An electrocardiographic algorithm for determining the location of pacemaker electrode in patients with right bundle branch block configuration during permanent ventricular pacing

The expected morphology of right ventricular pacing is a left bundle branch block (LBBB) pattern. However, right bundle branch block (RBBB) can also be seen during permanent right ventricular pacing. The aim of this study was to develop an electrocardiographic algorithm to differentiate this benign condition from septal and free wall perforation with subsequent left ventricular pacing. Three hundred consecutive patients who had permanent ventricular or dual-chamber pacemaker implantation between 1999 and 2000 were screened and 25 patients (8.3%) who exhibited RBBB configuration were included in the study. Echocardiograms and chest radiographs were evaluated in order to identify the pacing lead location in this group. The authors formed a study group with their own 25 patients and 22 cases of RBBB with permanent pacemaker from previous publications (total 47 patients). Frontal axis, QRS morphology in lead V(1), and the precordial transition point, which is defined as the precordial lead where R wave amplitude is equal to S wave amplitude, were examined. Placement of precordial leads V(1) and V(2) 1 interspace lower than the standard location (Klein maneuver) eliminated the RBBB pattern in 12 patients. RBBB pattern with "true right ventricular pacing" was detected in 24 of the 25 patients, and in 11 of the 22 patients reported in the literature (total 35 patients). Right ventricular pacing was correctly identified in 34 of 35 patients with use of criteria including left superior axis deviation, RS or qR morphology in lead V(1), and precordial transition at lead V(3) with a high sensitivity and specificity. A simple surface electrocardiogram can accurately predict the lead location in patients having RBBB morphology with right ventricular pacing.     

Echocardiographic Localization of an Inadvertently Placed Pacing Catheter in the Left Ventricle

This report describes a patient in whom a permanent transvenous pacemaker lead was placed unintentionally across the atrial septum and retained in the left ventricle for nearly 11 years before the error was recognized. A 12-lead electrocardiogram showed paced complexes with right bundle branch block configuration. This appearance raised suspicion that the pacemaker electrode might be in the left ventricle and this was confirmed by two-dimensional echocardiography. Two-dimensional echocardiography is useful for the diagnosis of pacing lead malplacement and should be performed in any patient who develops right bundle branch block pattern on the surface electrocardiogram following pacemaker implantation.     

右室心尖部起搏时体表心电图V1导联呈右束支阻滞图形分析

目的分析右室心尖部起搏患者V1导联呈现右束支阻滞图形的特点、出现的可能机制以及鉴别诊断方法。方法选取北京大学人民医院2005—2007年于右室心尖部植入起搏电极的患者,分析患者完全右室起搏时V1导联呈右束支阻滞图形患者的超声心动图、胸部X线等资料,并与同期V1导联呈左束支阻滞图形变化的右室起搏患者以及植入左室心外膜电极的患者的临床资料以及体表心电图特点进行对比。结果共有9例患者术后完全心室起搏时V1导联呈右束支阻滞图形,术后超声心动图以及胸部X线检查证实起搏电极均位于右心室,QRS波平均电轴为-61.7±15.6,与随机选取50例术后体表心电图呈左束支阻滞的右室电极植入患者心电图相比,QRS波电轴差异无统计学意义(P>0.05),与7例行左室心外膜起搏者QRS波电轴差异有统计学意义(P<0.05)。呈右束支阻滞者其肢体导联I、aVL导联QRS波均直立,与呈左束支阻滞患者相同,而左室心外膜起搏者其I、aVL导联QRS波为负向。结论当患者V1导联呈右束支阻滞形态时可通过I、aVL导联QRS波形态和QRS波电轴可以判断是否为右室起搏。     

New‐onset intrinsic and paced QRS morphology of right bundle branch block pattern after atrioventricular nodal ablation: Longitudinal dissociation or anatomical bifurcation?

We performed left bundle pacing combined with atrioventricular nodal (AVN) ablation in a patient with persistent atrial fibrillation and refractory symptomatic heart failure. The major findings were new‐onset intrinsic and paced QRS morphology of right bundle branch block (RBBB) pattern after AVN ablation which was performed at a more atrial site compared with the pacing site and the paced RBBB pattern could not be corrected regardless of the pacing output. Longitudinal dissociation cannot explain this observation, while anatomical separation could. We also confirm this was proximal left bundle pacing rather than His bundle pacing.     

Transoesophageal left ventricular pacing in heart failure patients with permanent right ventricular pacing.

BACKGROUND: Previous studies of biventricular (BV) pacing for treatment of heart failure (HF) patients with left bundle branch block (LBBB) evaluated responders to BV pacing with acute transvenous left ventricular (LV) pacing and arterial pulse pressure (PP). The aim of this study was to assess transoesophageal LV pacing in evaluation of the haemodynamic response with a view to upgrading responders from permanent right ventricular (RV) pacing to BV pacing. METHODS AND RESULTS: Ten HF patients (age 62+/-8 years; one female, nine males) in NYHA III, LV ejection fraction 24+/-9% and permanent RV pacing by means of an implanted pacemaker or ICD were tested using transoesophageal LV pacing and PP. Permanently RV-paced HF patients were analysed with transoesophageal atrial sensed LV pacing in VAT mode with a different AV delay (n = 6) and with transoesophageal LV pacing in V00 mode during atrial fibrillation (n = 4). In five responders, PP was higher during transoesophageal LV pacing than PP during RV pacing (74+/-42 versus 57+/-31 mmHg, P = 0.015). Responders were upgraded by means of an LV lead via the coronary sinus in the posterior (n = 1) or posterolateral (n = 4) walls and after attaining a high LV pacing threshold with an epicardial LV lead on the anterior (n = 1) or anterolateral (n = 1) walls. NYHA class improved from 3 to 2+/-0.3 (P = 0.003) during 204+/-120 days follow-up and cardiac output increased from 4.4+/-1.5 to 5.6+/-1.7 l/min (P = 0.027) when comparing BV pacing and optimal AV delay with RV pacing. In five nonresponders, PP was not higher during transoesophageal LV pacing than during RV pacing. CONCLUSION: Transoesophageal LV pacing may be a useful technique to detect responders to BV pacing in permanently RV-paced HF patients.     

Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His-bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra-Hisian left bundle branch (LBB) or distal His-bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high-grade atrioventricular (AV) block and RBBB pattern.     

Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His‐bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra‐Hisian left bundle branch (LBB) or distal His‐bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high‐grade atrioventricular (AV) block and RBBB pattern.     

Chronic right ventricular apical pacing: Adverse effects and current therapeutic strategies to minimize them

The permanent cardiac pacemaker is the only effective therapy for patients with symptomatic bradycardia and hundreds of millions are implanted worldwide every year. Despite its undisputed clinical benefits, the last two decades have drawn much attention to the negative effects associated with long-term pacing of the right ventricle (RV). Experimental and clinical studies have shown that RV pacing produces ventricular dyssynchrony, similar to that of left bundle branch block, with consequent detrimental effects on cardiac structure and function, with adverse clinical outcomes such as atrial fibrillation, heart failure and death. Although clinical evidence largely comes from subanalyses of pacemaker and implantable cardiac defibrillator studies, there is strong evidence that patients with reduced left ventricular function are at high risk of suffering from the detrimental effects of long-term RV pacing. Biventricular pacing in cardiac resynchronization therapy devices can prevent ventricular dyssynchrony and has emerged as an attractive option in this patient group with promising results and more clinical studies underway. Moreover, there is evidence that specific pacemaker algorithms that minimize RV pacing can reduce the negative effects of RV stimulation on cardiac function and may also prevent clinical deterioration. The extent of the long-term clinical effects of RV pacing in patients with normal ventricular function and how to prevent this are less clear and subject to future investigation.     

Improving sudden cardiac death risk stratification by evaluating electrocardiographic measures of global electrical heterogeneity and clinical outcomes among patients with implantable cardioverter-defibrillators: rationale and design for a retrospective,multicenter, cohort study

Purpose

Transcatheter aortic valve replacement (TAVR) is an increasingly prevalent therapy in patients with severe symptomatic aortic stenosis. Conduction disturbances requiring permanent pacemaker (PPM) implantation are a known complication of TAVR. This study investigated the progression of cardiac conduction disease in the post-TAVR pacemaker population and identified predictors of post-TAVR right ventricular (RV) pacing dependence.

Methods

Prospectively collected echocardiographic, ECG, and PPM interrogation data of 262 consecutive patients who underwent TAVR with placement of a balloon-expandable valve at one institution from March 2012 to October 2016 were analyzed.

Results

A total of 25 patients (11.1%) required post-TAVR PPM implantation. Seventeen patients who received PPMs did not require RV pacing at 30 days. Nine of these 17 patients had no RV pacing requirement within 10 days. Pre-existing right bundle branch block (RBBB) (OR 105.4, 4.52–2458.5, p?=?0.0002), bifascicular block (OR 12.50, 1.60–97.65, p?=?0.02), intra-procedural complete heart block (OR 12.83, 1.26–130.52, p?=?0.03), and QRS duration >?120 ms (OR 70.43, 3.23–1535.22, p?=?0.0002) on pre-TAVR ECG were associated with RV pacing dependence at 30 days.

Conclusions

Sixty-eight percent of patients meeting post-procedural guideline indications for PPM did not require RV pacing at 30 days. Fifty-two percent of these patients demonstrated recovery of sinus node function or AV conduction within 10 days post-implant. RBBB, intra-procedural complete heart block, bifascicular block, and QRS duration >?120 ms were associated with RV pacing dependence at 30 days. These findings suggest that post-TAVR conduction disturbances may be acutely reversible in a significant proportion of patients receiving PPM within 10–30 days of implant.

     

Evolution of right bundle branch block and other intraventricular conduction abnormalities in the transplanted human heart

We performed 12-lead electrocardiography (ECG) repeatedly in 13 patients with cardiac transplants. QRS block occurred at some point in 12 patients and its course was either sporadic, progressive, persistent or fluctuating (5, 3, 3 and 1 patient (s), respectively). In the first postoperative week, complete or incomplete right bundle branch block (RBBB) occurred in 10 patients. Left anterior fascicular block also occurred in 3 of the 10 patients. However, the block(s) subsided within 1 month in the 3 and 2 more patients. Nonspecific block, isolated left anterior fascicular block and left bundle branch block also occurred occasionally. QRS block was unrelated to the occurrence of cardiac rejection, catheter injury, right ventricular pressure or volume overloading, left ventricular function, and the length of ischemic time of the donor heart. Two patients have had permanent RBBB since the immediate postoperative period despite a normal donor electrocardiogram before harvesting. The temporal courses of QRS block varied widely in 9 patients. Thus, different mechanisms may have been active in various postoperative periods. The occurrence of QRS block was unrelated to morbidity and mortality in the recipients. Therefore, longer observation will likely establish the benign nature of the QRS block in this disease.     

Chronic bundle branch block and use of temporary transvenous pacemakers during coronary arteriography

A retrospective analysis of 217 consecutive patients with chronic bundle branch blocks undergoing cardiac catheterization was done to evaluate the need for temporary transvenous pacing during coronary arteriography. In patients without temporary right ventricular pacemakers (n = 185), only one episode of high-grade atrioventricular block occurred during coronary arteriography which required the urgent use of temporary pacing. All other bradyarrhythmias, including five episodes of transient asystole (greater than 3-sec pause) and four episodes of atrioventricular block (second degree or higher) were successfully managed without pacemaker utilization. Patients with prophylactic right ventricular pacemakers (n = 32) had a greater prevalence of ventricular fibrillation than those without pacing electrodes located in the right ventricle (2% vs. 9% respectively; P less than 0.05). These findings suggest that routing prophylactic pacemaker insertion during coronary arteriography in patients with chronic bundle branch block is not warranted and may place the patient at risk for developing iatrogenic ventricular arrhythmias.     

Natural history of combined right bundle branch block and left anterior hemiblock (bilateral bundle branch block)

One hundred fifteen patients with combined right bundle branch block (RBBB) and left anterior hemiblock (LAH) were separated into two groups depending upon whether RBBB and LAH was associated with acute myocardial infarction (group I, 32 patients) or was a chance electrocardiographic finding (group II, 83 patients).In 10 patients in group I complete heart block developed and in six patients high grade second degree atrioventricular (A-V) block developed. The incidence of serious arrhythmia was twice and mortality was three times the average for the coronary care unit (CCU).The majority of patients in group II had clinical evidence of advanced myocardial disease as manifested by congestive heart failure, healed myocardial infarction and left ventricular dyskinesia. During a cumulative observation period of 262 patient years, complete heart block developed in only two patients, whereas second-degree A-V block of sufficiently high degree to necessitate permanent cardiac pacing developed in three patients.It is concluded that (1) combined RBBB and LAH usually reflects advanced myocardial disease, (2) the clinical course is determined more by the myocardial disease than by the conduction disorder, (3) prophylactic cardiac pacing is not warranted in chronic RBBB and LAH, and (4) cardiac pacing has little impact on mortality when RBBB and LAH are associated with acute myocardial infarction.     

Diminished left ventricular dyssynchrony and impact of resynchronization in failing hearts with right versus left bundle branch block.

OBJECTIVES: We compared mechanical dyssynchrony and the impact of cardiac resynchronization therapy (CRT) in failing hearts with a pure right (RBBB) versus left bundle branch block (LBBB). BACKGROUND: Cardiac resynchronization therapy is effective for treating failing hearts with conduction delay and discoordinate contraction. Most data pertain to LBBB delays. With RBBB, the lateral wall contracts early so that biventricular (BiV) pre-excitation may not be needed. Furthermore, the magnitude of dyssynchrony and impact of CRT in pure RBBB versus LBBB remains largely unknown. METHODS: Dogs with tachypacing-induced heart failure combined with right or left bundle branch radiofrequency ablation were studied. Basal dyssynchrony and effects of single and BiV CRT on left ventricular (LV) function were assessed by pressure-volume catheter and tagged magnetic resonance imaging, respectively. RESULTS: Left bundle branch block and RBBB induced similar QRS widening, and LV function (ejection fraction, maximum time derivative of LV pressure [dP/dt(max)]) was similarly depressed in failing hearts with both conduction delays. Despite this, mechanical dyssynchrony was less in RBBB (circumferential uniformity ratio estimate [CURE] index: 0.80 +/- 0.03 vs. 0.58 +/- 0.09 for LBBB, p < 0.04; CURE 0-->1 is dyssynchronous-->synchronous). Cardiac resynchronization therapy had correspondingly less effect on hearts with RBBB than those with LBBB (i.e., 5.5 +/- 1.1% vs. 29.5 +/- 5.0% increase in dP/dt(max), p < 0.005), despite similar baselines. Furthermore, right ventricular-only pacing enhanced function and synchrony in RBBB as well or better than did BiV, whereas LV-only pacing worsened function. CONCLUSIONS: Less mechanical dyssynchrony is induced by RBBB than LBBB in failing hearts, and the corresponding impact of CRT on the former is reduced. Right ventricular-only pacing may be equally efficacious as BiV CRT in hearts with pure right bundle branch conduction delay.     

Acute comparative effect of right and left ventricular pacing in patients with permanent atrial fibrillation

We tested the hypothesis that left ventricular (LV) pacing is superior to right ventricular (RV) apical pacing in patients undergoing atrioventricular (AV) junction ablation and pacing for permanent atrial fibrillation.The potential benefit of LV over RV pacing needs to be evaluated without the confounding effect of other variables that can influence cardiac performance.An acute intrapatient comparison of the QRS width and echocardiographic parameters between RV versus LV pacing was performed within 24 h after ablation in 44 patients. Both modes of pacing were also compared with pre-implantation values.Compared with RV pacing, LV pacing caused a 5.7% increase in the ejection fraction (EF) and a 16.7% decrease in the mitral regurgitation (MR) score; the QRS width was 4.8% shorter with LV pacing. Similar results were observed in patients with or without systolic dysfunction and/or native left bundle branch block, except for a greater improvement in MR in the latter group. Compared with pre-ablation measures, the EF increased by 11.2% and 17.6% with RV and LV pacing, respectively; the MR score decreased by 0% and 16.7%; and the diastolic filling time increased by 12.7% and 15.6%.Rhythm regularization achieved with AV junction ablation improved EF with both RV and LV pacing; LV pacing provided an additional modest but favorable hemodynamic effect, as reflected by a further increase of EF and reduction of MR. The effect seems to be equal in patients with both depressed and preserved systolic functions and in those with and without native left bundle branch block.     

Stability of the ECG features of complete right bundle branch block over time: a methodological study for implementation in research and clinical practice

Since research is concentrated to a large extent on patients with left bundle branch block, we aimed at evaluating the hypothesis that measurements of certain intervals and other characteristics of the ECG may change over time in patients with right bundle branch block (RBBB), and to design a model, which could be implemented in research and clinical practice, irrespective of the specific ECG features present. The duration of the QRS complex, QT, QTc, and PR intervals, the frontal QRS axis, the heart rate and the presence of hemiblocks, atrioventricular blocks, and atrial fibrillation were compared in the 1st and last of all available ECGs for each patient. Also, a subgroup of patients who had a ventricular aneurysm (VA) was compared with the remaining patients, with respect to the above variables. This longitudinal analysis included all of the patients with RBBB followed in our Cardiology Clinic. There were no significant changes in the ECG variables from the two ECGs recorded 487.6 +/- 410.1 (range 0-1,476) days apart, in the two comparisons carried out in 151 patients with RBBB. Comparison of the above-described ECG intervals and characteristics of patients with RBBB were found to be stable over the time course of the investigation. This methodological study is presented as a model to be used serially and prospectively in research and clinical practice for the follow-up of patients with bundle branch block, VA, dilated cardiomyopathy, congestive heart failure, or those considered for cardiac resynchronization therapy.     

Permanent pacing using a coronary sinus lead in a patient with univentricular physiology: an extended application of biventricular pacing technology.

In the past, patients requiring permanent pacing with difficult right ventricular (RV) access were usually subjected to epicardial pacing by a surgical approach. This report describes a young patient with univentricular physiology following repeated palliative surgery for complex congenital heart disease. The patient had symptomatic complete heart block and a dual chamber pacemaker with transvenous atrial and ventricular leads was implanted successfully. The ventricle was paced through the posterolateral cardiac vein with a lead specially designed for cardiac resynchronization therapy. This case illustrates an extended application of the recently developed coronary sinus lead in selected patients, when conventional RV endocardial pacing is impossible.     

Recurrent symptomatic bilateral bundle branch block in a 74-year-old patient with a prosthetic aortic valve: a description of a case and review of the literature

This report concerns a 74-year-old patient who had undergone aortic valve replacement 11 years earlier. On admission, the patient complained of shortness of breath when climbing two flights of stairs; there was no history of dizziness, fainting or sensations of arrhythmias. An ECG at rest showed first-degree atrioventricular (A-V) block together with left bundle branch block (LBBB). On bicycle ergometry, there was a fall in blood pressure and in heart rate due to a second-degree (2:1) A-V block along with the LBBB. After termination of exercise, the PR interval increased further from 0.24 s to >0.3 s, together with right bundle branch block (RBBB) and 1:1 A-V conduction instead of LBBB. Finally, at a constant atrial rate of 98/min, the RBBB disappeared, LBBB recurred, again with 2:1 A-V conduction. The diagnosis was bilateral BBB together with first degree A-V block at rest and higher-degree A-V block on effort. The patient underwent pacemaker implantation and was discharged shortly thereafter free of symptoms.     

Right and left ventricular activation sequence in patients with heart failure and right bundle branch block: a detailed analysis using three-dimensional non-fluoroscopic electroanatomic mapping system

Three-dimensional mapping in RBBB and heart failure. INTRODUCTION: Recently, right bundle branch block (RBBB) was proved to be an important predictor of mortality in heart failure (HF) patients as much as left bundle branch block (LBBB). We characterized endocardial right ventricular (RV) and left ventricular (LV) activation sequence in HF patients with RBBB using a three-dimensional non-fluoroscopic electroanatomic contact mapping system (3D-Map) in order to provide the electrophysiological background to understand whether these patients can benefit from cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Using 3D-Map, RV and LV activation sequences were studied in 100 consecutive HF patients. Six of these patients presented with RBBB QRS morphology. The maps of these patients were analyzed and compared post hoc with those of the other 94 HF patients presenting with LBBB. Clinical and hemodynamic profile was significantly worse in RBBB group compared to LBBB. Patients with RBBB showed significantly longer time to RV breakthrough (P<0.001), longer activation times of RV anterior and lateral regions (P<0.001), and longer total RV endocardial activation time (P<0.02) compared to patients with LBBB. Time to LV breakthrough was significantly shorter in patients with RBBB (P<0.001), while total and regional LV endocardial activation times were not significantly different between the two groups. CONCLUSIONS: Degree of LV activation delay is similar between HF patients with LBBB and RBBB. Moreover, patients with RBBB have larger right-sided conduction delay compared to patients with LBBB. The assessment of these electrical abnormalities is important to understand the rationale for delivering CRT in HF patients with RBBB.     

Bradyarrhythmias, abnormalities of conduction, and indications for pacing in acute myocardial infarction

Bradyarrhythmias and conduction disturbances are not infrequently observed in association with acute MI. The sinus node artery is supplied by the right coronary circulation only slightly more often than the left. As a result of concomitant vagotonia, however, sinus node dysfunction is more common with inferior infarction. This influence, as well as a predominantly right-sided circulation, also makes AV nodal block more frequent with such infarctions. Bradyarrhythmias due to sinus or AV nodal dysfunction often require only observation. If symptomatic, they are usually responsive to vagolytic or chronotropic drugs, but may necessitate pacemaker therapy often only on a temporary basis. The distal conduction system including the bundle branches is supplied mainly, but not exclusively, by the left anterior descending artery. Thus, acute bundle branch block is often associated with anterior MI. The indications for both temporary and permanent prophylactic pacing in this situation remain controversial. Several authors have made recommendations based on risk stratification. We would temporarily pace patients with anterior or indeterminate infarctions and new right or left bundle branch block, and probably those with bilateral bundle branch block of indeterminate age. All patients with new bilateral or alternating bundle branch block should be paced, regardless of infarct site. Permanent prophylactic pacing would appear indicated in patients exhibiting alternating bundle branch block or perhaps new right bundle branch block and left posterior hemiblock. In contrast to this group, the treatment of patients who develop sudden complete heart block, whether transient or permanent, is clear-cut. These patients require continuous (temporary followed without interruption by permanent) pacemaker therapy (Table 3).     

左束支起搏心电图的特点观察

目的通过比较自身心律、左束支起搏、右室心尖部或右室流出道起搏时心电图的形态和QRS波群时限等,找寻左束支起搏心电图的特征表现。方法选取拟行左束支起搏42例患者,记录标准12导联体表心电图,通过测量,分别比较自身心律、左束支起搏及右室心尖部/右室流出道起搏时QRS波群时限、电轴、形态及ST段的差异。结果自身心律与左束支起搏相比,QRS波群时限无统计学差异(P=0. 49),但与右室心尖部/右室流出道起搏相比,具有显著差异(P <0. 000)。左束支起搏组,V1导联呈特征性"M"或"r SR"的比例为76. 19%; a VR导联亦可呈特征性"M"或"r SR"表现,比例为78. 57%。对于自身心律为右束支阻滞者,左束支区域起搏仅V1导联呈"M"或"r SR",a VR导联呈QS型,而无特征性"M"或"r SR"表现。与经典的右束支阻滞心电图比较:左束支起搏ST段和T波改变无规律性。结论左束支起搏心电图QRS波群时限和电轴与自身心律相比无显著差别,V1及a VR导联均可见特征性"M"或"r SR"表现,右束支阻滞患者仅V1导联呈特征性表现,但依靠心电图的特征性"M"或"r SR"...