右心室不同部位起搏对心脏收缩同步性及心功能的影响

目的比较右心室流出道（right ventricular outflow tract,RVOT）起搏与右心窀心尖部（riht ventficular apex,RVA）起搏对心脏收缩同步性指标及收缩功能的影响。方法2004年1月至2005年1月在我院植入VVL／VVIR,DDD／DDDR起搏器的患者,随机接受RVA起搏和RVOT起搏。植入前检查12导联体表心电罔及超声心动图,记录QRS时限、左心室舒张末内径（LVEDD）、左心房内径（LAD）、左心事射血分数（LVEF）。植入后记录心室起搏状态下的QRS时限。随访时间为2年,随访内容包括LVEDD、LAD、LVEF,同时应用脉冲组织多普勒技术测定心室问激动延迟（IVMD）以及左心室内收缩同步性指标（Ts-SD）。结果共随访30例患者,其中RVA起搏17例,RVOT起搏13例,两组患者间年龄、性别及心血管疾病等基本情况筹异无统计学意义。植入前两组患者问QRS时限、LVEDD、LAD及LVEF差异无统计学意义,植入后RVOT起搏状态下QRS时限较RVA起搏明显缩短[（140．15±11．36）ms对（160．76±23．68）ms,P=0．033],植入后两组间IVMD[（25．7±9．1）mS对（36．7±10．0）ms,P=0．076]比较差异无统计学意义,两组问Ts—SD（13．34ms对42．96ms,P=0．001）比较差异有统计学意义;植入后随访两年,两组患者间LAD差异无统计学意义[（43±6）ms对（42±9）ms,P=0．759],同RVA组相比,RVOT组LVEDD缩小[（5．10±0．76）mm对（5．28±0．40）mm,P=0．048],LVEF明显增加（0．56±0．04对0．52±0．02,P=0．001）。结论同右心窄流出道起搏相比,右心室心尖部起搏对患者心功能呈负性影响,且加重左心室内不同步收缩。     

右心室流出道与右心室心尖部起搏对心室收缩同步性和心功能的影响

目的研究右心室流出道(right ventricular outflow tract,RVOT)间隔部和右心室心尖部(right ventricularapex,RVA)起搏对心脏收缩同步性、收缩功能的影响,探讨RVOT间隔部起搏的意义。方法 50例病态窦房结综合征患者分为RVOT组(n=25)和RVA组(n=25),起搏器置入1个月后通过调整房室间期使心室节律全部为起搏节律或房室结自身下传节律,观察起搏参数,并行超声心动图检查。结果RVOT组与RVA组电极导线植入时间、X线曝光时间比较,差异无统计学意义(P>0.05)。全部患者未出现植入并发症。两组随访1个月时起搏参数比较,差异无统计学意义(P>0.05)。RVOT组和RVA组起搏后的QRS波时限较前明显增宽,差异有统计学意义[RVOT组:(135±8)ms vs.(88±8)ms,P<0.001;RVA组:(154±8)ms vs.(90±6)ms,P<0.001]。RVA组起搏后QRS波时限较RVOT组增宽更为明显,差异有统计学意义(P<0.001)。两组起搏后室间机械延迟(interventricularmechanical delay,IVMD)和室间隔-左心室后壁收缩运动延迟时间(septal-to-posteriowall motion delay,SPWMD)较起搏前均显著增加,差异有统计学意义(P<0.001)。RVA组起搏后IVMD和SPWMD绝对值较RVOT组显著延长,差异有统计学意义[IVMD:(38±7)ms vs.(24±5)ms,P<0.001;SPWMD:(118±21)ms vs.(60±11)ms,P<0.001]。两组左心室舒张末内径及左心室射血分数比较,差异无统计学意义(P>0.05)。结论右心室起搏会造成心室收缩不同步,RVOT起搏对心室收缩不同步的影响较RVA起搏小,提示RVOT起搏是较为生理的起搏位点。     

Chronic Effect of Right Ventricular Pacing on Left Ventricular Rotational Synchrony in Patients with Complete Atrioventricular Block

Background: Chronic effect of right ventricular (RV) pacing on left ventricular (LV) rotational synchrony is unknown. The aim of this study is to assess chronic effect of RV pacing on LV rotational synchrony using two‐dimensional ultrasound speckle tracking imaging. Methods and Results: Thirty‐one patients who underwent dual‐chamber pacemaker implantation for complete atrioventricular block, and age‐ and sex‐matched 10 healthy controls were assessed. We divided our patients into RV apical (RVA, n = 16) and RV outflow tract (RVOT, n = 15) pacing groups. We compared echocardiographic parameters such as LV rotational synchrony between pacing groups and healthy control. We defined Q to peak rotation interval as the interval from the beginning of the Q‐wave to the peak apical counter‐clockwise or peak basal clockwise rotation. We calculated apical–basal rotation delay by subtracting basal Q to peak rotation interval from apical one as the representative of rotational synchronization. Apical–basal rotation delay of RVA pacing was significantly longer than that of healthy control (100 ± 110 vs. ?6 ± 15 ms, P = 0.002), while there was no statistically significant difference between RVOT pacing and healthy control (?3 ± 99 vs. ?6 ± 15 ms, P = 0.919). Conclusions: LV rotation during RVOT pacing is synchronous at 15 months after pacemaker implantation, while RVA pacing provokes LV rotational dyssynchrony by inducing delayed apical rotation at 7 years after pacemaker implantation in patients with complete atrioventricular block. (Echocardiography 2011;28:69‐75)     

Pacing-Induced Electromechanical Ventricular Dyssynchrony Does Not Acutely Influence Right Ventricular Function and Global Hemodynamics in Children with Normal Hearts

Background: Right ventricular (RV) pacing may be detrimental to ventricular function. However, the acute effects of electromechanical dyssynchrony on RV function are not well characterized in children. We studied acute effects of electromechanical dyssynchrony, induced by RV apical and RV outflow pacing, in children with normal hearts, evaluating electromechanical synchrony, hemodynamic response, and RV function. Methods: Seventeen children (mean ± SD, 12 ± 4 years) with normal cardiac structure/function were paced after accessory pathway ablation, at baseline (AOO), and with AV pacing (DOO) from the RV apex and RV outflow. QRS duration was determined from surface ECG. Intra‐ and interventricular mechanical dyssynchrony and regional ventricular function were determined using tissue Doppler imaging. Global RV systolic and diastolic functions were assessed by RV dP/dT_max and RV dP/dT_neg using pressure‐tipped transducers. Regional RV function was assessed by tissue Doppler imaging. Cardiac index (CI) and blood pressures were measured. Results: RV apical and outflow pacing induced significant electromechanical dyssynchrony manifested by lengthening of the QRS duration, increased LV intraventricular delay (49 ± 34 ms, 53 ± 43 ms, respectively, P < 0.001), and increased interventricular delay (60 ± 29 ms, 55 ± 37 ms, P < 0.0001) versus AOO pacing. However, there was no change in blood pressure, CI, RV dp/dT_max, RV dP/dT_neg, or regional tissue Doppler velocities, indicating preserved hemodynamics and preserved global and regional RV systolic and diastolic function. Conclusions: In children with normal cardiac function and structure, pacing‐induced electromechanical dyssynchrony did not acutely affect RV systolic and diastolic function and did not acutely alter global hemodynamics. Therefore, electromechanical dyssynchrony may only be an important therapeutic target in the setting of decreased RV function.     

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。     

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。     

Right ventricular outflow versus apical pacing in pacemaker patients with congestive heart failure and atrial fibrillation

INTRODUCTION: Prior studies suggest that right ventricular apical (RVA) pacing has deleterious effects. Whether the right ventricular outflow tract (RVOT) is a more optimal site for permanent pacing in patients with congestive heart failure (CHF) has not been established. METHODS AND RESULTS: We conducted a randomized, cross-over trial to determine whether quality of life (QOL) is better after 3 months of RVOT than RVA pacing in 103 pacemaker recipients with CHF, left ventricular (LV) systolic dysfunction (LV ejection fraction < or = 40%), and chronic atrial fibrillation (AF). An additional aim was to compare dual-site (RVOT + RVA, 31-ms delay) with single-site RVA and RVOT pacing. QRS duration was shorter during RVOT (167 +/- 45 ms) and dual-site (149 +/- 19 ms) than RVA pacing (180 +/- 58 ms, P < 0.0001). At 6 months, the RVOT group had higher (P = 0.01) role-emotional QOL subscale scores than the RVA group. At 9 months, there were no significant differences in QOL scores between RVOT and RVA groups. Comparing RVOT to RVA pacing within the same patient, mental health subscale scores were better (P = 0.03) during RVOT pacing. After 9 months of follow-up, LVEF was higher (P = 0.04) in those assigned to RVA rather than RVOT pacing between months 6 and 9. After 3 months of dual-site RV pacing, physical functioning was worse (P = 0.04) than during RVA pacing, mental health was worse (P = 0.02) than during RVOT pacing, and New York Heart Association (NYHA) functional class was slightly better (P = 0.03) than during RVOT pacing. There were no other significant differences between RVA, RVOT and dual-site RV pacing in QOL scores, NYHA class, distance walked in 6 minutes, LV ejection fraction, or mitral regurgitation. CONCLUSION: In patients with CHF, LV dysfunction, and chronic AF, RVOT and dual-site RV pacing shorten QRS duration but after 3 months do not consistently improve QOL or other clinical outcomes compared with RVA pacing.     

Prevalence of mechanical dyssynchrony in patients with heart failure and preserved left ventricular function (a report from the Belgian Multicenter Registry on dyssynchrony)

The present study evaluated the prevalence of mechanical inter- and intraventricular dyssynchrony in patients with heart failure and preserved left ventricular (LV) ejection fraction (LVEF). We studied 138 patients with heart failure (age 67+/-11 years; 76% men); 60 patients had preserved LVEF (>40%). Using conventional Doppler echocardiography, an interventricular mechanical delay>or=40 ms was defined as interventricular dyssynchrony. Using pulse-wave tissue Doppler imaging, the time from the beginning of the QRS complex to onset of systolic motion was measured in 4 basal LV segments. A dispersion of >or=60 ms was defined as intraventricular dyssynchrony. The prevalence of inter- and intraventricular dyssynchrony was lower in patients with preserved LVEF than in those with reduced LVEF (17% vs 41%, p<0.01 for interventricular dyssynchrony, 18% vs 36%, p<0.01 for intraventricular dyssynchrony). However, patients with preserved LVEF and a QRS width>or=120 ms had higher values for the parameters for inter- and intraventricular dyssynchrony than patients with a QRS width<120 ms (interventricular mechanical delay 33+/-20 vs 20+/-16 ms, p<0.05; tissue Doppler imaging dispersion 42+/-26 vs 33+/-22 ms, p<0.05). In patients with a QRS width>or=120 ms, the prevalence of inter- and intraventricular dyssynchrony was comparable for patients with preserved and reduced LVEF (42% vs 55%, p=NS for interventricular dyssynchrony and 45% vs 46%, p=NS for intraventricular dyssynchrony). In conclusion, the prevalence of inter- and intraventricular dyssynchrony was low (17% and 18%, respectively) in patients with heart failure and preserved LVEF. However, in the presence of a QRS width of >or=120 ms, this prevalence increased to almost 50%, comparable to that for patients with heart failure and reduced LVEF and a QRS width of >or=120 ms.     

右室双部位起搏与双室同步起搏的急性血液动力学对比研究

比较右室双部位 (RV Bi)起搏和双室 (BiV)同步起搏对血液动力学的影响 ,并与右室心尖部 (RVA)、右室流出道 (RVOT)、左室基底部 (LVB)起搏相比较 ,明确双部位起搏是否优于单部位起搏。 15例患者中病窦综合征 8例、Ⅲ度房室阻滞 7例。分别行RVA、RVOT、LVB、RV Bi、BiV起搏 (VVI,6 0～ 90次 /分 ) ,测定心输出量 (CO)和心脏指数(CI)、肺毛细血管嵌顿压 (PCWP)和QRS波时限 (QRSd)。结果 :①与RVA起搏相比 ,RVOT、LVB、RV Bi、BiV起搏CI分别增加了 7.5 %、11.3%、15 .5 %和 17.2 % ,PCWP分别降低了 14.9%、10 .3%、2 1.7%和 2 0 .0 % (P均 <0 .0 1)。②RV Bi、BiV起搏较RVOT、LVB起搏的CO、CI增高而PCWP降低 (P均 <0 .0 5 )。③RV Bi与BiV起搏、RVOT与LVB起搏之间CO、CI和PCWP无显著差异。④RVOT、RV Bi、BiV起搏的QRSd(分别为 12 8± 11,111± 16 ,10 3± 13ms)较RVA起搏 (146± 18ms)时显著缩短 (P≤ 0 .0 0 1) ,而LVB起搏 (142± 15ms)与RVOT、RVA起搏时无显著差异。结论 :RV Bi起搏和BiV同步起搏的急性血液动力学效果无明显差异 ,但双部位起搏的效果明显优于单部位起搏 ;双部位起搏的QRSd也比单部位起搏明显缩短     

右心室起搏导线位置对心脏再同步治疗效果的影响

目的 评价右心室起搏导线位置对心脏再同步治疗（CRT）效果的影响.方法 71例顽固性心力衰竭患者接受CRT手术,53例左心室导线植入侧壁或侧后壁,18例植入前壁或下壁（非侧后壁）;48例右心室导线植入心尖部,23例植入流出道间隔部.术前记录受试者心功能（NYHA分级）、QRS时限（QRSd）、左心室射血分数（LVEF）、左心室舒张末期内径（LVEDD）及左心室收缩末期内径（LVESD）;术后6个月对上述参数进行随访,比较不同右心室起搏部位对CRT临床疗效的影响.结果 术后6个月,右心室心尖部起搏组LVEF高于流出道间隔部起搏组[（0.44±0.07）对（0.40±0.07）,P=0.048],余心功能、QRSd、LVEDD、LVESD等各项指标均差异无统计学意义（P＞0.05）.根据左心室起搏部位进一步分为侧壁或侧后壁与非侧后壁两组,就侧壁或侧后壁组,右心室心尖部起搏较间隔部起搏可更好地提高心输出量LVEF[（0.45±0.07）对（0.40±0.08）,P=0.027],改善心功能[（2.59±0.59）对（3.00±0.68）,P=0.038],对于非侧后壁组,比较右心室心尖部与流出道间隔部起搏,各项指标均差异无统计学意义（P＞0.05）.结论 若无视左心室起搏部位,右心室心尖部起搏略优于流出道间隔部起搏;而对于左心室侧壁和/或侧后壁起搏者,应尽量将右心室导线置于心尖部,以获得较好疗效.     

Interventricular and intraventricular dyssynchrony in idiopathic dilated cardiomyopathy: a prognostic study with fourier phase analysis of radionuclide angioscintigraphy

OBJECTIVES: The study evaluated the prognostic value of interventricular and intraventricular dyssynchrony in idiopathic dilated cardiomyopathy (IDC). BACKGROUND: Biventricular pacing is an emerging treatment for patients with dilated cardiomyopathy and ventricular dyssynchrony. The prognostic values of interventricular and intraventricular dyssynchrony have not been previously compared. METHODS: A total of 103 patients with IDC were studied. Left bundle branch block was present in 25% of patients. Equilibrium radionuclide angiography was performed and Fourier phase analyses were examined in both ventricles. Difference between the mean phase of left ventricle (LV) and right ventricle (RV) assessed interventricular dyssynchrony, and standard deviations (SDs) of the mean phase in each ventricle assessed intraventricular dyssynchrony. RESULTS: The QRS duration was related to both interventricular and intraventricular dyssynchrony. A degradation of the hemodynamic status was associated with an increase in intraventricular dyssynchrony but not in interventricular dyssynchrony. With a follow-up of 27 +/- 23 months, 18 patients had a major cardiac event (7 cardiac deaths; 11 worsening, leading to heart transplantation). The SDs of the LV and RV mean phase and QRS duration were predictors of cardiac event (all p < 0.0001), but interventricular dyssynchrony was not. Among 13 univariate predictors of cardiac event, the only independent predictors were an increased SD of LV mean phase (p = 0.0004) and an increased pulmonary capillary wedge pressure (p = 0.009). CONCLUSIONS: Intraventricular dyssynchrony evaluated with phase analysis of radionuclide angiography is an independent predictor of cardiac event in IDC. The prognosis is related to intraventricular rather than to interventricular dyssynchrony in IDC.     

Left ventricular versus biventricular pacing: a randomized comparative study evaluating mid-term electromechanical and clinical effects

BACKGROUND: Although left ventricular (LV) pacing has been proposed as an alternative to biventricular (BIV) pacing for heart failure (HF) patients, few comparative data are available on the electromechanical effects of these pacing modalities at mid-term follow-up. AIM: To investigate the clinical and echocardiographic effects of LV versus BIV pacing in a mid-term randomized study. METHODS: After implantation of a device with LV/BIV pacing capabilities, 22 patients with chronic HF and left bundle branch block were randomized to LV or BIV pacing. Patients were assessed both preimplantation and after 3 months by clinical examination, ECG and echocardiography with pulsed tissue Doppler imaging. RESULTS: At 3 months LV pacing improved clinical parameters, LV ejection fraction (+5%, range 5-8%, P = 0.007) and intraventricular dyssynchrony (-40 ms, range -50 to -15 ms, in septal to lateral delay, P = 0.008) to a similar extent to BIV pacing. A decrease in interventricular mechanical delay (-25 ms, range -40 to -5 ms, P = 0.008) and QRS duration (-28 ms, range -40 to -5 ms, P = 0.008) was observed in BIV, but not in LV patients. CONCLUSION: In this pilot evaluation, LV pacing appeared to be associated with clinical benefits similar to BIV pacing at mid-term follow-up, and this was combined with an improvement in intraventricular dyssynchrony, regardless of variations in interventricular dyssynchrony and QRS duration. Echocardiographic evaluation of intraventricular dyssynchrony seems to be an appropriate method for assessing the chronic response to LV pacing.     

Acute pacing-induced dyssynchronous activation of the left ventricle creates systolic dyssynchrony with preserved diastolic synchrony

Introduction: Patients with heart block have conventionally received a pacemaker that stimulates the right ventricular apex (RVA) to restore heart rate control. While RVA pacing has been shown to create systolic dyssynchrony acutely, dyssynchrony can also occur in diastole. The effects of acute RVA pacing on diastolic synchrony have not been investigated. RVA pacing acutely impairs diastolic function by increasing the time constant of relaxation, decreasing the peak lengthening rate and decreasing peak negative dP/dt. We therefore hypothesized that acute RVA pacing would cause diastolic dyssynchrony in addition to creating systolic dyssynchrony.
Methods and Results: Fourteen patients (13 ± 4 years old) with non-preexcited supraventricular tachycardia underwent ablation therapy with subsequent testing to confirm elimination of the tachycardia substrate. Normal cardiac structure and function were then documented on two-dimensional echocardiography and 12-lead electrocardiography prior to enrollment. Tissue Doppler images were collected during normal sinus rhythm (NSR), right atrial appendage pacing (AAI), and VVI-RVA pacing during the postablation waiting interval. Systolic and diastolic dyssynchrony were quantified using cross-correlation analysis of tissue Doppler velocity curves. Systolic dyssynchrony increased 81% during RVA pacing relative to AAI and NSR (P < 0.01). Diastolic synchrony was not affected by the different pacing modes (P = 0.375).
Conclusion: Acute dyssynchronous activation of the LV created by RVA pacing resulted in systolic dyssynchrony with preserved diastolic synchrony in pediatric patients following catheter ablation for treatment of supraventricular tachycardia. Our results suggest that systolic and diastolic dyssynchrony are not tightly coupled and may develop through separate mechanisms.     

Ventricular contraction abnormalities in dilated cardiomyopathy: effect of biventricular pacing to correct interventricular dyssynchrony

OBJECTIVE: To measure ventricular contractile synchrony in patients with dilated cardiomyopathy (DCM) and to evaluate the effects of biventricular pacing on contractile synchrony and ejection fraction. BACKGROUND: Dilated cardiomyopathy is characterized by abnormal ventricular activation and contraction. Biventricular pacing may promote a more coordinated ventricular contraction pattern in these patients. We hypothesized that biventricular pacing would improve synchrony of right ventricular and left ventricular (RV/LV) contraction, resulting in improved ventricular ejection fraction. METHODS: Thirteen patients with DCM and intraventricular conduction delay underwent multiple gated equilibrium blood pool scintigraphy. Phase image analysis was applied to the scintigraphic data and mean phase angles computed for the RV and LV. Phase measures of interventricular (RV/LV) synchrony were computed in sinus rhythm and during atrial sensed biventricular pacing (BiV). RESULTS: The degree of interventricular dyssynchrony present in normal sinus rhythm correlated with LV ejection fraction (r = -0.69, p < 0.01). During BiV, interventricular contractile synchrony improved overall from 27.5 +/- 23.1 degrees to 14.1 +/- 13 degrees (p = 0.01). The degree of interventricular dyssynchrony present in sinus rhythm correlated with the magnitude of improvement in synchrony during BiV (r = 0.83, p < 0.001). Left ventricular ejection fraction increased in all thirteen patients during BiV, from 17.2 +/- 7.9% to 22.5 +/- 8.3% (p < 0.0001) and correlated significantly with improvement in RV/LV synchrony during BiV (r = 0.86, p < 0.001). CONCLUSIONS: Dilated cardiomyopathy with intraventricular conduction delay is associated with significant interventricular dyssynchrony. Improvements in interventricular synchrony during biventricular pacing correlate with acute improvements in LV ejection fraction.     

Acute Effects of Single‐site Pacing from the Left and Right Ventricle on Ventricular Function and Ventricular–Ventricular Interactions in Children with Normal Hearts

Objective. We studied, as a physiological benchmark, acute effects of right ventricular (RV) apical, RV outflow, and left ventricular (LV) pacing in children with normal cardiac function on LV and RV function and ventricular–ventricular interactions. Design. The design of the study was a prospective, acute intervention. Setting. The study was conducted in a tertiary care electrophysiology laboratory. Population and Methods. Seven children (mean ± SD, 12 ± 4 years) were paced after accessory pathway ablation, at baseline (AOO), and with atrioventricular pacing (DOO) from the RV apex, RV outflow, and left ventricle. Outcome Measures. Right ventricular dP/dT_max and RV dP/dT_neg (high‐fidelity transducer‐tipped catheters, Millar Instruments, Houston, TX, USA), cardiac index (Fick), blood pressure, and QRS duration were measured at each pacing condition. Intra‐ and interventricular mechanical dyssynchrony, systolic‐ and diastolic peak tissue velocities, and isovolumic acceleration were recorded by tissue Doppler imaging at the lateral mitral, septal, and tricuspid annuli at each condition. Results at each pacing condition were compared by repeated‐measures analysis of variance. Results. Pacing prolonged QRS duration, causing electrical dyssynchrony (86 ± 19 ms [baseline], 141 ± 44 ms [RV apex], 121 ± 18 ms [RV outflow], and 136 ± 34 ms [LV], P < .01). Right ventricular outflow pacing caused LV intraventricular delay (63 ± 52 vs. 12 ± 7 ms, P < .05). Right ventricular apical pacing caused interventricular delay (61 ± 29 vs. 25 ± 18 ms, P < .05). There were no significant changes in blood pressure, cardiac index, RV dp/dT_max, RV dP/dT_neg, regional tissue velocities, or isovolumic acceleration during any of the pacing conditions, indicating preserved ventricular function and hemodynamics. No important ventricular–ventricular interactions were seen. Conclusions. In children with normal cardiac anatomy and function, single‐site RV apical, RV outflow, and LV pacing induce electromechanical dyssynchrony without significantly changing ventricular function or hemodynamics, or adversely affecting ventricular–ventricular interactions.     

Hemodynamic improvement by right ventricular septal pacing in elderly patients with chronic atrial fibrillation and slow ventricular response

Background and objectives Right ventricular apical (RVA) pacing has been reported impairing left ventricular (LV) performance. Alternative pacing sites in right ventricle (RV) has been explored to obtain better cardiac function. Our study was designed to compare the hemodynamic effects of right ventricular septal (RVS) pacing with RVA pacing. Methods Ten elderly patients with chronic atrial fibrillation (AF) and long RR interval or slow ventricular response (VR) received VVI pacing. The hemodynamic difference between RVS and RVA pacing were examined by transthoracic echocardiography (TTE). Results Pacing leads were implanted successfully at the RVA and then RVS in all patients without complication. The left ventricular (LV) parameters, measured during RVA pacing including left ventricular ejection fraction (LVEF), FS, stroke volume (SV) and peak E wave velocity (EV) were decreased significantly compared to baseline data, while during RVS pacing, they were significantly better than those during RVA pacing. However, after 3-6 weeks there was no statistical significant difference between pre- and post- RVS pacing. Conclusions The LV hemodynamic parameters during RVA pacing were significantly worse than baseline data. The short term LV hemodynamic parameters of RVS pacing were significantly better than those of RVA pacing; RVS pacing could improve the hemodynamic effect through maintaining normal ventricular activation sequence and biventricular contraction synchrony in patients with chronic AF and slow ventricular response.(J Geriatr Cardiol 2005,2(2): 103-106).     

心力衰竭患者QRS波间期与心脏机械收缩功能失同步化的相关性研究

目的评价充血性心力衰竭(CHF)患者QRS间期与左右心室间、左心室内不同步运动参数的相关关系。方法 81例CHF患者及26名健康体检者作为对照组纳入本研究。行常规及彩色组织多普勒显像(TDI)检查。以左、右心室问收缩延迟(IVMD)>33ms定义室间不同步运动,以二尖瓣环6位点中任意2点QRS波起始至心室收缩顶峰的间期(TsP)最长延迟>121ms,或6位点TsP的标准差(TsP-SD)>47ms定义左心室内收缩不同步。比较QRS≥120 ms与QRS<120ms的CHF患者室间、室内不同步发生率,分析QRS间期与室间、室内不同步参数的相关关系。结果 CHF患者IVMD较对照组明显延长[(25.7±16.3)ms比(12.8±8.8)ms,P<0.0001],IVMD与QRS间期呈明显正相关(r=0.44,P<0.0001)。CHF伴QRS≥120ms(n=31)者室间不同步发生率明显高于CHF伴QRS<120ms者(n=50)(66.7%比20.9%,P<0.05)。CHF患者TsP最长延迟及TsP-SD较对照组明显延长,TsP最长延迟及TsP-SD与QRS间期呈弱相关。结论 CHF患者室间不同步运动发生率明显高于对照组,ORS间期增宽与室间不同步的关系可能更密切。     

Synchronous Ventricular Pacing without Crossing the Tricuspid Valve or Entering the Coronary Sinus—Preliminary Results

Background: Right ventricular apical (RVA) pacing promotes tricuspid regurgitation (TR), electromechanical dyssynchrony, and ventricular dysfunction. We tested a novel intramyocardial bipolar lead to assess whether stimulation of the atrioventricular septum (AVS) produces synchronous ventricular activation without crossing the tricuspid valve (TV). Methods: A lead with an active external helix and central pin was placed on the AVS and the RVA in three dogs. High‐density electroanatomic (EA) mapping was performed of both ventricles endocardially and epicardially. Intracardiac echocardiography was used to access ventricular synchrony. Results: The lead was successfully deployed into the AVS in all cases with consistent capture of the ventricular myocardium without atrial capture or sensing. The QRS duration was less with AVS compared with RVA pacing (89 ± 4 ms vs. 100 ± 11 ms [P < 0.0001, GEE P = 0.03]). There was decreased delay between color Doppler M‐mode visualized peak contraction of the septum and the mid left ventricular free wall with AVS compared with RVA pacing (89 ± 91 ms vs. 250 ± 11 ms [P < 0.0001, GEE P = 0.006]). Activation time between the mid septum and mid free wall was shorter with AVS versus RVA pacing (20.4 ± 7.7 vs. 30.8 ± 11.6 [P = 0.01, GEE P = 0.07]). The interval between QRS onset to earliest free wall activation was shorter with AVS vs. RVA pacing (19.2 ± 6.4 ms vs. 31.1 ± 11.7 ms [P = 0.005, GEE P = 0.02]). Conclusion: The AVS was successfully paced in three dogs resulting in synchronous ventricular activation without crossing the TV.     

Cardiac resynchronization pacing therapy

Approximately one third of patients with congestive heart failure and systolic dysfunction have an intraventricular conduction delay that is manifested as a QRS duration >120 ms. An intraventricular conduction delay adversely affects ventricular performance by causing dyssynchrony in ventricular activation. When ventricular dyssynchrony is present, simultaneous left and right ventricular pacing or cardiac resynchronization therapy can improve ventricular synchrony. This can lead to an improvement in hemodynamics, ventricular remodeling, mitral regurgitation, exercise capacity and quality of life. Candidates for cardiac resynchronization therapy include patients with advanced congestive heart failure that is refractory to medical therapy, a QRS duration >130 ms, left ventricular ejection fraction <0.35 and sinus rhythm. Because patients who are candidates for biventricular pacing are at high risk of sudden death, they should be considered for implantation of a biventricular pacing device that also provides defibrillation therapy. This paper reviews biventricular pacing for congestive heart failure, including results of acute hemodynamic studies and randomized clinical trials, patient and device selection, and procedural issues.     

Long‐Term Mechanical Consequences of Permanent Right Ventricular Pacing: Effect of Pacing Site

Optimal Right Ventricular Pacing Introduction: Long‐term right ventricular apical (RVA) pacing has been associated with adverse effects on left ventricular systolic function; however, the comparative effects of right ventricular outflow tract (RVOT) pacing are unknown. Our aim was therefore to examine the long‐term effects of septal RVOT versus RVA pacing on left ventricular and atrial structure and function. Methods: Fifty‐eight patients who were prospectively randomized to long‐term pacing either from the right ventricular apex or RVOT septum were studied echocardiographically. Left ventricular (LV) and atrial (LA) volumes were measured. LV 2D strain and tissue velocity images were analyzed to measure 18‐segment time‐to‐peak longitudinal systolic strain and 12‐segment time‐to‐peak systolic tissue velocity. Intra‐LV synchrony was assessed by their respective standard deviations. Interventricular mechanical delay was measured as the difference in time‐to‐onset of systolic flow in the RVOT and LV outflow tract. Septal A’ was measured using tissue velocity images. Results: Following 29 ± 10 months pacing, there was a significant difference in LV ejection fraction (P < 0.001), LV end‐systolic volume (P = 0.007), and LA volume (P = 0.02) favoring the RVOT‐paced group over the RVA‐paced patients. RVA‐pacing was associated with greater interventricular mechanical dyssynchrony and intra‐LV dyssynchrony than RVOT‐pacing. Septal A’ was adversely affected by intra‐LV dyssynchrony (P < 0.05). Conclusions: Long‐term RVOT‐pacing was associated with superior indices of LV structure and function compared with RVA‐pacing, and was associated with less adverse LA remodeling. If pacing cannot be avoided, the RVOT septum may be the preferred site for right ventricular pacing. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1120‐1126)