Native QRS complex duration predicts paced QRS width in patients with normal left ventricular function and right ventricular pacing for atrioventricular block

Introduction

Prolonged paced QRS duration is a predictor of development of heart failure during chronic right ventricular pacing. One determinant of paced QRS width might be His-Purkinje system dysfunction, manifested in wide native (escape or conducted beat) QRS complexes in patients with atrioventricular (AV) block.

Methods

Fifty patients with normal left ventricular function who are undergoing implantation of a pacemaker for AV block were enrolled. The duration of the QRS complex was measured on the surface electrocardiogram during escape rhythm in 28 patients with total AV block and during conducted beats in 22 patients with second-degree, fixed ratio (2:1 or 3:1) AV block, as well as during ventricular paced rhythm after pacemaker implantation in all patients.

Results

A close, positive correlation was found between native and paced QRS duration in the second-degree AV block group (R = 0.74, P < .001). This association was also significant but less pronounced in the total AV block group (R = 0.46, P = .014).

Conclusion

Native QRS width, especially in case of fixed ratio (2:1 or 3:1) second-degree AV block, is a predictor of paced QRS duration in patients with AV block and normal left ventricular function. Wide QRS complex before implantation may carry a higher risk of developing heart failure with right ventricular pacing.     

右室间隔起搏与心尖部起搏对完全性房室传导阻滞患者心功能影响的比较

目的:初步探讨右室间隔起搏(RVSP)和右室心尖部起搏( RVAP)对完全房室传导阻滞( CAVB) 患者心功能的影响。方法:87例因CAVB植入起搏器的患者, 其中45例行RVSP术(RVSP组)，42例行RVAP术(RVAP组)，分别对术前及术后6、12和18个月，患者的QRS波时限、左室舒张末内径（LVEDD）、 左室射血分数（LVEF）、每搏量（SV）、心脏指数（CI）、加速度指数（ACI）进行检查比较。结果:所有患者均完成12个月随访, 79例完成18个月随访。术后RVAP组QRS波时限较RVSP组明显增宽(P<0.05)，术后12个月RVAP组LVEF、SV、ACI均较RVSP组明显降低(P<0.05)，术后18个月RVAP组LVEDD较RVSP组明显增大(P<0.05)，RVAP组CI均较RVSP组降低，但尚未达到显著性差异。结论:RVSP较RVAP有利于CAVB患者心功能的保护。     

Ventricular function and long-term pacing in children with congenital complete atrioventricular block

Objective: To determine the sequela of right ventricular pacing in children with congenital complete atrioventricular block.
Background: Pacing is a well-accepted therapy for patients with congenital complete atrioventricular block. The long-term sequela of right ventricular pacing in this population has not been well described.
Methods: We performed a cohort study on all patients with congenital complete atrioventricular block who underwent pacemaker implantation at our institution from 1972 to 2004. Patients with associated congenital heart disease or ventricular dysfunction prior to pacemaker implantation were excluded.
Results: A total of 63 patients were included in the study. The median age at pacemaker implantation was 6.5 years, with an average follow-up of 9.9 years. The cumulative dysfunction free survival at 20 years was 92%. In total, four patients (6%) were noted to develop LV dysfunction an average of 15.1 years after pacemaker implantation. Of 30 patients who were paced for >10 years, only three (10%) developed echocardiographic evidence of LV dysfunction. Right ventricular apex pacing and prolonged QRS duration were found to be predictive of decreased long-term LV systolic function (P < 0.05).
Conclusions: Left ventricular dysfunction in patients with congenital complete atrioventricular block is a rare finding, even in those who have been paced for more than 10 years. Right ventricular apex pacing and prolonged QRS duration may be associated with decreased ventricular function over time. At this time, with such a low incidence of cardiac dysfunction, right ventricular pacing should be considered an acceptable first-line therapy in this population.     

New-onset heart failure after permanent right ventricular apical pacing in patients with acquired high-grade atrioventricular block and normal left ventricular function

Introduction: Emerging data have suggested that right ventricular (RV) apical pacing results in progressive left ventricular (LV) dysfunction and contributes to the development of heart failure (HF). This study aimed to investigate the prevalence and clinical predictors for the development of new-onset HF after long-term RV apical pacing in patients with acquired atrioventricular (AV) block who require permanent pacing.
Methods: We studied the clinical outcomes after long-term RV apical pacing for acquired AV block in 304 patients without a prior history of HF. All patients had >90% ventricular pacing as determined by device diagnostic data.
Results: After a median follow-up of 7.8 years, 79 patients (26.0%) developed new-onset HF after RV apical pacing. Univariate Cox-regression analysis revealed that older age at the time of pacemaker implantation (P < 0.001), the presence of coronary artery disease (CAD) (P < 0.001) or atrial fibrillation (P = 0.03), VVI pacemaker (P < 0.001), wider paced QRS duration (P < 0.001), and new-onset myocardial infarction (P < 0.001) were predictors for HF. Multivariate analysis revealed that older age at implantation (Hazard ratio [HR] 1.06, 95% confidential interval [CI] 1.04–1.09, P < 0.001), CAD (HR 1.98, 95% CI 1.12–3.50, P < 0.05), and a wider paced QRS duration (HR 1.27 for each 10 ms increment, 95% CI 1.11–1.45, P = 0.001) were independent predictors of HF. Furthermore, cardiovascular mortality was significantly increased in those with HF (36.7% vs. 2.7%, P < 0.001).
Conclusions: After a median follow-up of 7.8 years, permanent RV apical pacing was associated with HF in 26% of patients. Elderly age at the time of implant, a wider paced QRS duration and the presence of CAD independently predicted new-onset HF. More importantly, HF after RV apical pacing was associated with a higher cardiovascular mortality.     

Electrocardiographic features of ventricular pacing lead in the middle cardiac vein vs. right ventricular apex in a patient with persistent left superior vena cava

A 53-year-old woman with sinus node dysfunction underwent dual-chamber pacemaker implantation through a persistent left superior vena cava draining into the coronary sinus, which was detected at the time of implantation. We managed to fix the ventricular lead in the right ventricular (RV) apex by forming a clockwise loop in the right atrium. Inadvertently, the lead was placed in the middle cardiac vein resembling RV apical position under fluoroscopic guidance. The paced QRS complex showed a pattern of tall R in V₁ through V₃, RS in V₄ through V₅, and QS in V₆.The pacing lead was carefully manipulated back into the RV apex, with the paced QRS complex showing a pattern of right bundle branch block, rR' in V₁ through V₂, and QS in V₃ through V₆. Careful attention to the surface electrocardiogram helps in distinguishing the pacing site even in those patients showing a pseudo–right bundle branch block pattern with RV apical pacing.     

A randomized comparison of permanent septal versus apical right ventricular pacing: short-term results

OBJECTIVES: This study compared chronic right ventricular (RV) pacing at the septum versus apex. BACKGROUND: Chronic RV apical pacing may be detrimental to ventricular function. This randomized, pilot study examined whether, compared with apical, permanent septal pacing preserves cardiac function. METHODS: Ablation of the atrioventricular junction for permanent AF, followed by implantation of a DDDR pacemaker connected to two ventricular leads was performed in 28 patients. One lead screwed into the septum and another placed at the apex were connected to the atrial and ventricular port, respectively. Septum or apex was paced by programming AAIR or VVIR modes, respectively. Patients were randomly assigned, 4 months later, to pacing at one site for 3 months, and crossed over to the other for 3 months. New York Heart Association class, QRS width and axis, left ventricular ejection fraction (LVEF), exercise duration, and peak oxygen uptake were measured. Results in patients with LVEF > 45% and < or = 45% were compared. RESULTS: Septal pacing was associated with shorter QRS (145 +/- 4 msec vs 170 +/- 4 msec, P < 0.01) and normal axis (40 degrees +/- 10 degrees vs -71 +/- 4 degrees , P < 0.01). At 3 months, among patients with baseline LVEF < or = 45%, LVEF was 42 +/- 5% after septal pacing versus 37 +/- 4% after apical pacing (P < 0.001). CONCLUSION: In contrast to RV apical pacing, chronic RV septal pacing preserved LVEF in patients with baseline LVEF < or = 45%.     

Assessment of heart failure and left ventricular systolic dysfunction after cardiac pacing in patients with preserved left ventricular systolic function

BACKGROUND: There is an accumulating data suggesting the deleterious effects of right ventricular pacing on left ventricular performance. Such pacing mimics left bundle branch block resulting in a prolonged QRS duration and causes ventricular asynchrony. AIMS: The purpose of this study is to assess heart failure and left ventricular systolic function after cardiac pacemaker implantation in patients with atrioventricular block and preserved systolic left ventricular function. Secondly, we sought to search for predictive factors of developing left ventricular dysfunction after pacing. METHODS: In this prospective study, we included patients who had been implanted for at least six months. They underwent medical history and examination, 12 leads electrocardiogram and echocardiography before pacemaker implantation and when attending to routine pacemaker follow up. RESULTS: Forty-three patients (22 men and 21 women, age 71+/-12 years) were included in this study. Twenty-nine patients had DDD pacing and 14 VVI pacing. The ventricular lead was implanted in the apex in all patients. After a median follow up of 18+/-11 months, 11 patients (25%) developed signs of congestive heart failure. NYHA was higher after implantation (1.64+/-0.7 versus 2.27+/-0.8, p>0.00001). Left ventricular ejection fraction decreased significantly during follow up (60+/-6% versus 51+/-13%, p=0.0002). Eleven (25%) patients developed left ventricular dysfunction. We compared patients who had left ventricular ejection fraction (LV EF) less or equal to 40% (group A) and patients having LV EF greater than 40% (group B) after implantation. Patients in group A had a paced QRS width significantly larger than group B (181+/-32 ms versus 151+/-26 ms, p=0.002), a significantly prolonged intra left ventricular electromechanical delay (115+/-59 ms versus 45+/-35 ms, p<0.0001) and interventricular delay (44+/-29 ms versus 27+/-18 ms, p=0.02). Age, sex, diabetes hypertension, pacing mode and percentage of ventricular pacing were similar in both groups. A paced QRS width of 180 ms had the best sensitivity and specificity for detecting left ventricular dysfunction: sensitivity=54% and specificity=93%, p=0.01, area under the curve=0.75. CONCLUSION: Patients with atrioventricular block and preserved left ventricular systolic function at baseline decrease significantly left ventricular ejection fraction after pacing. Induced ventricular asynchronism plays a major role in the deterioration of left ventricular function. Prolonged paced QRS width is a good predictor of left ventricular dysfunction after pacing. Larger prospective studies are needed to confirm these data.     

Electrocardiographic predictors of validated right ventricular outflow tract septal pacing for correct localization of transthoracic echocardiography

Background

Electrocardiographic (ECG) characteristics of true right ventricular outflow tract (RVOT) septal pacing have not been clearly demonstrated.

Hypothesis

We hypothesized that ECG parameters would help operators differentiate true RVOT septum from non‐septal septum.

Methods

We analyzed 151 patients who underwent pacemaker implantation with a ventricular lead in the RVOT. Transthoracic echocardiographic (TTE) determination of pacing sites was applied in all patients after implantation. A 12‐lead ECG was recorded during forced ventricular pacing.

Results

According to TTE orientation, pacing at the RVOT septum was achieved in 94 patients (62.3%). Compared with nonseptal pacing, septal pacing had significantly shorter QRS duration (139.2 ± 18.5 ms vs 155.5 ± 14.7 ms; P < 0.001). More frequent negative or isoelectric QRS vector in lead I (76% vs 32%; P < 0.001), lead II/III R‐wave amplitude ratio < 1 (52% vs 25%; P = 0.001), and aVR/aVL QS‐wave amplitude ratio < 1 (59% vs 32%; P = 0.001) were observed in septal pacing. Transitional zone (TZ) score (3.8 ± 0.96 vs 4.2 ± 0.90; P = 0.004) and TZ index (0.3 ± 0.5 vs 0.6 ± 0.7; P = 0.008) were significantly lower in septal pacing than in nonseptal pacing, respectively. In multivariate analysis, paced QRS duration and negative or isoelectric QRS vector in lead I independently predicted RVOT septal pacing (P < 0.001). At ROC curve analysis, paced QRS duration ≤145 ms identified RVOT septal pacing with 85.1% sensitivity and 78.9% specificity.

Conclusions

This study reveals the heterogeneity of lead placement within the RVOT. Narrower paced QRS duration and negative or isoelectric QRS vector in lead I independently predict RVOT septal pacing.     

Effect of right ventricular pacing site on QRS width

To assess the effect of various right ventricular pacing sites on QRS duration, we enrolled 50 patients (mean age, 64 ± 13 years; 36 men); 16 had bradycardia and 34 had tachycardia. The right ventricle was arbitrarily divided into 5 sections: high and low right ventricular outflow tract, mid septum, low septum, and apex. Right ventricular pacing was performed using an electrode catheter at each of the 5 sites. QRS duration was 162 ± 20 ms during high right ventricular outflow tract pacing, 143 ± 17 ms during low right ventricular outflow tract pacing, 151 ± 20 ms during mid-septal pacing, 163 ± 16 ms during low-septal pacing, and 167 ± 18 ms during apical pacing. Paced QRS duration was shorter during low right ventricular outflow tract and mid-septal pacing compared to apical pacing in 34 patients. There was a difference of 10 ms or less in the paced QRS duration between these pacing sites in the other 16 patients. QRS duration was shortest when the septum was paced in the right ventricle. However, QRS duration was similar during pacing in the septum and the apex in 32% of patients.     

Preferred left ventricular lead position for upgrade from right ventricular pacing to cardiac resynchronization therapy

Introduction

Cardiac resynchronization therapy (CRT) is well-established for treating symptomatic heart failure with electrical dyssynchrony. The left ventricular (LV) lead position is recommended at LV posterolateral to lateral sites in patients with left bundle branch block; however, its preferred region remains unclear in patients being upgraded from right ventricular (RV) apical pacing to CRT. This study aimed to identify the preferred LV lead position for upgrading conventional RV apical pacing to CRT.

Methods

We used electrode catheters positioned at the RV apex and LV anterolateral and posterolateral sites via the coronary sinus (CS) branches to measure the ratio of activation time to QRS duration from the RV apex to the LV anterolateral and posterolateral sites during RV apical pacing. Simultaneous biventricular pacing was performed at the RV apex and each LV site, and the differences in QRS duration and LV dP/dt_max from those of RV apical pacing were measured.

Results

Thirty-seven patients with anterolateral and posterolateral LV CS branches were included. During RV apical pacing, the average ratio of activation time to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.90 ± 0.06 vs. 0.71 ± 0.11, p < .001). The decreasing ratio of QRS duration and the increasing ratio of LV dP/dt_max were higher at the LV anterolateral site than at the posterolateral site (45.7 ± 18.0% vs. 32.0 ± 17.6%, p < .001; 12.7 ± 2.9% vs. 3.7 ± 8.2%, p < .001, respectively) during biventricular pacing compared with RV apical pacing.

Conclusion

The LV anterolateral site is the preferred LV lead position in patients being upgraded from conventional RV apical pacing to CRT.     

右室心尖部起搏与右室流出道起搏对Ⅲ度房室传导阻滞患者疗效的对比研究

目的:比较右室心尖部起搏与右室流出道起搏对Ⅲ度房室传导阻滞患者心室间运动同步性及左室内运动同步性,以及对患者心功能的影响。方法:选取因Ⅲ度及高度房室传导阻滞患者置入双腔起搏器患者共38例。其中心室电极置入右室流出道者20例(RVOT组),置入右室心尖部18例(RVA组),超声心动图术前测量左室舒张末内径(LVEDD),左室收缩末内径(LVESD)、左室射血分数(LVEF)、E/A值、心室间激动延迟时间(IVMD)、室间隔与左心室后壁间收缩延迟时间(SPWMD)。术后1个月、12个月随访。结果:术后1个月,与RVOT组比较,RVA组IVMD、SPWMD明显延长[IVMD(39.83±6.01)∶(31.95±7.86)ms,P=0.02],[SP-WMD(97.83±20.81)∶(84.6±10.89)ms,P=0.023]。术后12个月,与ROVT组比较,RVA组LVEDD明显增大[(49.11±2.39)∶(47.4±1.96)mm,P=0.02],LVESD明显增大[(34.28±3.41)∶(32.5±1.5)mm,P=0.04];LVEF明显降低[(59.56±3.38)∶(62.8±2.14)%,...     

Effects of right ventricular pacing on intra-left ventricular electromechanical activation in patients with native narrow QRS

Some patients with right ventricular (RV) apical pacing show contractile asynchrony of the left ventricle. Whether the asynchrony is due to RV pacing or was a preexistimg condition remains unknown. The aim of this study was to evaluate how much pacing from the RV apex affects left ventricular (LV) electromechanical activation and to assess whether the extent of LV asynchrony during RV pacing can be predicted by clinical, electrocardiographic, or echocardiographic findings obtained during spontaneous rhythm. We evaluated 56 patients with narrow QRS and preserved atrioventricular conduction who received permanent backup RV pacing. Intra-LV electromechanical activation was assessed during spontaneous rhythm and during pacing using tissue Doppler echocardiography. An abnormal intra-LV electromechanical delay (EMD) (defined as a >41-ms difference between the faster and slower activated LV wall) was found in 15 patients (27%) during spontaneous rhythm and 28 patients (50%) during RV pacing (p<0.001). Of the 9 baseline variables (age, gender, history of heart failure, QRS duration in spontaneous rhythm and during pacing, LV end-diastolic and end-systolic diameters, LV ejection fraction, and intra-LV EMD in spontaneous rhythm), an abnormal baseline intra-LV EMD and QRS duration of >85 ms were independent predictors of an abnormal intra-LV delay during RV pacing. RV apical pacing induces asynchrony of LV contractions in a substantial percentage of patients but not in all. Although normal baseline intra-LV electromechanical activation cannot exclude the development of significant asynchrony during RV pacing, the presence of preimplant LV asynchrony predicts for a worsening of this detrimental effect.     

QRS波时限对起搏器依赖患者心脏功能的影响

目的:观察右心室起搏QRS波时限对起搏器依赖患者心脏功能的影响。方法:选取在我院诊断为Ⅲ度房室传导阻滞并行永久性右心室起搏的患者112例,以起搏QRS波时限将患者分为A组(起搏QRS波时限<190ms)和B组(起搏QRS波时限≥190ms),并对每例患者进行临床评估和心脏彩色多普勒超声检查,动态随访心脏功能,以随访期间出现明显心功能下降为终点,观察起搏QRS波时限与心脏功能的关系。同时根据随访期间是否出现心功能下降将患者分为心功能下降组(Y组)和心功能无下降组(N组),并进行各因素与心功能下降之间的单因素分析,取P<0.1的因素纳入Logistic回归模型,寻找影响起搏器依赖患者心功能的因素。结果:平均随访(45.46±23.00)个月,40例(28.57%)出现明显心功能下降,其中,A组24例(27.27%),B组16例(66.67%),2组间差异有统计学意义(P=0.0004),Y组的起搏QRS波时限较N组明显延长[(176.58±22.71)∶(159.74±20.23)ms,P<0.0001]。多元Logistic逐步回归分析结果显示,左心室舒张末期内径增大、射血分数下降、左束支传导阻滞、起搏QRS波时限≥190ms、年龄及起搏时间是起搏器依赖患者心功能下降的危险因素。结论:起搏QRS波时限延长是心脏功能下降和心力衰竭发生的危险因素,可以作为起搏器依赖患者起搏后心脏功能下降的预测指标。除此之外,左心室增大、左束支传导阻滞、射血分数降低、年龄及起搏时间也是起搏器依赖患者心脏功能下降的危险因素。     

Functional abnormalities in patients with permanent right ventricular pacing: the effect of sites of electrical stimulation

OBJECTIVES: We sought to evaluate the long-term effects of alternative right ventricular pacing sites on myocardial function and perfusion. BACKGROUND: Previous studies have demonstrated that asynchronous ventricular activation due to right ventricular apical (RVA) pacing alters regional myocardial perfusion and functions. METHODS: We randomized 24 patients with complete atrioventricular block to undergo permanent ventricular stimulation either at the RVA (n = 12) or right ventricular outflow (RVOT) (n = 12). All patients underwent dipyridamole thallium myocardial scintigraphy and radionuclide ventriculography at 6 and 18 months after pacemaker implantation. RESULTS: After pacing, the mean QRS duration was significantly longer during RVA pacing than during RVOT pacing (151 +/- 6 vs. 134 +/- 4 ms, p = 0.03). At six months, the incidence of myocardial perfusion defects (50% vs. 25%) and regional wall motion abnormalities (42% vs. 25%) and the left ventricular ejection fraction (LVEF) (55 +/- 3% vs. 55 +/- 1%) were similar during RVA pacing and RVOT pacing (p > 0.05). However, at 18 months, the incidence of myocardial perfusion defects (83% vs. 33%) and regional wall motion abnormalities (75% vs. 33%) were higher and LVEF (47 +/- 3 vs. 56 +/- 1%) was lower during RVA pacing than during RVOT pacing (all p < 0.05). Patients with RVA pacing had a significant increase in the incidence of myocardial perfusion defects (p < 0.05) and a decrease in LVEF (p < 0.01) between 6 and 18 months, but patients with RVOT pacing did not (p > 0.05). CONCLUSIONS: This study demonstrates that preserved synchronous ventricular activation with RVOT pacing prevents the long-term deleterious effects of RVA pacing on myocardial perfusion and function in patients implanted with a permanent pacemaker.     

Analysis of ventricular performance as a function of pacing site and mode

Emerging data from experimental and clinical studies have shown that right ventricular (RV) apical pacing led to abnormalities of ventricular activation and contraction, and impairment of myocardial perfusion with adverse left ventricular (LV) remodeling, which was associated with increased risk of cardiac morbidity and mortality. As a result, there is a growing interest in searching for methods to minimize unnecessary RV pacing and preserving normal ventricular activation with alternative ventricular pacing sites. The risk of developing heart failure (HF) after RV apical pacing depends on the interactions between patient-specific factors (baseline atrial rhythm, intrinsic atrioventricular and ventricular conduction, LV ejection fraction, and the presence of HF and myocardial infarction) and pacing-related factors (mode of pacing, site of ventricular pacing, paced QRS duration, and percentage and duration of pacing). In patients with intact atrioventricular conduction, atrial-based pacing should be used to avoid unnecessary ventricular pacing. In patients requiring ventricular pacing, the potential benefits of alternate ventricular pacing sites, such as RV or LV septa, or even biventricular pacing in different patient populations remain unclear and warrant further long-term prospective clinical trial evaluations especially in those patients who are at a higher risk of developing HF after RV apical pacing.     

Ⅲ度房室传导阻滞患者行不同房室间期起搏对血流动力学及功能的影响

目的探讨Ⅲ度房室传导阻滞(AVB)患者不同房室间期(AVD)起搏对血流动力学及功能的影响。方法选择植入双腔起搏器的Ⅲ度AVB患者51例,按不同AVD分为前后4期:A期AVD为心房感知(SAV)90 ms、心室起搏(PAV)120 ms;B期为SAV 120 ms、PAV 150 ms;C期为SAV 150 ms、PAV 180 ms;D期为SAV 180 ms、PAV 210 ms。每期观察2个月,分别比较Ⅲ度AVB患者4期心电图QRS波时限和形态,血清氨基末端脑钠肽前体(NT-proBNP)水平及心脏超声左房内径(LAD)、左室收缩末期内径(LVDs)、左室舒张末期内径(LVDd)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)、左室射血分数(LVEF)及二、三尖瓣返流等参数。结果Ⅲ度AVB患者行不同AVD起搏时LAD、LVDd、LVDs、IVST、LVPWT及LVEF无变化;而二尖瓣及三尖瓣返流随AVD的延长而依次减少;起搏QRS波时限A期较D期长(149.21±8.10 ms vs 145.27±6.94 ms,P<0.05);NT-proBNP随AVD的延长而减少(中位值分别为365.51,327.54,279.13和270.10 pg/ml)。结论Ⅲ度AVD患者不同AVD起搏对心脏血流动力学会产生影响,短期内对心脏的结构及功能影响不明显,选择起搏间期为SAV180 ms、PAV 210 ms时患者的获益最大。     

右室流出道间隔起搏与心尖部起搏的对比研究

目的 研究右室流出道(RVOT)间隔部起搏应用的安全性和有效性.方法 入选安装心脏永久起搏器患者65例,按起搏部位随机分为右室流出道间隔部起搏组(31例)和右室心尖部(RVA)起搏组(34例),记录并比较二组术中、术后起搏参数,并比较二组间的QRS时限,记录并比较二组术前、术后的左室舒张末内径(LVEDD)、左室射血分...     

右室心尖部起搏患者起搏QRS波时限与左室结构和功能关系探讨

目的评价起搏QRS波时限与左心结构和功能的关系。方法入选106例右室心尖起搏患者,分成左室射血分数(LVEF)<0.55的病例组(n=48)和LVEF>0.55的对照组(n=58)。通过常规体表心电图测得起搏QRS波时限,行超声心动图检查获取左房内径(LAD)、收缩末期左室内径(LVESD)、舒张末期左室内径(LVEDD)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)及LVEF,评价患者的纽约心功能分级,同时检测患者的N端-B型利钠肽前体(NT-proBNP)水平,分析起搏QRS波时限与以上各指标的关系。结果①起搏QRS波时限与LVEDD(r=0.577,P<0.001)、LVESD(r=0.627,P<0.001)、LAD(r=0.241,P=0.013)、IVST(r=0.345,P<0.001)、LVP-WT(r=0.349,P<0.001)均呈正相关,与LVEF负相关(r=-0.570,P<0.001),与纽约心功能分级正相关(r=0.527,P<0.001),与NT-proBNP对数正相关(r=0.265,P=0.024)。②以起搏QRS波时限≥200ms诊断左室收缩功能不全,灵敏度和特异度分别为85.42%和70.69%。结论对于右室心尖部起搏的患者,起搏QRS波时限是一个简便而实用的初步判断心脏结构和功能的指标。     

Acute Effects of Intraoperative Multisite Ventricular Pacing on Left Ventricular Function and Activation/Contraction Sequence in Patients with Depressed Ventricular Function

Multisite Pacing Effect on LV Function. Introduction : We hypothesized that simultaneous right and left ventricular apical pacing would result in improvement in left ventricular function due to improved coordination of segmental ventricular contraction. Structural changes in ventricular muscle present in dilated cardiomyopathy compromise ventricular excitation and mechanical contraction.
Methods and Results : Eleven patients with depressed left ventricular function having cardiac surgery underwent epicardial multisite pacing with continuous transesophageal echocardiographic imaging. Quantitative measurement of percent fractional area change was performed, and segmental changes in contraction sequence resulting from simultaneous right and left ventricular pacing were assessed by application of phase analysis to recorded transesophageal images. There was no statistically significant difference between the paced QRS duration achieved with simultaneous right and left ventricular apical pacing and the native QRS duration (139 ± 39 msec vs 106 ± 18 msec, P = NS), but all other paced modes resulted in longer QRS durations. Percent fractional area change improved with simultaneous right and left ventricular apical pacing hut not with other paced modes (41.5 ± 11.9 vs 34.3 ± 9.7, P < 0.01). Phase analysis demonstrated a resequencing of segmental left ventricular activation/contraction when compared to baseline ventricular activation.
Conclusion : Simultaneous right and left ventricular apical pacing results in acute improvements in global ventricular performance in patients with depressed ventricular function. Improvements may result from pacing-induced global coordination through recruitment of left and right ventricular apical and septal segments critical to effective ventricular contraction.     

右心室流出道间隔部起搏对完全性房室传导阻滞患者心功能的影响

目的：比较右心室流出道间隔部（RVS）起搏与右心室心尖部（RVA）起搏对左右心室间收缩同步性、左室重构及心功能的影响。方法：①入选Ⅲ度房室传导阻滞患者61（男39,女22）例,随机分入RVS部起搏组（RVS组,n=33）和RVA部起搏组（RVA组,n=28）。②比较两组患者植入术中及术后12月心室电极导线参数（起搏阈值、R波感知及阻抗）的差异。③观察两组患者术前及术后12月QRS波时限;术后应用组织多普勒同步图（TSI）分别测定两组左、右心室侧壁基底部收缩达峰时间差（△Ts）。评价心室间不同步的程度。④行多普勒超声心动图（UCG）检查,观察两组术前及术后12月左室舒张末期内径（LVEDD）及左室射血分数（LVEF）的变化,比较不同起搏部位对心功能的影响。结果：①两组患者测试的起搏阈值、R波感知及导线阻抗无统计学差异。②两组患者术后QRS波时限均较术前延长（均P〈0．01）,RVA组较RVS组延长更为明显（P〈0．01）。RVS组与RVA组ATs分别为（27±14）ms和（90±22）ms,有统计学差异（P〈0．01）。③术后12／了＇月两组LVEDD均较术前增加,RVA明显大于RVS组[（54±5）mm阮（51±5）mm,P〈0．05]。RVA组术后12月LVEDD较术前明显增加[（54±5）mmvs．（50±4）mm,P〈0．05],术后12月两组LVEF均较术前降低[RVS组：（0．58-4-0．14）傩．（0．63±0．09）,P〈0．01;RVA组：（0．51±0．12）伽．（0．64±0．13）,P〈0．01],组间比差异不显著。结论：RVS起搏对心室问同步性、左室重构的影响要优于RVA起搏。