Natural history of combined right bundle branch block and left anterior hemiblock (bilateral bundle branch block)

One hundred fifteen patients with combined right bundle branch block (RBBB) and left anterior hemiblock (LAH) were separated into two groups depending upon whether RBBB and LAH was associated with acute myocardial infarction (group I, 32 patients) or was a chance electrocardiographic finding (group II, 83 patients).In 10 patients in group I complete heart block developed and in six patients high grade second degree atrioventricular (A-V) block developed. The incidence of serious arrhythmia was twice and mortality was three times the average for the coronary care unit (CCU).The majority of patients in group II had clinical evidence of advanced myocardial disease as manifested by congestive heart failure, healed myocardial infarction and left ventricular dyskinesia. During a cumulative observation period of 262 patient years, complete heart block developed in only two patients, whereas second-degree A-V block of sufficiently high degree to necessitate permanent cardiac pacing developed in three patients.It is concluded that (1) combined RBBB and LAH usually reflects advanced myocardial disease, (2) the clinical course is determined more by the myocardial disease than by the conduction disorder, (3) prophylactic cardiac pacing is not warranted in chronic RBBB and LAH, and (4) cardiac pacing has little impact on mortality when RBBB and LAH are associated with acute myocardial infarction.     

The significance of bundle branch block during acute myocardial infarction.

Analysis of the course of 71 patients with acute myocardial infarction complicated by bundle branch block (BBB) confirms a high incidence of atrioventricular (A-V) block (42 per cent) and severe pump failure (35 per cent) in these patients. Hospital mortality was not correlated with BBB per se, but rather with the associated development of second or third degree A-V block (57 per cent with A-V block vs. 12 per cent without A-V block; p less than .0005) or severe pump failure (35 per cent with vs. 11 per cent without severe pump failure; p less than .001). However, late mortality was high and not significantly different among those surviving hospitalization whether transient A-V block was present or absent. Eight of 11 late deaths were sudden. Temporary pacing could not be shown to alter hospital survival statistically, but made the onset of complete heart block a hemodynamically smooth and clinically undetectable event in several patients who later survived. The place of permanent pacing in these patients cannot be clearly determined on the basis of this study or in the available literature. More data obtained either by pooling the experience of several centers or from a prospective randomized study are needed to determine the indications for permanent pacemakers.     

Bundle branch block in acute myocardial infarction

The management of patients with acute myocardial infarction complicated by bundle branch block is a significant clinical problem and represents 8% to 13% of patients with acute infarction. This study reviews the records of 606 patients with myocardial infarction admitted to our coronary care unit. Forty-seven (8%) had complete bundle branch block. The risk of developing high-degree AV block in these 47 patients was reviewed. There are no established therapeutic guidelines for patients with pre-existing bundle branch block and left bundle branch block in acute myocardial infarction. We found a high risk of progression in patients with pre-existing bifascicular block in the presence of anterior wall infarction (25%) as well as in patients with left bundle branch block with acute anterior wall infarction (100%). On the basis of our data and careful review of the literature, we recommend prophylactic pacemaker insertion in these high-risk groups.     

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.     

Bundle-branch block in middle-aged men: risk of complications and death over 28 years. The Primary Prevention Study in G?teborg, Sweden.

AIMS: To investigate the long-term fate of men with bundle-branch block (BBB) from a general population sample. METHODS AND RESULTS: Data were derived from 7392 men without a history of myocardial infarction or stroke, born between 1915 and 1925 and investigated between 1970 and 1973. All participants were followed from the date of their baseline examination until 1998. We identified 70 men with right-BBB and 46 men with left-BBB at baseline. In men with right-BBB, there was no increased risk of myocardial infarction, coronary death, heart failure, or all-cause mortality during follow-up. The multiple-adjusted hazard ratio for progression to high-degree atrioventricular block was 3.64 (99% confidence interval 0.79-16.72). In men with left-BBB, the hazard ratio for high-degree atrioventricular block was 12.89 (4.13-40.24). However, hazard ratio for all-cause mortality was 1.85 (1.15-2.97) when compared with men without BBB, mostly due to outside hospital coronary deaths, whose hazard ratio was 4.22 (1.90-9.34). CONCLUSION: The presence of BBB was strongly associated with future high-degree atrioventricular block that was more pronounced for left-BBB. Men with left-BBB have a substantially increased risk of coronary death, mainly due to sudden death outside the hospital setting.     

心电图J／R比值对下壁心肌梗死并发房室阻滞的预测价值

目的探讨急性下壁心肌梗死早期心电图表现对高度房室阻滞的预测价值以及与冠状动脉病变的关系。方法分析97例急性下壁心肌梗死患者早期心电图（下壁导联）J／R≥0．5的发生情况，部分病例结合冠脉造影结果，探讨其对房室阻滞的预测价值。结果27例（21．6％）在心肌梗死急性期发生二度以上房室阻滞。有房室阻滞者，心电图下壁导联J／R≥0．5多于无房室阻滞者（69．56％vs30．44％，p〈0．01）。冠状动脉造影显示，有房室阻滞者，右冠状动脉近中段的高度狭窄明显多于无房室阻滞者（100％vs58．33％）。结论急性下壁心肌梗死伴房室阻滞者的病损冠脉以右冠状动脉多见，下壁导联心电图J／R≥0．5对下壁心肌梗死合并房室阻滞的发生有一定的预测价值。     

Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His‐bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra‐Hisian left bundle branch (LBB) or distal His‐bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high‐grade atrioventricular (AV) block and RBBB pattern.     

Permanent pacing in patients with transient trifascicular block during acute myocardial infarction

Patients with acute myocardial infarction and transient complete atrioventricular (A-V) block in association with right bundle branch block and left anterior hemiblock have a high incidence rate of late sudden death presumably due to recurrent A-V block. Over a 5 year period, 18 patients demonstrated right bundle branch block and left anterior hemiblock and had transient complete block during an acute myocardial infarction and survived to hospital discharge. Of six patients who did not have permanent pacing, five died suddenly (one was lost to follow-up) with a mean survival time of 2.4 months after hospital discharge. Twelve subsequent patients received permanent demand pacemakers and had a significantly improved prognosis with a mean survival time of 18 months (P < 0.001). Six patients were still alive at an average follow-up time of 20 months. Prophylactic permanent pacing significantly improves the prognosis after acute myocardial infarction in this select subgroup of patients.     

Prognostic Factors in Atrioventricular Block Complicating Acute Myocardial Infarction

Summary: Atrioventricular block (A-V block) was documented in 150 (13.8%) of 1083 patients with acute myocardial infarction. Those with A-V block differed significantly from the remainder, being older, having higher peak levels of serum lactic dehydrogenase and a greater incidence of left ventricular failure and of death in hospital.
These differences were due mainly to the inclusion of 90 patients with complete heart block (CHB). Among those patients whose CHB complicated anterior infarction there was a significantly greater incidence of previous infarction.
Lesser grades of A-V block and right bundle branch block (RBBB) commonly heralded the onset of CHB, which occurred more frequently in those with inferior infarction.
Markers of death in those with CHB were anterior infarction, RBBB, and a slow subsidiary pacemaker with a wide ventricular complex. Pacing is recommended for all patients with CHB and for those with RBBB; the reasons for this are presented in detail.     

Significance of first degree heart block (prolonged P--R interval) in bifascicular block

To test the hypothesis that first degree heart block in the presence of a QRS pattern of bifascicular block is related to conduction delay in the remaining fasclcle, we reviewed the His bundle records of 63 patients with a pattern of bifascicular block and compared the H-V intervals of the 41 patients without first degree heart block with those of the 22 patients with P-R prolongation. The following conclusions were drawn from analysis of our cases and those studied and reported by others: (1) In the presence of first degree heart block a significant number of these patients will have a normal H-V interval. (2) More than 50 percent of patients with a pattern of left or right bundle branch block and right axis deviation have a prolonged H-V interval regardless of the P-R interval, and the correlation of P-R and H-V prolongation is not statistically significant (P > 0.05 and < 0.1). (3) In patients with a pattern of right bundle branch block and left axis deviation, the presence of P-R prolongation suggests abnormality of the H-V interval (P < 0.005), although 30 percent of the patients with this finding will have a normal H-V interval and the H-V interval cannot be predicted in individual patients. (4) His bundle electrography is essential to determine accurately the presence of trifascicular block in individual patients whether the P-R interval is normal or prolonged.     

Right ventricular apical activation times in patients with conduction disturbances occurring during acute transmural myocardial infarction.

His bundle and right ventricular apical electrograms were recorded in 18 patients with acute transmural myocardial infarction in whom catheter insertion was considered necessary for clinical reasons. The V-RVA and H-V intervals were of normal duration (5 to 30 and 35 to 55 msec, respectively) in five patients (Group 1) with persistently narrow (less than 100 msec) QRS complexes. In contrast, 13 patients (Group 2) who manifested a "complete" right bundle branch block pattern within 96 hours after admission had prolonged V-RVA intervals (range 50 to 80 msec, mean 59.2 msec) and H-V intervals that were at the upper limits of normal or prolonged (range 55 to 90 msec, mean 63 msec). In 6 of these 13 patients, the duration of the V-RVA interval became normal when the "complete" right bundle branch block pattern disappeared and was replaced by a "complete" left bundle branch block pattern in three patients and by narrow QRS complexes in the three other patients. This study showed that transmural myocardial infarction in itself did not increase the duration of the V-RVA interval even when "complete" left bundle branch block was present. Moreover, a prolonged V-RVA interval coexsting with a "complete" right bundle branch block pattern was not due to distal right bundle branch block but resulted from a conduction disturbance located in the proximal portions of the right bundle, or perhaps, even within the His bundle itself.     

Bradyarrhythmias, abnormalities of conduction, and indications for pacing in acute myocardial infarction

Bradyarrhythmias and conduction disturbances are not infrequently observed in association with acute MI. The sinus node artery is supplied by the right coronary circulation only slightly more often than the left. As a result of concomitant vagotonia, however, sinus node dysfunction is more common with inferior infarction. This influence, as well as a predominantly right-sided circulation, also makes AV nodal block more frequent with such infarctions. Bradyarrhythmias due to sinus or AV nodal dysfunction often require only observation. If symptomatic, they are usually responsive to vagolytic or chronotropic drugs, but may necessitate pacemaker therapy often only on a temporary basis. The distal conduction system including the bundle branches is supplied mainly, but not exclusively, by the left anterior descending artery. Thus, acute bundle branch block is often associated with anterior MI. The indications for both temporary and permanent prophylactic pacing in this situation remain controversial. Several authors have made recommendations based on risk stratification. We would temporarily pace patients with anterior or indeterminate infarctions and new right or left bundle branch block, and probably those with bilateral bundle branch block of indeterminate age. All patients with new bilateral or alternating bundle branch block should be paced, regardless of infarct site. Permanent prophylactic pacing would appear indicated in patients exhibiting alternating bundle branch block or perhaps new right bundle branch block and left posterior hemiblock. In contrast to this group, the treatment of patients who develop sudden complete heart block, whether transient or permanent, is clear-cut. These patients require continuous (temporary followed without interruption by permanent) pacemaker therapy (Table 3).     

Significance of isolated H-V interval prolongation in symptomatic patients without documented heart block

Paced and unpaced control groups were followed to establish the roles of pacers and infranodal (H-V) conduction in 59 patients with symptoms consistent with intermittent heart block (HB). To reduce the number of variables compared with previous studies, patients were included only when (1) prior ECG monitoring and medical-neurologic evaluation failed to document HB or other cause for symptoms; (2) His bundle studies were normal or showed only H-V prolongation, and (3) there was no history of a recent myocardial infarction. Of 35 patients with prolonged H-V interval, 18 received permanent pacers, while 17 remained unpaced. Eighteen unpaced patients constituted the normal H-V Group (after two were lost to follow-up and four received pacers). All groups were similar in types of heart diseases, NYHA classification, general medical condition, age and sex, thus providing adequate controls.All patients with normal H-V intervals remained stable (no deaths or progression to HB) for a mean follow-up period of 22 months. Among 18 patients with prolonged H-V intervals who received pacers, there were three deaths, none sudden, during a mean of 23 months; four patients developed HB unaccompanied by symptoms. Among 17 patients with prolonged H-V intervals who were not paced, eight died (three suddenly) and three progressed to HB with symptoms, leaving only six stable after six months follow-up. All these parameters were significantly worse in the unpaced patients with prolonged H-V intervals.These results suggest that patients with intermittent symptoms consistent with heart block, whose H-V interval is ≥ 60 msec. should receive a permanent pacer even if intermittent HB cannot be documented before implant.     

The Prognostic Value of the HV Interval in Patients with Acute Myocardial Infarction and Bundle Branch Block

Summary: HV intervals were measured in 42 of 119 patients in the acute phase of myocardial infarction associated with bundle branch block (BBB). The mean HV intervals of patients with right, left and incomplete bilateral BBB were similar. The hospital and subsequent mortality of patients with prolonged HV intervals did not differ significantly from that of patients with normal HV intervals. The HV interval appeared to remain stable over the following months in most patients in whom it was re-measured. We conclude that the HV interval cannot be used to select patients who might benefit from prophylactic long term pacing.     

The Prognostic Value of the HV Interval in Patients with Acute Myocardial Infarction and Bundle Branch Block

Summary: HV intervals were measured in 42 of 119 patients in the acute phase of myocardial infarction associated with bundle branch block (BBB). The mean HV intervals of patients with right, left and incomplete bilateral BBB were similar. The hospital and subsequent mortality of patients with prolonged HV intervals did not differ significantly from that of patients with normal HV intervals. The HV interval appeared to remain stable over the following months in most patients in whom it was re-measured. We conclude that the HV interval cannot be used to select patients who might benefit from prophylactic long term pacing.     

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.     

Intermittent bundle branch blocks in a patient with uncommon-type atrioventricular nodal reentrant tachycardia and enhanced atrioventricular nodal conduction

We report on a patient with uncommon-type atrioventricular (AV) nodal reentrant tachycardia with a short tachycardia cycle length (235-270 ms), in whom transient wide QRS tachycardia with both left bundle branch block and right bundle branch block aberrancy were followed by narrow QRS complexes. In addition, His-ventricular (H-V) block and a sudden prolongation of the H-V interval occurred during the tachycardia. As the determinant of these unusual findings, the possibility that the anterograde limb of the reentry circuit has an enhanced AV nodal conduction property is discussed, as is the clinical significance of this type of tachycardia.     

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.     

Anterograde and retrograde bradycardiac block in the His-Purkinje system. Finding in a patient with acute myocardial infarction

A patient with an acute inferior myocardial infarction developed a complete atrioventricular block and intermitent periods of atrioventricular conduction with QRS complexes showing right bundle branch block associated with left anterior hemiblock. Recordings of the His bundle electrogram showed that the atrioventricular block was infrahisian and that in periods of resumed atrioventricular conduction, the His-ventricle (H-V) interval was long. Ventricular escape beats showed concealed conduction to the atrioventricular node. Anterograde atrioventricular conduction was always resumed through the left posterior division when the preceding division when the preceding intervals between ventricular escape beats and the atrium (V-A intervals) were shorter than 580 msec. The same phenomenon occurred with right ventricular pacing. A retrograde His potential could be observed. Retrograde conduction of ventricular escape beats and ventricular paced beats was blocked if the H-V interval and the interval between the His bundle and the ventricular paced beat (H-V interval) were long (more than 600 msec and 550 msec, respectively). The existence of an intermittent anterograde and retrograde bradycardiac infrahisian block was inferred from the previously mentioned data; a fixed retrograde atrial nodal block was also present.     

Effect of bundle branch block patterns on mortality in hospitalized patients with heart failure

A widened QRS interval is associated with increased mortality in patients with heart failure (HF). However, the prognostic significance of the type of bundle branch block (BBB) pattern in these patients is unclear. The data of 4,102 patients with HF hospitalized during a prospective national survey were analyzed to investigate the association between BBB type and 1-year mortality in 3,737 patients without pacemakers. Right BBB (RBBB) was present in 381 patients (10.2%) and left BBB (LBBB) in 504 patients (13.5%). RBBB and LBBB were associated with increased 1-year mortality on univariate analysis (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.15 to 1.81, and OR 1.20, 95% CI 0.97 to 1.47, respectively). In patients with systolic HF, after adjusting for multiple risk factors, only RBBB was found to be an independent predictor of mortality (RBBB vs no BBB OR 1.62, 95% CI 1.12 to 2.33, and RBBB vs LBBB OR 1.71, 95% CI 1.09 to 2.69). This correlation was stronger in patients with lower left ventricular ejection fractions and was also maintained in patients without acute myocardial infarctions. Analyzing the data for all patients with HF, there was a trend for increased mortality in the RBBB group only (adjusted OR 1.21, 95% CI 0.94 to 1.56). LBBB was not related to mortality in patients with either systolic HF or preserved ejection fractions. In conclusion, RBBB rather than LBBB is an independent predictor of mortality in hospitalized patients with systolic HF. This prognostic marker could be used for risk stratification and the selection of treatment.