Right Bundle Branch Block Patients Research Articles

Right Ventricular Outflow Septal Pacing as Cardiac Resynchronization Therapy in Patients with Right Bundle Branch Block – Results in 50 Patients

Background: Cardiac resynchronization therapy has been shown to improve left ventricular performance in patients with left ventricular dysfunction and a left-sided interventricular conduction delay. This is performed by placing a pacing lead on the lateral left ventricular wall to stimulate the area normally stimulated by the left bundle branch. In patients with right bundle branch block (RBBB), pacing the right bundle branch could also result in resynchronization. Previous studies have shown that right ventricular outflow septal (RVOS) pacing does, in fact, utilize the native conduction system. Methods: 53 consecutive patients, 42 male/11 female, aged 75 ± 10.8 yr, with RBBB and indications for pacing underwent RVOS lead placement using commercially available pacing systems. The patients subsequently underwent bedside A-V optimization to achieve the narrowest QRS duration and most “normal” QRS complex. Echocardiography was performed to evaluate changes in wall motion comparing baseline with optimal pacing. Results:Baseline mean QRS duration 145 ± 18.1 msOptimized mean QRS duration 110 ± 20.7 msAverage Optimal AV Delay 205 ± 45.9 msAverage decrease in QRS duration 34 ± 21.4 msp < 0.001Echocardiography demonstrated improvement in septal contraction abnormalities.Conclusions: 1) RVOS pacing in RBBB patients can significantly narrow the QRS complex on ECG. 2) Septal contraction abnormalities due to RBBB can be improved with RVOS pacing and optimal A-V timing. 3) Further studies are warranted to evaluate this therapy in a heart failure population.

Incidence and clinical impact of right bundle branch block in patients with acute myocardial infarction: ST elevation myocardial infarction versus non-ST elevation myocardial infarction

Both left bundle branch block and right bundle branch block (RBBB) have been associated with increased inhospital and long-term mortality in patients with acute ST elevation myocardial infarction (STEMI). However, the prognostic role of RBBB in acute non-ST elevation myocardial infarction (NSTEMI) is not well known. Therefore, the aim of the study was to evaluate the incidence and clinical impact of RBBB in patients with NSTEMI compared to patients with STEMI. From the German prospective multicenter registry "Maximal Individual Therapy of Acute Myocardial Infarction" (MITRA PLUS), 6,403 consecutive patients with NSTEMI and 20,233 patients with STEMI were analyzed. Patients with left bundle branch block were excluded. The median follow-up time for NSTEMI was 378 days and for STEMI 479 days. A total of 455 (7.1%) patients with NSTEMI and 894 (4.4%) patients with STEMI presented with RBBB on admission. In general, RBBB patients were older, more often had comorbidities, and less often received short-term inhospital treatment according to guidelines. In STEMI, RBBB patients had higher peak enzyme levels and lower left ventricular ejection fraction (LV-EF) than patients without BBB. Right bundle branch block in STEMI was associated with an increased inhospital and long-term mortality. In NSTEMI, however, peak enzyme levels and LV-EF were similar in both groups with and without RBBB. Right bundle branch block in NSTEMI was not independently associated with a worse outcome. Unlike RBBB in STEMI, RBBB in NSTEMI is not an independent predictor of inhospital and long-term mortality.

Magnetic Dispersion of the Late Repolarization in Brugada Syndrome

Magnetocardiography (MCG) is a new noninvasive modality for recording cardiac depolarization and repolarization and was used in the present study to evaluate abnormalities in patients with Brugada syndrome (BS). The MCG findings of 10 BS, 21 right bundle branch block (RBBB), and 34 normal patients were compared. On the horizontal spatiotemporal activation graph (STAG), the r' waves were more frequently located on the right side in the RBBB than in the normal (p=0.001) or BS groups (p=0.001). The maximum current angles of the r' wave fell into the northwest axis in all BS patients as compared to having a right axis deviation in 19 of 21 RBBB patients (90.4%, p=0.001). In the magnetic field and current density vector maps during late repolarization, the BS group had a non-dipole pattern more frequently and a higher number of poles compared with the normal (p=0.001) and RBBB groups (p=0.001). During depolarization, the horizontal STAG location and maximum current angle of the r' wave were beneficial in differentiating BS from RBBB and normal. The magnetic dispersion was a more frequently observed finding in BS patients than in RBBB and normal patients during late repolarization.

Left ventricular electromechanical delay in patients with heart failure and normal QRS duration and in patients with right and left bundle branch block

We sought to define the reference values of intra-left ventricular (LV) electromechanical delay (EMD), and to assess the prevalence (and pattern) of intra-LV dyssynchrony in patients with heart failure (HF) and normal QRS and in patients with right and left bundle branch block. We used tissue Doppler imaging echocardiography and a six-LV wall model to study LV EMD in 103 patients [41 with HF and normal QRS, 22 with right bundle branch block (RBBB), and 40 with left bundle branch block (LBBB)], and in 59 controls. In controls, the median intra-LV EMD was 17 ms, (inter-quartile range 13-30); 95% of controls had a value < or =41 ms. Patients showed a longer intra-LV EMD than controls: 33 ms (20-57) in patients with normal QRS, 32 ms (23-50) in RBBB patients, and 50 ms (30-94) in LBBB patients. Intra-LV dyssynchrony (defined as intra-LV EMD >41 ms) was present in 39, 36, and 60% of the patients, respectively. On average, HF patients showed the same pattern of activation as controls, from the septum to the posterior wall, but activation times were significantly prolonged. In RBBB patients the activation sequence was directed from inferior to anterior and in LBBB from anterior to inferior wall. Left ventricular dyssynchrony was present in several patients with HF and normal QRS, and in patients with RBBB; conversely, 40% of LBBB patients showed values of LV EMD within the normal range. Left ventricular activation sequence was different between groups. Assessment of LV synchronicity by means of imaging techniques may be more important than QRS duration or morphology in selecting patients for cardiac resynchronization treatment.

Electrocardiographic Characteristics of Patients with Ebstein's Anomaly Before and After Ablation of an Accessory Atrioventricular Pathway

The abnormal development of the tricuspid valve in patients with Ebstein's anomaly results in several activation abnormalities including delayed intraatrial conduction, right bundle branch block (RBBB), and ventricular preexcitation. The aim of the present study was to define the ECG characteristics before and after ablation of an accessory A-V pathway (AP) in patients with Ebstein's anomaly. A series of 226 consecutive patients with Ebstein's anomaly was studied. Sixty-four patients (28%) had documented tachycardia. Thirty-three patients with recurrent tachycardia were found to have a single right-sided AP that was successfully ablated (study group). Thirty patients without tachycardia served as the control group. Only 21 of 33 patients (62%) had a typical ECG pattern of preexcitation. In addition, none of the patients had an ECG pattern of RBBB during sinus rhythm. In contrast, 28 of 30 (93%) patients in the control group had RBBB (P < 0.001). Radiofrequency catheter ablation resulted in appearance of RBBB in 31 of 33 (94%) patients. The absence of RBBB in patients with Ebstein's anomaly and recurrent tachycardia had a 98% sensitivity and 92% specificity for the diagnosis of an AP. The positive predictive value was 91% (0.77, 0.97 CI 95%) and the negative predictive value was 98% (0.85, 0.99 CI 95%). One-third of patients with Ebstein's anomaly and symptomatic tachyarrhythmias have minimal or absent ECG features of ventricular preexcitation. In these patients, the absence of RBBB pattern is a strong predictor of an AP.

Cardiac resynchronization therapy in patients with right bundle branch block: Analysis of pooled data from the MIRACLE and Contak CD trials

Clinical trials of cardiac resynchronization therapy (CRT) have not included many patients with right bundle branch block (RBBB). We pooled data from two randomized controlled trials of CRT (Multicenter InSync Randomized Clinical Evaluation [MIRACLE] and Contak CD) in order to assess outcomes of patients with RBBB. A total of 61 patients with RBBB were identified, 34 of whom were randomized to the CRT group and 27 to the control group. The data from these patients were entered into a new database and analyzed. Baseline demographics were not different between the two groups (mean age 65.5 +/- 11.3 years vs 69.5 +/- 9.6 years; male gender 91% vs 85%; patients with coronary disease 76.5% vs 88%; QRS duration 167 ms vs 164 ms; all P = NS). Outcome variables (New York Heart Association [NYHA] class, 6-minute hall walk distance, peak oxygen consumption (VO2), Minnesota Living with Heart Failure quality-of-life scores, left ventricular ejection fraction, and norepinephrine levels) were analyzed at randomization, 3 months, and 6 months. (1) With the exception of NYHA class, patients with RBBB as the qualifying wide QRS did not derive significant benefit from CRT in any of the other parameters studied at 3 or 6 months. (2) RBBB patients who received active CRT showed significant improvements in NYHA class by 6 months and trends toward improvement in 6-minute walk distance, quality-of-life scores, and norepinephrine levels. However, control patients also showed significant improvement in NYHA class by 6 months but showed no improvement in objective measurements (VO2, 6-minute walk distance, left ventricular ejection fraction, and norepinephrine levels), consistent with a placebo effect. Analysis of a larger cohort of patients with RBBB undergoing CRT may demonstrate significant benefit, but the current analysis does not support the use of CRT in patients with RBBB.

Bundle-branch block and in-hospital mortality in acute myocardial infarction. National Registry of Myocardial Infarction 2 Investigators.

Left bundle-branch block (BBB) is considered an important predictor of poor outcome in patients with acute myocardial infarction, but the consequences of right BBB are not well understood. To 1) estimate the prevalence of left and right BBB in patients with myocardial infarction; 2) compare the clinical characteristics of and treatments received by patients with left, right, or no BBB; and 3) determine the independent association of left BBB and right BBB with in-hospital death. Retrospective cohort study. Multicenter registry of 1571 U.S. hospitals. 297,832 patients with acute myocardial infarction who had left, right, or no BBB on initial electrocardiography. Presence and type of BBB, clinical characteristics of patients, therapies given, and in-hospital death. Patients with left BBB (n = 19,967; 6.7%) or right BBB (n = 18,354; 6.2%) were older and had more comorbid illness and congestive heart failure than patients with no BBB. Among patients for whom thrombolytic therapy was clearly indicated, fewer patients with left or right BBB (16.6% and 32.0%, respectively) than patients with no BBB (66.5%) received this therapy (P < 0.001). Fewer patients with left or right BBB (60.6% and 67.3%, respectively) than patients with no BBB (75.6%) received aspirin within the first 24 hours (P < 0.001), and fewer patients with left or right BBB (23.9% and 31.8%, respectively) than patients with no BBB (40.4%) received beta-blockers within the first 24 hours (P < 0.001). Unadjusted in-hospital mortality rates were almost twice as high for patients with left or right BBB (22.6% and 23.0%, respectively) as for patients with no BBB (13.1%) (P < 0.001). Compared with no BBB and no ST-segment elevation, left BBB was associated with a 34% increase (odds ratio, 1.34 [95% CI, 1.28 to 1.39]) and right BBB was associated with a 64% increase (odds ratio, 1.64 [CI, 1.57 to 1.71]) in the risk for in-hospital death, after adjustment for potential confounders. In patients with acute myocardial infarction, prevalences of right and left BBB are similar. Patients with BBB have more comorbid conditions, are less likely to receive therapy, and have an increased risk for in-hospital death compared with patients with no BBB. Compared with left BBB, right BBB seems to be a stronger independent predictor of in-hospital death.

Incidence and prognostic significance of right bundle branch block in patients with acute myocardial infarction receiving thrombolytic therapy

We assessed the incidence and prognostic significance of right bundle branch block (RBBB) in patients with acute myocardial infarction (AMI) receiving thrombolytic therapy. A prospective, one-year follow-up study involving 681 consecutive patients treated with thrombolytic agents for AMI was performed. Seventy-four patients developed RBBB (46% new-onset, 24% old and 30% indeterminate). RBBB was more common in older patients with large anterior AMI. New-onset RBBB were often transient (56%) and 84% of them resolved within 12 h after admission. Complicating events during the hospital phase, such as ventricular arrhythmias and development of heart failure, were more frequent in patients with RBBB. In-hospital and one-year mortality were higher in patients with RBBB (22.9 and 40.5% compared to 7.9 and 12.3% respectively in patients without block, both p<0.001). New-onset, non-transient RBBB were associated with the highest mortality rates (73% at one-year follow-up). By multivariate analysis, RBBB was retained as independent predictor of in-hospital and one-year mortality. We conclude that new-onset RBBB in patients receiving thrombolytic therapy for AMI is often transient. The development of RBBB has a negative and independent prognostic impact on the survival during the hospital phase and at one-year follow-up.

Exercise testing and thallium-201 emission computed tomography in patients with intraventricular conduction disturbances

The specificity of exercise thallium-201 emission computed tomography for coronary artery disease was assessed in patients with intraventricular conduction disturbances. Eighty-seven patients were studied: 33 with right bundle branch block (RBBB), 11 with RBBB and left-axis deviation, 11 with left (L)BBB, 12 on right ventricular pacing, and 20 with Wolff-Parkinson-White (WPW) syndrome. A control group of 349 consecutive patients with normal intraventricular conduction was also examined. The specificity of diagnosis of coronary artery disease in patients with LBBB (30%), right ventricular pacing (44%) or RBBB plus leftaxis deviation (50%) was significantly lower than in patients with normal intraventricular conduction (94%; p < 0.01). In contrast, there was no significant difference between specificity in patients with RBBB (86%) or WPW syndrome (90%) and patients with normal intraventricular conduction. Perfusion defects were found in the anterior, septal and inferior segments in patients with LBBB, and in the septal and inferior segments in patients with RBBB plus left-axis deviation despite the absence of coronary stenosis. Furthermore, diffuse slow washout was seen more often in patients with WPW syndrome (35%) than in controls who had normal intraventricular conduction (11%; p < 0.05), despite a good exercise performance in the former group. This study suggests that there is an increased incidence of abnormal perfusion and clearance during exercise thallium-201 emission computed tomography in patients with intraventricular conduction disturbances.

Phase image characterization of ventricular contraction in left anterior hemiblock.

We investigated whether or not left anterior hemiblock is present in patients with left axis deviation using first-harmonic Fourier analysis of gated blood-pool images. Gated blood-pool images were taken in 50 patients without contraction abnormality. They included 14 normal subjects, 8 patients with right bundle branch block (RBBB), 20 with left axis deviation (LAD) and 8 with both RBBB and LAD (RBBB + LAD). ECG gated blood-pool scans were acquired in the anterior and "best septal" left anterior oblique projections. First, the phase images were displayed cinematically as a continuous-loop movie. Next, for quantitative analysis of the phase image, the whole left ventricular and left ventricular high lateral regions of interest were drawn. The "regional phase shift" (RPS) was then defined as (RPS = A-a) where "A" is the mean value of the whole left ventricular phase angles and "a" is that of phase angles in the high lateral region. The left ventricular phase changes and the RPSs in the RBBB and LAD groups were similar to those in the normal group. In the RBBB + LAD group, the latest phase changes occurred in the high anterolateral region. The RPSs of this group were significantly lower than those in the other 3 groups (p less than 0.01). These data suggest that left anterior hemiblock might coexist with RBBB in patients with RBBB + LAD, whereas left anterior hemiblock might not exist in the majority of patients with LAD alone.

Risk of right bundle-branch block and complete heart block during pulmonary artery catheterization.

The need for the prophylactic insertion of a pacemaker before pulmonary artery catheterization in patients with pre-existing left bundle-branch block (LBBB) is controversial. To determine the incidence of new right bundle-branch block (RBBB) and complete heart block during bedside pulmonary artery catheterization, 293 patients undergoing 307 pulmonary artery catheterizations were prospectively studied. Nine patients had pacemaker rhythms and 19 patients had an RBBB on their precatheterization ECGs and therefore were excluded from analysis. In the remaining 279 pulmonary artery catheterizations, eight (3%) were associated with the development of a new RBBB. None of the 14 patients with a pre-existing LBBB developed complete heart block. The incidence of complete heart block during pulmonary artery catheterization of patients with previous LBBB was not higher than the incidence of RBBB in patients without underlying conduction defects. Because of the rare but grave consequences of RBBB in patients with pre-existing LBBB, we recommend the use of standby external pacemakers and equipment for transvenous pacemaker insertion in these patients during pulmonary artery catheterization. We do not recommend prophylactic pacemaker insertion.

Right bundle-branch block in coronary artery disease: a hemodynamic and angiographic study.

Thirty-four patients with right bundle-branch block (RBBB) and coronary artery disease (CAD) (RBBB was not pre-existent to clinical development of CAD) and 52 consecutive CAD patients without conduction disturbances were studied and compared to verify whether the presence of RBBB implies more severe and extensive left ventricular myocardial damage as well as more severe CAD. The two groups did not differ either in age or in New York Heart Association functional class. The incidence or location of previous myocardial infarction (MI) was not different in the two groups. No significant differences were found in left ventricular volumes or ejection fraction. Higher end-diastolic left ventricular pressure and more severe and diffuse left ventricular wall asynergy were present in RBBB patients. At coronary arteriography, more severe involvement of the right coronary artery in CAD patients without conduction disturbances was the only significant finding. The group of patients with CAD and RBBB without MI showed significantly less involvement of the left anterior descending coronary artery and significantly more severe damage of the inferior wall of the left ventricle than the group with CAD without RBBB and MI. Patients with inferior wall MI and RBBB had more severe asynergy of the posterobasal region of the left ventricle than did patients with inferior wall MI without RBBB. The group of patients with anterior wall MI and RBBB had a higher left ventricular end-diastolic pressure, a lower left ventricular ejection fraction, and a greater extent of myocardial damage compared to similar patients of the control group. The groups with MI and RBBB had the same Gensini's score as similar groups without RBBB. (ABSTRACT TRUNCATED AT 250 WORDS)

Sequence and timing of ventricular wall motion in patients with bundle branch block. Assessment by radionuclide cineangiography.

We determined the sequence and timing of inward ventricular wall motion by least-square phase analysis of radionuclide cineangiograms in 10 patients with left bundle branch block (LBBB), five patients with right bundle branch block (RBBB) and 11 patients with normal conduction. All LBBB and RBBB patients had normal coronary arteries and no segmental wall motion abnormalities. The left ventricle (LV) was divided into eight segments and the right ventricle (RV) into three; sequence and timing were scored by three observers. In normal subjects, wall motion begins in either or both ventricles and ends in the LV or both ventricles. In patients with LBBB it begins in the RV and ends in the LV; in patients with RBBB is begins in the LV and ends in the RV or both ventricles. The intraventricular wall motion is also altered in the ventricle ipsilateral to a bundle branch block. In LBBB, the mean time of onset of LV wall motion is delayed 1.9 frames (38 msec), whereas RV wall motion is normal. In RBBB, the onset of RV wall motion is delayed 1.3 frames (26 msec), whereas LV wall motion is not delayed.

Avoidance of surgical right bundle branch block in ventricular septal defect.

Right bundle branch block (RBBB) has been the most frequent conduction disturbance in postoperative patients with a large ventricular septal defect. It has long been considered as an insignificant postoperative sequela. However, recent documentation of its possible deleterious effects on cardiac performance led us to modify the standard technique in an attempt to avoid the postoperative RBBB. In addition to approaching the defect through the right atriotomy, special care was taken for suture placement at the inferior margin and the antero-inferior corner of the defect of defect of perimembranous type. With this technical modification, the frequency of surgical RBBB in patients with a large perimembranous defect has decreased from 31.3 to 8.3 per cent.

Survival in Patients With Intraventricular Conduction Defects

All 42,000 electrocardiograms taken at the University of Oregon Health Sciences Center from 1969 through 1971 were reviewed; 325 patients (0.77%) had left bundle-branch block (LBBB) or right bundle-branch block (RBBB) with axis deviation (AD). In December 1974, 90% were contacted or found to be dead. The five-year survival rate (actuarial technique) (mean +/- SE) was 45.5 +/- 2.9%. It was significantly worse than that of age- and sex-matched "controls." In most patients the cause of death could not be determined. Survival of 164 LBBB patients (40.7 +/- 4.1%) at five years was not significantly worse than that of 161 RBBB and AD patients (49.5 +/- 4.2%). Those with syncope did no worse in terms of survival than did those without. The five-year survival in coronary artery disease patients was 33.7 +/- 4.4%, in those with primary conduction system disease (20% of patients), it was 50.6 +/- 6.6%. It will be necessary to know the causes of death and of syncope in conduction disease patients before it can be determined whether or not pacemakers can prevent either.

Etiology of right bundle-branch block in patients undergoing total correction of tetralogy of Fallot.

The electrocardiographic (ECG) pattern of right bundle-branch block (RBBB) occurs routinely in patients after open-heart surgery for tetralogy of Fallot (TF). To determine the etiology of the RBBB pattern, 14 patients with TF, seven with ventricular septal defects (VSD), and one with pulmonary stenosis (PS) were studied during and after cardiac surgery. Bipolar electrograms from 10 selected right ventricular epicardial sites were recorded simultaneously with an ECG. Records were obtained before and immediately after vertical right ventriculotomy, after infundibular resection, and after repair of a ventricular septal defect (VSD). The vertical ventriculotomy alone was always associated with significant prolongation of the time of epicardial activation only to the recording sites lateral to the incision with prolongation of the QRS complex by an average of 39 msec, and with the appearance of an RBBB ECG pattern. Infundibular resection and VSD repair were not associated with any changes in the electrophysiologic parameters measured. A retrospective analysis of 251 patients with TF, VSD, and PS revealed a 100% incidence of RBBB pattern in the electrocardiograms of only those who had undergone ventriculotomy. It can be concluded that the RBBB pattern seen postoperatively in patients with TF is due to changes in right ventricular activation secondary to the vertical ventriculotomy.