动态心电图对起搏器植入术后患者的随访价值

目的探讨动态心电图对起搏器植人术后患者合并心律失常、心肌缺血及起搏器的工作状态的检测效果。方法回顾性分析196例植入起搏器的患者的一般资料、植入起搏器类型及动态心电图对其术后合并心律失常、心肌缺血及起搏器的工作状态的检测资料。结果根据植入起搏器的类型将人选患者分为5组,其中心室起搏心室感知抑制型（ventricle pace-making ventricle sensation inhibitory,VVI）组120例：心房起搏心房感知抑制型（atriumpace-making atrium sensation inhibitory,AAI）组32例：心房心室双起搏双感知双反应型（duplicate pace-making duplicate sensation duplicate response,DDD）组25例：心室起搏心房心室感知双反应型（ventricle pace-making duplicate sensation duplicate response,VDD）组14例;埋藏式心脏复律除颤器（implantable cardioverter defibrillator,ICD）组5例。动态心电图观察发现VVI组中心律失常发生率、起搏器功能障碍发生率和ST-T改变发生率比AAI组,DDD组,VDD组高,ICD组例数太小,未作比较,但因5组例数相差悬殊,未做统计分析。动态心电图对起搏器功能障碍检出率及ST-T改变检出牢均比常规心电图的检出率高[24．5％（48／196）比4．1％（8／196）,36．7％（72／196）比17．3％（34／196）,P均〈0．05]。结论动态心电图是起搏器植入术后患者的重要随访手段。     

DDD起搏器:心房和心室通道的感知不应期(114)

正DDD起搏器为双腔起搏器,其心房和心室各有独立的感知系统,两个独立的系统分别与AAI和VVI起搏器一样,当感知到患者自身心电信号或起搏脉冲发放后都将启动感知系统的不应期。左图中(2)和(3)分别为心室和心房的感知系统不应期,而心房的感知不应期又与起搏器设置的房室间期AVI值相同。     

VVI起搏心电图

VVI起搏心电图属单腔心室起搏心电图,是熟悉和学习起搏心电图的基本功,我国目前VVI起搏器仍占起搏器植入总量的50%以上。因此,心电图和内科医师必须首先掌握VVI起搏心电图。1.VVI起搏器的基本概念VVI起搏器的3个代码分别指起搏器起搏的心腔为心室腔(用V表示)、感知的心腔为心室     

不同起搏方式对病窦综合征患者房颤发生率的影响

目的　比较病窦综合征患者经心室按需起搏 (VVI)和心房起搏 [包括单心房起搏(AAI)、房室双腔起搏 (DDD)和双房起搏 ]治疗术后前 5年房颤的发生率。方法　对永久性人工心脏起搏器植入术后 5年以上、资料完整的 117例病窦综合征患者进行连续随访 ,平均随访时间(69.3± 6.7)个月 ,其中VVI起搏 83例 ,心房起搏 3 4例。随访内容包括临床表现、心电图和起搏器参数等 ,部分患者有Holter检查资料 ,分析 5年内两组病例房颤的发生率。结果　病窦综合征患者心脏起搏治疗前 5年内总的房颤发生率为 17.0 9% (2 0 /117) ,其中经VVI起搏的 83例患者房颤发生率为 2 2 .89% (19/83 ) ,经心房起搏的 3 4例患者房颤发生率为 2 .94% (1/3 4) ,后者房颤的发生率显著低于前者 (P <0 .0 1)。结论　在起搏治疗的病窦综合征患者中 ,术后前 5年心房起搏比心室起搏治疗有较低的房颤发生率     

中老年起博器植入患者的动态心电图分析

目的探讨动态心电图（DCG）监测对起搏器起搏及感知功能异常的诊断价值。方法采用美国惠普43400B型DCG分析系统,对95例年龄在50岁以上植入起搏器的患者进行随访,分析起搏、感知功能及与起搏器相关的心律失常并与常规心电图对照。结果共检出起搏器功能障碍23例,其中间歇性起搏功能障碍2例（占2%）,间歇性感知功能障碍21例（占22%）。检出与起搏器相关的心律失常17例（18%）。而常规心电图仅发现感知功能障碍2例。两种检查方式在检测间歇性感知功能障碍及与起搏器相关的心律失常方面存在显著性差异（P<0.01）。检出起搏功能异常的差异性未达到显著水平。DCG对3种类型（AAI、VVI、DDD）之间感知功能异常检出率无显著性差异。根据DCG结果,进行临床相应处理后,起搏器的起搏及部分感知功能障碍消失,相关心律失常引起的临床症状逐渐消失。结论起搏器的起搏、感知功能障碍及与起搏器相关的心律失常多为间歇性发生,DCG对其检出率较高,并可系统了解起博器工作状态及各种心律失常,是对起博器随访的重要手段之一。     

生理性与非生理性起搏对术后房性心律失常的影响

探讨病窦综合征 (SSS)、房室阻滞 (AVB)患者安置生理性起搏器 (AAI/DDD)与非生理性起搏器 (VVI)对术后房性心律失常的影响 ,分别对 4 6例AAI/DDD与 6 1例VVI起搏患者进行术前及术后近 1年的心电图、动态心电图、心脏超声心动图检查随访。结果 :AAI/DDD组房性心律失常的发生率由术前的 5 0 %降至术后的 32 % ,VVI组发生率由术前的 4 4 .2 %上升至术后的 6 5 .5 % ,差异有显著性 (P <0 .0 1)。AAI/DDD组术后左室射血分数和心输出量改善 (P <0 .0 5 ) ,房室大小无明显变化 (P >0 .0 5 ) ;VVI组术后左室射血分数和心输出血下降 ,心房、心室扩大 (P <0 .0 1)。结论 :生理性起搏优于非生理起搏 ,前者有利于消除心律失常、改善心功能。     

心脏起搏对心动过缓患者心功能及房性心律失常的影响

目的:评价不同起搏方式(DDD方式和VVI方式)对长期心脏起搏患者心功能及心律失常的影响。方法:分别对43例VVI起搏治疗和32例DDD起搏治疗患者进行临床、心电图、超声心动图的定期随访,随访时间平均为34±6.8个月和32±8.3个月。结果:与治疗前比较,R波抑制型起搏器(VVI)组随访期左房内径明显增大,左室射血分数(LVEF)显著减退(P均<0.05);房室全能型起搏器(DDD)组左房内径、LVEF无显著差异;与DDD组比较,VVI组左房内径明显增大(P<0.01),LVEF显著减退(P<0.01),房性心律失常明显增加(P<0.01),心功能显著恶化(级别显著增加),P<0.05。结论:DDD心脏起搏器可显著改善心功能,减少房性心律失常,比VVI起搏器为佳。     

心室起搏心律不适患者的起搏器参数优化

目的通过对起搏器参数的优化,尽可能减少心室起搏,提高患者生活质量。方法 2005年1月~2013年10月在我院病态窦房结综合征(SSS)患者植入双腔起搏器后心室起搏时诉胸闷、心悸不适,82例患者,设置最长的房室间期(AVD),延长心室后心房不应期(PVARP)至450ms,关闭心室自动阈值夺获功能,如仍有不适症状,通过起搏器程控仪较长时间监测或Holter等检查方法查找发生心室起搏的原因,并进行相应的处理。结果 62例病人症状消失,仍有20例有不适症状。导致心室起搏的原因及处理方法如下:(1)2例活动后因起搏器频率适应性功能致心房起搏频率增加后,出现二度I型房室阻滞,关闭频率适应性起搏功能后症状缓解;(2)2例因心房误感知设置较高的感知灵敏度后心室起搏消失;(3)2例提高心房起搏电压,1例重新植入心房电极,解决了心房失夺获从而避免了心室起搏;(4)5例阵发性房速/房扑患者缩短心室后心房空白期,使模式转换能发生,3例心房率较慢的房速患者设置为DDI模式,5例房颤患者降低下限频率,减少了心室起搏。结论心室起搏心律不适患者设置较长的AV间期,设置PVARP 450ms,关闭心室自动阈值夺获功能,如仍有不适症状,通过起搏器程控仪进行较长时间的心电监护或动态心电图检查找出导致心室起搏的原因,并对起搏器相关参数进行设置,能有效减少或消除心室起搏。     

病窦综合征患者心房起搏的随访结果

<正> 病窦综合征患者既可以选择心房起搏方式(AAI),也可以选择心室起搏方式(VVI),或双腔起搏(DDD).但DDD起搏费用偏高,而使部分病人难以接受,VVI起搏方式存在室房分离,因而难以保持心房收缩时对心室充盈的辅助泵作用,起搏器综合征,心房颤动,心力衰竭,血栓栓塞等并发症均较高,而且不能改善生存率.AAI起搏保持了房室顺序及心室同步功能,具有良好的血流动力学效应.是近年来病窦综合征患者主要的起搏方式之一.本文对45例心房起搏患者进行了随访,现报告如下.     

心房颤动致DDD起搏器介导的心动过速一例

<正> 患者男性,58岁。因头晕、黑矇7个月,晕厥3次入院。心电图示:窦性心率40bpm。食管心房调搏:窦房结恢复时间2700ms同时出现继发性窦性停搏达4700ms,文氏阻滞点<120bpm,未诱发出快速心律失常及心房颤动(简称房颤)。提示:窦房结功能衰竭,房室传导不良。临床拟诊:冠心病,病态窦房结综合征,阿-斯综合征。于1991年11月27日安装CPI公司Delta TRS 937 DDD起搏器,术中安置心房电极时,由于反复机械刺激心房而诱发房颤,待起搏器植入体内,心电图示:心室起搏频率过速(120～125ppm)。此时起搏器为DDD工作方式,其有关参数:起搏频率65ppm,最大频率(MTR)125ppm,房室延迟150ms,心房感知度0.75mV,心室搏动后的心房不应期(PVARP)250ms,疑为起搏器介导的心动过速(PMT)。采用程控器程控为VVI型,心动过     

射频消融和DDD起搏器治疗典型心房扑动伴缓慢心室率五例

目的探讨典型心房扑动(简称房扑)伴缓慢心室率的介入治疗。方法5例房扑伴缓慢心室率患者,房扑频率240～260次/分,房室传导比例5:1～6:1。1例患者已置入VVI起搏器,但仍有症状。对房扑采用解剖学影像定位法消融下腔静脉与三尖瓣环的峡部。对缓慢心室率采取DDD起搏器治疗(1例VVI改换DDD)。结果消融中房扑终止,峡部达双相阻滞,房扑终止后1例为Ⅱ度Ⅱ型房室传导阻滞,4例为Ⅲ度房室传导阻滞。均成功置入DDD起搏器。随访7～37个月,房扑未见复发,起搏器工作良好,患者症状消失。结论射频消融和DDD起搏器联合治疗典型房扑伴缓慢心室率患者有效而且安全。     

VVI mode cardiac pacing: cause or risk factor of cerebral embolism?]

Epidemiological studies suggest that VVI pacing is associated with a higher risk of embolic complications than atrial or dual chamber pacing. However, no studies have been performed on pacemaker patients admitted to a neurological department with a cerebral embolism. The authors report the cases of 8 patients (6 men and 2 women) with an average age of 74 years and having the following characteristics: 1) a cerebral embolism, 2) a permanent cardiac pacemaker (7 VVI and 1 DDD mode). The average delay between implantation of the pacemaker and the neurological complication was 31 months. Cardiological investigations at the time of admission showed: a clinically evident cause of cardiac embolism in 3 cases (2 with VVI and 1 with DDD pacing); paroxysmal or permanent atrial fibrillation in 4 cases with VVI pacing at the time of the embolic event (in only one case at the time of implantation); various echocardiographic abnormalities in 6 of the 7 patients who underwent this examination, mainly left atrial dilatation (6/7), septal wall motion abnormalities in all related to ventricular pacing and unexplained left ventricular dilatation in 2 patients with VVI pacemakers. These results suggest that although the etiology of cerebral embolism was probably multifactorial in some patients, VVI packing probably a predisposing role, though not the only cause, and could be considered to be an embolic risk factor as suggested by previous epidemiological studies. These preliminary retrospective data should be interpreted cautiously taking into account the small population size. Prospective studies on pacemaker patients with cerebral embolism are required.     

A review of pacemakers that physiologically increase rate: The DDD and rate-responsive pacemakers

There is little question that the rate responsive pacemaker is beneficial and affords better exercise responsiveness than the VVI by increasing cardiac output during exercise. Each method for controlling rate promises certain advantages, and experiences other compromises in practical implementation. The development of better sensor technology is necessary before some potentially sound methods of control can be investigated practically. Some methods will likely be indicated for certain patient groups, while other methods will better benefit other populations. A single rate responsive method that is superior to all others has not yet surfaced.Rate responsive pacemakers that sense parameters other than atrial rate are indicated in several cases, including sick sinus syndrome, atrial fibrillation, and atrial flutter which cause bradycardia. In fact, most patients with A-V block who would ordinarily receive a VVI pacemaker may benefit from a rate responsive pacemaker.Those patients with sick sinus syndrome and intact A-V conduction who are paced with atrial (AAI) or dual chamber (DDD) will receive the most obvious benefit by the addition of rate responsiveness to atrial pacing. VVI-paced patients in this population will also benefit, although they will lack the A-V synchronous contribution. A-V synchrony plays a less important role as pacing rate increases; the contribution of increased rate to cardiac output is more significant than synchrony at higher rates.^150–152 A-V synchrony may be more significant in compromised hearts, where large increases in rate are contraindicated.Patients with arrhythmias such as atrial fibrillation and flutter-precipitating bradycardia will benefit from rate responsiveness, because atrial rate is unstable and therefore unreliable for atrial-triggered pacing. These arrhythmias may accompany complete heart block due to disease, valve replacement or His-bundle ablation. Rate responsiveness not based on atrial rate is indicated to avoid the inappropriate ventricular rates that result from high atrial rates.For complete heart-block patients with normal atrial conduction and no atrial arrhythmias, the indicated pacing modes include VVI, rate responsive (VVI), and atrial-triggered pacing (such as DDD). Patients who are asymptomatic with VVI pacing may derive additional exercise tolerance and sense of well-being with a rate responsive pacemaker. The DDD appears to be indicated for patients who remain symptomatic at rest with VVI-mode pacing. However, for those not prepared for dual chamber implants, the rate responsive VVI pacemaker represent a second alternative.For patients who are in the lower functional classes based on the New York Heart Association scale and who can sustain an active fitness program, the rate responsive VVI provides higher ventricular rates without the threat of pacemaker-mediated tachycardia experienced with the DDD. For patients in the higher functional classes where exercise is less tolerated, the need is for efficient production of cardiac output during daily activities. The rate responsive VVI may allow lower basal rates increasing cardiac perfusion by lengthening diastole. During activity pacing rate can be increased moderately to provide a sense of well-being.The rate responsive techniques are at various stages of development. Obviously, the atrial-triggered (DDD) is the most developed.The practical use of pH awaits the development of a reliable sensor. Early clinical trials were abandoned because of the difficulty. The magnitude of the minute variations in pH constrains the sensor to having high stability. “pH” responds quickly and potentially has high specificity.QT-controlled pacemakers, which use the ventricular electrode for sensing, have been implanted in over 2,000 patients in Europe. Adequate T wave sensing and QT interval stability are necessary. QT interval responds quickly and has medium specificity.Pacemakers controlled by respiratory rate, using electrodes to sense transthoracic impedance, have been implanted in over 1,000 patients in Europe. The additional subcutaneous implantation of the remote impedance electrode is necessary. Respiratory rate responds quickly and has good specificity.Physical activity, sensed as acceleration within the pulse generator case, is being clinically tested in Europe and the United States. Implantation is similar to the standard VVI. Activity has fast response and medium to low specificity.Temperature-controlled pacemakers, using a thermistor in the pacing lead to sense blood temperature, have been implanted in Europe. Temperature has fast response to most forms of exercise and medium to others. The specificity is good.The stroke volume pacemaker awaits the development of a sensor. Right ventricular impedance proposed as the sensing means is technically obtainable, but requires more research to verify the technique's stability with catheter movement and right-to-left association. The response based on stroke volume should be fast; the specificity depends upon the sensor.Oxygen saturation, measured in venous blood, lacks a proven long-term sensor. Current efforts are focused toward optical and solid state sensors. An optical sensor unaffected by fibrin encapsulation is necessary. Long-term stability of solid state sensors has not been demonstrated.BP, or some function of pressure measured within the cardiovascular system, may prove to be an indicator for rate control. Sensor technology and physiologic understanding are still progressing. Other quantitites, such as circulating levels of catecholamines, are being considered.It is evident that the availability of a sensor is a key limitation to several techniques. More mature sensors will allow more optimal detection of physiologic needs. Also evident is the need for rate responsive pacemakers that complement the DDD to provide adequate treatment and sense of well-being to all pacing patients. These and future concepts for controlling pacemaker rate according to the body's needs provide the basis for tomorrow's pacemakers.     

Influence of Cardiac Pacing Mode on Left Atrial Appendage Flow Velocity: Implication to Systemic Embolism During VVI Pacing

Previous studies have shown that the incidence of thromboembolism is higher in patients with single-chamber ventricular demand (VVI) pacemakers than in patients with dual-chamber (DDD) pacemakers. However, data on left atrial appendage flow velocity in pacing patients are limited. To investigate the influence of the pacing mode on the left atrial appendage flow velocity, we studied 19 patients with permanent DDD pacemakers and measured the left atrial appendage flow velocity by transesophageal echocardiography at baseline (during DDD pacing) and after switching to VVI pacing. The indications for pacemaker implantation were second- and third-degree atrioventricular block (AVB group, n = 11) and sick sinus syndrome (SSS group, n = 8). Compared with the DDD pacing mode, there was a significant decrease in the left atrial appendage flow velocity during VVI pacing in both the SSS group (43 ± 14 vs 23 ± 7 cm / sec, P < 0.05) and the AVB group (59 ± 18 vs 41 ± 18 cm / sec, P < 0.05). In eight patients with persistent retrograde ventriculoatrial conduction during VVI pacing, the left atrial appendage flow velocity was markedly decreased (from 43 ± 16 to 25 ± 9 cm / sec, P < 0.05). In five (63%) of the eight patients, left atrial appendage flow velocity was less than 25 cm/sec. A reduction in left atrial appendage flow velocity when switching from DDD to VVI pacing may account for an increased risk of thrombus formation in the left atrial appendage (an increased thromboembolic risk in patients in sinus rhythm with VVI pacemakers).     

不同起搏模式对病态窦房结综合征患者心功能长期影响的探讨

目的前瞻性观察不同起搏模式对心功能长期的影响并探讨可能机制。方法 185例病态窦房结综合征（SSS）患者均采用常规方法经锁骨下静脉途径成功置入永久双腔心脏起搏器,术后即刻程控起搏器,根据SAS软件的PROC程序产生一组随机序列分为AAI（92例）及DDD（93例）起搏组。采用心脏超声观察术前,术后1、2、5年左室舒张末容积（LVEDV）、左室收缩末容积（LVESV）及左室射血分数（LVEF）的变化,比较两种起搏模式对左心功能的影响;术后1、2及5年进行随访结合起搏器程控记录房颤发生并记录DDD起搏组右室起搏百分比（VP%）,探讨VP%与心功能变化及房颤发生的关系。结果 AAI起搏组术前,术后1、2、5年随访LVEDV,LVESV及LVEF比较差异无统计学意义（P〉0.05）,DDD起搏组术前、术后1、2、5年LVEDV差异无统计学意义（P〉0.05）,术后5年LVESV（60.33±13.28）ml较术后1、2年增加,差异有统计学意义（F=2.7388,P〈0.05）,术后5年LVEF（41.75±8.74）%较术前、术后1、2年明显降低,差异有统计学意义（F=33.4393,P〈0.05）;AAI组与DDD组房颤的发生差异有统计学意义（P〈0.05）。术后5年DDD组中〈50%VP%,组中出现房颤患者为3例,≥50%VP%组中出现房颤患者为15例,两组之间房颤的发生率差异有统计学意义（P〈0.05）。结论在DDD起搏模式下,高的VP%可对患者的左心功能造成损害并增加房颤的发生。对于不合并房室传导阻滞的SSS患者,AAI起搏较DDD起搏能使患者更受益。     

Intermittent pacemaker dysfunction caused by digital mobile telephones

Objectives. This study was designed to evaluate possible interactions between digital mobile telephones and implanted pacemakers.Background. Electromagnetic fields may interfere with normal pacemaker function. Development of bipolar sensing leads and modern noise filtering techniques have lessened this problem. However, it remains unclear whether these features also protect from high frequency noise arising from digital cellular phones.Methods. In 39 patients with an implanted pacemaker 14 dual-chamber [DDD], 8 atrial-synchronized ventricular-inhabited [VDD(R)] and 17 ventricular-inhibited [VVI(R)] pacemarkers), four mobile phones with different levels of power output (2 and 8 W) were tested in the standby, dialing and operating mode. During continuous electrocardiographic monitoring, 672 tests were performed in each mode with the phones positioned over the pulse generator, the atrial and the ventricular electrode tip. The tests were carried out at different sensitivity settings and, where possible, in the unipolar and bipolar pacing modes as well.Results. In 7 (18%) of 39 patients, a reproducible interference was induced during 26 (3.9%) of 672 tests with the operating phones in close proximity (<10 cm) to the pacemaker. In 22 dual-chamber (14 DDD, 8 VDD) pacemakers, atrial triggering occurred in 7 (2.8%) of 248 and ventricular inhibition in 5 (2.8%) of 176 tests. In 17 VVI(R) systems, pacemaker inhibition was induced in 14 (5.6%) of 248 tests. Interference was more likely to occur at high power output of the phone and at maximal sensitivity of the pacemakers (maximal vs. nominal sensitivity, 6% vs. 1.8% positive test results, p = 0.009). When the bipolar and unipolar pacing modes were compared in the same patients, ventricular inhibition was induced early in the unipolar mode (12.5% positive test results, p = 0.0003).Conclusions. Digital mobile phones in close proximity to implanted pacemakers may cause intermittent pacemaker dysfunction with inappropriate ventricular tracking and potentially dangerous pacemaker inhibitions.     

永久性心脏起搏器86例临床分析

目的:分析不同心脏起搏部位及起搏模式对永久性心脏起搏治疗患者心功能及生活质量的影响。方法:入选2004年至2006年行永久性起搏器植入手术的患者86例,其中A组:单腔心室起搏(VVI)心尖起搏组(right ventricle apex RVA)31例;B组:VVI高位室间隔起搏组(right high-interventricular septum RHIVS)8例;C组:双腔心脏起搏(DDD)RVA起搏组38例;D组:DDD RHIVS起搏组9例。分别于起搏治疗前后行心电图、彩色多谱勒超声心动图检查,测量QRS波时限、心脏射血分数(EF)值,左心室舒张末期容积指数(EDVI)和收缩末期容积指数(ESVI),并进行明尼苏达心力衰竭患者生活问卷调查(MLHFQ)。结果:1.单腔起搏器组,无论RVA或RHIVS组术后心功能各项指标(EF、ESVI、ED-VI、MLHFQ)均有下降趋势,A组于术后6个月,B组于术后12个月时出现下降趋势。2.双腔起搏器RVA组于术后12个月时心功能出现下降趋势,而双腔RHIVS组术后与术前比较无明显变化。3.组间比较显示:D组心功能各项指标术后均高于A、B、C组。结论:DDD起搏优于VVI起搏,间隔部起搏明显优于心尖部起搏,特别是DDD间隔部起搏对患者的心功能及生活质量的影响最小,接近于生理起搏。     

Optimum pacing mode for patients with angina pectoris

A within patient double blind prospective study of symptoms and exercise tolerance was designed to determine the preferred pacing mode in 10 patients with programmable dual chamber pacemakers who also had angina pectoris. Patients were randomly allocated to one month in each of the following modes: ventricular pacing at 70 beats/min (VVI) or atrioventricular synchronous upper rate 150 beats/min (DDD 150) or 100 beats/min (DDD 100). Medications were unchanged throughout the study; none was taking beta blockers. At the end of each month patients underwent an exercise test. During each month patients recorded symptoms and their preferred pacing mode. DDD 100 was the preferred mode (seven patients). There was significantly less chest pain with this mode than with either of the other modes. There were significantly more episodes of dizziness in VVI, and two patients who developed pacemaker syndrome were unable to complete the pacing period. Three patients developed angina during exercise testing in DDD 150. Atrial synchronous ventricular pacing is better than ventricular pacing for the control of symptoms in patients with angina pectoris provided that the upper atrial tracking rate is limited.     

Optimum pacing mode for patients with angina pectoris.

A within patient double blind prospective study of symptoms and exercise tolerance was designed to determine the preferred pacing mode in 10 patients with programmable dual chamber pacemakers who also had angina pectoris. Patients were randomly allocated to one month in each of the following modes: ventricular pacing at 70 beats/min (VVI) or atrioventricular synchronous upper rate 150 beats/min (DDD 150) or 100 beats/min (DDD 100). Medications were unchanged throughout the study; none was taking beta blockers. At the end of each month patients underwent an exercise test. During each month patients recorded symptoms and their preferred pacing mode. DDD 100 was the preferred mode (seven patients). There was significantly less chest pain with this mode than with either of the other modes. There were significantly more episodes of dizziness in VVI, and two patients who developed pacemaker syndrome were unable to complete the pacing period. Three patients developed angina during exercise testing in DDD 150. Atrial synchronous ventricular pacing is better than ventricular pacing for the control of symptoms in patients with angina pectoris provided that the upper atrial tracking rate is limited.     

Our experience using continuous atrial stimulation in sick sinus syndrome

Temporary atrial pacing (AAI) was applied in 31 patients with sick sinus syndrome (S.S.S.), including 20 with tachycardia-bradycardia syndrome (t.b.s.). In all patients before pacemaker implantation atrioventricular conduction was estimated using rapid left atrial, transoseophegeal stimulation assuming Wenckebach's point over 120 imp./min to be a physiological one. In all cases, but one ventricular electrodes were implanted and connected with multiprogrammable pacemakers (MP). Follow-up time ranged from 3 to 38 months (mean 18,4). Electrode dislodgment was not observed. In 9 persons sensing disorders were observed but thanks to programming the pacemaker sensitivity they could be resolved almost in all of them. Second degree Mobitz type I a-v block occurred in 3 patients during a long-term follow-up. In one of them changing the pacing mode to VVI was necessary. In persons with tachycardia-bradycardia syndrome cardiac pacing together with pharmacologic therapy allowed to almost eliminate tachycardia attacks. Authors positively estimated AAI pacing mode.