Electrical characteristics of low atrial septum pacing compared with right atrial appendage pacing.

AIM: The study was designed to compare the electrical characteristics of atrial leads placed in the low atrial septum (LAS) with those placed in the right atrial appendage (RAA) associated with dual chamber pacing. METHODS: In 86 patients an active-fixation (St. Jude Medical's Tendril DX model 1388T) atrial lead was positioned in RAA and in 86 patients the same model atrial lead was placed in the LAS. Pacing thresholds, sensing thresholds, impedances and the Far Field paced R-Wave (FFRW) amplitude and timing were compared at 6 weeks and at 3 and 6 months. RESULTS: The pacing threshold did not differ between groups. Sensed voltage of the P-wave was higher in the LAS compared with the RAA at 3 and 6 months (P=0.004). Impedance was higher in the LAS at 6 weeks and 3 months (P=0.002) but this difference was no longer significant at 6 months (P=0.05). The atrial sensed FFRW voltage was significantly higher in the LAS position compared with the RAA at 3 and 6 months follow-up (P=0.0002). FFRW voltage>1 mV was seen in 87% of the RAA pacing group and in 94% of the LAS pacing group (P=ns). The time between the ventricular pacing stimulus and the sensed FFRW in the atrium, (V spike-FFRW) in RAA was longer than in LAS at all follow-up measurements (P=0.006). CONCLUSIONS: The electrical characteristics of LAS pacing makes this alternative position in the atrium safe and feasible. Though statistical differences were found in P-wave sensing (LAS higher voltage than in the RAA) and FFRW sensing was higher in the LAS compared with the RAA this did not interfere with the clinical applicability of the LAS as alternative pacing site.     

低位房间隔起搏与右心耳起搏的临床对比研究

目的 探讨低位房间隔起搏与右心耳起搏在植入操作时间、起搏参数方面的差异.方法 选取40例因窦房结功能障碍或成人获得性房室传导阻滞导致的缓慢型心律失常行起搏治疗的患者分为两组.其中,房间隔组20例,采用主动固定螺旋电极行低位房间隔起搏;右心耳组20例,采用被动固定翼状电极行右心耳起搏.对比两组电极植入操作时间,电极植入时、术后1个月、3个月的起搏参数（阈值和阻抗）.结果 房间隔组与右心耳组比较,心房电极植入操作时间和起搏参数在术中、术后1个月、3个月差异均无统计学意义（P＞0.05）.结论 低位房间隔起搏与右心耳起搏具有相似的电极植入操作时间以及相同的起搏参数,为临床起搏治疗的有效部位.     

Electrocardiographic characteristics in low atrial septum pacing

AIM: The aim of the study was to compare P-wave morphology and duration in pacing from the low right atrial septal wall and the high right atrial appendage (RAA). METHODS: The electrocardiogram (ECG) of 50 patients with low atrial septum (LAS) pacing and that of 50 patients with RAA pacing were compared with their electrocardiogram during sinus rhythm. RESULTS: In the frontal plane, patients with LAS pacing showed a superior P-wave axis between -60 degrees and -90 degrees . In all patients with RAA pacing, a P-wave axis between 0 degrees and +90 degrees was observed as in sinus rhythm. In the horizontal plane, all patients with LAS pacing had an anterior P-wave axis between +90 degrees and +210 degrees , whereas all patients with RAA pacing had a posterior P-wave axis between -30 degrees and -90 degrees . The terminal part of biphasic P waves in lead V 1 in LAS pacing was always positive, a pattern that was never observed in P waves of sinus origin or in RAA pacing. P-wave duration was longer with RAA pacing compared with LAS pacing (115 +/- 19 vs 80 +/- 14 milliseconds [ P < .01]). CONCLUSION: The total atrial activation time during LAS pacing is shorter than that during RAA pacing. The electrical atrial activation sequences in LAS pacing and RAA pacing are significantly different. The morphology of biphasic P waves in lead V1 during LAS pacing suggests that the initial part of activation occurs in the left atrium and the terminal part in the right atrium.     

右室起搏对左房容积指数及P波离散度的影响

目的 比较右室流出道间隔部(RVS)起搏与右室心尖部(RVA)起搏对左房容积指数、房性心律失常及P波离散度的影响.方法 选择RVS起搏及RVA起搏各36例,无器质性心脏病,其中DDD起搏30例,VVI起搏6例,行左房容积指数、24h房性心律失常、P波离散度(Pd)及最大P波时限(Pmax)检测,进行对比.结果 36例R...     

右心室心尖部起搏与右心室流出道起搏的临床研究

目的利用超声多普勒优化房室间期后,比较右心室心尖部（RVA）起搏与右心室流出道（RVOT）起搏对左、右心室间收缩同步性的差别。方法（1）共入选45例三度房室阻滞患者,其中男16例,女29例。RVA组31例,RVOT组14例,出院前进行程控。（2）将感知的房室间期（SAV）由70～170ms递增,每次递增20ms,分别行超声心动图检查,测定心肌做功指数（MPI）,将MPI最小时的SAV确定为最适SAV。比较不同起搏部位所测最适SAV的差异。（3）应用组织多普勒同步图（TSI）技术分别测量左、右心室侧壁基底部心肌收缩达峰时问,二者之差用ATs表示,代表室间不同步程度。比较不同起搏部位ATs的差异。结果（1）RVA与RVOT起搏的最适SAV分别为（80．0±9．8）ms对（92±18）ms,差异有统计学意义（P〈0．01）。（2）RVA与RVOT组室间隔与左心室侧壁收缩达峰时间差分别为（89．5±25．7）ms对（27．94-10．5）ms（P〈0．001）,左、右心室侧壁基底部收缩达峰时间之差分别为（88．3±23．4）ms对（29．54-16．7）ms,差异有统计学意义（P〈0．001）。结论与RVA起搏比较,RVOT起搏对心室收缩同步性影响较小,分析其效果与RVOT起搏部位有关。     

Immediate and long-term atrial sensing stability in single-lead VDD pacing depends on right atrial dimensions.

AIMS: Single-pass VDD is a physiological stimulation mode which requires a single-lead with a floating dipole to detect the atrial signal. We investigated the impact of right heart dimensions on immediate and long-term atrial sensing stability in VDD systems to draw guidelines for optimal atrial sensitivity programming. METHODS: Forty-one patients (23 males, mean age 73 +/- 11 years) with II or III degree AV block and normal sinus node function received a Thera VDD Medtronic 8948 pulse generator with Medtronic 5032 lead. Atrial sensing was evaluated at pre-discharge and during 12-months follow-up in the supine and upright positions, during normal and forced breathing. Atrial sensing variability, quantified by a D value (mV), which represents the difference between the maximum and the minimum atrial electrogram amplitude obtained during the various activities, was analyzed and related to right heart dimensions measured at echocardiography. RESULTS: Long-term appropriate atrial sensing was obtained in 40/41 patients. P wave mean amplitude at pre-discharge, during every specific activity, was predictive of 12-month values. No atrial oversensing was observed. According to the right atrial dimension (RAD), patients with RAD > 38 mm had a sensing variability significantly higher than those with RAD < or = 34 mm (D=1 + 1 Vs D=0.4+/-0.5; P<0.05). A linear relationship between D and RAD dimensions was observed (r=0.47; P<0.005). According to the distance from the roof of the right atrium to the right ventricular apex (RAVD), patients with RAVD < 93 mm had D=1.1 +/- 1, while patients with RAVD > 93 mm had D=0.5 +/- 0.4; P<0.05); a inverse correlation between RAVD and D was highlighted (r=-0.43; P<0.01). Using a cluster analysis, the combination of RAD and RAVD identified a subgroup (RAD > 30 mm and RAVD < 80 mm) at high risk of loss of AV synchrony with 67% sensitivity and 80% specificity. Nevertheless, apart from heart dimensions, no patient showed an atrial signal amplitude lower than 0.3 mV. CONCLUSIONS: According to our data, in VDD single-lead systems the amplitude of the atrial signal is stable over time in every physical activity. High RAD and low RAVD values may select patients with poor atrial sensing stability. Anyway, taking into account that no atrial oversensing was observed, atrial sensitivity setting at the highest value should be recommended.     

右室间隔部起搏与右室心尖部起搏的比较

目的:评价右室间隔部(RVS)起搏的稳定性及对比RVS起搏和右室心尖部(RVA)对血流动力学影响。方法:22例植入DDD起搏器患者,分为RVS组和RVA组,比较两组术中及术后起搏参数及血流动力学参数变化。结果:RVS组术中测试起搏阈值及电流均高于RVA组,术后1个月差异无统计学意义;RVS组QRS波群宽度较RVA组小(P0.05);RVS组X线曝光时间较RVA组长(P0.05);术中阻抗及R波振幅无显著差异。术后6个月,RVS组左室射血分数(LVEF)、心脏指数(CI)、每搏量(SV)、二尖瓣血流E峰和A峰最大充盈速度比值(E/A)较RVA组明显提高,术前两组无明显差异。结论:RVS起搏安全、有效,RVS起搏血流动力学参数明显优于RVA组。     

主动电极右室间隔部起搏的临床应用

目的 观察主动电极行右室流出道间隔部起搏的疗效.方法 以2008年5月至2013年5月在新乡市中心医院植入心脏起搏器的135例患者为研究对象,依据电极植入部位的不同分为四组:单腔起搏器(VVI)右室心尖部起搏组(52例,A组)、VVI右室间隔部起搏组(31例,B组)、双腔起搏器(DDD)右室心尖部起搏组(33例,C组)和DDD右室间隔部起搏组(19例,D组).分析四组在术后即刻及术后1、6、12、24个月的起搏阈值、导线阻抗、QRS波时限和心功能相关指标.结果 四组手术过程顺利,无并发症发生.B、D组术后即刻的起搏阈值较A、C组偏高,但差异无统计学意义(P>0.05).四组的起搏感知及阻抗均无明显差异.随访1年后,A、B、C组患者的心功能指标较D组有所下降,差异均有统计学意义(P<0.05).结论 右室流出道间隔部起搏较右室心尖部起搏更符合生理性起搏的特点,对心功能及心室重构的不良影响明显小于右室心尖部起搏.因此,DDD右室间隔部起搏是一种较为理想的心脏起搏方式.     

右心室心尖部起搏和右心室间隔部起搏对起搏参数和心电图的影响

目的评估右室间隔部起搏和右室心尖部起搏对起搏参数和双心室电同步性的影响。方法将20例植入DDD型起搏器患者随机为分2组（每组10例）:一组患者行间隔部起搏,一组行心尖部起搏;分析两组有效起搏时及1、3个月随访时各起搏参数差异;对比术中心室电极到位所需X射线曝光时间、术中及术后并发症;比较术前自身心律心电图、术后起博心电图的QRS波宽度、形态。结果有效起搏时心尖部和间隔部起搏电压阈值、电极阻抗、R波高度无显著差异。电极植入后第1、3个月随访,两组起搏参数之间无显著差异,且动态变化相似;心室电极到位所需X线曝光时间:心尖部为（203±127）s,间隔部为（581±124）s（P<0.01）。电极植入术中及术后均未出现并发症;术前和术后心电图Ⅱ导联QRS宽度:心尖部起搏组分别为（0.11±0.03）s、（0.19±0.02）s（P<0.05）;间隔部起搏组分别为（0.10±0.02）s、（0.12±0.02）s,术后QRS形态与术前心电图相似。术后间隔部起搏和心尖部起搏心电图的QRS波宽度对比,前者明显窄于后者（P<0.01）。结论右心室间隔部起搏和右心室心尖部起搏同样安全、有效,而且更符合生理性心室激动顺序,有利于双心室电激动的同步性。     

右心室间隔部起搏和右心室心尖部起搏对血流动力学的影响

目的:比较右心室间隔部(RVS)起搏和右心室心尖部(RVA)起搏对血流动力学的影响。方法:20 例置入DDD起搏器的患者,随机均分为2组,RVS组行RVS起搏,RVA组行RVA起搏;对比观察术前与术后心电图QRS波宽度和形态;比较2组术前和术后6个月随访的左室射血分数(LVEF)、心脏指数(CI)、每搏量 (SV)、二尖瓣血流E峰和A峰最大充盈速度比值(E／A)差异。结果:RVA组起搏心电图Ⅱ导联QRS时限度显著长于RVS组[(0．19±0．02)s:(0．12±0．02)s,P<0．01];术前2组LVEF、CI、SV和E／A均差异无统计学意义。与术前相比,RVA组6个月随访的LVEF、CI、SV和E／A均显著降低[(60．7±5．9)％:(54．8±6．4)％, (2．78±0．31):(2．49±0．26),(81．5±10．0):(68．6±12．5),(1．70±0．48):(1．20±0．39),均P<0．05], RVS组无明显变化[(62．7±6,4)％:(61．14±5．8)％,(2．74±0．33):(2．76±0．25),(82．2±9．2):(78．7±11． 5),(1．62±0．49):(1．61±0．40),均P>0．05]。6个月随访RVS组LVEF、CISV、SV、E／A均显著高于RVA 组(均P<0．05)。结论:RVA起搏扰乱了双心室电同步,导致血流动力学恶化,RVS起搏则尽可能地保证了双心室正常电激动和机械收缩顺序,对血流动力学无不良影响。     

双心房-右心室间隔上部三腔起搏对充血性心力衰竭伴阵发性心房颤动的治疗作用

充血性心力衰竭(CHF)伴病态窦房结综合征(SSS,慢-快型)的处理在临床上较为棘手.     

心房颤动患者右心室流出道间隔部起搏的可行性与安全性的观察

目的:通过右心室流出道间隔部（RVOTS）起搏与右心室心尖部(RVA)起搏的比较,评价RVOTS起搏的临床可行性与安全性。方法: 选择慢性心房颤动（房颤）伴长R-R间歇或缓慢心室率需植入永久起搏器患者68例,随机分配到RVOTS组（n=34）和RVA组（n=34）,RVOTS组将螺旋电极导线主动固定于RVOTS,RVA组将传统的翼状电极被动固定于右心室心尖部。分别记录每例患者术中X线曝光时间;术中及术后15 min、1、6、12个月时电极导线测试参数以及是否有并发症发生;测量自身及术后起搏心电图的QRS时限。结果: RVOTS组术中X线曝光时间 (12.8±5.4)min较RVA组（9.5±2.1）min长（P<0.01）,但随着手术熟练程度的增加,RVOTS组X线曝光时间逐渐缩短并接近RVA组;RVOTS组电极导线植入即刻起搏阈值与RVA组无统计学差异,导线植入15 min后及术后1、6、12个月时两组间起搏阈值无统计学差异;两组间R波振幅及阻抗在术中及术后各时期均无统计学差异;RVOTS组起搏心电图的QRS时限较RVA组显著缩短［(146±16)ms vs. (155±13)ms,P<0.05］;术中及随访期内无电极脱位、阈值增高、心肌穿孔及心包压塞等并发症。结论: 使用主动固定电极导线进行RVOTS起搏安全可行,且心室激动的电同步性优于RVA组。     

Far field R-wave sensing in Myotonic Dystrophy type 1: right atrial appendage versus Bachmann's bundle region lead placement

Aim of the present study was to investigate far field R-wave sensing (FFRS) timing and characteristics in 34 Myotonic Dystrophy type 1 (DM1) patients undergoing dual chamber pacemaker implantation, comparing Bachmann''s bundle (BB) stimulation (16 patients) site with the conventional right atrial appendage (RAA) pacing site (18 patients). All measurements were done during sinus rhythm and in supine position, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. There were no differences between both atrial sites in the Pmin and Pmean values of sensed P-wave amplitudes, as well as between UP and BP sensing configurations. The FFRS trsh was lower at the BB region in comparison to the RAA site. The mean BP FFRS trsh was significantly lower than UP configuration in both atrial locations. There were no significant differences in atrial pacing threshold, sensing threshold and atrial lead impedances at the implant time and at FFRS measurements. Bachmann''s bundle area is an optimal atrial lead position for signal sensing as well as conventional RAA, but it offers the advantage of reducing the oversensing of R-wave on the atrial lead, thus improving functioning of standard dual chamber pacemakers in DM1 patients.Key words: far field, oversensing, far field R-wave sensing, myotonic dystrophy type 1, atrial lead, Bachmann''s bundle     

Evaluation of biatrial pacing, right atrial pacing, and no pacing in patients with drug refractory atrial fibrillation.

It has been suggested biatrial pacing may prevent the recurrence of atrial fibrillation (AF). To further evaluate this hypothesis, we performed a randomized, single-blinded study in 19 patients with drug refractory AF. The study compared biatrial pacing with conventional right atrial (RA) pacing and a control period of inhibited pacing. The pacing modes utilized were DDD with a base rate of 70 beats/min for biatrial and RA pace (with and without biatrial resynchronization, respectively) and 40 beats/min for the control period. The duration of each pacing mode was 3 months. The number of AF episodes and their duration were obtained from pacemaker Holter memory (Chorus RM ELA Medical). Comparison of the control period (n = 11) with either pacing strategy showed a significant decrease in the total duration of AF (control 27 +/- 35 days, biatrial 8 +/- 15 days p = 0.02, RA 11 +/- 27 days p = 0.04). However, there was no effect on the number of AF episodes (control 79 +/- 108, biatrial 36 +/- 75 p = 0.32, RA 41 +/- 80 p = 0.11). The total percentage of atrial pacing also significantly increased when the control period (6 +/- 9%) was compared with both RA pace (62 +/- 33%, p = 0.008) and biatrial pace (63 +/- 31, p = 0.003). When biatrial pacing was compared with RA pace (n = 19), there was no significant difference in either the duration of AF (biatrial 16 +/- 26 days vs RA 19 +/- 31 days, p = 0.7) or the number of AF episodes (biatrial 56 +/- 91 vs RA 87 +/- 106, p = 0.34). In conclusion, pacing (either type) at a base rate of 70 beats/min has an antifibrillatory effect when compared with inhibited pacing at 40 beats/min. No additional benefit of biatrial pacing over right atrial pacing was demonstrated in this study.     

右心室流出道间隔部起搏与右心室心尖部起搏随机对照研究

目的应用组织多普勒方法随机对照研究右心室流出道间隔部（right ventficular outflow tract septum,RVOTS）起搏与右心室心尖部（fight ventricul arapical,RVA）起搏心脏同步性和心功能变化,探讨右心室流出道间隔部在主理性起搏中的临床意义。方法128例缓慢心律失常患者按单双数字随机分为两组,对病态窦房结综合征房室功能正常患者,起搏器植入术后根据心电图PR间期时间将起搏器AV间期调整,暂时关闭AV搜索功能以保证心室起搏。所有患者起搏器植入术后1、3、6个月定期随访,观察起搏参数、累积心室起搏百分比,同时行超声心动图检查。结果RVOTS起搏组与RVA起搏组电极导线植入时间、X线曝光时间差异有统计学意义（P〈0．01）,主动固定电极导线植入15min与植入即刻比较起搏阈值明显下降,分别为（0．76±0．21）mV和（1．13±0．25）mV（P〈0．01）。RVOTS起搏组和RVA起搏组QRS时限分别为（0．14±0．04）S、（0．16±0．03）S（P〈0．01）。随访6个月起搏参数两组之间差异无统计学意义。全部患者未出现植入并发症,随访6个月无电极导线移位、阈值增高。6个月RVOTS起搏组左心室同步指标明显优于RVA起搏组（P〈0．01）。左心室收缩末内径及舒张末内径两组比较无显著变化,左心室射血分数在RVA起搏组有所降低（P〈0．05）,心脏做功指数（Tei）、RVOTS起搏组与RVA起搏组比较差异有统计学意义（P〈0．05）,在RVA起搏组随访6个月与1个月比较差异有统计学意义（P〈0．01）。结论RVA起搏导致心脏收缩不同步,损害左心室功能。RVOTS起搏保持良好心脏收缩同步性、保护左心室功能,是较好的右心室起搏部位。     

R-wave amplitude responses to rapid atrial pacing: a marker for myocardial ischemia

Atrial pacing-induced changes in the sum of R-wave amplitude were measured in leads V5, X, Y, and Z at rates of 100 bpm (phase I), 150 bpm (phase II), and immediately after pacing (phase III) in 33 patients undergoing cardiac catheterization for evaluation of chest pain. Seventeen (51%) patients showed evidence of ischemia during atrial pacing (typical anginal pain and/or at least a 1 mm ST-segment depression) and 16 (49%) showed no evidence of ischemia. Mean R-wave amplitude changes from baseline in the ischemic patients were: phase I: -8% (p = not significant), phase II: +3% (p = not significant), and phase III: +13% (p less than 0.01); and in nonischemic patients: phase I: -11% (p less than 0.02), phase II: -18% (p less than 0.01), and phase III: +2% (p = not significant). These two distinct patterns of R-wave amplitude changes were highly sensitive (85%), specific (92%), and predictive (92%) for identifying patients with myocardial ischemia but did not correlate (p = not significant) with either the angiographically determined extent of coronary artery obstructive disease (CAD), resting left ventricular function, or the dynamic, atrial pacing-induced changes in left ventricular dimensions determined by M-mode and two-dimensional echocardiography. Thus, R-wave amplitude changes induced by atrial pacing can be used to identify patients with myocardial ischemia independent of coronary anatomy or resting left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)