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.     

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.     

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     

Right bundle branch block and conduction disturbances in Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy

Right bundle branch block is relatively frequent in the general population and is generally considered benign in healthy individuals. However, it has been associated with increased cardiovascular risk and all-cause mortality in various cohort studies. Indeed, the presence of right bundle branch block in subjects affected by cardiomyopathies or channelopathies is not rare and may conceal underlying electrocardiographic changes, thus making the diagnosis of such conditions more challenging. The purpose of this review is to analyze the prevalence and clinical significance of right bundle branch block in subjects affected by Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy.     

Three-year follow-up of patients with right bundle branch block and ST segment elevation in the right precordial leads: Japanese Registry of Brugada Syndrome. Idiopathic Ventricular Fibrillation Investigators

OBJECTIVES: We sought to determine the prevalence of right bundle branch block (RBBB) and ST segment elevation in the working Japanese population, as well as the event rate during a three-year prospective follow-up period. BACKGROUND: A poor prognosis of RBBB and ST segment elevation has been reported in Europe and South America, even in asymptomatic patients; however, a large population of asymptomatic patients with sporadic RBBB and ST segment elevation has not been studied. METHODS: Ten thousand 12-lead electrocardiograms (ECGs) were obtained during annual check-ups of working adults in the Tokyo area. This three-year prospective follow-up study consisted of 105 patients, including 20 with ventricular fibrillation, 18 with syncope and 67 who were asymptomatic. They were registered from 46 institutions in Japan. RESULTS: The prevalence of ECG abnormalities in working adults was 0.16%. A coved-type ST segment elevation was related to a history of cardiac events, and 18% of registered patients had PR prolongation and 9.5% had left-axis deviation. The cumulative cardiac event-free rate was 67.6% in the symptomatic group and 93.4% in the asymptomatic group (p = 0.0004) after three years. CONCLUSIONS: The recurrence rate of cardiac events in symptomatic patients was similar to that reported previously, but it was very low in sporadic asymptomatic patients. The ECG findings may help us to select patients for further examination and more accurate evaluation of their prognoses.     

Significance of right precordial ST elevation in experimental right ventricular infarction

We produced experimental isolated right ventricular infarction (RVI) with closed chest method, and examined ECG changes of right precordial leads and changes of cardiac output (C. O) in 19 dogs. As a result, ECG showed ST depressions in leads, II, III, aVF and V2-V6 and ST elevations in a VR lead in all 15 cases of the proximal occlusion of right coronary artery (RCA). In 10 of 15 dogs ST elevations in some right precordial leads occurred, and the sensitivity of ST elevation in single right precordial lead was 60% (V5R), 53% (V4R) and 47% (V3R and V1), respectively for the detection of RVI. When left circumflex artery (LCX) was occluded, ST elevation in V4R lead after RCA occlusion was blocked. Therefore, it is thought that the sensitivity of ST elevation in right precordial lead may be lower than expectation in identifying RVI. Concerning anterior chest leads, none of 15 dogs with RVI showed ST elevations in leads V2-V6 in this study. If ST elevations in right precordial leads did not appear, variation of C.O was small and C.O reduced in proportion to the extension of ST elevations in right precordial leads.     

Right bundle branch block and ventricular septal fibrosis in patients with hypertrophic cardiomyopathy

BackgroundRight bundle branch block (RBBB) is associated with ventricular septal fibrosis in patients with hypertrophic cardiomyopathy (HCM) after alcohol septal ablation, but little data are available in HCM patients without a history of septal ablation.MethodsMagnetic resonance late gadolinium enhancement (LGE) was performed in 59 HCM patients with no history of alcohol septal ablation. The location and extent of LGE were examined in relation to electrocardiographic features including RBBB.ResultsLGE volume was higher in 7 HCM patients with RBBB (7.3 ± 7.4 g/cm) than in patients without RBBB (2.9 ± 7.4 g/cm, p = 0.016). LGE volume was positively correlated to QRS duration of RBBB (correlation coefficient = 0.93, p = 0.023). The diagnostic value of RBBB was highly specific for the detection of LGE in the ventricular septum, with sensitivity 21% and specificity 94%.ConclusionsThe presence of RBBB may be a simple marker for detecting ventricular septal fibrosis in HCM patients who had no history of alcohol septal ablation. Further studies are necessary to confirm our findings.     

ST segment elevation in anterior precordial leads and right ventricular infarction. Apropos of 6 cases]

ST segment elevation in the anterior precordial chest leads may be observed in some cases of right ventricular infarction alone or associated with left ventricular inferior wall infarction. Six out of 700 patients admitted to our Coronary Care Unit over a 2 year period had right ventricular infarction with these electrocardiographic changes. In three cases, isolated right ventricular infarction was due to occlusion of a right marginal artery (N = 2) or of a small right coronary artery (N = 1) which only vascularised the right ventricle. In 2 cases, right ventricular infarction was associated with a recent or chronic left ventricular inferior wall infarct. This type of ST segment elevation may suggest a left ventricular anterior wall infarct especially when there are no changes in the inferior leads, as was the case in our first patient. However, the dome-like appearance of the ST segment, the reduction in amplitude of ST elevation from V2 to V5, the progressive regression of the ST changes without the appearance of Q waves, are more suggestive of the diagnosis of right ventricular infarction. In addition, normal left ventricular dilatation on echocardiographic examination rapidly confirms the diagnosis.     

Transient but marked ST elevation in precordial leads caused by ischemia of the isolated right ventricular branch

The present case is a 64 year-old man in whom transient but marked ST elevation was confirmed in the contralateral precordial leads (V1-3) during percutaneous transluminal coronary angioplasty (PTCA) of the proximal right coronary artery, suggesting that the patient had anteroseptal ischemia. The ST elevation persisted even after the balloon was deflated, and no changes in the left coronary artery were detected. In addition, blood flow in the affected area of the right coronary artery was favorable and there was a transient delay only in the right ventricular branch. Once blood flow in the right ventricular branch improved, ST returned to baseline, and when the right ventricular branch was again occluded by the balloon, ST elevation occurred in a reproducible manner. Hence, the electrocardiographic changes in the precordial leads were caused by occlusion of the right ventricular branch. It is rare to observe ST elevation caused by isolated right ventricular branch ischemia.