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     

特殊心房起搏算式对病态窦房结综合征阵发房颤疗效的观察

目的评价Vitatron Selection 900E或9000起搏器预防病窦综合征患者阵发房颤的疗效。方法28例病窦综合征伴阵发房颤患者植入Vitatron Selection 900E或9000起搏器。起搏器植入后2周内为稳定期,主要调整、优化感知和起搏参数;稳定期后1月为监测期,打开起搏器的房颤监测功能,观察房颤发生情况;其后根据监测阶段记录到的房颤可能的发生机制,启动相应的房颤预防性起搏算式。结果15例患者启动房早抑制;18例启动房早后反应;22例启动起搏调控;2例启动动运后频率控制;1例启动频率修整;2例启动房颤后反应。房颤预防阶段期与监测期相比,房颤负荷(11.4±6.8 vs 14.2±8.3)、阵发房颤数(112.1±87.6 vs130.6±98.5)均降低(P<0.5)。结论特殊心房起搏算式能减少病窦综合征患者房颤的发作次数,但要有效控制房颤,仍然需要配合药物等治疗。     

心房起搏治疗阵发性心房颤动的临床观察

近年来大量资料证实心房起搏有明显的抗房性心律失常作用 ,本研究对一组接受心房起搏治疗的缓慢型心律失常合并阵发性心房颤动 (房颤 )患者进行了回顾性分析。1.资料与方法 :选择 1993年 2月～ 2 0 0 0年 7月 ,对合并有阵发性房颤患者 38例植入永久性心房起搏装置 ,年龄 38～ 78(6 0± 17)岁。其中 33例为病窦综合征 (病窦 ) ,5例为高度房室传导阻滞。阵发性房颤指术前记录至少 1次房颤发作者。 5例病窦合并阵发性房颤患者 ,由于经济原因 ,行单纯右心房起搏 (ＡＡＩ) ;3例合并房间传导阻滞的患者 ,选择ＤＤＤ起搏器 ,行双心房 右心室三腔起…     

具有心房自动阈值管理功能起搏器在病窦综合征患者中的临床应用

目的观察具有心房自动阈值管理功能起搏器在病窦综合征患者中的临床应用情况。方法18例病窦综合征患者置人具有心房自动阈值管理功能起搏器（Enpulse系列7例,Sensial系列5例,Adapta系列6例）,于置入时,置入后1周、1个月、6个月采用起搏分析仪及体外起搏器程控仪测定心房起搏阈值和阻抗,利用ACM进行术后阈值和阻抗的动态观察。结果测定的心房阈值与ACM测定值差异无统计学意义;心房起搏阈值均〈1．0V,心房起搏阈值于置入1个月后有下降趋势,阻抗未见明显变化。预期使用寿命6个月时测定为（8．7±2．4）年。结论病窦综合征患者置入具有心房自动阈值管理功能的起搏器心房起搏安全有效,起搏器预期使用寿命延长。     

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。     

阵发性心房颤动合并病态窦房结综合征的导管射频消融心房-大静脉电隔离

目的 　总结顽固性阵发性心房颤动 (房颤 )伴病态窦房结综合征 (病窦综合征 )患者的心电图和动态心电图特点 ,评估心脏起搏和导管射频消融进行心房 肺静脉电隔离治疗的结果。　方法　 8例阵发性房颤患者 ,年龄 (6 0 7± 6 8)岁 ,5例有黑、 1例有晕厥发作史 ,病史 1～ 2 0 (7 6±6 0 )年。全部病例完成各项临床常规检查后行心内电生理检查和导管射频消融作心房 肺 (或上腔 )静脉电隔离治疗。　结果　 8例患者中 ,房颤每天均有发作的 5例 ,每周发作数次的 3例 ,有 4例植入心脏起搏器后不能控制发作。动态心电图示房颤终止后的平均窦性停搏时间为 (5 0± 1 9)s。心内电生理检查证实与房颤相关的靶静脉为上腔静脉 2例 ,左上肺静脉 3例 ,有 3例未能确定起源点。作射频消融电隔离大静脉共 2 2根 ,平均随访 (2 78±15 9)d ,无房颤发作 6例 (75 % ) ,2例复发病例行第 2次电隔离后分别随访 2个月和 2 5个月 ,均再无房颤发生。其中未植入起搏器的 4例多次动态心电图复查无窦性停搏发生 ,2 4h总心率均在正常范围。　结论　部分阵发性房颤伴病窦综合征的患者 ,导管射频消融电隔离大静脉能够完全消除房颤的发作 ,窦房结功能可以恢复 ,这一现象说明部分慢 快综合征患者的病窦综合征表现可能是继发性和可逆性的     

阵发房颤合并病窦综合征的射频消融治疗

目的总结顽固性阵发性房颤伴病窦综合征患者的心电图和动态心电图特点。评估心脏起搏和射频消融心房肺静脉电隔离治疗的结果。方法 5例阵发性房颤患者。年龄62(60.7±6.8)岁。4例有黑朦,1例有晕厥发作史,病史1~5(2.6±1.3)年。全部病例完行心内电生理检查和心房肺(或上腔)静脉电隔离。结果5例患者中,每周均有发作数次的3例,有2例植入DDD心脏起搏器,其中1例系导管射频消融术后1周植入起搏器,另1例系植入起搏器后房颤频繁发作行导管射频消融。动态心电图示房颤终止后的平均窦性停搏时间为5(5.0±1.9)s。心内电生理检查证实与房颤相关的靶静脉为上腔静脉1例,右上肺静脉1例,左上肺静脉2例,有1例未能确定起源点。作射频消融电隔离肺静脉共22根,平均随访3(2.78±1.59)月,无房颤发作。未植入起搏器的3例多次动态心电图复查无窦性停搏发生,24h总心率均在正常范围。结论部分阵发性房颤伴病态窦综合征的患者,导管射频消融电隔离肺静脉后能有效地消除房颤发作,窦房结功能可以恢复。建议对这些患者首先行肺静脉电隔离治疗控制房颤,然后根据自身心率的变化评估心脏起搏治疗的必要。     

长期心脏起搏对心房颤动发生率及其危险因素的临床研究

目的　观察长期心脏起搏心房颤动 (房颤 )的发生率及其影响因素 ,为选择起搏器种类和起搏方式提供理论和实践依据。方法　选择国内较大的三家医院安装人工心脏起搏器的患者进行了随访 ,回顾性分析房颤的发生情况 ,并且分析影响房颤的各种危险因素。结果　患者 30 6例 ,心房起搏占 2 1 9% ,心室起搏为 78 1%。平均随访 (5 11± 3 13)年 ,76例出现房颤。其中心房起搏和单纯心室起搏的患者房颤发生率分别为 5 97%和 30 12 % (P <0 0 1)。心室起搏组患者出现房颤 4年为33 % ,5年为 41% ,6年为 5 2 %。多元Logistic逐步回归分析表明 ,年龄和起搏方式是心脏长期起搏房颤独立预测因素 ,其相对危险度 (95 %可信限 )分别为 6 79和 6 94。结论　心室起搏与心房起搏比较 ,房颤的发生率高 ,并且随着起搏年限的增加而上升 ,患者有起搏适应证时应该尽量选择以心房为基础的起搏方式。除了起搏器类型可以影响房颤外 ,患者年龄也是一种与起搏器相关的主要因素 ,年龄越大 ,发生率越高。     

双腔起搏器置入患者术后心房颤动的发生情况及相关因素分析

目的分析因病态窦房结综合征(病窦)或高度房室传导阻滞置入双腔起搏器患者心房颤动(房颤)及无症状房颤的发生情况及其相关影响因素。方法选择因病窦及高度房室传导阻滞首次置入双腔起搏器的患者515例,其中病窦组221例,其中房颤106例,非房颤115例;房室传导阻滞组294例,其中房颤103例,非房颤191例。以起搏器置入指征、是否发生房颤及房颤发生时有无症状,分别比较患者的临床资料、房颤及无症状房颤的发生情况及影响因素。结果 515例患者中,房颤发生率为40.6%。房室传导阻滞组心室起搏、左心室舒张末内径较病窦组明显升高(P0.01)。房颤患者年龄、冠心病、心房起搏、左心房内径较非房颤患者明显升高(P0.05,P0.01)。无症状房颤患者年龄、冠心病和心室起搏较症状房颤患者明显升高(P0.05,P0.01)。多因素logistic回归分析显示,年龄、心房起搏、胺碘酮药物史是房颤的危险因素;而年龄(OR=0.957,95%CI:0.925~0.990,P=0.011)、心室起搏(OR=0.982,95%CI:0.972~0.992,P=0.000)是无症状房颤的危险因素。结论起搏器可以连续有效的监测房颤发作,尤其是无症状房颤发作。     

心房起搏比例对老年患者起搏术后心房颤动影响的回顾性分析

目的 通过观察无心房颤动（房颤）病史的老年病态窦房结综合征（病窦）患者在双腔起搏器植入后房颤负荷的变化,探讨心房起搏比例对老年患者起搏器植入后房颤的影响。方法 采用回顾性分析的研究方法。连续入选2006年1月至2012年1月在首都医科大学附属北京友谊医院心脏中心植入双腔起搏器的患者301例,进行常规随访（3.9±1.8）年,纳入最后统计的共283例患者。随访时读取起搏器内存储信息,记录心房早搏（房早）次数、最长房颤持续时间和房颤负荷;同时获取心房、心室起搏占总心搏的比例。评价心脏结构和功能。将心房起搏比例＞66%（66%为心房起搏比例中位数）设为高心房起搏比例组（141例）,心房起搏比例≤66%设为低心房起搏比例组（142例）。结果 与低心房起搏比例组相比,高心房起搏比例组患者房颤负荷（最长房颤持续时间和房颤负荷中位数）更低（P＜0.05）;且房早数量要少于低心房起搏比例组（P＜0.05）;但心室起搏比例在两组之间无明显差异（P＞0.05）。术前和术后两组患者的心脏结构和功能相比,差异无统计学意义（P＞0.05）。结论 对于起搏器植入后的房颤易患人群,高心房起搏比例可减少房颤事件。     

Effective prevention of atrial fibrillation by continuous atrial overdrive pacing after coronary artery bypass surgery

OBJECTIVES: The present study was aimed to evaluate the efficacy of a specific algorithm with continuous atrial dynamic overdrive pacing to prevent atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery. BACKGROUND: Atrial fibrillation occurs in 30% to 40% of patients after cardiac surgery with a peak incidence on the second day. It still represents a challenge for postoperative prevention and treatment and may have medical and cost implications. METHODS: Ninety-six consecutive patients undergoing CABG for severe coronary artery disease and in sinus rhythm without antiarrhythmic therapy on the second postoperative day were randomized to have or not 24 h of atrial pacing through temporary epicardial wires using a permanent dynamic overdrive algorithm. Holter ECGs recorded the same day in both groups were analyzed to detect AF occurrence. RESULTS: No difference was observed in baseline data between the two study groups, particularly for age, male gender, history of AF, ventricular function, severity of coronary artery disease, preoperative beta-adrenergic blocking agent therapy or P-wave duration. The incidence of AF was significantly lower (p = 0.036) in the paced group (10%) compared with control subjects (27%). Multivariate analysis showed AF incidence to increase with age (p = 0.051) but not in patients with pacing (p = 0.078). It decreased with a better left ventricular ejection fraction only in conjunction with atrial pacing (p = 0.018). CONCLUSIONS: We conclude that continuous atrial pacing with an algorithm for dynamic overdrive reduces significantly incidence of AF the second day after CABG surgery, particularly in patients with preserved left ventricular function.     

固有心率对心房起搏后病窦综合征合并阵发性心房颤动及心房扑动发生的影响

为了解心脏固有心率 (IHR)的变化对心房起搏后病窦综合征 (SSS)合并阵发性心房扑动 (AFL)和心房颤动(AF)发生率的影响 ,采用药物阻断 3 8例 SSS合并阵发性 AFL或 AF患者的心脏自主神经测定其 IHR,根据 Tose提出的正常 IHR标准将其分为 IHR正常组 (18例 )和 IHR异常组 (2 0例 ) ,后行心房起搏治疗。术后进行临床、心电图、2 4 h动态心电图的定期随访 ,随访时间分别为 2 2± 1.9和 2 5± 1.7个月。结果显示 :两组患者起搏器植入后阵发性 AFL、AF发作的频率及每次发作持续时间较植入前均显著减少 (P<0 .0 5 ) ;术后 IHR正常组阵发性 AFL、AF发作的频率及每次发作持续时间显著少于 IHR异常组 (P<0 .0 5 )。所有患者术后生活质量明显改善 ,无心衰、血栓栓塞发生。结果提示 :心房起搏可使 SSS合并阵发性 AFL或 AF的发生减少 ;IHR正常时 ,其作用明显优于IHR异常时。     

Temporary atrial epicardial pacing as prophylaxis against atrial fibrillation after heart surgery: a meta-analysis

INTRODUCTION: Recent studies have reported the use of temporary epicardial atrial pacing as prophylaxis for postoperative atrial fibrillation (AF). The aim of this study was to assess the effect of pacing therapies for prevention of postoperative AF using meta-analysis. METHODS AND RESULTS: Using a computerized MEDLINE search, eight pacing prophylaxis trials with 776 patients were included in the meta-analysis. Trials compared control patients to patients randomized to right atrial, left atrial, or biatrial pacing used in conjunction with either fixed high-rate pacing or overdrive pacing. Overdrive biatrial pacing (OR 2.6, CI 1.4-4.8), overdrive right atrial pacing (OR 1.8, CI 1.1-2.7), and fixed high-rate biatrial pacing (OR 2.5, CI 1.3-5.1) demonstrated a significant antiarrhythmic effect for prevention of AF after open heart surgery. Furthermore, studies investigating overdrive left atrial pacing and fixed high-rate right atrial pacing have been underpowered to assess efficacy. CONCLUSION: Biatrial overdrive and fixed high-rate pacing and right atrial fixed high-rate pacing reduced the risk of new-onset AF after open heart surgery, and the relative risk reduction is approximately 2.5-fold. These results imply that various pacing algorithms are useful as a nonpharmacologic method to prevent postoperative AF.     

Suppression of atrial fibrillation by atrial pacing.

BACKGROUND: Atrial fibrillation (AF) is a common arrhythmia in patients with an implanted pacemaker, but the role of atrial pacing in preventing AF is still unclear. METHODS AND RESULTS: Sixty-six patients (67.8+/-12.1 years) were enrolled: 54 with sick sinus syndrome (SSS), 11 with atrioventricular blocks (AVB), and 1 with SSS and AVB. The prevalence of AF was investigated. In 22 patients with AF, the AF burden was estimated under "back-up pacing" (40-50 beats/min), then under "atrial pacing" (60-85 beats/min). The prevalence of AF in the SSS group tended to be higher than that in the AVB group (48.1% vs 18.2%, p=0.06). The AF burden in patients with a percentage of atrial pacing (% atrial pacing) <50% was significantly greater than that in patients with % atrial pacing >or=50% (12.5+/-21.1% vs 4.2+/-10.3%, p<0.05). AF disappeared immediately after "atrial pacing" in 4 patients (18.2%). In 9 patients (40.9%), the AF burden decreased gradually, and AF disappeared in 6 patients (27.3%) after 207.9+/-130.2 days. CONCLUSION: The prevalence of AF may be higher in patients with SSS than in those with AVB. Atrial pacing has a preventive effect on AF, and the effect of atrial pacing is not always immediate but is progressive in some patients.     

Paroxysmal atrial fibrillation prevention by pacing in patients with pacemaker indication.

AIMS: The prevent-atrial fibrillation (AF) registry analyses the clinical relevance and usefulness of the four preventive pacing algorithms, available in a family of cardiac stimulators, to prevent atrial fibrillation. METHODS AND RESULTS: This study is a prospective, non-randomized, multicentre registry. Patients are eligible for the registry if they have sick sinus syndrome (SSS) with or without pre-existing atrial fibrillation. The preventive pacing algorithms were programmed for each patient on an individual basis using the diagnostic features of the devices. In the period from April 2000 to April 2001 a total of 68 patients (33 male, 35 female) has been included in the registry in 14 hospitals in Spain. Mean age was 72+/-12 years and the pacemaker indication was SSS in 15 patients (22%) and SSS with paroxysmal AF in 53 patients (78%). The median AF burden for the total group (n=32) was significantly reduced from 3.9 to 1.3% (67%, P=0.034, Wilcoxon signed rank test). The decrease in AF burden was accompanied by a non-significant decrease in the median number of episodes per day from 1.47 to 0.64 (a decrease of 56%). The average atrial pacing % was increased from 72 to 78%. CONCLUSIONS: The prevent-AF registry demonstrated the usefulness of four preventive pacing algorithms in daily clinical practice. During the registry a significant reduction in AF burden and all other endpoints was observed. Dedicated diagnostics were key to adapting the optimal pacing therapy during follow-up.     

Right atrial overdrive pacing does not prevent atrial fibrillation after coronary artery bypass surgery.

AIMS: The purpose of this prospective randomized study was to investigate the efficacy of atrial overdrive pacing (AOP) and bradycardia prevention pacing (BPP) in the prophylaxis of atrial fibrillation (AF) after coronary artery bypass surgery (CABG). METHODS: One hundred and twenty-four on-pump CABG patients were randomized into three groups: AOP, BPP, and NP (no pacing). AOP patients were paced via epicardial wires using an atrial preference pacing algorithm, and BPP patients were paced in the AAI mode with a base rate of 60/min. Patients were paced for 48 h starting on the first postoperative day. The endpoint of the study was the first onset of AF lasting longer than 5 min. RESULTS: Preoperative risk factors and surgical data of patients did not differ between the AOP, BPP and NP groups. Pacing was technically successful in 80.5% of patients in the AOP and in 92.7% in the BPP groups. The incidence of AF in the AOP (26.8%), BPP (19.5%) and NP (28.6%) groups did not differ significantly. In the AOP group, AF in three patients was probably induced by inappropriate pacing due to sensing failure. CONCLUSIONS: Atrial overdrive pacing and bradycardia prevention pacing were not effective in the prevention of AF after CABG.     

Pacemaker prevention therapies for the control of drug-refractory paroxysmal atrial fibrillation.

AIMS: Atrial septal pacing has been shown to prevent paroxysmal atrial fibrillation (PAF) refractory to drugs in patients without inappropriate bradycardia. This study assesses the effects of atrial septal pacing using new pacing algorithms designed to prevent the initiation or maintenance of PAF. METHODS AND RESULTS: Eleven Medtronic AT500 and 6 Guidant Pulsar Max pacemakers were implanted. The incremental benefit of prevention pacing therapies was compared with DDDR pacing by analysis of pacemaker-stored electrograms, ambulatory electrocardiography, symptoms and quality of life questionnaires. RESULTS: Atrial septal pacing reduced AF burden by >50% in 13/17 patients (76.5%). Activation of a combined pacing algorithm (atrial pacing preference; atrial rate stabilization; and post mode-switch overdrive pacing) in patients with AT500 pacemakers produced a marginal reduction in AF burden (mean %AF 0.61 ON, 0.73 OFF, P=0.53 ns). Conversely in the Pulsar Max group when atrial pacing preference was activated, AF burden was slightly increased (mean %AF 5.84 ON, 3.73 OFF,P =0.13). Symptoms improved with atrial septal pacing but did not change when prevention algorithms were activated. CONCLUSION: Atrial septal pacing resulted in a marked improvement in AF burden and symptoms. Activation of specific prevention pacing algorithms provided more continuous atrial pacing but had limited and heterogeneous effects on AF burden.     

Mechanisms of Biatrial Pacing for Prevention of Postoperative Atrial Fibrillation—Insights from a Clinical Trial

Atrial fibrillation (AF) occurs in a high proportion of patients after cardiac surgery and is associated with increased morbidity and longer hospital stay. Beta-blockers and amiodarone have been shown to reduce the incidence, but AF still occurs in up to 25% despite pre-treatment. The mechanisms of AF after cardiac surgery are presumably multifactorial. The transient nature of postoperative AF suggests a reversible trigger in patients with susceptible underlying electrophysiological substrates such as abnormal automaticity and conduction delay due to atrial incisions, ischemia and preexisting disease). These could result in atrial premature beats (APBs) and prolonged atrial activation causing lengthening of the P wave. Prophylactic atrial pacing (single- or multi-site) is reported to be effective in patients at high risk for postoperative AF. The mechanisms are probably a combination of preventing bradycardia-induced arrhythmias, overdrive suppression of APBs, eliminating compensatory pauses after APBs and reduction of dispersion of refractoriness. By reducing non-uniform and asynchronous activation resulting from anatomic or functional block, multi-site pacing could improve local excitability and reduce the window of opportunity for AF initiation. We found that the incidence of AF after coronary bypass surgery (CABG) was significantly reduced in patients who received prophylactic biatrial overdrive pacing (BiA) compared with single site left atrial (LA) or right atrial (RA) pacing or no pacing. (BiA 12.5% versus LA 36.4%; RA 33.3% or control 41.9%; P < 0.05). BiA pacing was associated with the greatest reduction of P wave dispersion compared with single site pacing or control (BiA 42 ± 8%; LA 13 ± 6%; RA 10 ± 9%; P < 0.05). Prophylactic postoperative BiA pacing is thus a reasonable and attractive strategy for reducing the risk for postoperative AF.     

AAI与DDD起搏对病窦综合征患者的影响

目的比较AAI与DDD起搏方式对有正常房室传导功能的病窦综合征患者预后的长期影响。方法104例因病窦综合征置入起搏器的患者,按不同起搏方式分为两组:AAI组36例,DDD组68例。术后随访内容包括起搏器程控,患者的症状、体征,心电图和/或动态心电图,超声心动图及心功能分级(NYHA)。主要终点为心房颤动(简称房颤)的发生率,次要终点为脑卒中的发生率,心功能分级及超声心动图检查指标。结果随访43.2±15.7(21～79)个月,①DDD组房颤发生率明显高于AAI组(20.6%vs5.6%,P<0.05),而脑卒中发生率无差异(7.4%vs2.8%,P>0.05);②左房内径、左室舒张末期内径和左室射血分数在AAI组置入前后无差异,而DDD组术后左房内径、左室舒张末期内径增大,左室射血分数下降(P均<0.05);③AAI组与DDD组比较,对心功能影响较小。结论对于房室传导功能正常的病窦综合征患者,与DDD起搏比较,AAI起搏房颤发生率较低,对心功能影响较小,更符合生理性。     

Sinus node electrogram study on sinus pacemaker shifts

The aim of this study was to investigate the sinus pacemaker shifts and its clinical significance. Spontaneous sinus pacemaker shifts and shifts after overdrive atrial pacing were assessed. A total of 43 cases, in whom stable sinus node electrograms (SNE) were obtained, were selected for the study, eight of the 43 cases had sick sinus syndrome (SSS group), the other 35 cases had no sinus node dysfunction (normal group). Sinus pacemaker shifts occurred spontaneously in 11.4% of the normal group and 12.5% of the SSS group respectively (P greater than 0.05); sinus pacemaker shifts were induced after overdrive atrial pacing in 25.7% of the normal group and 62.5% of the SSS group respectively (P less than 0.05). Sinus pacemaker shifts were characterized by loss or inversion of the primary positivity, with or without changes of P wave morphology on ECG, in association with significant prolongation of direct sinoatrial conduction time (SACTd) and sinus cycle length (SCL). The paper concludes: 1) the human sinus node has dominant and subsidiary foci; 2) after overdrive atrial pacing, sinus pacemaker shifts occur more frequently in patients with SSS than that in patients without SSS, which may be useful in evaluation of sinus node function.