双腔起搏器模式自动转换功能在慢-快综合征的临床应用

目的探讨双腔起搏器模式自动转换功能在慢-快综合征的应用价值.方法 8例慢-快综合征患者均置入具有模式自动转换功能(AMS)的双腔起搏器,心动过速频率设置为175 bpm.术后随访期为3个月,进行生活质量问卷调查,并详细调阅起搏器存储的心动过速发生情况和AMS启动情况.结果共发生了498次快速房性心律失常,每次均启动了AMS功能.当快速房性心律失常发作时(＞175 bpm),起搏模式由DDD(R)转变为DDI(R),而当心房率＜175 bpm时未发生模式自动转换,不适症状明显减少,冠心病者心肌缺血发作明显减轻.     

双腔起搏器自动工作方式转换功能在阵发性房性快速心律失常患者的评价

评价双腔起搏器自动工作方式转换功能的可靠性及临床应用效果。方法 10例患者，男性8例，女性2例，平均年龄62．31岁。因病态窦房结综合征及三度房室阻滞植入了带有自动工作方式转换功能(AMS)的双腔起搏器。10例患者中，8例伴有阵发性心房颤动，1例伴有阵发性心房扑动，1例伴有阵发性房性心动过速。带有AMS功能起搏器可在房性快速心律失常发生时，由跟踪房性频率的工作方式(DDD／DDDR)自动转换为非房性频率跟踪的工作方式(DDlR)。起搏器可自动将心律失常发生情况及发生AMS情况储存起来。患者植入起搏器后3个月进行随访，并用体外程控仪调出起搏器的储存信息进行分析。结果10倒患者中有6倒发生了274次阵发性心房颤动，持续时间为lOmin～2h不等，患者心房颤动的心室反应为207～400bpm。每次心房颤动，起搏器启动了AMS，心室反应频率在60～90bpm，4例未发生快速房性心律失常患者未启动AMS。结论 双腔起搏器AMS功能工作可靠，对于伴有阵发性房性快速心律失常患者，进行双腔起搏治疗时，应考虑应用带有AMS功能的双腔起搏器。     

美敦力起搏器的空白期心房扑动搜索功能

快速性房性心律失常发作时,起搏器的自动模式转换功能开启后会将心房跟踪模式自动转换为非心房跟踪模式,在自动模式转换过程中,起搏器需要识别快速性房性心律失常,但心房扑动发生时常因部分F波落于心室后心房空白期中不能被计数,使心房频率不能被正确识别而无法进行模式转换。美敦力公司针对这一问题,在自Kappa700系列后的起搏器中设置了空白期心房扑动搜索功能,空白期心房扑动搜索在DDD(R)、VDD(R)模式下可用。     

波士顿科学起搏器的心房扑动反应

波士顿科学起搏器的心房扑动(简称房扑)反应(AFR)是波士顿科学公司起搏器的一项功能,目的是当患者发生房扑时,如果心房率超过AFR程控频率,起搏器会马上转换为非跟踪模式工作,防止在心房易损期内的竞争性起搏导致的快速性房性心律失常的发生,同时,可以在发生快速性房性心律失常而未能模式转换时,避免因跟踪心房导致的快频率的心室起搏。     

AAISafeR起搏模式的长期随访观察

目的对置入具有AAISafeR功能的Symphony 2450起搏器的患者进行长期随访观察。方法入选40例患者,分别于置入起搏器后3个月、6个月,以后每年1次进行随访,观察左房内径(LAD)、左室舒张末期内径(LVEDD)及左室射血分数。通过起搏器程控计算心房起搏及感知百分比,心室起搏及感知百分比。同时记录房性心律失常的发生率。结果随访18±4.6(12～24)个月,心室起搏百分比23.5%±3.5%。与术前相比,术后LAD、LVEDD均有缩小(P<0.05)。相关分析显示,LAD、LVEDD与心室起搏百分比呈正相关。术后快速房性心律失常发作例数明显减少。结论AAISafeR起搏模式能够有效减少心室起搏百分比,减少房性心律失常的发生。     

动态心房超速起搏预防阵发性房性心律失常的临床应用

为评价动态心房超速起搏 (DAO)方式预防阵发性快速性房性心律失常的临床疗效 ,选择 5例患者 ,均为病窦综合征合并阵发性快速性房性心律失常 ,置入具有DAO功能的双腔起搏器。随访单盲把患者分为A组 :DAOon和B组DAOoff,半年后交换 ,共随访 12个月。每个月随访症状 ,每 3个月一次 2 4h动态心电图及程控仪随访自动模式转换 (AMS)次数。置入起搏器后胸闷、心悸、气促等症状较起搏器置入前改善。在DAOon时较off时这些症状进一步改善。 2 4h动态心电图随访快速性房性心律失常发作时间 :A组DAOon时 3 3 .8± 10 .7minvsDAOoff时 60 .4± 19.3min ,B组DAOoff时 5 5 .1± 17.6minvsDAOon时 3 7.2± 13 .5min。程控仪监测到AMS次数 :A组DAOon时64 9± 3 1minvsDAOoff时 5 796± 3 86min ,B组DAOoff时 5 5 69± 3 0 5minvsDAOon时 65 8± 2 9min。结论 :动态心房超速起搏方式具有一定的预防阵发性快速性房性心律失常的作用。     

永久起搏器安置术后的动态起搏心电图分析

目的了解永久起搏器安置术后起搏器的正常起搏功能、起搏功能障碍及可能发生的自身心律失常。方法分析84例永久起搏器安置术后随访者的动态起搏心电图。结果①83%为正常起搏功能,包括室性融合波和假性室性融合波;双腔起搏器中的上限频率+模式转换、心室安全起搏;单腔起搏器中的起搏器滞后功能;电张调整性T波改变;②17%起搏功能障碍,包括室房逆传、起搏功能异常、感知功能异常、起搏器介导性心动过速;③81%出现自身心律失常,包括室性早搏、房性早搏、心房纤颤、短阵房性心动过速、短阵室性心动过速。结论安置永久起搏器后起搏心电图变得复杂,只有对正常起搏及起搏器故障的心电图做出正确判断,才能及时正确处理,以避免起搏器故障造成严重后果。     

起搏器的休息频率功能对房性心律失常的近期影响

目的探讨起搏器的休息频率功能对房性心律失常的近期影响,评估其临床疗效和安全性。方法选择植入Identity Adx DDD 5286型双腔起搏器的病态窦房结综合征患者39例。起搏器植入后不打开休息频率,保持起搏器出厂设置;术后3个月随访时程控为在双腔起搏模式下打开休息频率,共随访6个月。比较起搏器植入前后及打开心房滞后模式后心房起搏百分比及房性心律失常的发生情况。结果与术前比较,术后3个月24 h动态心电图显示,房性期前收缩次数和房性心动过速、心房颤动阵数增加(U=4.19、4.28和4.39,均为P<0.05),相应的发作例数也增加(χ2=4.57、4.61和4.96,均为P<0.05)。与未打开休息频率模式比较,打开后心房的起搏百分比明显降低[56%(40%⁷3%)比84%(64%73%)比84%(64%⁹7%),P=0.03];24 h动态心电图显示,房性期前收缩次数和房性心动过速、心房颤动阵数明显减少(P<0.01),相应的发作例数也减少(P<0.01)。结论休息频率模式可以减少心房起搏的比例,减少房性心律失常的发生;打开休息频率模式安全可靠。     

双房同步起搏联合预防心房颤动的起搏治疗模式治疗快速房性心律失常的临床应用(附三例报告)

为观察三腔双房起搏联合预防心房颤动 (简称房颤 )的起搏治疗模式治疗快速性房性心律失常的临床效果。研究 3例房间传导阻滞合并快速性房性心律失常 ,并置入三腔双房同步起搏器的患者。起搏器具有房颤预防治疗功能。左房起搏通过冠状静脉窦置入 2 188电极导线 ,左右心房电极导线通过Y形转接器与双腔起搏器连接。DDTA起搏模式 ,随访 6个月 ,观察超驱动起搏、长间期抑制、房性早搏 (简称房早 )后加速起搏功能关闭和开启时 ,患者的临床症状、统计模式转换发生的次数、第一次至第二次房颤发作的间期、平均 2 4h房早记数。结果 :双房同步起搏后 ,患者快速房性心律失常的发作明显减少。超驱动起搏、长间期抑制、房早后加速起搏功能开启时 ,模式转换发生的次数减少、第一次至第二次房颤发作的间期延长、平均 2 4h房早记数明显减少。结论 :初步临床应用提示 :三腔双心房起搏联合预防房颤的起搏治疗模式治疗快速性房性心律失常可行且有效。     

起搏器特殊功能对起搏器植入术后阵发性心房颤动治疗效果一例

患者男性,81岁,病窦综合征,起搏器植入术后心悸。起搏器程控显示阵发性房性心动过速和心房颤动频繁发生。开启起搏器治疗房性心动过速/心房颤动的特殊功能后,患者临床症状明显改善,起搏器程控显示房性心动过速和心房颤动的发生明显减少。     

Preventricular Far-Field Sensing in the Atrial Channel of Dual Chamber Pacemakers—An Occasional Cause of Inappropriate Mode Switch

INTRODUCTION AND AIMS OF THE STUDY: Atrial oversensing may trigger false positive mode switch to an asynchronous mode in dual chamber pacemakers. While myopotential oversensing and far-field R wave sensing within the postventricular atrial refractory period are well characterized, data about oversensing (near-field P wave or far-field R wave) within the atrioventricular delay is limited. Aim of the study was to determine the incidence of preventricular oversensing in the atrial channel of current dual chamber pacemakers. METHODS: Consecutive patients with dual chamber pacemakers who were in sinus rhythm and who showed no myopotential oversensing were included in the study. Atrial sensitivity was programmed to the maximal available value and atrioventricular delay was prolonged when necessary for intrinsic atrioventricular conduction. RESULTS: Ten out of 100 (10%) patients showed oversensing within the atrioventricular delay at highest levels of atrial sensitivity, median sensing threshold for the signals was 0.35 mV, and the median coupling interval between preventricular atrial oversensing and the ventricular sensed event was 20 ms. CONCLUSION: The incidence of inappropriate mode switch caused by atrial preventricular oversensing related to near-field P wave or far-field R wave oversensing in dual chamber pacemakers is up to 10%. Interpretation of pacemaker Holters should consider oversensing within the atrioventricular delay as a differential diagnosis to true episodes of atrial tachyarrhythmias.     

Accuracy of mode switch algorithms for detection of atrial tachyarrhythmias

INTRODUCTION: In patients with permanent pacemakers, mode switching events often are interpreted as surrogate markers for atrial tachyarrhythmias. The aim of this study was to determine the accuracy of automatic mode switching algorithms in patients with permanent pacemakers for the diagnosis of atrial tachyarrhythmias. METHODS AND RESULTS: Forty patients with tachycardia-bradycardia syndrome and Medtronic Thera or Kappa 700 permanent pacemakers underwent Holter monitoring. Date, time of onset, and duration of each mode switch episode as recorded by the pacemaker and each atrial tachyarrhythmia episode as recorded by the Holter monitor were compared. Sixteen patients had a total of 54 atrial tachyarrhythmias documented on Holter monitoring (47 atrial fibrillation, 7 atrial flutter). Comparison of Holter data with pacemaker interrogation demonstrated that 53 (98.1%) of 54 atrial tachyarrhythmia episodes resulted in mode switching with one 13-second episode of mode switching during sinus rhythm. The sensitivity and specificity of mode switching for the duration of atrial tachyarrhythmias were 98.1% and 100%, respectively. The algorithms detected 98.9% of the total duration of atrial fibrillation and 96.4% of the total duration of atrial flutter. CONCLUSION: In patients with tachycardia-bradycardia syndrome and permanent pacemakers having these mode switching algorithms, mode switching events are reliable surrogate markers for atrial tachyarrhythmias. Therefore, mode switching may serve as a valuable tool for clinical decision making and further research into the natural history and burden of atrial tachyarrhythmias.     

Dual chamber pacing: how many patients remain in DDD mode over the long term?

OBJECTIVE--DDD pacing is better than VVI pacing in complete heart block and sick sinus syndrome but is more expensive and demanding. In addition, some patients have to be programmed out of DDD mode and this may have an important impact on the cost-effectiveness of DDD pacing. The purpose of this study was to determine how many patients remain in DDD mode over the long term (up to 10 years). DESIGN--A retrospective analysis of the outcome over 10 years of consecutive patients who had their pacemakers programmed initially in DDD mode. SETTING--A district general hospital. PATIENTS--249 patients with DDD pacemakers. Sixty two patients (24.9%) had predominantly sick sinus syndrome and 180 (72.3%) had predominantly atrioventricular conduction disease. Mean (range) complete follow up for this group of patients was 32 months (1-10 years). RESULTS--Cumulative survival of DDD mode was 83.5% at 60 months. Atrial fibrillation was the commonest reason for abandonment of DDD pacing. Atrial fibrillation developed in 30 patients (12%), with atrial flutter in three (1.2%). Loss of atrial sensing or pacing, pacemaker mediated tachycardia, and various other reasons accounted for reprogramming out of DDD mode in eight patients (3.2%). Overall, an atrial pacing mode was maintained in 91% and VVI pacing was needed in only 9%. CONCLUSIONS--With careful use of programming facilities and appropriate secondary intervention, most patients with dual chamber pacemakers can be maintained successfully in DDD or an alternative atrial pacing mode until elective replacement, although atrial arrhythmia remains a significant problem. There are no good reasons, other than cost, for not using dual chamber pacing routinely as suggested by recent guidelines and this policy can be achieved successfully in a district general hospital pacing centre.     

Vorhofflimmern: Stimulation und Schrittmachertherapie

Pacing therapy is well established in all cases of symptomatic bradyarrhythmic atrial fibrillation. In paroxysmal or persistent atrial fibrillation, the implanted dual chamber pacemaker device should incorporate an automatic mode switching algorithm. Mode switch in case of atrial fibrillation detection avoids pacemaker mediated rapid ventricular pacing during an atrial tachyarrhythmia and allows to perform dual chamber pacing during phases of sinus rhythm which is the preferable mode due to improved hemodynamics, rate adaptation, lower progress in atrial fibrillation burden and a lower rate of thromboembolic events as compared to ventricular pacing. PERSPECTIVE: The possibility to prevent from atrial fibrillation recurrencies by pacing is currently under investigation. Various methodological approaches, for example multisite or alternate single site pacing, preventive pacing algorithms or hybrid- and even triple-therapy concepts are used for that purpose. Due to the theoretical point of view, that all these pacing interventions may reduce atrial fibrillation but also have the potential to act in a proarrhythmic manner, the data from adequately designed trials is of major importance: Septal pacing and preventive pacing algorithms seem to have a beneficial effect in a limited number of so far available studies. CONCLUSION: In clinical practice, preventive pacing and/or placement of the atrial lead in a septal position should therefore be available in those patients with a conventional pacing indication in addition to symptomatic recurrent atrial fibrillation. Preventive pacing is so far with a significant and not-predictable amount of non-responders no "early" stage of therapy in patients with recurrent symptomatic atrial fibrillation and no additional conventional pacing indication.     

M-mode echocardiograms for determination of optimal left atrial timing in patients with dual chamber pacemakers

To determine if the A wave of the mitral valve echocardiogram can be used as a marker for left atrial (LA) activity and assist in the programming of dual chamber pacemakers, 156 echocardiograms with the mitral A wave present were obtained from 23 patients with dual chamber pacemakers, all of whom had bipolar esophageal recordings of LA depolarization. Twelve of these patients also underwent hemodynamic study with cardiac function determined at 5 different pacemaker settings: ventricular demand pacing and dual chamber sequential pacing at 0 or 25, 150, 200 and 250 ms programming atrioventricular (AV) delay. The time delay from right atrial pacing artifact to onset and peak of mitral A wave was linearly related to the time from atrial pacing artifact to LA depolarization on the esophageal lead (p less than 0.001). As pacing mode changed from dual chamber sequential pacing (DVI) mode to atrial synchronous-ventricular pacing (VDD), the A wave came earlier relative to the ventricular pacing spike, linearly related to the LA to ventricular extension with mode change determined with the esophageal lead (r = 0.94, p less than 0.001). The time from atrial pacing to peak of A wave was shorter in patients whose optimal programmed AV delay was 150 ms compared with those whose optimal AV delay was 200 or 250 ms (p less than 0.02). At the optimal programmed delay for cardiac output, the peak of the A wave was an average of 13 +/- 36 ms after the ventricular pacing spike.(ABSTRACT TRUNCATED AT 250 WORDS)     

Realisierbarkeit und Sicherheit einer alleinigen AAI(R)-Schrittmacherbehandlung beim isolierten symptomatischen Sinusknotensyndrom

Recent investigations prove that AAI(R) pacing is the "ideal" stimulation mode in isolated sick sinus syndrome. Nevertheless, in Germany this bradycardia is treated by AAI(R) pacemakers in less than 4% of cases compared to 25% in other countries. In our institution treatment of patients with isolated sick sinus syndrome is uniform and corresponds to the actual guidelines since the early 1990s; therefore the aim of our study was to analyze feasibility and safety of AAI(R) pacing in a retrospective study.Between 1998 and 2000, 52 of 165 patients (31.5%) with isolated sick sinus syndrome were treated by an AAI(R) pacemaker. The median follow-up duration was 51.5 months (minimal: 36 months). 6 patients died, in all cases unrelated to the stimulation mode. Three patients required reoperations, however, in only one case due to second degree AV block with the need for upgrading to DDD stimulation. Thus, the yearly incidence of this specific complication in the AAI(R) cohort is 0.64%.In conclusion, permanent atrial stimulation in isolated sick sinus syndrome is feasible in a quarter of all cases. It is safe if performed corresponding to actual guidelines. Additionally, single lead AAI(R) pacing is a cost-effective therapy and the only stimulation mode which, today, reliably prevents unnecessary right ventricular stimulation. If, on the other hand, algorithms providing automatic mode switching from AAI to DDD and vice versa are implemented reliably into all dual chamber pacemakers, single chamber atrial pacing will no longer be a subject for discussion.     

Single chamber atrial pacing: an underused and cost-effective pacing modality in sinus node disease

Objective—To determine the safety and cost effectiveness of single chamber atrial pacing in patients with sinus node disease.
Design—Retrospective follow up study.
Setting—Tertiary referral centre.
Patients—81 patients with single chamber atrial pacemakers implanted between 1992 and 1996.
Main outcome measures—The development of high grade atrioventricular block resulting in a further pacemaker procedure. The cost savings of changing our current pacing practice to conform with British Pacing and Electrophysiology Group guidelines.
Results—During the follow up period, four patients (5.8%) required a further procedure to upgrade their atrial pacemaker to a dual chamber system owing to the development of high grade atrioventricular block. In 1995 and 1996, 343 pacemakers were implanted in patients with sinus node disease; 19 (5.5%) received single chamber atrial pacemakers and 271 (79%) dual chamber pacemakers. If the current pacing practice was changed so that all patients received single chamber atrial pacemakers, with revision for symptomatic atrioventricular block, savings in excess of £206 000 would have been made in the two year period.
Conclusions—Atrial pacing in patients with sinus node disease is underused. The need for patients to undergo further procedures owing to the development of atrioventricular block is small and significant cost savings could be made by changing pacemaker practice.

Keywords: sinus node disease;  atrial pacing;  cost effectiveness     

Mode-Switch-Algorithmen: Programmierbarkeit und Nutzen

BACKGROUND: Automatic mode switching is defined as the ability of a pacemaker to reprogram itself from tracking to non-tracking mode in response to atrial tachyarrhythmias, and to regain tracking mode as soon as the tachyarrhythmia terminates. In contrast to upper rate behavior, mode switching does not only limit atrial tracking at a certain rate but actively drives the ventricular pacing rate back to lower rate or sensor rate as long as the atrial tachyarrhythmia persists. In contrast to DDD with mode switch, AV synchrony may be lost in DDIR mode if the sinus rate exceeds the sensor rate. DDD pacing with mode switching represents a valuable option in patients with AV block and paroxysmal atrial tachyarrhythmias. It may prevent the transition from paroxysmal to permanent atrial fibrillation after AV node ablation to a higher extent than VVI(R) pacing. On the other hand, patients with sinus node disease and normal AV conduction may benefit from DDIR mode with long AV interval. Mode switching should provide a rapid, sensitive and specific detection of atrial tachyarrhythmias, fast switch to non-tracking mode without ventricular pacing at the upper rate limit, adequate ventricular rate during the atrial tachyarrhythmia, rapid, sensitive and specific detection of conversion to sinus rhythm and fast switch back to tracking mode. In addition, oscillations between DDD and DDI mode with sudden ventricular rate changes should be avoided. MODE-SWITCHING ALGORITHMS: To achieve these aims, different mode-switching algorithms have been developed which all show specific disadvantages: reliable but slow response to atrial tachyarrhythmias, fast but unspecific switch to non-tracking mode, mode oscillations, inclination to inadequate mode-switching due to ventricular far-field sensing, failure to perform modeswitching during atrial flutter or intermittent atrial undersensing. Some of these problems can be avoided by careful atrial lead implantation providing atrial signals above 2 mV and avoiding ventricular far-field signals. Programming of mode-switching related parameters (e.g. atrial rate and number of fast beats required for mode switch), atrial blanking times, and atrial sensitivity can solve some of the problems with mode switching. Clinical results show a strong influence of device programming and atrial undersensing on mode-switching performance. Some data suggest a superiority of fast mode-switching algorithms with regard to clinical symptoms. However, loss of AV synchrony during sinus rhythm due to premature or inadequate mode switching may limit the benefit of fast mode switching. FURTHER DEVELOPMENTS: Improved performance may be achieved by a combination of different mode-switching algorithms (e.g. one algorithm for detection of atrial fibrillation, another one for detection of atrial flutter). In addition, programmability of several algorithms (e.g. mean atrial rate, beat-to-beat, x out of y) within the same device and atrial cycle-dependent sensitivity adjustment similar to automatic gain control in implantable defibrillators may further increase the clinical use of automatic mode switching.     

Doppler echocardiographic study of mitral and aortic flow at various rates and atrioventricular intervals in patients with dual chamber pacemakers

The aim of this study was to measure the changes in mitral and aortic blood flow induced by rate changes and different atrioventricular intervals in dual chamber pacemaker patients. Ten totally pacemaker dependant patients were studied under basal conditions, in double atrial and ventricular stimulation mode, by pulsed Doppler recordings of mitral and aortic flow, at three different pacing rates (80, 100 and 120/mn) and with three different atrioventricular intervals at each rate (short, 90 or 115 ms; medium, 165 or 190 ms; and long, 240 ms). The increase in pacing rate and prolongation of the atrioventricular interval significantly shortened the duration of mitral flow. Increasing the pacing rate induced a significant fall in stroke volume measured from the aortic flow. The optimal atrioventricular interval tended to shorten when the pacing rate was increased; a long atrioventricular interval had a deleterious effect on stroke volume compared with medium and short atrioventricular intervals; however, the difference between the short and medium atrioventricular intervals was not statistically significant even at 120 mn. These observations emphasise the hemodynamic advantages of shortening of the atrioventricular interval of dual chamber pacemakers when the pacing rate increases.