TAVR术后传导阻滞及起搏器植入的预测因子研究进展

主动脉瓣狭窄(AS)是由先天或后天因素所引起的瓣膜结构改变,其发病率随着年龄的增长而增加,在80岁以上人群中患病率可达到10%左右,其中严重主动脉瓣狭窄导致的猝死每年发生率约为 1%[1]。经导管主动瓣膜置换术 (TAVR)是一种安全可行的重度AS微创治疗方法,自2011年FDA首次获批应用于无法进行外科手术治疗的重度AS患者,其适应症不断拓展至中低手术风险人群的治疗。人工瓣膜的置入压迫位于主动脉根部的房室传导系统,导致术后心脏传导异常的发生,永久起搏器的植入(PPMI)是其治疗手段。TAVR术后PPMI与患者预后密切相关。因此,本文对TAVR术后传导功能障碍发生及PPMI进行综述。     

Rapid reversal of heart failure by correcting left bundle branch block induced by transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) induced pathological damage in cardiac conduction system leads to symptomatic bradycardia and electric dyssynchrony such as left bundle branch block (LBBB) is associated with an increased risk for heart failure. Left bundle branch pacing (LBBP) has emerged as an alternative method for delivering physiological pacing to achieve electrical synchrony of the left ventricle. We report a case of heart failure patient with new onset LBBB (NO‐LBBB) induced by TAVR, LBBP corrected the NO‐LBBB and reversed the heart function with stable capture and correction threshold.     

Permanent left atrial and left ventricular single-lead DDD pacing with a coronary sinus electrode

This report describes a patient with drug refractory severe chronic congestive heart failure, first-degree AV block, and wide QRS complexes of 175-ms duration with left bundle branch block who was successfully treated by a left-sided dual chamber pacemaker system using a single-lead coronary sinus electrode. Left atrial and ventricular signal amplitudes, left atrial and ventricular pacing thresholds were 2.5 mV, 13 mV, 1.8 V and 0.7 V (0.5 ms), respectively. Using DDD pacing with an optimal 120-ms AV delay the QRS duration decreased to 150 ms and the mitral filling pattern improved. Three months after implantation the patient's functional status improved from NYHA Class III-IV to Class II.     

Anatomy of the cardiac conduction system

The specialized cardiomyocytes that constitute the conduction system in the human heart, initiate the electric impulse and result in rhythmic and synchronized contraction of the atria and ventricles. Although the atrioventricular (AV) conduction axis was described more than a century ago by Sunao Tawara, the anatomic pathway for propagation of impulse from atria to the ventricles has been a topic of debate for years. Over the past 2 decades, there has been a resurgence of conduction system pacing (CSP) by implanting pacing leads in the His bundle region in lieu of chronic right ventricular pacing that is associated with worse clinical outcomes. The inherent limitations of implanting the leads in the His bundle region has led to the emergence of left bundle branch area pacing in the past 3 years as an alternative strategy for CSP. The clinical experience from performing CSP has helped electrophysiologists gain deeper insight into the anatomy and physiology of cardiac conduction system. This review details the anatomy of the cardiac conduction system, and highlights some of the recently published articles that aid in better understanding of the AV conduction axis and its variations, the knowledge of which is critical for CSP. The remarkable evolution in technology has led to visualization of the cardiac conduction system using noninvasive, nondestructive high‐resolution contrast‐enhanced micro‐computed tomography imaging that may aid in future CSP. We also discuss from anatomical perspective, the differences seen clinically with His bundle pacing and left bundle branch area pacing.     

Early Conduction Disorders Following Percutaneous Aortic Valve Replacement

Background: Percutaneous aortic valve replacement (PAVR) may be an alternative therapy for patients with severe aortic stenosis who are denied valve surgery because of age and comorbidity. Data are few regarding the incidence of early conduction disorders (CD) after PAVR. We examined the incidence and characteristics of CD in the immediate postoperative period after PAVR, and the need for permanent pacemaker (PPM) implantation.
Methods and Results: Between June 2007 and June 2008 30 patients (mean age = 82.1 ± 8.5 years) underwent PAVR in our institution. The incidence of new, postoperative CD, diagnosed by 12-lead or 24-hour Holter electrocardiogram, was 68.0%. Left bundle branch block was the most common conduction abnormality, with an incidence of 45.8%. The incidence of complete atrioventricular block requiring PPM implantation was 20%.
Conclusions: We observed a higher incidence of early conduction disorders and need for PPM implantation after PAVR than generally reported after surgery. Whether this observation is clinically important requires larger prospective studies and follow up.     

Bundle brunch reentrant ventricular tachycardia with two distinct conduction patterns in a patient with complete right bundle branch block

We report a rare case of bundle branch reentrant ventricular tachycardia [BBRVT]. A 67-year-old female was admitted for management of wide QRS tachycardia (right bundle branch block [RBBB] and a southwest axis). The mapping procedure revealed the tachycardia circuit consisted of the left anterior fascicle (LAF) as an antegrade, and the right bundle as a retrograde pathway. She presented RBBB during sinus rhythm. LAF ablation changed the tachycardia configuration to a northwest axis and prolonged the cycle length. Left posterior fascicle ablation terminated the tachycardia, and complete atrioventricular block occurred, which showed the unidirectional conduction over the right bundle.     

Nonischemic dilated cardiomyopathy: results of noninvasive and invasive evaluation in 310 patients and clinical significance of bundle branch block

Background: The survival of patients with idiopathic dilated cardiomyopathy (IDCM) at III and IV stages of New York Heart Association (NYHA) is decreased in those with a bundle branch block (BBB) compared to those without BBB. Less is known on the prognosis of patients at earlier stages of NYHA and who had a left BBB (LBBB) or right BBB (RBBB). We sought to evaluate the prevalence and the clinical significance of LBBB or RBBB in patients with IDCM and classes I and II of NYHA. Methods: Clinical data, noninvasive, and invasive studies were consecutively collected in 310 patients, with IDCM, followed up to 4.8±3.7 years. Results: Seventy‐six patients (25%) had LBBB, 21 (7%) had RBBB, and 212 had no BBB. Patients with BBB were older than other patients (P < 0.009). Left ventricular ejection fraction (LVEF) was lower in LBBB than in RBBB and other patients (P < 0.05). Syncope was more frequent in BBB than in absence (P < 0.05). Incidence of spontaneous ventricular tachycardia (VT) and atrial fibrillation, VT induction, total cardiac events, and sudden death were similar in the presence or absence of BBB. Deaths by heart failure and heart transplantations tended to be more frequent in BBB than in absence. Conclusions: LBBB was present in 25% of patients with IDCM; RBBB was rare. Patients with BBB were older and had more frequent syncope than patients without BBB; LVEF was lower in LBBB than in RBBB or in absence of BBB. BBB did not increase the risk of spontaneous VT, VT induction, or sudden death, and tended to increase deaths by heart failure and the indications of heart transplantation.     

Rate-dependent aberrancy and cardiac resynchronization therapy

Left bundle branch block (LBBB) can result in significant dyssynchrony in left ventricular (LV) contraction, ultimately leading to cardiac remodeling. LBBB can be rate dependent and may appear with LV systolic dysfunction. Cardiac resynchronization therapy (CRT) has been demonstrated to improve hemodynamics as well as clinical symptoms in patients with LBBB. We describe the case of a 57-year-old man who underwent CRT implantation due to exertional dyspnea, rate-dependent LBBB, and impaired left LV systolic function.     

Complete Atrioventricular Block Associated with Non-penetrating Cardiac Trauma in a 40-year-old Man

Background

Myocardial contusion is a rare complication of blunt chest trauma. Transient conduction and rhythm problems, right ventricular dysfunction, or pulmonary embolism may occur after chest trauma, but these complications almost always occur early in the post-operative period.

Objectives

The objective is to describe a case illustrating that trauma may induce high-grade atrioventricular block.

Case Report

We report the case of a patient who developed delayed onset of complete atrioventricular block after transient complete atrioventricular block and alternating bundle branch block secondary to blunt chest trauma.

Conclusion

Even with an injury that does not seem to be caused by direct penetrating trauma to the heart, maybe every trauma patient needs an electrocardiographic evaluation. It is important to note that myocardial healing is a continuous process after trauma, and additional pathology may be revealed later in the course of healing from myocardial contusion.     

Transient Right Bundle Branch Block Causing R Wave Attenuation Postdefibrillation

Transient and significant decrease in R wave amplitude, associated with transient right bundle branch block, was noted to occur after defibrillation in a defibrillator patient. The mechanism is probably stunning of the right bundle branch, causing right intraventricular conduction delay and decrease in signal amplitude reaching the endocardial sensing dipoles.     

急性心肌梗死伴发右束支传导阻滞的临床特征分析

目的探讨急性心肌梗死（AMI）伴发新出现的完全性右束支传导阻滞（CRBBB）的临床意义。方法选取AMI患者169例,分为2组,AMI伴发新出现的CRBBB患者36例作为CRBBB组,单纯AMI患者133例作为非CRBBB组,对2组患者的心功能Killip分级、心律失常发生率及住院病死率等临床资料进行对比性分析。结果CRBBB组梗死部位多为前壁或广泛前壁,梗死动脉多为前降支近端;CRBBB组CK和CKMB峰值、心功能Killip平均分级和分级≥Ⅲ级发生率、恶性室性心律失常发生率、缓慢型心律失常发生率以及院内病死率均显著高于非CRBBB组,但其左心室射血分数（LVEF）显著低于非CRBBB组,组间比较差异有统计学意义（P〈0.05）。结论AMI伴发新出现的持续性CRBBB,提示临床病情凶险,预后不良,可作为AMI患者病情恶化的一个很有价值的预测指标。     

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.     

Transcatheter aortic valve replacement: the changing paradigm of aortic stenosis treatment

Aortic stenosis is the most common cause for valvular surgery in the USA. For nearly 50 years, surgical aortic valve replacement has been the standard of care for symptomatic patients; unfortunately, a significant number of patients are not referred to surgery owing to advanced comorbidities and age. Transcatheter aortic valve replacement has emerged as an effective therapy for patients at high risk for surgery. Through device innovations and accumulated experience, the safety and efficacy of the procedure has improved since its inception. Transcatheter valve replacement has been found superior to medical therapy in inoperable patients with aortic stenosis, yet many questions remain as to which patients are appropriate for this exciting and novel therapy.