Dynamic electrocardiographic changes after aborted sudden death in a patient with Brugada syndrome and rate-dependent right bundle branch block

A 37-year-old man with Brugada syndrome and dynamic changes of the ST-segment morphology observed after an episode of aborted sudden death is described. On admission, after 3 syncopal episodes during nighttime, his electrocardiogram showed right bundle branch block (RBBB) with a J-point elevation of 0.6 mV in lead V 2 . Changes observed in the following days included a diminished J-point elevation and intermittent "saddle-back" type of morphology. During a previous 2-year follow-up, intermittent, complete, acceleration-dependent RBBB was documented. Right ventricular intracavitary tracings showed an RS pattern with a broad S wave in the unipolar electrogram; the time of onset of intrinsic deflection in this electrogram was 60 milliseconds. To our knowledge, this is the first report of an intracavitary demonstration of complete RBBB in Brugada syndrome.     

完全性左束支阻滞和右束支阻滞心电图结果分析

目的 了解完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.方法 分析108 610例常规心电图检测结果,分别统计完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.结果 108 610例门诊及住院患者资料,完全性左束支阻滞19例,占0.18％;右束支阻滞3 794例,占3.49％;完全性左束支阻滞发生率在不同性别之间差异无统计学意义（Х^2=1.707,P=0.191）,不同年龄之间比较差异有统计学意义（Х^2=209.874,P＜0.05）;右束支阻滞发生率在不同性别之间、不同年龄之间比较,差异均有统计学意义（Х^2=986.046,P＜0.05;Х^2=1 483.286,P＜0.05）.结论 60岁以上老年人的完全性左束支阻滞和右束支阻滞发生率较高,应定期进行常规心电图检查,及时发现异常情况并进行相应的处理.     

The Brugada Syndrome

The Brugada syndrome is a genetically determined disease caused by mutations of the cardiac sodium channel. The disease affects mainly males in their forties and causes sudden cardiac death because of polymorphic ventricular tachycardia. These patients have a structurally normal heart. The electrocardiogram of this syndrome shows, spontaneously or after Class 1 antiarrhythmic drugs, ST segment elevation in leads V₁ to V₃ and a pattern resembling a right bundle branch block. Phase 2 reentry between epi‐ and endocardiac layers is responsible for the arrhythmias. The only effective treatment at present is implantation of a cardioverter defibrillator. A.N.E. 2000;5(1):88–91     

Prevalence of asymptomatic ST segment elevation in right precordial leads with right bundle branch block (Brugada-type ST shift) among the general Japanese population

OBJECTIVE—To examine the modality and morbidity of asymptomatic ST segment elevation in leads V1 to V3 with right bundle branch block (Brugada-type ST shift).
METHODS—8612 Japanese subjects (5987 men and 2625 women, mean age 49.2 years) who underwent a health check up in 1997 were investigated. Those with Brugada-type ST shift underwent the following further examinations over a two year period after the initial check up: ECG, echocardiogram, 24 hour Holter monitoring, treadmill exercise testing, signal averaged ECG, and slow kinetic sodium channel blocker loading test (cibenzoline, 1.4 mg/kg).
RESULTS—Asymptomatic Brugada-type ST shift was found in 12 of 8612 (0.14%) subjects. Eleven of these 12 subjects were followed up. Follow up ECG exhibited persistent Brugada-type ST shift in seven of 11 (63.6%) subjects. ST shift was transformed from a saddle back to a coved type in three subjects. None of the subjects had morphological abnormalities or abnormal tachyarrhythmias. Positive late potentials were found in seven of 11 (63.6%) subjects. Augmentation of ST shift was shown by both submaximal exercise and drug administration in one of the 11 subjects (9.1%).
CONCLUSIONS—Asymptomatic subjects with Brugada-type ST shift were not unusual, at a rate of 0.14% in the general Japanese population. Almost all of the subjects had some abnormalities in non-invasive secondary examinations. Additional and prospective studies are needed to confirm the clinical significance and the prognosis of asymptomatic Brugada-type ST shift.


Keywords: Brugada syndrome; signal averaged electrocardiogram; sodium channel blocker; sudden death     

ST segment elevation, right bundle branch block and sudden death: Brugada's syndrome

Brugada's syndrome is one of the main causes of sudden death in young adults without a structural heart disease. This is an electrical cardiac illness secondary to a mutation of SCN5A gene of chromosome 3 that has a dominant autosomic transmission pattern. This mutation implies the dysfunction of the sodium channel that increases the Ito, loosing the dome of the epicardiac action potential phase two. An "all or none" repolarization pattern ensues and gives rise to a phase two reentry. This kind of reentry is responsible for the initiation and perpetuation of malignant ventricular arrhythmias among these patients. The clinical characteristics of the syndrome are the right bundle branch block, ST segment elevation from V1 to V3 leads and sudden death or syncope. In some patients, a pharmacological test must be done with ajmaline or procainamide to unmask the electrocardiographic changes. At present, the only effective treatment is the implantable cardioverter defibrillator (ICD). This device has the capability to reduce mortality from 40% annually to 0% at ten years. Pharmacological treatment is not useful.     

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。     

Alternating right and left bundle branch block aberration during atrial tachycardia

In a patient with atrial tachycardia with a rate of 200 per minute, the A-V conduction ratio was at times 2:1, but often it was 4:3 or 3:2 with progressive P-R interval prolongation (Wenckebach mechanism, an expression of presumable A-V nodal block). In each episode of 4:3 conduction, the first QRS complex was narrow, and the 2 ensuing beats were wide due to aberrant conduction. Aberration did not occur with a constant configuration, but in consecutive episodes of 4:3 conduction ratio there was a regular alternation of left bundle branch block and right bundle branch block. The pattern was explained by concealed retrograde conduction into the anterogradely blocked bundle branch. This caused 2 distinct effects: (1) shifting “to the right” of the refractory period of the affected bundle branch, resulting in maintenance of aberration with the same configuration, if consecutive atrial impulses were conducted to the ventricles, and (2) shortening of the effective cycle of the affected bundle branch, resulting in aberration due to block of the controlateral bundle branch, whenever a pause occasioned by a nonconducted atrial impulse was followed by restoration of 1:1 conduction for 2 or more consecutive beats.     

Influence of meals on variations of ST segment elevation in patients with Brugada syndrome

Background: Glucose-induced insulin secretion is one of the contributing factors to fluctuation of ST segment elevation in Brugada syndrome.
Objectives: The purpose of this study was to explore the influence of meals on variations of ST elevation in Brugada syndrome.
Methods: We assessed changes of ST segment elevation in lead V1-3 on ECG before and after taking meals, at midnight, and at 3:00 a.m. in 20 patients with Brugada syndrome. Plasma glucose, insulin, and K⁺ concentrations were measured. Variations of ST elevation were defined as morphological changes and/or augmentation of ST segment level by >1.0 mm.
Result: Variations of ST segment morphology or elevation level after meals were observed in 15 of 20 patients (75%). ST elevation was augmented most markedly after dinner (3.3 ± 1.7 mm) and decreased both at midnight (2.6 ± 1.3 mm: P < 0.01 vs after dinner) and at 3:00 a.m. (2.4 ± 1.2 mm: P < 0.01 vs after dinner). Morphologic changes and elevation levels of ST segment were associated with changes in glucose-induced insulin levels after meals, being highest after dinner (47 ± 33 μU/mL) and decreasing significantly at midnight (7 ± 4 μU/mL) and at 3:00 a.m. (5 ± 2 μU/mL). There were no correlations between ST elevation and changes in serum K⁺ level or heart rate.
Conclusions: The present findings suggest that variations of ST elevation are frequently associated with meals. Aggravation of ST elevation is most prominent in the evening to night after dinner rather than the period between midnight and early morning. This information may help to predict event times at high risk for life-threatening arrhythmias in Brugada syndrome.     

左束支起搏对合并右束支传导阻滞患者的心电学影响

目的探讨左束支起搏对症状性心动过缓合并右束支传导阻滞患者的心电学影响。 方法连续纳入2019年1月1日至2021年12月31日因症状性心动过缓合并完全性右束支传导阻滞并在厦门大学附属心血管病医院心内科拟行左束支起搏的患者,记录标准12导联体表心电图。比较左束支起搏术前与术后V₁导联QRS波形态、QRS时限、右心室延迟激动时间（dRVAT）、左心室达峰时间（LVAT）及心室间延迟时间（IVD）的差异。 结果共入选53例患者,年龄（72.15±9.39）岁,男34例。其中46例（86.79%,46/53）成功完成左束支起搏。术前V₁导联以rsR’型为主38例（38/46,83%）,术后QRS形态以Qr型为主29例（29/46,63%）。左束支起搏可以显著缩短QRS时限［（149.09±12.81）ms对（112.46±9.64）ms,P<0.001）］,其中35例（76.08%,35/46）患者的QRS时限完全纠正,10例（21.73%,10/46）部分纠正,1例（2.17%,1/46）未纠正;IVD显著缩短［（58.28±12.54）ms对（34.34±8.87）ms,P<0.001］;但在dRVAT方面左束支起搏术前与术后差异无统计学意义［（100.47±12.40）ms对（100.86±10.57）ms,P=0.955］。与术前相比,左束支起搏延长LVAT［（42.46±6.95）ms对（66.53±10.83）ms,P<0.001］。 结论左束支起搏可显著缩短完全性右束支传导阻滞患者的QRS时限,并改善其心室间电学同步性,产生以Qr型为主的起搏后QRS波形态。     

Familial cardiomyopathy underlies syndrome of right bundle branch block,ST segment elevation and sudden death

Objectives. We sought to assess whether structural heart disease underlies the syndrome of right bundle branch block, persistent ST segment elevation and sudden death.Background. Ventricular fibrillation and sudden death may occur in patients with a distinctive electrocardiographic (ECG) pattern of right bundle branch block and persistent ST segment elevation in the right precordial leads.Methods. Sixteen members of a family affected by this syndrome underwent noninvasive cardiac evaluation, including electrocardiography, Holter ambulatory ECG monitoring, stress testing, echocardiography and signal-averaged electrocardiography; two patients had electrophysiologic and angiographic study. Endomyocardial biopsy was performed in one living patient, and postmortem examination, including study of the specialized conduction system, was performed in one victim of sudden death.Results. Five years before a fatal cardiac arrest, the proband had been resuscitated from sudden cardiac arrest due to recorded ventricular fibrillation. Serial ECGs showed a prolonged PR interval, right bundle branch block, left-axis deviation and persistent ST segment elevation in the right precordial leads, in the absence of clinical heart disease. Postmortem investigation disclosed right ventricular dilation and myocardial atrophy with adipose replacement of the right ventricular free wall as well as sclerotic interruption of the right bundle branch. A variable degree of right bundle branch block and upsloping right precordial ST segment was observed in seven family members; four of the seven had structural right ventricular abnormalities on echocardiography and late potentials on signal-averaged electrocardiography. A sib of the proband also had a prolonged HV interval, inducible ventricular tachycardia and fibrofatty replacement on endomyocardial biopsy.Conclusions. An autosomal dominant familial cardiomyopathy, mainly involving the right ventricle and the conduction system, accounted for the ECG changes and the electrical instability of the syndrome.     

不典型Brugada综合征V1～V3室性期前收缩ST段明显抬高的临床意义

目的探讨室性期前收缩V1～V3导联ST段明显抬高对Bmgada综合征的诊断及心源性晕厥的预警意义。方法回顾分析一例两次室性心动过速及心室颤动发作前的心电图，观察V1～V3室性期前收缩对ST段抬高的类型及程度的影响。结果两次晕厥前均有频发室性期前收缩，V1～V3ST段均呈马鞍型明显抬高，更濒临晕厥的一次室性期前收缩的ST段抬高更明显；同导联窦性心动的ST段抬高程度无明显改变。结论V1～V3室性期前收缩时ST段“扩增”抬高，伴有同一导联窦性心动ST段抬高如常，亦是支持Bmgada综合征诊断的一种有力佐证，ST段抬高越明显，可能预示更濒临晕厥发作。     

Recurrent extensive anterior myocardial infarction with left and right bundle branch block

The diagnosis of myocardial infarction with left bundle branch block is difficult. We report a case of 56‐year‐old man with old extensive anterior myocardial infarction and left bundle branch block (masked each other). The recurrent myocardial infarction indicated right bundle branch block and first‐degree atrioventricular block, making a clear diagnosis of complicated and interesting ECG.     

A balanced translocation disrupting SCN5A in a family with Brugada syndrome and sudden cardiac death

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Brugada syndrome masked by complete left bundle branch block: A clinical and functional study of its association with the p.1449Y>H SCN5A variant

SCN5A gene variants are associated with both Brugada syndrome and conduction disturbances, sometimes expressing an overlapping phenotype. Functional consequences of SCN5A variants assessed by patch-clamp electrophysiology are particularly beneficial for correct pathogenic classification and are related to disease penetrance and severity. Here, we identify a novel SCN5A loss of function variant, p.1449Y>H, which presented with high penetrance and complete left bundle branch block, totally masking the typical findings on the electrocardiogram. We highlight the possibility of this overlap combination that makes impossible an electrocardiographic diagnosis and, through a functional analysis, associate the p.1449Y>H variant to SCN5A pathogenicity.