Impact of Temporary Interruption of Right Ventricular Pacing for Heart Block on Left Ventricular Function and Dyssynchrony

Background: The increasing data suggest an association between chronic right ventricular (RV) and left ventricular (LV) dysfunction. We sought to determine the effect of temporary interruption of long-term RV pacing on LV function and mechanical dyssynchrony in children and young adults with complete heart block.
Methods: Twelve patients aged 20.0 ± 7.4 years with congenital heart block (group I) and six patients aged 22.7 ± 11.0 years with surgically acquired heart block (group II) with RV pacing were studied. The pacing rate was reduced to less than patient's intrinsic heart rate and maintained for 5 minutes. The LV ejection fraction (EF), three-dimensional systolic dyssynchrony index (SDI), two-dimensional global longitudinal strain and strain rate, and Doppler-derived isovolumic acceleration before and after interruption of RV pacing were compared.
Results: The LVEF and GLS increased while QRS duration decreased after the pacing interruption in both the groups (all P < 0.05). While SDI decreased in both groups I (6.8 ± 2.3%– 3.8 ± 0.8%, P = 0.001) and II (9.2 ± 4.1 %– 5.0 ± 1.6%, P = 0.032), it remained higher in group II than in group I (P = 0.046) after the pacing interruption. The prevalence of LV dyssynchrony (SDI > 4.7%) decreased in group I (83 %– 25%, P = 0.006) but not in group II (67 %– 50%, P = 0.50). The %increase in LVEF correlated positively with %reduction of LV SDI (r = 0.80, P = 0.001).
Conclusions: Temporary interruption of chronic RV pacing acutely improves LV dyssynchrony and systolic function in children and young adults, the magnitude of which is greater in patients with congenital than those with surgically acquired heart block. (PACE 2010; 41–48)     

不同起搏方式对患者左心结构与功能及NT-proBNP的影响

【目的】探究生理性起搏（DDD）和非生理性起搏（VVI）对心脏结构及 N-末端脑钠肽前体（NT-proBNP）的影响,并为起搏器植入心脏后的应对策略积累经验。【方法】选取本院心内科于2012年1～12月收治的65例接受起搏器治疗患者,根据不同起搏方式进行分组。其中对照组患者采取 VVI,研究组采取DDD,比较两组患者在植入起搏器前后左心室结构和功能及 NT-proBNP水平变化。【结果】两组患者在植入起搏器前的左心房内径（LAD）、左心室舒张末期内径（LVD）、室间隔厚度（IVST）、左心室后壁厚度（PWT）、左心室射血分数（EF）方面差异无统计学意义（P ＞0．05）;植入起搏器后,研究组 LAD小于对照组（P ＜0．05）,EF高于对照组（P ＜0．05）。两组患者在起搏器植入前 NT-proBNP 值差异无统计学意义（P ＞0．05）;安置起搏器后,研究组 NT-proBNP值低于对照组（P ＜0．05）。【结论】有起搏器植入适应证的患者,为减少起搏对心脏结构和功能的影响,应当选择房室顺序起搏为宜。     

右室流出道起搏对心功能影响的Meta分析

目的 系统评价右室流出道起搏对心功能的影响。 方法 计算机检索Cochrane 图书馆（2008 年第4 期）、PubMed、EMbase,同时检索CBM、CNKI、VIP 和万方数据库,检索时间截至2010 年1 月,收集右室流出道（RVOT）起搏与右室心尖部（RVA）起搏比较对心功能影响的随机对照试验（RCT）,并按Cochrane 协作网推荐的方法进行质量评价、资料提取和Meta 分析。 结果 共纳入16 个RCT,包括926 例患者。Meta 分析结果显示：①左室射血分数：RVOT 组在3 个月和18 个月的左室射血分数均高于RVA 组,差异有统计学意义［WMD= 3.53,95%CI（1.02,6.04）;WMD= 8.94,95%CI（7.35,10.52）］。② QRS 波时限：术后即时RVOT 组和RVA 组相比,QRS波时限有所减小,差异有统计学意义［WMD= –22.42,95%CI（–31.05,–13.80）］,然而3 个月后差异无统计学意义［WMD= –13.88,95%CI（–29.75,2.00）］。③ 起搏参数：RVOT 组在术后即时的起搏阈值（V）高于RVA 组,而3 个月后,与RVA 组无差别。在感知阈值和阻抗方面,即时和术后3 个月时两者之间均无差异。 结论 相对于心尖部起搏,虽然短期内右室流出道起搏可以提高心脏功能,但长期结果仍有待于观察。限于目前研究对右室流出道起搏的长期结果报道不足,仍然需要大样本、多中心随机对照试验进一步证实右室流出道起搏的优越性。     

Left Heart Pacing and Cardioembolic Stroke

Three patients with inadvertently positioned left heart pacemaker leads were admitted for neurological symptoms consistent with embolic stroke. In one of them, the pacemaker lead crossed the interatrial septum, the mitral valve, and entered the left ventricle. In another it was erroneously placed through the subclavian artery, across the aortic valve, and into the left ventricular chamber In the third patient, the right ventricular lead of a DDD pacemaker was placed in the coronary sinus and the right atrial lead crossed the interatrial septum, and intermittently entered the left ventricular cavity. Once anticoagulation was initiated, symptoms resolved; they recurred when the level of anticoagulation dropped leading to a major stroke in one of the patients. Two of the patients were on aspirin at the onset of symptoms. We believe that every approach must be considered to remove the malpositioned lead. Otherwise, full dose anticoagulation must be initiated since antiplatelet therapy alone does not confer adequate protection against stroke.     

右心室不同部位起搏对左心功能影响的对比研究

目的 探讨右心室不同部位起搏对左心功能的影响.方法 22例起搏器植入患者术中行右心室室间隔(RVS)及右心室心尖部(RVA)瞬间起搏,对照2种方法对左心功能的影响,其中12例最终行RVA起搏,10例行RVS起搏,随访6个月观察左心功能变化.超声检测指标包括:左心室射血分数(LVEF)、每搏量(SV)、二尖瓣环平均收缩期峰值速度和舒张早期峰值速度(Mean Vs和MeanVe)、左心室收缩末容量(LVESV)和舒张末容量(LVEDV).结果 22例患者术中瞬间起搏与术前心功能比较,RVA起搏时LVEF和SV减低,RVS起搏时心功能无变化;术后6个月,RVA起搏组12例LVEF、SV、Mean Vs和MeanVe较术前均降低,RVS起搏组10例心功能与术前比较无差异.结论 瞬间和长期的RVA起搏均可降低左心功能,RVS起搏对左心功能无明显影响.     

右心室不同部位起搏对心脏结构和左心功能的影响

[目的]对比研究右心室不同部位起搏对患者心脏结构和左心功能的影响.[方法]90例Ⅲ度或高度房室传导阻滞患者, 随机分为三组, A组行右室流入道（RVIS）间隔部起搏,B组行右室流出道（RVOT）间隔部起搏,C组行右心室心尖部（RVA）起搏. 观察三组手术中情况,监测术中血流动力学变化及手术曝光时间,比较三组术后随访的起搏器工作情况,心电图QRS波宽度,左心功能及血浆中B型钠尿肽（BNP）的差异.[结果]术中监测血流动力学,A组及B组明显优于C组.术后随访观察,A组及B组心电图QRS波宽度明显窄于C组,A组及B组具有更好的心脏功能.[结论]右心室间隔部起搏无论右室流出道起搏还是右室流入道间隔部起搏都是安全,有效的,比右室心尖部起搏更有利于双心室电激动的同步性,且长期对心脏结构及心功能影响也较少.     

犬有创左右心功的相关性分析

用右心漂浮导管测定正常犬及心衰犬右心功指标：ＳＶ、ＣＯ、ＣＩ,用左心导管测定±ＬＶＰ、±ｄｐ／ｄｒ,两组实验指标提示不管是正常心功能状态或心衰状态,用右心漂浮导管测出的泵功能指标均能良好反映左心室收缩功能情况,但不能全面反映舒张功能情况。推测是由于舒张功能与泵功能呈非线性关系所致。     

Left Ventricular Function During Physiological Cardiac Pacing: Relation to Rate, Pacing Mode, and Underlying Myocardial Disease

The hemodynamic effects of cardiac pacing at different rates and in different modes were studied in 21 patients who were candidates for permanent pacemaker implantation. Nine of these had primary conduction disturbances (PCD), ten had ischemic heart disease (IHD), seven with additional cardiac failure (CHF), and two had hypertrophic cardiomyopathy (HCM). In patients with PCD, atrial (AOO) and AV sequential (DVI) pacing did not change systolic blood pressure and pulse pressure but ventricular (VVI) pacing caused a progressive fall in these measurements, especially as heart rate increased. Ventricular volume and stroke volume (counts) derived from radionuclide ventriculography (RVG) decreased progressively with higher pacing rates, especially during VVI pacing. Cardiac output was maintained during VVI pacing by the increase in heart rate; during AOO and DVI pacing, cardiac output increased. Similar but more marked differences were observed in patients with IHD and CHF and the changes were even greater in the patients with HCM. Left ventricular (LV) ejection fraction changed little with increasing heart rate in PCD but decreased progressively with the onset of ischemia in IHD and CHF. There was no difference in ejection fraction in the different pacing modes. Graphs related to LV contractility (end-systolic pressure-volume relations) showed that AOO pacing produced the highest and VVI pacing produced the lowest curves of myocardial contractility in all patient groups, except that at higher rates the AOO curve shifted down again in patients with IHD and CHF, presumably with the onset of myocardial ischemia. This study showed that physiological pacing produced the best hemodynamic results in all patient groups. Higher pacing rates should be avoided in patients with ischemic heart disease while VVI pacing should not be used in patients with HCM. Blood pressure and RVG studies during temporary pacing are useful in selecting the optimal pacing system in an individual patient when the clinical choice is not clear.     

Left Ventricular Pressure Measurement During Noninvasive Transcutaneous Cardiac Pacing

In a pacemaker-dependent patient, the hemodynamic response during external transcutaneous and endocardial sequential pacing was evaluated by left ventricular pressure monitoring. A single ventricular pacing mode with hemodynamic effect of atrioventricular asynchrony was shown during external pacing.     

Electrocardiographic Characteristics of Pacing From the Right Atrial Appendage During Atrioventricular Sequential Pacing

In the interpretation of electrocardiograms recorded during atrioventricular sequential pacing, uncertainty frequently arises in the assessment for evidence of atrial capture. In the present study, electrocardiographic characterization of pacing from the right atrial appendage as a component of atrioventricular pacing was performed on tracings obtained from 16 patients with bipolar dual chamber pacing units, and from 18 patients with unipolar dual chamber pacing units in which large overshoot potentials occurred following the atrial pacing spike. Atrial complexes resulting from bipolar pacing of the right atrial appendage were found to be uniformly prolonged and of diminished amplitude compared to those in sinus rhythm; they were also noted to contain sequential inferoposterior and leftward-posterior component vectors. The exponential overshoot-decay complex associated with unipolar atrial pacing appeared as a vector directed along the axis from the pulse generator to the pacing lead; the degree to which this deflection interfered with identification of atrial capture in various leads was thus largely dependent on pulse generator location. It was concluded that careful systematic inspection of multiple electrocardiographic leads will generally permit the characteristic features of pacing the right atrial appendage to be recognized, thus facilitating correct interpretation of atrial capture during atrioventricular sequential pacing.     

二维斑点追踪成像评价长期右心室心尖部起搏对左心室心肌收缩功能的影响

目的 采用二维斑点追踪成像(STE)检测长期右心室心尖部起搏(RVAP)对左心室(LV)心肌收缩功能的影响.方法 行DDDR模式起搏器植入的高度或Ⅲ度房室传导阻滞患者47例,均为RVAP,在术前3d及术后1年采用STE检测左心室收缩同步性指标TAS-POST、左心室射血分数(LVEF)、心肌纵向二维应变(LS)和径向应变(RS).将TAS-POST≥130 ms定义为左心室收缩不同步.62例年龄和性别匹配的正常人作为对照组.结果 术后TAS-POST延长,心肌LS减低,RS则无显著变化.9例患者TAS-POST＞130 ms,长期RVAP导致左心室收缩不同步的发生率为19.15％.结论 长期RVAP可导致左心室心肌局部纵向收缩功能减低,且收缩同步性下降,STE 可以准确评价左心室心肌收缩功能和收缩同步性.     

Is Right Ventricular Outflow Tract Pacing an Alternative to Left Ventricular/Biventricular Pacing?

The right ventricular apex has been used as the traditional pacing site since the development of transvenous pacing in 1959. Some studies suggest that pacing the right ventricular apex may cause remodeling and is harmful. In the past decade, there have been a multitude of studies of the hemodynamic, electrophysiological, electrocardiographic, and clinical effects of ventricular pacing at other sites. Pacing of the left ventricle singly or with biventricular pacing has emerged as an effective and safe therapy for moderate to severe congestive heart failure in patients with prolonged QRS complexes. Studies of alternate right ventricular sites, like the right ventricular outflow tract, have given mixed results. Not all patients can be treated with left ventricular pacing, which is a time-consuming and difficult procedure. Right ventricular pacing is easier and less expensive than left ventricular pacing and further study of additional right ventricular sites seems warranted. (PACE 2004; 27[Pt. II]:871–877)     

组织多普勒成像评价DDD型右室心尖部起搏的左室收缩同步性和收缩功能的关系

目的 采用组织多普勒成像(TDI)检测右室心尖部起搏(RVAP)对于左室同步性和收缩功能的影响,并探讨两者的关系.方法 57例因病窦综合症(SSS)行RVAP治疗患者,在术前及术后(17±6)个月采用TDI检测左室12节段收缩期达峰时间的标准差(Ts-SD)作为同步化参数,并测量左室收缩功能.结果 根据术后TDI结果,分为同步组(36例)和不同步组(21例).同步组左室收缩末容积小于不同步组,射血分数则大于不同步组.且Ts-SD和射血分数显著负相关.结论 长期RVAP可导致左室收缩不同步和收缩功能减低,且前者是后者的主要原因.TDI技术可以准确评价左室收缩同步性.     

Worsening Left Ventricular Apical Peak Strain Early After Right Ventricular Pacing

We aimed to determine the effect of short-term right ventricle pacing (RV) on left ventricle (LV) mechanics using speckle tracking analysis. Conventional echocardiography and two-dimensional strain imaging was studied in 38 patients, mean age 81.6 ± 7.0, that had undergone pacemaker placement and were greater than 90% ventricularly paced. Mean duration of 24 months of RV pacing resulted in a significant decline in: LV apical diastolic rotational velocities (−59.0 ± −38.9 °/s to −28.0 ± −11.5 °/s, p 0.02), peak strain in the LV apical septal wall (−15.6 ± 8.5 to −13.5 ± 7.6, p 0.02), peak strain in LV apical lateral wall (−13.4 ± 8.9 to −11.4 ± 7.3, p 0.02). Thus, with only 24 months of RV pacing, there was a significant decline in peak strain of the LV apex and in apical diastolic rotational velocity that could account for eventual decline in left ventricular function.     

高龄老年人右室心尖部及室间隔上部起搏对心功能的影响

【目的】探讨高龄老年人右室心尖部（RVA）和室间隔上部（RVUS）起搏对心功能的影响,寻找最佳起搏部位。【方法]89例行DDD起搏器治疗的患者：男84例,女5例,平均年龄84（75～95）岁,分为RVA组44例,RVUS组45例。对比分析两组起搏器间术前、术后3个月、6个月和1年心脏超声指标：心排血量（CO）、每搏输出量（sV）、射血分数（EF）、左室舒张末内径（LVDd）和血脑利钠肽（BNP）等的变化。【结果】RVA组治疗后心功能较起搏治疗前恶化,且随着起搏时间的延长恶化程度加重,而RVUS组心功能较起搏治疗前明显改善,且随着起搏时间的延长改善的越明显,与RVA组比较,具有统计学意义（P〈0．05）。【结论】高龄老年人RVUS优于RVA,可明显改善心功能,值得在高龄老年人中推广。     

Comparative Left Ventricular Function Following Atrial, Septal, and Apical Single Chamber Heart Pacing in the Young

Ventricular pacing, typically initiated from a RV apical electrode, inherently causes abnormal biventricular activation, decreases LV function, and causes histopathological changes. Since pacing initiated in childhood can he expected to have a more protracted course compared with the adult, the consequences of this alteration in LV hemodynamics gain added significance among the young pacemaker recipient. The purpose of this study was to evaluate the potential of improving paced LV function by a septal electrode implant site. Acute alterations in cardiac index, LV pressure, and contraction indices, including dP/dt, Vmax. and Vpm, were compared among 22 patients (median age 10 years) with normal cardiac anatomy during intracardiac electrophysiological studies. LV hemodynamics were measured during intrinsic rhythms and following 15 minutes of atrial, HV apical, and septal pacing at an appropriate exercise rate for age of 150 ppm. Results showed a significant decrease in LV dP/dt, Vmax, and Vpm, and increase in LV end-diastolic pressure only with apical pacing. Septal pacing, in spite of loss of any atrial contribution to ventricular filling, maintained comparable indices with intrinsic and atrial paced rhythms. This study demonstrates that normalized LV function is maintained by septal and deteriorates with apical pacing acutely among young, nonischemic hearts. Continued evaluation of appropriate pacing electrode designs to permit septal implant is needed to ensure optimal chronically paced LV function.     

犬左室急性心肌缺血状态下右心功能的超声应变率研究

目的 应用应变率显像(SRI)技术研究犬左室急性心肌缺血状态下对右心功能的影响.方法 10只犬,分别于冠状动脉左前降支结扎前、后10 min采集心尖四腔观图像,测量缺血前后右室壁、右房壁及三尖瓣环的收缩期应变率(SSR)、舒张早期应变率(ESR)、舒张晚期应变率(ASR)、右室射血分数(RVEF)和用导管法测肺动脉收缩压(PASP).结果 左室局部急性心肌缺血后,PASP增加(P＜0.05),RVEF降低(P＜0.05),右室壁和三尖瓣环的SSR、ESR及ASR降低(P＜0.05),右房壁SSR和ASR增加(P＜0.05).心肌缺血前,右室壁SR与右房壁SR无明显相关性,缺血后两者呈负相关.心肌缺血前后RVEF值与右室壁及三尖瓣环的SSR峰值均呈正相关.缺血后PASP分别与右室壁SSR和RVEF呈负相关.结论 左室前壁急性心肌缺血可引起右室壁舒缩功能减退和PASP增加,右房壁舒缩功能代偿性增加,三者之间有一定的相关性.