. From a literature review on this topic, we noticed that older pacemakers had a higher rate of being affected by mobile phones when compared to newer ones. This is probably due to the fact that new generation of PM are more protected against electromagnetic field, being equipped with RF feedthrough filters incorporated to the internal PM circuitry. In some experiments conducted by our group, we found that modulated RF signals are somehow demodulated by the PM internal non-linear circuit elements, if no feedthrough assembly is incorporated inside the PM. Such demodulation phenomenon poses a critical problem because digital cellular phones use extremely low-frequency modulation (as low as 2 Hz), that can be mistaken for normal heartbeat. The feedthrough assembly seems instead to prevents the RF signals from accessing the PM enclosure, thus attenuating EMI signals over a broad range of frequencies.