Determination of the Left Bundle Branch Refractoriness by Distal His Bundle Pacing in Patients with Left Bundle Branch Block

Electrophysiological studies were carried out in two patients with an idiopathic leff bundle branch block. Consisfenl distal His bundle pacing resulted in the normalization of the QRS complex in both pa lien ts. Extrastimulation during basic distal His pacing at several cycle lengths was carried out successfully. Using this technique, the refractory periods of the left bundle branches were measured and found to be within the normal range. In addition, they decreased with the shortening of the basic cycle length. These results demonstrated the possibility of determining the refractoriness of the left bundle branch by His bundle pacing in patients with left bundle branch block. Hypotheses are postulated about the presumed location of the lesion responsible for the left bundle branch block.     

Determination of the Left Bundle Branch Refractoriness by Distal His Bundle Pacing in Patients with Left Bundle Branch Block

Electrophysiological studies were carried out in two patients with an idiopathic leff bundle branch block. Consisfenl distal His bundle pacing resulted in the normalization of the QRS complex in both pa lien ts. Extrastimulation during basic distal His pacing at several cycle lengths was carried out successfully. Using this technique, the refractory periods of the left bundle branches were measured and found to be within the normal range. In addition, they decreased with the shortening of the basic cycle length. These results demonstrated the possibility of determining the refractoriness of the left bundle branch by His bundle pacing in patients with left bundle branch block. Hypotheses are postulated about the presumed location of the lesion responsible for the left bundle branch block.     

Cardiac Resynchronization Therapy in Non‐Left Bundle Branch Block Morphologies

Introduction: In select patients with systolic heart failure, cardiac resynchronization therapy (CRT) has been shown to improve quality of life, exercise capacity, ejection fraction (EF), and survival. Little is known about the response to CRT in patients with right bundle branch block (RBBB) or non‐specific intraventricular conduction delay (IVCD) compared with traditionally studied patients with left bundle branch block (LBBB). Methods: We assessed 542 consecutive patients presenting for the new implantation of a CRT device. Patients were placed into one of three groups based on the preimplantation electrocardiogram morphology: LBBB, RBBB, or IVCD. Patients with a narrow QRS or paced ventricular rhythm were excluded. The primary endpoint was long‐term survival. Secondary endpoints were changes in EF, left ventricular end‐diastolic and systolic diameter, mitral regurgitation, and New York Heart Association (NYHA) functional class. Results: Three hundred and thirty‐five patients met inclusion criteria of which 204 had LBBB, 38 RBBB, and 93 IVCD. There were 32 deaths in the LBBB group, 10 in the RBBB, and 27 in the IVCD group over a mean follow up of 3.4 ± 1.2 years. In multivariate analysis, no mortality difference amongst the three groups was noted. Patients with LBBB had greater improvements in most echocardiographic endpoints and NYHA functional class than those with IVCD and RBBB. Conclusion: There is no difference in 3‐year survival in patients undergoing CRT based on baseline native QRS morphology. Patients with RBBB and IVCD derive less reverse cardiac remodeling and symptomatic benefit from CRT compared with those with a native LBBB. (PACE 2010; 590–595)     

Alternation of Right Bundle Branch Block with Beats Showing Normal Conduction and with a Less Complete Right Bundle Branch Block Pattern

We report the case of an 80-year-old man with a preexistent right bundle branch block (RBBB) who underwent dobutamine stress echocardiography. As the sinus cycle length gradually decreased during the stress test, he first developed a 2:1 RBBB pattern alternating with beats showing normal conduction and then an alternating 2:1 less complete and more complete RBBB pattern. An elucidation of the potential mechanism of the latter very rare phenomenon is provided.     

完全性左束支传导阻滞的心动超声图分析

目的探讨心动超声上室壁运动异常与完全性左束支传导阻滞(LBBB)的相关性及临床意义.方法对16例心电图诊断为LBBB的病例与心动超声检查对照分析.结果 16例心电图完全性左束支传导阻滞(LBBB)患者,在超声心动图上显示有左室壁运动异常14例(14/16.87%),表现为:室间隔与左室后壁矛盾运动.结论表明完全性左束支传导阻滞(LBBB)与超声心动左室壁运动异常相关性良好.     

Body Surface Laplacian Mapping in Patients with Left or Right Ventricular Bundle Branch Block

Body surface Laplacian maps (BSLMs) have been previously reported to provide enhanced capability in localizing and resolving multiple spatially separate myocardial events. However, only a few studies have been reported on the clinical applications of BSLM. To test the clinical utility of BSLMs, BSLMs and body surface potential maps (BSPMs) during ventricular depolarization for complete right or left ventricular bundle branch block (CRBBB or CLBBB) were studied in ten patients in each group. As a control group, ten healthy subjects were also studied using the same procedure. One hundred and twenty-eight electrodes were placed uniformly over the entire chest and back of the subjects. BSLMs were computed from recorded potentials, using a numerical algorithm. The BSLMs showed multiple and more localized positive and negative activities compared with the BSPMs. In healthy subjects, the BSLMs showed multiple areas of positive activity overlying the RV, LV, and the RV outflow, and negative activity corresponding to RV free-wall breakthrough and LV anterolateral breakthrough sites, whereas the BSPMs could not separate RV and LV activities. In the patients with CRRRR, the BSLMs showed more localized areas of activity corresponding to the LV apex breakthrough and LV lateral breakthrough, and separated LV lateral and posterior activation. In the patients with CLBBB, the BSLMs showed multiple RV activation, and propagating activation of LV from lateral to posterior. The BSLMs appear to provide enhanced capability in detecting multiple ventricular electrical events associated with normal and abnormal conduction and a more detailed activation sequence of both ventricles in healthy subjects and in the patients with CRBBB and CLBBB. BSLM may provide an important alternative to other imaging modalities in localizing cardiac electrical activity noninvasively.     

Inadvertent Catheter-Induced Right Bundle Branch Block in a Patient with Preexistent Left Bundle Branch Block and Recurrent Macroreentrant Ventricular Tachycardia

This article describes the inadvertent, catheter-induced induction of right bundle branch block resulting not only in transient complete infra-His heart block but also in temporary interruption of the macroreentry circuit of ventricular tachycardia. A patient with preexistent left bundle branch block and spontaneous ventricular tachycardia based upon the bundle branch reentry mechanism underwent electrophysiological testing for the evaluation of sotalol drug efficacy. In search of an optimal His-bundle recording, the manipulation of a 6 Fr quadripolar catheter caused a right bundle branch block, thus advancing the preexistent left bundle branch block to complete heart block. Retrograde ventriculoatrial conduction remained unaffected. The macroreentrant tachycardia with left bundle branch block configuration was no longer inducible. While the patient continued on unchanged sotalol medication (320 mg/d) he required temporary pacing for 16 hours until the block subsided. A subsequent induction attempt demonstrated initiation of the tachycardia. Finally, guided by invasive testing, the patient successfully received amiodarone therapy (300 mg/d). The patient completed an uneventful follow up of 27 months. No progression of conduction delay was observed. This case suggests that the inadvertent induction of right bundle branch block prevents the initiation of ventricular tachycardias relying on bundle branch reentry. Therefore, missed diagnosis or misinterpretation of antiarrhythmic drug efficacy might occur if there is no electrophysiological reevaluation after right bundle branch recovery.     

Retrograde Supernormal Conduction, Gap Phenomenon in Concealed Accessory Atrioventricular Pathways

We present four patients with the Wolff-Parkinson-White syndrome who exhibited retrograde supernormal conduction or gap phenomenon in concealed accessory pathways. In the first patient, ventricular extrastimulus testing revealed retrograde block at the coupling interval of 520 msec and reappearance of conduction at the coupling interval of 370 msec. In a second patient, 1:1 retrograde conduction was not present but supernormal conduction was demonstrated at coupling intervals of 360 msec to 310 msec during the ventricular extrastimulus testing when the basic drive consisted of atrioventricular (AV) simultaneous pacing. In a third patient, ventricular extrastimulus testing demonstrated retrograde conduction through the accessory pathway only at coupling intervals of 400 msec to 360 msec. In a fourth patient, retrograde block occurred at the coupling interval of 340 msec and retrograde "slow" conduction reappeared at coupling intervals of 300 msec to 250 msec (gap phenomenon) only when the basic drive consisted of AV simultaneous pacing. Thus, concealed accessory pathways may exhibit retrograde supernormal conduction or gap phenomenon. Ventricular extrastimulus testing consisting of AV simultaneous pacing during the basic drive may facilitate demonstration of these unusual properties.     

DTI评价完全性左束支传导阻滞患者心室除极顺序

目的本文探讨多普勒组织成像（ＤＴＩ）技术评价完全性左束支传导阻滞（ＣＬＢＢＢ）患者心室除极的可行性。方法应用多普勒组织加速度图及脉冲频谱图检测１０例ＣＬＢＢＢ患者心室除极顺序,并与正常组（２５例）进行对照。结果①ＣＬＢＢＢ心室最早除极部位位于右室前壁心尖段,与正常组迥然不同（Ｐ＜０．０００１）;②剑下四腔切面显示ＣＬＢＢＢ心室除极顺序为：右室前壁心尖、室间隔心尖、右室前壁全部、室间隔全部、左室前侧壁心尖、左室前侧壁全部;正常人心室除极顺序则为：室间隔基中部、室间隔心尖、右室前壁心尖及左室前侧壁心尖、右室前壁全部、左室前侧壁基部。③和正常组比较,ＣＬＢＢＢ患者右室前壁电除极收缩耦联正常（Ｐ＞０．０５）,而各左室壁除极明显延迟（Ｐ＜０．０００５）,前间隔除极方向由心尖指向心底。结论能显示心室肌收缩顺序的ＤＴＩ技术可直观、实时、精确地反映ＣＬＢＢＢ的心室电除极状态。     

Left Bundle Branch Block Pattern Complicating the Electrocardiographc Evaluation of Acute Myocardial Infarction

The ECG diagnosis of ischemic heart disease is made more difficult in the setting of left bundle branch block (LBBB). The ECG diagnosis of prior or remote myocardial infarction (MI) is extremely difficult in this setting. Furthermore, the associated—and expected—ST-segment-T-wave abnormalities of LBBB may mimic acute ischemic change. However, ECG detection of abnormalities arising from acute ischemic cardiac disease in the setting of LBBB can be valuable. Several strategies are available to the emergency physician (EP) to assist in the correct interpretation of this ECG pattern, including: a knowledge of the anticipated ST-segment-T-wave changes of LBBB and, consequently, the ability to recognize ischemic morphologies; the performance of serial ECGs demonstrating dynamic changes encountered in ischemic patients; and a comparison with previous ECGs. Three cases are reported in which an analysis of the 12-lead ECG in the setting of LBBB assisted the EP in establishing the correct diagnosis of acute Ml and applying timely, appropriate therapy.     

Multiple Conduction Delays within the His Bundle

His Bundle recordings in a 75-year-old male with complete heart block exhibited split His Bundle potentials with three components thus demonstrating multiple conduction delays within the bundle of His.     

Electrophysiologic Study of Tachycardia-Dependent Paroxysmal His Bundle Block in Man

Electrophysiologic sludy was performed in a potienl with tachycardia-dependent paroxysmal atrioventricular block. The site of block was within the His bundle. The effective refractory period of the His bundle was markedly prolonged and it was comparable to the critical atrial cycle length producing type II His bundle block. The most likely mechanism of paroxysmal atrioventricular block was repetitive concealed penetration of the blocking zone by nonconducted impulses that reached the proximal His bundle. Enhancing the blocking ratio at the atrioventricular nodal level resulted in improvement of overall atrioventricular conduction.     

Adult Acute Rheumatic Fever: A Rare Case Presenting with Left Bundle Branch Block

In contrast to the more common electrocardiographic patterns seen in acute rheumatic fever, such as first-degree heart block, the appearance of left bundle branch block is rare. An adult patient with acute rheumatic fever presented with left bundle branch block on admission, subsequently had sudden cardiac arrest. She was resuscitated successfully and required temporary pacing. An echocardiogram and radionuclide ventriculography were compatible with interventricular septal involvement in the rheumatic carditis. After 20 days of steroid therapy, the left bundle branch block pattern of the electrocardiogram disappeared. A possible mechanism for the development of complete heart block in acute rheumatic fever is discussed. It is suggested that patients with acute rheumatic carditis who have electrocardiographic manifestations of prolonged P-R interval and left bundle branch block should be managed with prophylactic pacing.     

Intrahisian Functional Bundle Branch Block

A patient with functional complete left bundle branch block is presented. The site of block was localized to the area of the His bundle. This case demonstrates that functional complete left bundle branch block may be due to longitudinal dissociation in the His bundle.     

右束支阻滞在急性心肌梗死中的意义

目的　了解伴随急性心肌梗死 (AMI)出现的右束支传导阻滞 (RBBB)的临床和预后意义。方法　将我院 5年收治的伴有新出现的持续性RBBB的AMI共 2 0例作为观察组 ,梗死部位均累及前间壁或前壁。将同期收治的无束支传导阻滞的前间壁或前壁AMI共 3 0例作为对照组 ,两组AMI患者在症状发生后 2 4小时收入院。分析两组的临床经过、住院病死率及一年随访。结果　观察组血清CK MB平均峰值为 2 46.2± 14 6.8U ,明显高于对照组的 10 6.2± 5 8.6U (P <0 .0 2 )。观察组 5 0 %并发室性心动过速或心室颤动 ,对照组为 2 5 %。观察组心功能受损更严重 ,Killip平均级别为 2 .46± 0 .65 ,对照组为 1.2 0± 0 .3 8(P <0 .0 5 ) ,左心室舒张末内径观察组为 5 6.6± 10 .0mm ,对照组为 46.0± 4.6mm (P <0 .0 5 ) ,左心室射血分数观察组为 0 .46± 0 .0 4,对照组为 0 .66± 0 .0 8(P <0 .0 0 2 )。观察组的住院病死率为 2 5 % ,对照组住院病死率为 3 %。结论　伴随AMI新出现的持续RBBB是临床预后不良的标志。     

Fascicular Parasystole Associated with Tachycardia-Dependent Right Bundle Branch Block

A 43-year-old female with a chief complaint of palpitation was subjected to clinical electrophysiological studies. Initial standard 12-lead ECG revealed that her palpitation was caused by fascicular parasystole firing at the basic cycle length of 1.25-1.40 seconds, and that both sinus and parasystolic beats were associated with left anterior fascicular block and tachycardia-dependent RBBB. His-bundle electrocardiogram suggested that the parasystolic focus was located in the proximal portion of the anterior fascicle of the left bundle branch and that the site of tachycardia-dependent conduction block was located in the main right bundle branch. These findings suggest that diffuse pathological changes in the intraventricular conducting system were responsible for both the conduction block and automatic impulse formation in the present case.     

二维斑点追踪技术评估左束支起搏早期左房功能

目的 采用二维斑点追踪成像技术（2D-STI）对左束支起搏（LBBP）早期左房功能进行评价。 方法 纳入完成永久起搏器植入术的患者共47例,其中LBBP组26例,右室间隔部起搏（RVP）组21例,术后1月随访,另选取20例健康人作为对照组。通过2D-STI分析并计算左房储存功能期应变（LASr）、管道功能期应变（LAScd）和辅泵功能期应变（LASct）、左室总体纵向应变（GLS）和各切面总体纵向应变（GLS-AP2、GLS-AP3、GLS-AP4）用于评价左房、左室功能,计算左室17节段纵向应变达峰时间标准差（Tp-SD）、达峰时间最大差值（Tp-dif）用于评价左室内同步性。 结果 各组左房功能参数比较,LBBP组和RVP组LASr、RVP组LAScd明显降低,差异均有统计学意义（P<0.05）。左室功能分析显示,LBBP组、RVP组GLS-AP2、GLS-AP3、GLS-AP4和GLS均较对照组明显降低,RVP组Tp-SD、Tp-dif较其余两组明显增大,差异均有统计学意义（P<0.05）。LBBP组和RVP组Tp-SD、Tp-dif均与LAScd呈正相关。 结论 采用2D-STI技术可评估左束支起搏术后早期左房功能。与RVP相比,LBBP左室内同步性更好,有利于保护左房管道功能。     

Comparison in the Same Patient of Aberrant Conduction and Bundle Branch Reentry After Dofetilide, a New Selective Class III Antiarrhythmic Agent

Dofetilide may induce aberrant intraventricular conduction due to its Class III effect. This report describes an atrial fibrillation patient in whom intraventricular conduction was studied before and after dofetilide using multiple endocardial recordings. Dofetilide provoked aberrant conduction during atrial fibrillation, and aberrancy could be mimicked with programmed atrial stimulation after restoration of sinus rhythm. However, during right ventricular slimulation, isolated bundle branch reentrant beats were recorded after induction of critical retrograde conduction delays. This occurred in the setting of relatively large differences in refractoriness between the right bundle branch and the right ventricular myocardium. This favored distal retrograde bundle branch block during ventricular extrastimulation, in turn enhancing bundle branch reentry. This potendal proarrhythmic mechanism deserves close attention in the further deveiopmeni of dofetilide and also of other new "pure" Class III agents.