Changes in Tachycardia Cycle Length with Varying Degrees of Right Bundle Branch Block: What Is the Mechanism?

The present case contributes to understanding the mechanism and differential diagnosis of a wide QRS complex tachycardia with varying degrees of right bundle branch block morphology.

Factores asociados al bloqueo de rama derecha en adultos mayores / Factors associated with right bundle branch block in older adults

RESUMEN Introducción: Existe poca literatura sobre la asociación entre el bloqueo de rama derecha y factores de riesgo como la hipertensión y la diabetes en pacientes de Latinoamérica y Perú. Objetivo: Determinar los factores asociados al bloqueo de rama derecha en adultos mayores. Métodos: Estudio transversal que incluyó 376 pacientes adultos mayores atendidos en el Hospital Almanzor Aguinaga Asenjo, Lambayeque-Perú. La variable dependiente fue la presencia de bloqueo de rama derecha y las variables independientes fueron edad, sexo, antecedente de hipertensión arterial y diabetes. Se estimaron razones de prevalencia e intervalos de confianza al 95 %. Resultados: De 376 pacientes, la mayoría eran varones (55,9 %), la edad media fue de 75,6 años, el 11,4 % tuvo antecedente de hipertensión y el 9 % era diabético. El 41 % tuvo diagnóstico de bloqueo de rama derecha. En la regresión múltiple; el sexo femenino (RP=1,53, IC 95 %: 1,21 - 1,95), antecedente de hipertensión (RP=1,55; IC 95 %: 1,21 - 2,00) y diabetes mellitus (RP=1,49, IC 95 %: 1,12 - 2,00) se asociaron de forma positiva a presentar bloqueo de rama derecha. El modelo anidado seleccionó las variables: sexo femenino (RP=1,54, IC 95 %: 1,21 - 1,96) y antecedente de hipertensión arterial (RP=1,61, IC 95 %: 1,25 - 2,08). Conclusión: El sexo femenino, antecedente de hipertensión arterial y de diabetes mellitus se asocian positivamente a presentar bloqueo de rama derecha.

ABSTRACT Introduction: There is little literature on the association between right bundle branch block and risk factors such as hypertension and diabetes in patients in Latin America and Peru. Objective: To determine the factors associated with right bundle branch block in older adults. Methods: Analytical cross-sectional study completed by 376 elderly patients treated at Almanzor Aguinaga Asenjo Hospital, Lambayeque-Peru. The dependent variable was the presence of right bundle branch block, and the independent variables were age, sex, history of hypertension, and diabetes. Prevalence ratios and 95 % confidence intervals were estimated. Results: Of 376 patients, the majority were male (55,9 %), the mean age was 75,6 years, 11,4 % had a history of hypertension and 9 % were diabetic; 41 % had a diagnosis of right bundle branch block. In simple regression, the frequency of right bundle branch block was 56 % (PR= 1,56; 95 % CI: 1,22-1,99), 65 % (PR=1,65; 95 % CI: 1,26 - 2,15) and 59 % (PR= 1,59; CI 95 %: 1,18 - 2,14) higher in women, hypertensive and diabetics; respectively. In the multiple regression; female sex (PR= 1,53; 95 % CI: 1,21 - 1,95), history of hypertension (PR= 1,55; 95 % CI: 1,21 - 2,00) and diabetes mellitus (PR= 1,49; 95 % CI: 1,12 - 2,00) were positively associated with right bundle branch block. The nested model selected the variables: female sex (PR= 1,54; 95 % CI: 1,21 - 1,96) and history of arterial hypertension (PR= 1,61; 95 % CI: 1,25 - 2,08). Conclusion: Female sex, history of arterial hypertension and diabetes mellitus were positively associated with presenting right bundle branch block in older adults.

Patient With Presyncope and Variable PR Interval and QRS Morphology.

We describe the case of a 72-year-old female patient, presenting with presyncope and variable PR Interval and changing QRS morphology on the electrocardiogram. Differential diagnosis is discussed. (Level of Difficulty: Beginner.).

Electrocardiographic Recognition of Unprotected Left Main ST-Segment Elevation Myocardial Infarction: Looking Beyond aVR.

ST-segment elevation in aVR has traditionally been used for electrocardiographic identification of left main coronary artery (LM) myocardial infarction. We present two ST-segment elevation myocardial infarction (STEMI) cases with acute total occlusion of the LM without aVR ST-segment elevation. This report reviews the different electrocardiographic discriminators suggestive of unprotected LM STEMI. (Level of Difficulty: Intermediate.).

[Management of heart failure with His bundle pacing in right bundle branch block: case report]. / Manejo de la insuficiencia cardiaca con estimulación hisiana en bloqueo de rama derecha: reporte de caso.

La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.

Manejo de la insuficiencia cardiaca con estimulación hisiana en bloqueo de rama derecha: reporte de caso / Management of heart failure with His bundle pacing in right bundle branch block: case report

Resumen La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.

Abstract Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.

A rare combination of atrial and intraventricular conduction disturbances: Atypical type I advanced interatrial block, left posterior fascicular block and transient right bundle branch block.

According to the first 2012 consensus report about interatrial block, the diagnosis of advanced interatrial block (A-IAB) consists of a P-wave duration ≥120 ms with biphasic "plus-minus" (±) polarity in the three leads of the inferior wall in the electrocardiogram. At the end of 2018, a new concept was introduced: the atypical A-IAB due to changes in the polarity or duration of the P-wave. The prevalence of these atypical patterns in different scenarios is currently unknown, but the patterns should be considered as risk factors of embolic stroke of undetermined source. When the A-IAB pattern is associated with clinical arrhythmic manifestations, it is known as the Bayés' Syndrome. We present a characteristic case of atypical A-IAB, and the rare left posterior fascicular block and transient right bundle branch block.

Fascicular Blocks: Update 2019.

Many advances in the knowledge of medical science are due to the observation of an unknown phenomenon that remains an open question. A plausible hypothesis must be demonstrated and proved through a scientific method in order to be accepted by the scientific community and the same results must be reached by following either the same or different techniques. The original case described by Rosenbaum MB et al., in this review triggered a series of anatomic and physiologic investigations with clinical and experimental observations that supported the trifascicular nature of the intraventricular conduction system of the heart and the concept of hemiblocks. The recognition and description of the left fascicular blocks made by the Argentinian School of Electrocardiology bridged an important gap in electrocardiography and many electrocardiograms that could not be explained until that moment could finally be understood. This review intends to redefine reliable criteria for the electrocardiographic and vectorcardiographic diagnosis of left fascicular blocks [hemiblocks]. The anatomy of the left bundle branch is also discussed to better understand the incidence, prevalence, clinical significance and main causes of left anterior and left posterior hemiblock either isolated or associated with right bundle branch block. This review offers the reader a reappraisal of the trifascicular nature of the intraventricular conduction system regarding the anatomy of the left bundle branch system and its pathophysiological and clinical significance.

Transient high-degree right bundle branch block masking the type 1 Brugada ECG pattern associated with possible transient early repolarization syndrome.

The Brugada syndrome (BrS) was the last electrocardiographic syndrome described in the 20th century. The initial description included right bundle branch block (RBBB), persistent ST-segment elevation in the right precordial leads, absence of structural heart disease, and propensity to unexplained syncope and/or sudden death mainly during nocturnal rest. Currently, we know that the first three components are not constant or true since RBBB is present in only 28% of cases, the ST-segment elevation is dynamic, at times absent, and there are discrete structural changes in the right ventricular outflow tract. Additionally, the presence of RBBB can hide the typical type 1 Brugada ECG pattern. We present a very unusual case of spontaneous transient RBBB that revealed a hidden type 1 Brugada ECG pattern that could be seen in the beat with normal ventricular conduction.

Electro-vectorcardiographic demonstration of bifascicular block associated with ventricular preexcitation.

Down syndrome occurs more frequently in the offsprings of older pregnant women and may be associated with atrioventricular septal defect. This refers to a broad spectrum of malformations characterized by a deficiency of the atrioventricular septum and abnormalities of the atrioventricular valves caused by an abnormal fusion of the superior and inferior endocardial cushions with the midportion of the atrial septum and the muscular portion of the ventricular septum.

Hallazgos clínicos y electrocardiográficos en pacientes pediátricos con comunicación interauricular / Clinical and electrocardiographic findings in pediatric patients with atrial septal defects

Introducción: La comunicación interauricular (CIA) es una cardiopatía congénita frecuente, cuyo diagnóstico es difícil en pacientes paucisintomáticos. Sin tratamiento, puede complicarse con insuficiencia cardiaca, arritmias e hipertensión pulmonar. El electrocardiograma puede proporcionar indicios de esta cardiopatía. Objetivo: Describir los hallazgos clínicos y electrocardiográficos de pacientes portadores de CIA. Materiales y Métodos: Trabajo retrospectivo, de pacientes menores de 18 años, evaluados cardiológicamente de enero 2008 a diciembre de 2013. Se describen las variables electrocardiográficas y semiológicas sugestivas de CIA. Resultados: Hubo 77 pacientes con CIA. Los motivos de consulta más frecuentes entre los pacientes con CIA fueron el soplo cardiaco, el síndrome de Down y la disnea. En el examen físico de los pacientes con CIA: soplo sistólico en 69% y R2 desdoblado en 56%. En el electrocardiograma, los pacientes tuvieron QRS de 79 ms, eje eléctrico desviado hacia la derecha, BIRD y notch. Los criterios de sobrecarga ventricular derecha (SVD) más frecuentes fueron la onda S profunda en V6 y la onda R alta en V1. La auscultación de un R2 desdoblado en el examen físico, así como la SVD y el patrón notch fueron los hallazgos más frecuentes en pacientes con CIA. Conclusión: el electrocardiograma constituye una herramienta válida en la evaluación de pacientes con sospecha de CIA pero precisa de la combinación de hallazgos clínicos para llegar al diagnóstico.

Introduction: Atrial Septal Defect (ASD) is a frequent congenital heart disease, the diagnosis of which is difficult in paucisymptomatic patients. Without treatment, it can lead to heart failure, arrhythmias and pulmonary hypertension. The electrocardiogram may provide evidence of this condition. Objective: To describe the clinical and electrocardiographic findings of patients with ASD. Materials and Methods: This was a retrospective study of patients under age 18 who underwent cardiac evaluation from January 2008 to December 2013. The electrocardiographic and clinical finding variables suggestive of ASD are described. Results: There were 77 patients with ASD. The most frequent reasons for consultation among patients with ASD were heart murmur, Down syndrome and dyspnea. Findings on physical examination of patients with ASD were: systolic murmur in 69% and S2 split in 56%. On the electrocardiogram, the patients had QRS of 79 ms, electric axis deviated to the right, Incomplete Right Bundle Branch and notch pattern. The most frequent right ventricular volume overload (RVVO) criteria were the deep S wave in V6 and the high R wave in V1. Auscultation of a split S2 on the physical examination, as well as the RVVO and the notch pattern were the most frequent findings in patients with ASD. Conclusion: the electrocardiogram is a valid tool in the evaluation of patients with suspected ASD but requires the combination of clinical findings to reach the diagnosis.

Case report: Posterior myocardial infarction in presence of right bundle branch block: an old concept with new findings.

BACKGROUND: The diagnosis of acute ischaemic coronary syndromes in presence of an intra-ventricular conduction disturbance represents a clinical challenge. In the cardiac segmentation model the posterior wall is replaced by the basal inferior segment. However, in the clinical scenario of acute coronary syndrome the concept of posterior myocardial infarction (PMI) endures. The association of a PMI and right bundle branch block (RBBB) is a rare condition characterised by broad R waves and ventricular repolarization disorders in right precordial leads in both entities, which could lead to misinterpretation and delay in reperfusion therapy. CASE SUMMARY: We describe a case report of a 74-year-old man with acute chest pain and an electrocardiogram with broad R waves, a 4 mm ST-segment downsloping (excessively discordant) in right precordial leads, RBBB, and ST-segment elevation in posterior leads. There was resolution of ST-segment downsloping in right precordial leads after percutaneous coronary intervention and stenting of the circumflex artery, with disturbance of the repolarization process only attributable to RBBB. DISCUSSION: Patients with acute chest pain with RBBB and a ST segment with an excessive downsloping (out of proportion of what is expected in isolated RBBB) suggest PMI with occlusion of the circumflex coronary artery.

Ashman phenomenon dynamicity during atrial fibrillation: the critical role of the long cycles.

A case of a patient with Atrial Fibrillation and intermittent wide complex beats. What's the mechanism?

Clinical Impact of Baseline Right Bundle Branch Block in Patients Undergoing Transcatheter Aortic Valve Replacement.

OBJECTIVES: This study sought to assess the influence of baseline right bundle branch block (RBBB) on all-cause and cardiovascular mortality as well as sudden cardiac death (SCD) among patients undergoing transcatheter aortic valve replacement (TAVR). BACKGROUND: Few data exist regarding the late clinical impact of pre-existing RBBB in TAVR recipients. METHODS: A total of 3,527 patients (mean age 82 ± 8 years, 50.1% men) were evaluated according to the presence of RBBB on baseline electrocardiography. Intraventricular conduction abnormalities were classified according to the American Heart Association, American College of Cardiology Foundation, and Heart Rhythm Society recommendations for standardization and interpretation of the electrocardiogram. TAVR complications and causes of death were defined according to Valve Academic Research Consortium 2 definitions. RESULTS: RBBB was present on baseline electrocardiography in 362 patients (10.3%) and associated with higher 30-day rates of permanent pacemaker implantation (PPI) (40.1% vs. 13.5%; p < 0.001) and death (10.2% vs. 6.9%; p = 0.024). At a mean follow-up of 20 ± 18 months, pre-existing RBBB was independently associated with all-cause mortality (hazard ratio [HR]: 1.31; 95% confidence interval [CI]: 1.06 to 1.63; p = 0.014) and cardiovascular mortality (HR: 1.45; 95% CI: 1.11 to 1.89; p = 0.006) but not with SCD (HR: 0.71; 95% CI: 0.22 to 2.32; p = 0.57). Patients with pre-existing RBBB and without PPI at discharge from the index hospitalization had the highest 2-year risk for cardiovascular death (27.8%; 95% CI: 20.9% to 36.1%; log-rank p = 0.007). In a subanalysis of 1,245 patients without PPI at discharge from the index hospitalization and with complete follow-up regarding the need for PPI, pre-existing RBBB was independently associated with the composite of SCD and PPI (HR: 2.68; 95% CI: 1.16 to 6.17; p = 0.023). CONCLUSIONS: Pre-existing RBBB was found in 10% of TAVR recipients and was associated with poorer clinical outcomes. Patients with baseline RBBB without permanent pacemakers at hospital discharge may be at especially high risk for high-degree atrioventricular block and/or SCD during follow-up. Future studies should evaluate strategies aimed at the early detection of patients at risk for late development of high-degree atrioventricular block.

Trastornos de conducción ventricular y miocardio inactivable / Ventricular conduction disorder in presence of dead myocardium

Un bloqueo de rama izquierda (BRIHH) de grado avanzado, i.e. con fenómeno de "salto de onda" extenso, hace que la activación septal anormal de origen a fuerzas electromotrices de mayor duración y magnitud respecto a las normales. Por eso se establece una preponderancia eléctrica septal respecto a las paredes libres ventriculares. La coexistencia de una zona de miocardio inactivable antero-septal con un BRIHH de grado avanzado hace que el "salto de onda" comience en porciones postero-septales inferiores. Por ende, los electrodos izquierdos externos ven alejarse los primeros frentes de la activación ventricular y registran ondas Q. La presencia de miocardio inactivable en la pared libre ventricular izquierda permite al electrodo externo correspondiente registrar la morfología del complejo intraventricular homolateral: R¯S. Un BRIHH de grado intermedio da origen a un "salto de onda" limitado de derecha a izquierda. Cuando dicho bloqueo se asocia a la presencia de miocardio inactivable septal, se reducen las manifestaciones del bloqueo izquierdo pero están presentes las de la necrosis: pérdida de la manifestación del primer vector septal derecho y registro de ondas Q en las derivaciones izquierdas. A causa de un bloqueo de rama derecha (BRDHH) de grado avanzado, con "salto de onda" extenso, también se originan fuerzas electromotrices septales predomi nantes. La coexistencia de una zona de miocardio inactivable anteroseptal con un BRDHH de grado avanzado hace que el "salto de onda" de izquierda a derecha comience en porciones postero-septales bajas. Así los electrodos de las derivaciones transicionales ven alejarse los primeros frentes del "salto de onda" y registran: ondas Q. Una zona inactivable parietal derecha, transmural, permite a los electrodos externos correspondientes registrar la morfología polifásica del complejo intra-ventricular homolateral. Un BRDHH de grado intermedio, asociado a necrosis antero-septal, se caracteriza por reducción de los signos de bloqueo y presencia de ondas Q en las derivaciones precordiales derechas y transicionales.

In the presence of an advanced degree left bundle branch block (LBBB) with an extensive "Jumping wave" phenomenon, the septal activation abnormally spreading originates septal electromotive forces of greater duration and consequently more important than normal ones. The coexistence of an inactive anteroseptal myocardium with an advanced degree block causes the phenomenon of "Jumping wave" begins in postero-septal regions. Therefore the external left electrodes see the first ventricular activation fronts moving away and register Q waves. The presence of transmural inactive myocardium in the free left ventricular wall permits the corresponding external electrodes to record the morphology of the ipsilateral intraventricular complex: R¯S. An intermediate degree LBBB produces a limited right to left "Jumping wave" phenomenon. When it is associated to septal inactive myocardium, the electrical manifestations of left block are reduced, but those of myocardial necrosis persist: loss of the manifestation of first right septal vector and presence of Q waves in left leads. Because of an advanced degree right bundle branch block (RBBB) with an extensive "Jumping wave" phenomenon, electromotive septal forces of greater duration and consequently more important than normal ones, are originated also. The coexistence of inactive antero-septal myocardium with an advanced degree RBBB causes the phenomenon of "Jumping wave" begins in inferior postero-septal regions. Therefore, the transitional leads see the first fronts of the said phenomenon moving away and register Q waves. The presence of inactive transmural right parietal myocardium permits the corresponding external electrodes to record the morphology of the ipsilateral polyphasic intraventricular complex. An intermediate degree RBBB, associated to antero-septal necrosis, is characterized by the reduction of the electrocardiographic signs of the said block and the presence of Q waves in the right precordial and transitional leads.

In-hospital outcome in patients with ST elevation myocardial infarction and right bundle branch block: A sub-study from RENASICA II, a national multicenter registry / Evolución intrahospitalaria en pacientes con infarto agudo del miocardio con elevación del segmento ST y bloqueo de rama derecha: Sub-estudio de RENASICA II, un registro nacional multicéntrico

Objective: Compare in-hospital outcome in patients with ST-elevation myocardial infarction with right versus left bundle branch block. Methods: RENASICA II, a national mexican registry enrolled 8098 patients with final diagnosis of acute coronary syndrome secondary to ischemic heart disease. In 4555 STEMI patients, 545 had bundle branch block, 318 (58.3%) with right and 225 patients with left (41.6%). Both groups were compared in terms of in-hospital outcome through major cardiovascular adverse events; (cardiovascular death, recurrent ischemia and reinfarction). Multivariable analysis was performed to identify in-hospital mortality risk among right and left bundle branch block patients. Results: There were not statistical differences in both groups regarding baseline characteristics, time of ischemia, myocardial infarction location, ventricular dysfunction and reperfusion strategies. In-hospital outcome in bundle branch block group was characterized by a high incidence of major cardiovascular adverse events with a trend to higher mortality in patients with right bundle branch block (OR 1.70, CI 1.19 - 2.42, p < 0.003), compared to left bundle branch block patients. Conclusion: In this sub-study right bundle branch block accompanying ST-elevation myocardial infarction of any location at emergency room presentation was an independent predictor of high in-hospital mortality.

Objetivo: Comparar la evolución hospitalaria en pacientes con infarto agudo del miocardio con bloqueo de rama derecha versus bloqueo de rama izquierda. Método: El Registro Nacional de Síndromes Coronarios Agudos II, incluyó 8098 pacientes con síndrome coronario agudo, de los cuales 4555 corresponden a infarto con elevación del segmento ST. De ellos, se demostró en 545 bloqueo de rama: 318 (58.3%) tuvieron bloqueo de rama derecha y 227 (41.6%) bloqueo de rama izquierda. Fueron comparados en términos de mortalidad hospitalaria y eventos cardiovasculares mayores adversos. Se realizó un análisis multivariado para identificar mortalidad hospitalaria a través de eventos mayores entre pacientes con ambos bloqueos de rama. Resultados: No hubo deferencia estadísticamente significativa en ambos grupos en relación con características basales, tiempo de isquemia, localización del infarto, disfunción ventricular o estrategia de reperfusión utilizada. Los pacientes con infarto agudo del miocardio de cualquier localización y bloqueo de rama derecha tuvieron mayor tendencia para mortalidad hospitalaria y eventos cardiovasculares mayores (OR 1.70, IC 1.19-2.42, p < 0.003) vs. pacientes con bloqueo de rama izquierda. Conclusión: En el infarto agudo del miocardio con elevación del segmento ST, el bloqueo de rama derecha fue un predictor independiente de alta mortalidad hospitalaria.

Estudo de perfusão miocárdica em portadores de bloqueio de ramo direito / Myocardial perfusion study in patients with right bundle branch block

PURPOSE: To evaluate the sensitivity and specificity of myocardial perfusion scintigraphy in the detection of coronary artery disease in patients with right bundle branch block (RBBB). METHODS: Thirty one patients (24 male, 62.3 +/- 10.5 years) with RBBB, submitted to myocardial perfusion scintigraphy associated with exercise (n = 7) or dipyridamole (n = 24) and previous cinecoronariography were studied retrospectively. Left ventricle scintigraphic image was divided in three segments corresponding to the three main epicardic coronary territories in a total of 93 segments. Cineangiographic and scintigraphic data were then compared according to the different artery territories. RESULTS: Twenty three patients had significant lesions (> or = 60) in one or more coronary arteries and eight had no obstruction. Forty nine segments were irrigated by normal coronary arteries and 44 were related to arteries that had significant lesions. Twenty out of twenty three patients showed alterations in perfusion (sensitivity = 87). All patients without coronary obstructions showed normal perfusion scintigraphy (specificity = 100). One of the segments perfused by normal coronaries showed abnormal scintigraphy. Scintigraphy showed perfusion defects in 29 out of 44 segments with coronary obstructions. Sensitivity and specificity of the method for each arterial territory were 72and 100(left descending coronary artery), 67and 94(right coronary artery), 55and 100(circunflex coronary artery), respectively. CONCLUSION: The presence of RBBB does not modify the sensitivity and specificity of the method in the detection of coronary artery disease.

Histopatologia da porção trabecular do ramo direito do feixe de His em chagásicos crônicos com bloqueio de ramo direito / Histopathology of the Trabecular Segment of the Right Bundle Branch in Chronic Chagasic Patients with Right Bundle Branch Block

PURPOSE--To evaluate possible morphological changes in chronic chagasic of the right bundle trabecular branch (RB) with right branch block (RBB) and to draw clinicopathological correlations. METHODS--Eight RBB chronic chagasic septo-marginal trabeculae (SMT) (group A), six left branch block (LBB) chagasic SMT (group B) and six SMT from non-chagasics with no heart disease (group C) were analyzed. Every SMT was completely embedded in paraffin, sub-serially sectioned to the end of the paraffin-block and the sections were processed for pathological study. RESULTS--Right bundle branch trabecular segment mononuclear infiltrate and/or fibrosis were found for 87.5 (7/8) of group A, 50 por cento (3/6) of group B and 16.6 por cento (1/6) of group C. Moderate mononuclear infiltrate and fibrosis were noted respectively for 3 and 1 cases, from group A. For the remaining group A cases and for all the group B and C cases the mononuclear infiltrate and fibrosis were slight. CONCLUSION--The frequency and degree of RB lesions might explain some of RBB. On the other hand, the absence of lesions in one case RBB and the slight degree of RB lesions in chagasics with LBB and in one non-chagasic case indicate that sometimes it is not possible to establish electrocardiographic-pathological correlations after TSM histological examination