Right bundle-branch block and left axis deviation in acute myocardial infarction

Of 114 patients with acute myocardial infarction admitted consecutively to a coronary care unit, 10 had recent antero-septal myocardial infarction associated with right bundle-branch block and obvious left axis deviation, and I had recent antero-septal myocardial infarction with right bundle-branch block and right axis deviation. Attention is drawn to the high mortality (7 out of 11 patients), due mainly to cardiogenic shock. Frequent complications were sudden complete heart block (5 patients) and ventricular asystole (4 patients) without previous lengthening of the atrioventricular conduction time. An external on-demand pacemaker was inserted in 10 patients, and no patient died of complete heart block or ventricular asystole.     

Long-term prognosis after acute anterior infarction with atrioventricular block.

The purpose of this study was to evaluate the need for permanent pacing in patients who have survived the effects of anterior myocardial infarction with complete heart block and have returned to sinus rhythm but who are left with impairment of intraventricular conduction. We have reviewed 52 patients with complete heart block complicating recent anterior myocardial infarction. Temporary pacing was instituted in all patients. There were 25 hospital survivors who were followed for an average of 49 months. Long-term pacing was established in 4 patients. Of the 21 patients in sinus rhythm, 14 had partial bilateral bundle-branch block with either right bundle-branch block and left anterior hemiblock or right bundle-branch block and left posterior hemiblock; at the end of the follow-up period, 10 of these 14 were alive and well. Furthermore, permanent pacing failed to prevent sudden death in 2 patients. At the present time, therefore, we conclude that long-term pacing is not justified in patients, otherwise asymptomatic, with partial bilateral bundle-branch block persisting after transient complete heart block in anterior myocardial infarction.     

Detection of late arrhythmia and conduction disturbance after correction of tetralogy of Fallot.

The electrocardiographic conduction disturbances were evaluated retrospectively, in relation to prognosis, in 196 patients who underwent correction of tetralogy of Fallot. The follow-up was one to 20 years (mean 10). After surgery complete right bundle-branch block occurred in 187 patients (95%), right bundle-branch block and left axis deviation in 17 patients (9%), and progressive conduction defects, either left axis deviation or right bundle-branch block, developed during follow-up in 21 patients (11%). Nine patients (4.6%) died suddenly and two patients developed complete heart block late after the operation. Though late sudden death or complete heart block occurred in 19 per cent of patients with progressive conduction defects as opposed to 4 per cent of the group with stable conduction defects, the difference was not significant. Twenty-four hour ambulatory electrocardiographic monitoring was performed in 74 patients; 41 per cent had significant (Lown grade 2, 3, or 4) ventricular arrhythmias. The incidence of ventricular arrhythmia in the group with progressive conduction defects (80%) was significantly higher than in the group with stable conduction defects (30%). As occult arrhythmia may be the cause of sudden death, it is important to identify these patients.     

Prognostic Factors in Right Bundle-Branch Block Complicating Acute Myocardial Infarction

Summary: Seventy patients with right bundle-branch block (RBBB), comprising 6% of 1083 patients with acute myocardial infarction, were admitted to our coronary care unit (CCU) over a five-year period. Thirty-eight of them died in hospital. Their prognosis was not altered significantly by the presence of complete heart block (CHB), bilateral bundle-branch block or the site of infarction and serum enzyme levels. Hospital mortality was lower ( p <0.015) among eight patients with transient RBBB of whom one died. The high mortality appeared to be due mainly to extensive infarction.
All 32 survivors were followed from two to 50 months and 15 have died. Four patients who had had bilateral bundle-branch block or CHB died suddenly. Although no sudden deaths occurred in those with RBBB alone the mortality at six, 12 and 18 months did not differ significantly from patients with bilateral bundle-branch block.
Of the 17 patients still alive eleven have persistent RBBB, one has bilateral bundle-branch block, one has required permanent pacing for Stokes-Adams attacks and four have a QRS complex of normal duration.
The late sudden deaths suggest that permanent pacing may have a place in the management of patients with bilateral bundle-branch block surviving infarction.     

Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation.     

Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation.     

The incidence, clinical characteristics and prognostic significance of a left bundle-branch block associated with an acute myocardial infarct

To assess the current incidence and meaning of left bundle-branch block associated with acute myocardial infarction we studied 1,239 patients consecutively admitted in three hospitals. Left bundle branch block was present in 42 cases (3.3%). Compared to the patients without left bundle-branch block, those with left bundle-branch block were older (70 +/- 8.8 versus 63.9 +/- 11.4 years; p < 0.001), and had a more prevalent history of diabetes, angina, myocardial infarction and heart failure. Left bundle-branch block was associated more frequently with female gender and poor left ventricular ejection fraction. Patients with left bundle branch block were admitted with a longer interval from the onset of the symptoms (7.8 +/- 6.3 versus 5.4 +/- 6.7 hours; p < 0.01) and received in a lesser rate thrombolytics agents (21% versus 56%; p < 0.001), than those without left bundle-branch block. Complications significatively associated with left bundle-branch block were: complete AV block; heart failure and one-year mortality (40.4% versus 19.5%, p < 0.01). Female gender, age and heart failure were independent predictors of mortality whereas left bundle-branch block was not. In conclusion, current incidence of left bundle-branch block in acute myocardial infarction is lower than that referred in the pre-thrombolytic era. Left bundle-branch block is accompanied by a low rate of thrombolysis, whereas a higher mortality rate of these patients seems to depend on their clinical characteristics.     

The relative risk of spontaneous complete atrioventricular block in elderly patients with impaired intra-ventricular conduction.

We reviewed 144 consecutive patients with symptomatic high grade atrioventricular block. Cases due to congenital heart disease, acute myocardial infarction, cardiac surgery or digitalis toxicity were excluded. Of the remaining, we chose 71 patients in whom atrioventricular conduction was observed either intermittently during complete heart block (CHB) or in electrocardiograms taken within two years prior to documentation of CHB. The mean age was 69 years, with the peak incidence in the seventh decade in 43 men and eight decade in 28 women. Bundle branch block (BBB) was present in 76% of patients as follows: 47% had right BBB (20% with normal QRS axis, 20% with left axis deviation and 7% with right axis deviation), 17% had left BBB (11% with normal QRS axis and 6% with left axis deviation) and 12% had either alternating BBB, right BBB with alternating axis deviation or atypical BBB. "Trifascicular block" patterns accounted for 21% of the total group of CHB. We also studied the prevalence of various patterns of BBB in a group of 2000 random hospital patients of comparable age and sex exclusive of those with acute myocardial infarction and heart surgery. The risk of CHB for the various patterns of BBB was calculated relative to normal intraventricular conduction. All patterns of BBB carried a considerably increased relative risk of CHB, (P smaller than .01). The relative risk was highest for RBBB with left axis deviation and lowest for LBBB with normal or left axis deviation. In the men, 74% had QRS patterns of "bifascicular" or "trifascicular" block during atrioventricular conduction. By contrast, 71% women had atrioventricular beats showing either no BBB or right BBB with normal QRS axis. QRS pattern during CHB was unchanged from that during atrioventricular conduction in 52% if cases (rabge 38%-76% with different QRS patterns) suggesting idiojunctional pacemaker. CHB in these cases was thought to be due probably to coexistent disease in the AV node or His bundle. Although the concept of uni-, bi- and trifascicular block patterns has been useful in identifying patients at greater risk of CHB, the predictability of the electrocardiogram has obvious limitations, particularly in women.     

His bundle recordings in right bundle-branch block coexisting with iatrogenic right ventricular pre-excitation

Iatrogenic right ventricular pre-excitation failed to abolish right bundle-branch block in two patients. When `exclusive' His bundle pacing was performed, the QRS complexes, St-V, and St-LVE intervals were similar to the ventricular deflections, H-V, and V-LVE (intervals) recorded during sinus rhythm. `Exclusive' pacing of the ordinary muscle at the right ventricular inflow tract produced a complete left bundle-branch block pattern without abnormal left axis deviation. Pacing of both His bundle and ordinary muscle yielded combination complexes in which the right bundle-branch block pattern persisted.     

Sudden death after operative repair of tetralogy of Fallot.

The clinical and necropsy findings in 3 patients with tetralogy of Fallot who died suddenly after corrective operation are presented. Early postoperative electrocardiograms of 2 patients showed coexistent right bundle-branch block and left anterior hemiblock; one of these developed complete atrioventricular block and required a pacemaker. In the third a pacemaker. In the third patient, postoperative electrocardiograms showed anterior myocardial infarction. At necropsy, there was gross and histological evidence of myocardial infarction in each patient. After operation, extensive myocardial fibrosis and the development of right bundle-branch block and left anterior hemiblock are possible factors causing cardiac arrhythmias and sudden death.     

Sudden death after operative repair of tetralogy of Fallot

The clinical and necropsy findings in 3 patients with tetralogy of Fallot who died suddenly after corrective operation are presented. Early postoperative electrocardiograms of 2 patients showed coexistent right bundle-branch block and left anterior hemiblock; one of these developed complete atrioventricular block and required a pacemaker. In the third a pacemaker. In the third patient, postoperative electrocardiograms showed anterior myocardial infarction. At necropsy, there was gross and histological evidence of myocardial infarction in each patient. After operation, extensive myocardial fibrosis and the development of right bundle-branch block and left anterior hemiblock are possible factors causing cardiac arrhythmias and sudden death.     

Vectorcardiographic study of QRS loop in patients with left superior axis deviation and right bundle-branch block

Thirty-four elderly patients with right bundle-branch block and left axis deviation were studied vectorcardiographically utilizing the McFee-Parungao system. Atherosclerosis, arterial hypertension, angina pectoris, cardiac enlargement, and heart failure were common clinical features in this series. Moreover, intermittent advanced degree of atrioventricular block was present in 10 out of the 34 patients.     

Ventricular tachycardia of right bundle-branch block--left axis deviation morphology and organic heart disease.

Most series of patients with ventricular tachycardia (VT) of right bundle-branch block (RBBB)-left axis deviation (LAD) morphology include young individuals with no overt evidence of structural heart disease. In the present report, the clinical and electrophysiologic findings in two patients with verapamil-responsive VT and organic heart disease are described.     

Vectorcardiographic study of QRS loop in patients with left superior axis deviation and right bundle-branch block

Thirty-four elderly patients with right bundle-branch block and left axis deviation were studied vectorcardiographically utilizing the McFee-Parungao system. Atherosclerosis, arterial hypertension, angina pectoris, cardiac enlargement, and heart failure were common clinical features in this series. Moreover, intermittent advanced degree of atrioventricular block was present in 10 out of the 34 patients.The vectorcardiograms might be readily classified into two basic patterns, types A and B. In type A (19 cases), the frontal plane loop was open-faced. The initial vectors were directed anteriorly, inferiorly, and to the right. The mid-temporal vectors were located in the left postero-superior octant, and the late portion of the loop was inscribed anteriorly to the right with conspicuous conduction delay. Those vectorcardiographic features associate the characteristic patterns of left superior intraventricular block with complete right bundle-branch block.The type B vectorcardiograms (15 cases) demonstrated anterior clockwise loops in the horizontal plane and superior counterclockwise loops in the frontal plane. From a review of the published reports and from personal data, the authors assume that both vectorcardiographic patterns may result from an abnormal spread of excitation resulting from bilateral branch conduction disturbances.     

The effect of position of the heart on the electrocardiogram: I. The electrocardiogram in revived perfused human hearts in normal position

Eight cases of revived human heart in which a reasonably normal type of electrocardiographic curve was obtained have been studied with regard to both the localization of extrasystoles and bundle-branch block.With the heart in normal position it is found that the extrasystoles were similar to those described by Barker, Macleod and Alexander.The right and left bundles were cut in five instances, and the results indicate with the heart in normal position that a lesion of the right bundle is characterized by a deflection that is downward in Lead I and upward in Lead III.When the left bundle was cut with the heart in normal position or with left axis deviation, the electrocardiographic curve was characterized by an upward deflection of the complex in Lead I and a downward deflection in Lead III.Changes in position of the heart greatly modify the character of the curves of both extrasystoles and bundle-branch block.Shifting of the human heart to the left in one instance gave a right axis deviation (old terminology); shifting of it to the right gave a left axis deviation. Rotation of the heart also causes variation in the electrical axis.     

Left bundle-branch block with right axis deviation—a unique aberrancy during supraventricular tachycardia

A tachycardia with left bundle-branch block morphology and right axis deviation points to the diagnosis of ventricular tachycardia. Conversely, any supraventricular tachycardia with left bundle-branch block is typically associated with a normal or leftward QRS axis. We present the case of a 34-year-old man showing atrioventricular nodal reentrant tachycardia with left bundle-branch block/right axis deviation as an exception to this rule.     

A clinicopathological study on the electrical axis of the heart in 1,000 autopsy cases.

The electrical axis of the heart in 1,000 aged people more than 56 years of age was classified as normal axis in 58%, left axis deviation in 17.4%, mild left axis devaition in 21.9%, and right axis deviation in 2.7%. Pathological examination disclosed that left axis deviation was associated with myocardial infarction in 20%, right bundle branch block in 16%, but showed no significant relationships with coronary sclerosis, myocardial fibrosis and cardiac hypertrophy. Right axis deviation was associated with right bundle branch block in 66.7% and right ventricular hypertrophy in 22.2%     

Electrophysiological factors of left bundle-branch block.

Left bundle-branch block is rarely an isolated disorder of conduction, additional disorders being found in 29 of 30 patients studied by intracardiac stimulation techniques. These included disorders of sinus node function (prolonged maximum sinus node recovery time (corrected) in 23%, prolonged sinuatrial conduction time in three of eight patients), atrioventricular node function (prolonged AH interval in 33%, prolonged effective and functional refractory periods in 37% and 74%, respectively), "His bundle to right bundle branch" conduction (prolonged HV interval in 53%), and ventriculoatrial conduction (absent in 62%). It is postulated that at least half of the cases of left bundle-branch block were incomplete, even though the duration of the QRS complex exceeded 120 ms, because of (further) leftward deviation of the mean frontal QRS axis with sufficiently premature atrial extrastimuli. Block may be complete or incomplete in left bundle-branch block with left axis deviation of -30 degrees or more on the standard electrocardiogram.     

Four cases of right-sided bundle-branch block and one case of atrioventricular block in three generations of a family

Four cases of complete right bundle-branch block and one case of atrioventricular heart block, all occurring within three generations of the same family, are described. The 4 patients with bundle-branch block had no symptoms, whereas the patient with atrioventricular heart block suffered Adams-Stokes attacks from the age of 13 and died at 47 years of age. A 33-year-old man with bundle-branch block had a normal electrocardiogram at the age of 7, suggesting that inherited bundle-branch block does not necessarily manifest itself during the first years of life.     

Electrocardiographic Predictors of Mortality in Acute Anterior Wall Myocardial Infarction With Right Bundle Branch Block and Right Precordial Q-Waves (qRBBB)

BackgroundPublished data on the clinical, electrocardiographic, and angiographic profile of acute anterior-wall ST-elevation myocardial infarction (STEMI) with right bundle branch block with q in leads V1, V2 (qRBBB) are scarce. The aim of this study was to estimate the incidence of short-term mortality and in-hospital complications in acute qRBBB STEMI and identify the electrocardiographic (ECG) predictors of a poor outcome.MethodsWe conducted a single-centre retrospective study among the patients with acute anterior-wall STEMI and qRBBB pattern on ECG. All relevant clinical and treatment data were collected from the electronic medical records. All the ECGs taken during the index hospitalization were subjected to detailed analysis.ResultsAmong the 272 qRBBB patients included in the study, 64% had thrombolysis in myocardial infarction (TIMI) risk score of ≥6, and 41% were in Killip class III or IV at the time of presentation. The in-hospital mortality rate was 42.6%. There was a high incidence of ventricular tachyarrhythmias (12%), complete heart block (13%), heart failure (69%), and cardiogenic shock (52%). Extreme deviation of mean QRS axis to the right (180 to 269 degrees) in the baseline ECG was associated with high in-hospital mortality (odds ratio: 13.43; 95% confidence interval: 1.48-122.03; P = 0.021).ConclusionsAcute qRBBB myocardial infarction is a sinister form of acute coronary syndrome that entails high in-hospital mortality and morbidity, necessitating early recognition and prompt institution of reperfusion therapy. Extreme deviation of QRS axis to the right (180 to 269 degrees) is a significant electrocardiographic predictor of in-hospital mortality.