儿童矫正性大动脉转位伴Ⅲ度房室阻滞的VDD生理性？…

一例１１岁矫正性大动脉转位（ＳＬＬ）的女性患儿有晕厥史１０年，超声心动图证实心内无分流，动态心电图及是生理检查均证实为Ⅲ度房室阻滞，窦房结功能正常，安置ＶＤＤ生理性起搏器，感知与起搏电极间距为１３ｃｍ，Ｐ波振幅２．２ｍＶ，心房感知０．７５ｍＶ心室起搏阈值０．４Ｖ，术后观察心房感知率９８％，给心内无分流的心脏畸形患者安置起搏器要充分考虑生理和生长发育的需要，如合理选择起搏器类型和电极长度，进行电生理     

VDD起搏治疗幼儿完全性房室阻滞(附一例报告)

一例３．５岁的女性幼儿因室间隔缺损修补术致迟发性完全性房室阻滞（ＣＡＶＢ）而安置ＶＤＤ起搏器。经锁骨下静脉途径埋置单根心房感知、心室触发起搏电极，使之于右房内塑形并贴靠房壁；起搏器埋于同侧皮下胸大肌筋膜上囊袋内。术中测得起搏阈值０．１Ｖ、脉宽０．４ｍｓ、电极阻抗５２０Ω、Ａ波振幅１．５ｍＶ、Ｖ波振幅１０．６ｍＶ，Ａ波感知设定０．２５ｍＶ。术后房室同步起搏率１００％，临床症状改善。表明ＶＤＤ起搏器不仅埋置简便，而且具有房室同步、频率应答等生理性起搏特点，是治疗幼儿ＣＡＶＢ的理想起搏方式。     

应用非螺旋直电极进行AAI起搏器安置术

应用非螺旋直电极代替Ｊ形电极，普通直导丝代替Ｊ形导丝，为４０例病窦综合征患者安置了心房按需起搏器。即刻起搏阈值０．７２±０．３５Ｖ，感知灵敏度为１．２±０．３ｍＶ与Ｊ形或螺旋电极基本相同。全部患者术后起搏功能正常，除１例因感知灵敏度进行性升高致感知欠佳外，余３９例感知功能良好。未见电极脱位。笔者认为，采用作螺旋直电极安置ＡＡＩ起搏器具有临床实用价值。     

单根电极导管VDD起搏系统的临床应用和随访

对１３例窦房结功能正常的高度房室传导阻滞患者植入单根电极导管ＶＤＤ起搏系统，并进行随访观察。结果显示：术中所测Ａ波平均振幅为２．４±１．４ｍＶ；随访期间（平均１１±４．９个月）Ａ波感知阈值无显著性变化（Ｐ＞０．０５），房室同步起搏率保持在１００％，无心房感知不良、肌电干扰和起搏器介导性心动过速等并发症。表明单电极导管ＶＤＤ起搏系统具有植入简便和房室同步功能稳定的特点，是高度房室传导阻滞伴窦房结功能正常者的理想治疗方法。     

单根电极心室起搏双腔感知双重反应型起搏器心房感知功能的测试观察

目的：观察单根电极心室起搏双腔感知双重反应型起搏器（ＶＤＤ）心房电极感知功能的稳定性。方法：测试了１４例安装单根电极ＶＤＤ的患者在不同体位、扩胸运动及日常活动时的心房漂浮电极的最低感知阈值。并将术中测得的Ｐ波与术后测得的心房最低感知阈值做相关及线性回归分析。结果：１４例中有１２例患者不同体位的心房感知阈值不一致。其中９例在坐、立位时感知阈值最低，将心房感知阈值调至较最低感知阈值低两档的位置后做Ｈｏｌｔｅｒ检查，全部患者心房感知、房室顺序起搏功能良好。扩胸运动中无一例患者出现过度感知。术中所测Ｐ波振幅与术后测得的最低心房感知阈值相关性良好（ｒ＝０．６９，Ｐ＜０．０５）。结论：单根电极ＶＤＤ可替代双电极导管的双腔起搏双腔感知双重反应型起搏器（ＤＤＤ），用于窦房结功能正常的高度房室传导阻滞患者的起搏治疗。     

心房感知不良导致心室安全起搏1例

患者男性 ,６２岁 ,因病态窦房结综合征置入Ｂｉｏｔｒｏｎｉｋ公司产ＡｃｔｒｏｓＤＤＤＤ型起搏器 ,起搏参数为 :ＤＤＤ模式 ,基础频率６０次／ｍｉｎ ,滞后频率ＯＦＦ ,睡眠频率５５次／ｍｉｎ,上限频率１３０次／ｍｉｎ ,动态房室间期１８０／１００ｍｓ,安全房室间期 (ＳＡＶＤ)１００ｍｓ,心房、心室不应期为４２５／３００ｍｓ,心房、心室起搏电压均为３．６Ｖ ,起搏脉宽均为０．４ｍｓ,感知灵敏度为１．５／２．５ｍＶ ,心室空白期为２４ｍｓ。术后心电图示起搏器心房电极感知不良 ,心室频繁安全起搏。心电图 (图１)Ａ、Ｂ行心房感…     

单根电极VDD起搏器的初步应用（附七例报告）

自１９９４年１～１０月共为７例（完全性房室传导阻滞６例、高度房室传导阻滞１例）病人应用了单电极ＶＤＤ起搏器。术后随诊３～１２（平均６．５±２．５）个月，动态心电图监测全部达到心房同步起搏的目的，其中１例有个别间断性Ｐ波感知差而自动转为ＶＶＩ起搏，但总的Ｐ波感知率在９８％以上。如植入病例经严格选择（窦房功能正常的房室传导阻滞），单电极ＶＤＤ起搏可代替双腔ＤＤＤ起搏。     

植入起搏电极参数的测定和随访

为了解起搏阈值、起搏阻抗和感知阈值的变化，对４２根心房电极和４９根心室电极进行了随访。结果显示：心房电极慢性期起搏阈值为１．１７±０．３５Ｖ／０．５ｍｓ，出现波动者６例（２７．３％），心室电极为１．２７±０．３８Ｖ／０．５ｍｓ，出现波动者７例（３０．４％）；１９根电极的起搏阻抗在急性期均有波动，慢性期为５８５．６±１５０Ω，慢性期出现波动者２例（１０．５％）；１１根心房电极慢性期感知阈值（Ｐ波振幅）与植入时相一致。     

单根电极VDD起搏器的初步应用：附七例报告

自１９９４年１－１０月共为７例病人应用了单电极ＶＤＤ起搏器。术后随诊３－１２个月，动态心电图监测全部达到心房同步起搏的目的，其中１例有别间断性Ｐ波感知差而自动转为ＶＶＩ起搏，但总的Ｐ波感知率在９８％以上，如植入病例经严格选择，单电极ＶＤＤ起搏呆代替双腔ＤＤＤ起搏。     

心房不起搏三例

例１女性，６８岁，临床诊断：冠心病，陈旧性下壁、后壁、右室心肌梗死，窦性停搏，交界区逸搏心律。安置ＤＤＤ起搏器时发现心房电极更换了多个部位、起搏电压达１０Ｖ，均不能起搏心房，也不能下传心室，故改为ＶＶＩ起搏。例２女性，９岁，发现心跳慢６年，晕厥２次入...     

Atrial Sensing and AV Synchrony in Single Lead VDD Pacemakers: A Prospective Comparison to DDD Devices with Bipolar Atrial Leads

INTRODUCTION: Single lead VDD pacing has offered an alternative to DDD systems in patients with isolated AV block. Up to now, however, the relative performance of these pacemaker systems was not systematically compared. METHODS AND RESULTS: Three hundred sixty patients who received either a VDD pacemaker (n = 180) or a DDD device (n = 180) with a bipolar atrial lead were investigated prospectively for a mean period of 30 +/- 13 months. Pacemaker function was analyzed by telemetry, Holter monitoring, and exercise ECG. Time of implantation and fluoroscopy was significantly lower with VDD devices (44.3 +/- 5.1 min vs 74.4 +/- 13.5 min and 4.6 +/- 2.5 min vs 10.3 +/- 5.6 min in DDD pacemakers, respectively). Intermittent atrial undersensing occurred in 23.3% of patients with a VDD pacemaker and in 9.4% with DDD devices (NS). The incidence of atrial tachyarrhythmias did not differ between the VDD (6.7%) and the DDD group (6.1%). Sinus node dysfunction developed in 1.9% of patients, but the vast majority (85.7%) of patients were asymptomatic. There was a tendency for a higher rate of operative revisions in the DDD group (6.1% vs 3.3% in VDD pacemakers, P = 0.15). Cumulative maintenance of AV-synchronized pacing mode was 94.9% in patients with VDD pacemakers and 92.1% with DDD devices (NS). CONCLUSION: With the benefit of a simpler implant procedure, long-term outcome of single lead VDD pacing is equivalent to DDD pacing in patients with AV block and preoperative normal sinus node function.     

Single-pass lead VDD pacing system in children and adolescents: report of twenty-four patients

The dual-chamber pacing systems allow for AV synchrony, but generally require the placement of two separate transvenous leads. Single-lead atrioventricular synchronous pacing system (VDD) using single-pass leads has been accepted as therapeutic alternative for atrioventricular block with normal sinus node function. The aim of this study is to evaluate clinical performance of single-pass lead VDD pacing systems in 24 consecutive patients in a ten-year period. The study group includes 17 (70.8%) male and 7 (28.8%) female patients.The mean age and mean weight during pacemaker implantation was 10.4 +/- 3.8 years (4-17 years) and 30 +/- I I kg (13.5-55 kg), respectively. The patients have been followed for 7-84 months (median 42 months). The percentage of atrial sensing-ventricular pacing changed from 75 to 99.9% at the last control. During the follow-up period, pacing mode was changed to VVIR due to complete loss of AV synchrony in five patients (21%). Four of them had underlying cardiac disease. In these patients loss of AV synchrony might be related to cardiac enlargement/abnormal cardiac anatomy or small atrial dipole-ventricular tip length. Despite the loss of AV synchrony in post surgical AV block or dilated cardiomyopathy, single-lead VDD pacing systems can be successfully used in children with complete AV block and normal sinus node function. Patients and lead selection should be taken into consideration for the maintenance of AV synchrony.     

Feasibility of dual-chamber (DDD) pacing via a single-pass (VDD) pacing lead employing a floating atrial ring (dipole): case series, future considerations, and refinements

The objective of this study was to assess the feasibility of DDD pacing from a standard single-pass VDD pacemaker system. Over the past 2 decades significant advances have been made in the development of single-pass VDD pacing systems. These have been shown in long-term prospective studies to effectively preserve atrioventricular (AV)synchrony in patients with AV block and normal sinus node function. What remains problematic is the development of a single-pass pacing system capable of DDD pacing. Such a lead configuration would be useful in those patients with peripheral venous anomalies and in younger patients with congenital anomalies, which may require lead revisions in the future. In addition, with the increased use of resynchronization (biventricular pacing) therapy, the availability of a reliable single-pass lead will minimize operative time, enhance patient safety, and minimize the amount of hardware within the heart. The feasibility of DDD pacing via a Medtronic Capsure VDD-2 (Model #5038) pacing lead was evaluated. Twenty patients who presented with AV block and normal sinus node function were recruited for this study. Atrial pacing thresholds and sensitivities were assessed intraoperatively in the supine position with various respiratory maneuvers. Five patients who agreed to participate in long-term follow-up received a dual-chamber generator and were evaluated periodically over a 12-month period. Mean atrial sensitivity was 2.35 +/- 0.83 mV at the time of implantation. Effective atrial stimulation was possible in all patients at the time of implantation (mean stimulation threshold 3.08 +/- 1.04 V at 0.5 ms [bipolar], 3.34 +/- 0.95 V at 0.5 ms [unipolar]). Five of the 20 patients received a Kappa KDR701 generator, and atrial electrical properties were followed up over a 1-year period. There was no significant change in atrial pacing threshold or incidence of phrenic nerve stimulation over the 1-year follow-up. A standard single-pass VDD pacing lead system was capable of DDD pacing intraoperatively and during long-term follow-up. Despite higher than usual thresholds via the atrial dipole, pacemaker telemetry revealed < 10% use of atrial pacing dipole over a 12-month period, which would minimally deplete the pacemaker's battery. In addition, the telemetry confirmed appropriate sensing and pacing of the atrial dipole throughout the study period. At this time such systems can serve as back-up DDD pacing systems with further refinements required to optimize atrial thresholds in all patients.     

Pre-implant determinants of adequate long-term function of single lead VDD pacemakers.

AIMS: An inherent limitation of single lead VDD pacing is the inability to stimulate the atria. Reprogramming and upgrading the pacemaker system may be required when sinus node dysfunction, atrial undersensing, or atrial fibrillation develop. We evaluated whether routine clinical information is sufficient to select patients to benefit in long-term from VDD pacing. METHODS AND RESULTS: We collected data on 12-lead and monitored electrocardiograms and routine clinical information at implantation of a VDD pacing system in 350 consecutive patients with grade II or III atrioventricular conduction block. The age at implantation was 74.5 +/- 8.0 years, and the follow-up lasted 1.5 +/- 1.5 years. The cumulative maintenance of VDD pacing mode was 91.%. Loss of VDD mode was due to permanent atrial fibrillation in 16 (4.6%), sinus node dysfunction in six (1.7%). atrial undersensing in 11 (3.1%). Chronic atrial fibrillation developed in 23% of patients who had heart enlargement in chest x-ray and a history of paroxysmal atrial fibrillation or flutter. A criterion of normal sinus rate at implantation sufficiently predicted adequate sinus node function. Poor atrial sensing was not predicted by pre-implant characteristics. CONCLUSIONS: According to our data, adequate sinus-driven atrial rate and no history of paroxysmal atrial fibrillation and cardiac enlargement predict maintenance of the VDD pacing mode in elderly patients treated for heart block. Routine information available at implantation is sufficient to guide acceptance of single lead VDD pacing therapy.     

Long-term evaluation of a new single lead VDD pacemaker]

Since June 1988 we have implanted 36 VDD pacemakers with single lead catheter which has floating differential sensing (Phymos). The patients were affected by 2nd and 3rd degree AV block with normal sinus node function. The reliability of the pacing system was assessed acutely and after 1 and 3 months and then every six months with ECG, Holter 24 hours monitoring, exercise stress test and nifedipine test. Two patients died during the follow-up period and two had atrial fibrillation. In the remaining patients an AV synchronization between 95 and 100% was demonstrated.     

VDD起搏对缓慢性心律失常心力衰竭的血液动力学影响

为了评估ＶＤＤ起搏对缓慢性心律失常心力衰竭的血液动力学影响，对２１例心功能Ⅲ～Ⅳ级的缓慢性心律失常病人安置ＶＤＤ起搏器，并用Ｓｗａｎ－Ｇａｎｚ导管监测起搏前和起搏后３０ｍｉｎ、２４ｈ、４８ｈ、７２ｈ的心输出量（ＣＯ）、心脏指数（ＣＩ）、右房压（ＲＡＰ）、平均肺动脉压（ＭＰＡＰ）和肺毛细血管楔嵌压（ＰＣＷＰ），并记录各时期的心房率（ＡＲ）和心室率（ＶＲ）。结果：ＶＲ在术后即时及各时期显著升高（Ｐ均＜０．０５），ＣＯ、ＣＩ在起搏后３０ｍｉｎ即显著升高〔分别为４．１８±０．８１Ｌ／ｍｉｎｖｓ２．８１±０．９３Ｌ／ｍｉｎ、２．３６±０．６６Ｌ／（ｍｉｎｍ２）ｖｓ１．１８±０．６３Ｌ／（ｍｉｎｍ２），Ｐ均＜０．０５〕，起搏４８ｈ达高峰；ＲＡＰ、ＭＰＡＰ、ＰＣＷＰ在起搏后３０ｍｉｎ无显著改变（Ｐ＞０．０５），但２４ｈ开始显著性下降（分别为１．２８±０．４１ｋＰａｖｓ１．４１±０．３４ｋＰａ、２．６０±０．５１ｋＰａｖｓ３．４０±０．５６ｋＰａ、３．１０±０．５６ｋＰａｖｓ３．５４±０．６８ｋＰａ，Ｐ均＜０．０５），７２ｈ后进一步降低。结果提示ＶＤＤ起搏治疗能显著改善缓慢性心律失常心力衰竭的血液动力学，可作为治疗缓慢性心?     

Sensing of 2 atrial rhythms by a pacemaker in a transplanted heart

A patient who had undergone orthotopic heart transplantation received a VDD pacemaker for AV block. The pacemaker sensed both the recipient and donor atrial rhythms. The atrial lead must be implanted in the donor atrium: a double atrial electrogram requires a different atrial site unless programmable atrial sensitivity can establish preferential sensing of donor P waves.     

Development of sinus node disease in patients with AV block: implications for single lead VDD pacing

OBJECTIVE: To investigate the incidence of sinus node disease after pacemaker implantation for exclusive atrioventricular (AV) block. DESIGN: 441 patients were followed after VDD (n = 219) or DDD pacemaker (n = 222) implantation for AV block over a mean period of 37 months. Sinus node disease and atrial arrhythmias had been excluded by Holter monitoring and treadmill exercise preoperatively in 286 patients (group A). In 155 patients with complete AV block, a sinus rate above 70 beats/min was required for inclusion in the study (group B). Holter monitoring and treadmill exercise were performed two weeks, three months, and every six months after implantation. Sinus bradycardia below 40 beats/min, sinoatrial block, sinus arrest, or subnormal increase of heart rate during treadmill exercise were defined as sinus node dysfunction. RESULTS: Cumulative incidence of sinus node disease was 0.65% per year without differences between groups. Clinical indicators of sinus node dysfunction were sinus bradycardia below 40 beats/min in six patients (1.4%), intermittent sinoatrial block in two (0.5%), and chronotropic incompetence in five patients (1.1%). Only one of these patients (0.2%) was symptomatic. Cumulative incidence of atrial fibrillation was 2.0% per year, independent of the method used for the assessment of sinus node function and of the implanted device. CONCLUSIONS: In patients undergoing pacemaker implantation for isolated AV block, sinus node syndrome rarely occurs during follow up. Thus single lead VDD pacing can safely be performed in these patients.     

The Current Status of Single Lead Dual Chamber Sensing and Pacing

The use of single lead, atrial synchronous ventricular (VDD) pacing in patients with high grade atrioventricular (AV) block and normal sinus node function is an acceptable alternative to dual chamber (DDD) pacing. Implantation and follow up procedures are simplified, and cost is usually reduced by more than the cost of an additional atrial lead. With the use of either diagonally arranged dipole or closely spaced ring electrodes, reliable atrial sensing can be achieved using differential atrial amplifier and high atrial sensitivity. Also oversensing is infrequently observed using provocation tests and dynamic recordings, clinical undersensing is unusual and minimized by programming to the highest atrial sensitivity. However, as atrial pacing is not possible, loss of AV synchrony and rate response may occur for unrecognized or progressive sinus node disease and lower rate limit. The development of single lead dual chamber pacing system may overcome this limitation. Recent studies have demonstrated that atrial pacing can be effective either with the use of a special pacing lead configuration or via floating atrial electrode with a novel stimulation method. Overlapping Biphasic Impulse (OLBI) can reduce atrial pacing threshold. Early clinical experience suggested that this new pacing method can provide effective and reliable atrial pacing with a relatively low incidence of diaphragmatic pacing. Thus the problem of atrial sensing is solved with a single pass lead but further long term evaluation is required to assess the efficacy and feasibility of new instrumentation for single lead dual chamber pacing.