Presence Of Right Bundle Branch Block Research Articles

Effects of ventricular conduction block patterns on mortality in hospitalized patients with dilated cardiomyopathy: a single-center cohort study

BackgroundVentricular conduction blocks (VCBs) are associated with poor outcomes in patients with known cardiac diseases. However, the prognostic implications of VCB patterns in dilated cardiomyopathy (DCM) patients need to be evaluated. The purpose of this study was to determine all-cause mortality in patients with DCM and VCB.MethodsThis cohort study included 1119 DCM patients with a median follow-up of 34.3 (19.5–60.8) months, patients were then divided into left bundle branch block (LBBB), right bundle branch block (RBBB), intraventricular conduction delays (IVCD) and narrow QRS groups. The all-cause mortality was assessed using Kaplan-Meier survival curves and Cox regression.ResultsOf those 1119 patients, the all-cause mortality rates were highest in patients with IVCD (47.8, n = 32), intermediate in those with RBBB (32.9, n = 27) and LBBB (27.1 %, n = 60), and lowest in those with narrow QRS (19.9 %, n = 149). The all-cause mortality risk was significantly different between the VCB and narrow QRS group (log-rank χ2 = 51.564, P < 0.001). The presence of RBBB, IVCD, PASP ≥ 40 mmHg, left atrium diameter and NYHA functional class were independent predictors of all-cause mortality in DCM patients.ConclusionsOur findings indicate that RBBB and IVCD at admission,but not LBBB, were independent predictors of all-cause mortality in patients with DCM.

Heart rate recovery in asymptomatic patients with Chagas disease.

BackgroundChagas disease patients with right bundle-branch block (RBBB) have diverse clinical presentation and prognosis, depending on left ventricular (LV) function. Autonomic disorder can be an early marker of heart involvement. The heart rate recovery (HRR) after exercise may identify autonomic dysfunction, with impact on therapeutic strategies. This study was designed to assess the HRR after symptom-limited exercise testing in asymptomatic Chagas disease patients with RBBB without ventricular dysfunction compared to patients with indeterminate form of Chagas disease and healthy controls.MethodsOne hundred and forty-nine subjects divided into 3 groups were included. A control group was comprised of healthy individuals; group 1 included patients in the indeterminate form of Chagas disease; and group 2 included patients with complete RBBB with or without left anterior hemiblock, and normal ventricular systolic function. A symptom-limited exercise test was performed and heart rate (HR) response to exercise was assessed. HRR was defined as the difference between HR at peak exercise and 1 min following test termination.ResultsThere were no differences in heart-rate profile during exercise between healthy individuals and patients in indeterminate form, whereas patients with RBBB had more prevalence of chronotropic incompetence, lower exercise capacity and lower HRR compared with patients in indeterminate form and controls. A delayed decrease in the HR after exercise was found in 17 patients (15%), 9% in indeterminate form and 24% with RBBB, associated with older age, worse functional capacity, impaired chronotropic response, and ventricular arrhythmias during both exercise and recovery. By multivariable analysis, the independent predictors of a delayed decrease in the HRR were age (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.03 to 1.21; p = 0.010) and presence of RBBB (OR 3.97; 95% CI 1.05 to 15.01; p = 0.042).ConclusionsA small proportion (15%) of asymptomatic Chagas patients had attenuated HRR after exercise, being more prevalent in patients with RBBB compared with patients in indeterminate form and controls.

Left Ventricular Asynchrony in Patients with Right Bundle Branch Block and Normal Ejection Fraction

The role of right bundle branch block (RBBB) for the induction of left ventricular (LV) asynchrony is discussed controversially. The objective of this study was to assess presence and degree of LV asynchrony in patients with RBBB, left bundle branch block (LBBB), or left anterior hemiblock (LAH) and normal LV function. We included 15 patients with RBBB, 13 patients with RBBB and concomitant LAH, 10 patients with pure LBBB, and 100 healthy controls into this study. All patients had normal LV function. Interventricular asynchrony was assessed as the difference of the right and LV ejection delay. Intraventricular delay was obtained by tissue synchronicity imaging-guided tissue Doppler imaging measurement. Interventricular and left intraventricular asynchrony were linked to the presence of an LBBB. No left intraventricular asynchrony was noted during pure RBBB; interventricular delays were negative (aortic flow preceding pulmonary flow) in the presence of RBBB. In patients with normal LV function, intraventricular asynchrony depends on the presence of an LBBB and interventricular asynchrony is inversed in the presence of RBBB.

Predictors of long-term benefit of cardiac resynchronization therapy in patients with right bundle branch block

The aims of this study were: (i) to characterize consecutive cardiac resynchronization therapy (CRT) recipients with right bundle branch block (RBBB) in comparison with left bundle branch block (LBBB) and (ii) to identify independent predictors of long-term outcome among CRT recipients with RBBB. The presence of RBBB has been associated with poorer prognosis after CRT compared with LBBB; however, little is known about the differences in cardiac mechanics between RBBB and LBBB patients. Furthermore, predictors of favourable outcome after CRT in patients with RBBB have not been identified. Five hundred and sixty-one consecutive CRT recipients (89 with RBBB and 472 with LBBB) underwent echocardiography before and 6 months after CRT to determine left ventricular (LV) size and function, and interventricular and LV dyssynchrony (as measured by tissue Doppler imaging). Long-term follow-up to identify a composite endpoint of all-cause mortality or heart failure hospitalization was available. Right bundle branch block patients exhibited a higher prevalence of male gender, ischaemic heart disease, atrial fibrillation, and lower exercise capacity when compared with LBBB patients, despite smaller LV volumes. In addition, the extent of both interventricular and LV dyssynchrony was less in RBBB patients. Six months after CRT, RBBB patients also showed limited LV reverse remodelling. At long-term follow-up, LV dyssynchrony and mitral regurgitation were identified as independent predictors of all-cause mortality or heart failure hospitalization among RBBB patients. Left ventricular dyssynchrony may be an important determinant of outcome following CRT in patients with RBBB and may help in the selection of CRT candidates.

Letter by Williams et al Regarding Article, “Bundle-Branch Block Morphology and Other Predictors of Outcome After Cardiac Resynchronization Therapy in Medicare Patients”

To the Editor: To date, several limited, nonrandomized series of patients with right bundle-branch block (RBBB) have demonstrated conflicting results with respect to the response to cardiac resynchronization therapy in this patient group. As yet, no prospective randomized, controlled trials have evaluated the effect of cardiac resynchronization therapy in a medically refractory heart failure population with RBBB. The article by Bilchick et al1 demonstrates that the presence of RBBB is a powerful predictor of poor outcome after cardiac resynchronization and cardioverter-defibrillator therapy. This can be explained in part by the higher incidence of ischemic cardiomyopathy in the RBBB patient group in comparison with the patient group with left bundle-branch block, and by the possibility of underlying right ventricular (RV) dysfunction in the RBBB group, as well, although the authors do …

Prolongation of QRS duration and axis deviation in the right bundle branch block are not markers for left ventricular systolic dysfunction

Right bundle branch block (RBBB) is not commonly associated with structural heart disease and left ventricular (LV) systolic dysfunction. The purpose of the present study was to determine whether the QRS duration and degree of right axis deviation (RAD) or left axis deviation (LAD) in patients with RBBB predicted a subset of patients with significant LV systolic dysfunction. In the present prospective study, 75 of 200 consecutive patients with RBBB had their ejection fraction (EF) evaluated by echocardiography. The relationship among QRS duration, axis and EF was derived. There were no significant differences in sex and EF among the patients with a normal axis, RAD or LAD. The EFs of patients with a normal axis (n=27), RAD (n=15) and LAD (n=33) were 52±15%, 49±14% and 46±17%, respectively (P=0.35). The mean EF (46±16%) of patients with a QRS duration of 150 ms or greater (n=53) was not significantly different from the mean EF (49±18%) of patients with a QRS duration of less than 150 ms (n=22) (P=0.54). For patients with a QRS of 120 ms or greater and less than 150 ms (n=22), QRS of 150 ms or greater and 180 ms or less (n=48), and QRS of greater than 180 ms (n=5), the mean EFs were 49±18%, 47±16% and 44±7%, respectively (P=0.78). There was no significant correlation between QRS duration and EF in all patients (r=0.03, P=0.83), EF and RAD (r=0.38, P=0.16) or EF and LAD (r=0.26, P=0.14). In patients with RBBB, the QRS duration and axis do not have a significant relationship with EF. Furthermore, prolongation of the QRS duration (150 ms or greater) in the presence of RBBB is not a marker of significant LV systolic dysfunction.

Electrocardiographic and further predictors for permanent pacemaker requirement after transcatheter aortic valve implantation

The objective of this study was to identify electrocardiographic (ECG) and further predictors for atrioventricular (AV) block with a need for pacemaker (PM) implantation after transcatheter aortic valve implantation (TAVI). Pre- and post-procedural ECGs of patients with severe aortic stenosis and ongoing TAVI were investigated in a prospective study. From 50 consecutive patients enrolled in the study (mean age 80 +/- 6 years, 46% men), 17 (34%) experienced an AV block with subsequent requirement of a permanent PM [16 of 36 (44.4%) with CoreValve System and 1 of 14 (7.1%) with Edwards Sapiens System]. In patients with right bundle branch block (RBBB), PM implantation had to be performed more frequently [6 of 6 (100%) with CoreValve System and none with Edwards Sapiens System], P = 0.005. An AV block (Mobitz II second degree and third degree) occurred mostly within the first 24 h (range: Days 0-13) after the index procedure. No recovery of AV conduction with a change in PM indication occurred in a mean follow-up time of 13 +/- 6 days. Our data demonstrate that patients with pre-operative RBBB and those receiving CoreValve prosthesis are at a significantly higher risk for PM implantation after TAVI. Therefore, patients with the presence of RBBB before TAVI may be at lower risk for PM implantation using the Edwards Sapiens System.

Right Bundle Branch Block and Impaired Left Ventricular Function as Evidence of a Left Ventricular Conduction Delay

The indications and efficacy of cardiac resynchronization therapy (CRT) have not been sufficiently clarified in patients with right bundle branch block (RBBB). This study included 55 patients with normal QRS morphology and duration (Control-Gr) and 49 patients with complete RBBB (CRBBB-Gr). Using tissue Doppler imaging, the time difference (TD) between the electromechanical delay of the septal wall, left ventricular (LV) lateral wall, and right ventricular free wall were measured. Using tissue tracking imaging, the coefficient of the time variation from the beginning of the QRS to the peak displacement time of 6 regions of the LV (CV-PMDLV) was calculated. The TD between the septal wall and that of the LV lateral wall (TDSEPT-LAT) did not differ between the Control-Gr and RBBB-Gr. However, a significant difference was found in the TDSEPT-LAT between the CRBBB patients with LV systolic dysfunction (ejection fraction (EF) < or =50%) and those with normal LV function (EF >50%; p<0.001). The CV-PMDLV was greater in the CRBBB patients with LV systolic dysfunction than in those with a normal LV function (p<0.05). The RBBB-Gr patients with LV dysfunction and a great TDSEPT-LAT, improved clinically after the CRT. The presence of RBBB and LV dysfunction may indicate LV dyssynchrony and a heterogeneous mechanical dysfunction.

Risk Factors for Requirement of Permanent Pacemaker Implantation After Aortic Valve Replacement

The aim of this study was to evaluate the frequency of requirement for permanent pacing and related risk factors after aortic valve replacement. Among 465 patients operated between 1994 and 2004, 19(4.1%) patients with a mean age 49.9 +/- 17.2 years required the implantation of a permanent pacemaker. Eleven of them were female (57.9%). The main indication was aortic stenosis (89.5%). Severe annular calcification was documented in 78.9% of them, and the aortic valve was bicuspid in 57.9%. Risk factors for permanent pacing after aortic valve replacement (AVR) identified by univariate analysis were female sex, hypertension, preoperative ejection fraction, aortic stenosis, annular calcification, bicuspid aorta, presence of right bundle branch block (RBBB) or left bundle branch block (LBBB), prolonged aortic cross-clamp and perfusion times, and preoperative use of calcium channel blockers. Multivariate analysis showed that female sex (p = 0.01, OR; 5.21, 95% CI: 1.48-18.34), annular calcification (p < 0.001, OR; 0.05, 95% CI: 0.01-0.24), bicuspid aortic valve (p = 0.02, OR; 0.24, 95% CI: 0.07-0.84), presence of RBBB (p = 0.009, OR; 0.03, 95% CI: 0.003-0.44) or LBBB (p = 0.01, OR; 0.13, 95% CI: 0.02-0.69), hypertension (p = 0.03, OR; 0.22, 95%CI: 0.05-0.89), and total perfusion time (p = 0.002, OR; 1.05, 95% CI: 1.01-1.08) were associated risk factors. Irreversible atrioventricular block requiring a permanent pacemaker implantation is an uncommon complication after AVR. Risk factors are annular calcification, bicuspid aorta, female sex, presence of RBBB or LBBB, prolonged total perfusion time, and hypertension.

Diagnosis of Ventricular Aneurysm and Other Severe Segmental Left Ventricular Dysfunction Consequent to a Myocardial Infarction in the Presence of Right Bundle Branch Block: ECG Correlates of a Positive Diagnosis Made via Echocardiography and/or Contrast Ventriculography

A diagnostic ECG sign of a ventricular aneurysm (VA) consequent to a myocardial infarction (MI) in the presence of complete left bundle branch block was recently described, and consists of the presence of ST-segment elevation (+ST), instead of the expected ST-segment depression (-ST), in leads V4-6. Generally, complete right bundle branch block (RBBB) is associated with -ST in ECG leads V1-3. We hypothesized that stable +ST, instead of the expected -ST in leads V1-3 in patients with RBBB could be also diagnostic of a VA and other severe segmental left ventricular dysfunction (VA/SSD). Thus, this study was performed to explore the feasibility of using the ECG to diagnose a VA/SSD in the presence of RBBB, and to evaluate the determinants of such diagnosis. The frequency of +ST > or =1 mm in leads V1-3 was assessed in patients with RBBB, prior MI, and a VA/SSD diagnosed by echocardiography and/or contrast left cine-ventriculography. The ECG correlates for a positive or negative diagnosis of a VA/SSD were explored. Out of 4197 files of our cohort of the Cardiology Clinic, RBBB was detected in 175 patients. Of these, 28 had an old MI, and had a VA/SSD diagnosed by > or =1 of noninvasive and/or invasive non-ECG tests. Twenty-one of these 28 patients had stable +ST in > or =1 of leads V1-3 (Group 1), and 7 did not (Group 2). Thus, the sensitivity of this ECG criterion for the diagnosis of VA/SSD was 75%, and the specificity was 100% in this highly selective group. VA/SSD in the septal and anterior myocardial regions was more frequent in the patients of Group 1, than in the patients of Group 2 (P = 0.03 and 0.02, correspondingly). The number of myocardial territories involved with the VA/SSD, or the ejection fraction were not different in the two groups (P = 0.65 and 0.55, correspondingly). VA/SSD can be diagnosed in the presence of RBBB by the concordant to the QRS repolarization changes (+ST) in leads V1-3. Positivity of this ECG marker for VA/SSD correlates with involvement of the septal or anterior myocardial regions, and represents mechanistically a superimposition of primary repolarization alterations, overcoming the secondary such changes.

False-Negative and False-Positive ECG Diagnoses of Q Wave Myocardial Infarction in the Presence of Right Bundle-Branch Block

Right bundle-branch block (RBBB) has not traditionally been seen as an obstacle to ECG diagnosis of Q wave myocardial infarction (MI) – in clinical electrocardiography and vectorcardiography – because this conduction disturbance is not believed to cause significant alterations in the spatial orientation of initial excitation wavefronts. In the era of large-scale clinical trials, however, where serial ECG analysis is among the major diagnostic tools in MI classification, both false-positive and false-negative diagnoses of MI in the presence of RBBB have become increasingly evident. Because of the limited detectability of Q wave MI by ECG in the presence of RBBB, the electrocardiographic finding of Q wave MI should not be regarded as an independent diagnostic tool. It is best to utilize independent corroboration to establish the diagnosis of transmural infarction when RBBB is present. Further investigations are warranted to better delineate sensitivity, specificity, and predictive value of Q wave MI in the presence of RBBB.

"Brugada" syndrome: clinical data and suggested pathophysiological mechanism.

The occurrence of ventricular fibrillation (VF) in the absence of any structural heart disease is classified as “primary electrical disease” or (in the absence of any relevant findings) “idiopathic VF.” This diagnosis implies that the arrhythmogenic substrate is inherent to the excitable and conducting properties of the heart. With the exception of a positive family history, demographic variables are, as a rule, not very helpful in establishing the diagnosis of primary electrical disease.1 The paradigm of primary electrical disease is the long-QT syndrome (LQTS), in which altered ionic channel function secondary to mutations in genes encoding ion channels has been shown to underlie QT-interval prolongation.2 3 In 1992, Brugada and Brugada4 described 8 patients with a history of aborted sudden death and a distinct ECG pattern, consisting of right bundle-branch block (RBBB) with ST-segment elevation in the right precordial leads (V1, V2, and V3, Figure 1⇓) and normal QT interval in the absence of any structural heart disease (as determined by routine clinical, biochemical, echocardiographic, and angiographic examinations). In 4 of the reported patients, a family history was suspected. Figure 1. ECG tracings of 1 patient originally described by Brugada and Brugada.4 Tracings show RBBB with ST-segment elevation in right precordial leads. There is marked left axis deviation, suggesting presence of left anterior hemiblock. In presence of RBBB, QTc is prolonged (482 ms). Patients with these unique ECG abnormalities have been recognized as a distinct subgroup in male Thai patients presenting with cardiac arrest due to VF.5 In northeastern Thailand, sudden unexpected death, typically occurring during sleep, is a leading cause of death in young men, and 40% of these patients have a family history of sudden death.6 The suspected inherited occurrence of the entity strongly suggested possible involvement …

Echocardiographic and Clinical Predictors of Mortality in Chronic Chagas' Disease.

BACKGROUND: In a prospective epidemiological study of chronic Chagas' disease, several clinical and echocardiographic variables were analyzed as predictors of mortality. METHODS: Among 960 subjects seropositive for Chagas' disease who were examined between June 1981 and June 1992, 283 had echocardiograms. RESULTS: During a mean follow-up period of 48.3 +/- 36.4 months (range, 1-156 months), 108 subjects died. Echocardiographic end-diastolic and -systolic left ventricular internal dimensions, fractional shortening, radius-to-thickness ratio, left ventricular mass, mitral E-point septal separation, and 17 other nonechocardiographic variables were predictors of death on univariate analysis (P < 0.001 for each). On stepwise multiple regression analysis of 215 subjects, significant risk covariates in a Cox model analysis were clinical group (P < 0.0001), M-mode echocardiographic E-point septal separation of 22 mm (P = 0.003), presence of first- or second-degree heart block (P = 0.003), chest radiologic cardiothoracic ratio >/= 0.55 (P = 0.012), presence of electrocardiographic ST segment elevation on precordial leads (P = 0.014), age >/= 56 years (P = 0.028), and presence of right bundle-branch block (P = 0.045). Patients with an apical aneurysm on two-dimensional echocardiography had an increased mortality (Chi-square = 11.5, P < 0.001). CONCLUSIONS: Echocardiography is a valuable tool to assess the risk of death in prospective studies on chronic Chagas' heart disease.

Electrocardiographic diagnosis of left ventricular hypertrophy in the presence of complete right bundle branch block

There are few data evaluating electrocardiographic diagnosis of left ventricular (LV) hypertrophy in the presence of right bundle branch block (BBB). This study assesses the relative value of multiple electrocardiographic variables for detecting LV hypertrophy in patients with right BBB. LV hypertrophy was defined as LV mass ≥215 g calculated from the Penn method using standard M-mode echo measurements. Sixty-two patients were evaluated (ages 41 to 94) and 35 had LV hypertrophy. None of the electrocardiographic criteria was sensitive; the best was mean QRS axis ≤−30 ° (sensitivity 52%) and excessive negative P terminal force (sensitivity 28%). Several electrocardiographic variables were specific: Sokolow index ≥35 mm (100%), RV 5 or RV 6 ≥25 mm (96.3%), RI + SIII ≥25 mm (92.6%) and intrinsicoid deflection ≥0.05 seconds (88.5%). Conventional electrocardiographic criteria do not reliably detect LV hypertrophy in the presence of right BBB, but several criteria are relatively specific for LV hypertrophy.

Intraventricular conduction disturbances after correction of tetralogy of Fallot: can bifascicular and trifascicular block be diagnosed from the surface ECG?

To determine the origin of conduction disturbances commonly seen in the ECG after correction of Fallot's tetralogy, 36 children underwent electrophysiologic studies; these included endocardial recordings of right ventricular (RV) and left ventricular (LV) apical activation and His-bundle recordings. The surface ECG showed a pattern of complete right bundle branch block (RBBB) in 22, and RBBB with left-axis deviation (LAD)--so-called bifascicular block--in nine; the remaining five had RBBB, LAD, and a long PR interval, often considered as indicating trifascicular block. Eight of 22 patients with RBBB and normal axis had delayed RV apical activation (36%), indicating a proximal lesion. Of nine patients with RBBB and LAD, four only had delayed RV apical activation (44%); in the other five, therefore, the RBBB pattern was due to a peripheral lesion (ventriculotomy); they cannot be considered as having true bifascicular block. LV activation was not delayed in any case. In five cases, the surface ECG suggested trifascicular block (long PR in the presence of RBBB and LAD). His-bundle recordings showed the HV interval to be prolonged in only two cases, at the upper limit of normal in two, and short in one. The AH interval was prolonged in all and was mainly responsible for the long PR interval. Thus, the surface ECG is not a reliable tool for making a diagnosis of true bifascicular block and trifascicular damage after correction of Fallot's tetralogy. This may explain controversies existing about the prognosis of such conduction abnormalities.

Coronary arteriographic findings in symptomatic right bundle branch block

Of 5,132 consecutive patients who had coronary arteriography for chest pain, 103 (2%) had right bundle branch block (RBBB), 66 (64%) of whom had no electrocardiographic evidence of concomitant myocardial infarction (Ml); 23 patients had evidence of Ml of the inferior wall, 8 of the anterior wall and 6 of the lateral wall. The incidence, location or severity of coronary artery disease (CAD) in patients with RBBB alone were not significantly different from those in 110 similarly symptomatic patients with normal ECGs. However, significantly more left ventricular contraction abnormalities, especially in the anteroapical area, were found in patients with RBBB (p < 0.01). Similarly, patients with RBBB and inferior Ml, compared with 60 similarly symptomatic patients with inferior Ml without RBBB, showed no significant differences in location, incidence or severity of CAD. However, more left ventricular contraction abnormalities in the apical area were found in patients with RBBB (p < 0.025). Thus, the presence of RBBB does not suggest more severe or extensive CAD; however, RBBB does predict more left ventricular contraction abnormalities.

Left anterior hemiblock obscuring the diagnosis of right bundle branch block in acute myocardial infarction.

Thirty cases in which transient left anterior hemiblock (LAHB) obscured the diagnosis of right bundle branch block (RBBB) appearing during the first days of an acute myocardial infarction (AMI) are presented. Twenty-eight of the patients with AMI had a clear septal wall involvement, while the remaining two had an anterolateral and lateral wall AMI, respectively. These intraventricular conduction defects developed 2-120 hours (mean 64.9 +/- 26 hours) after the acute event, and persisted for 24 hours to 7 days (mean 63.1 +/- 35 hours). The ECG was characterized by a pure LAHB with wide QRS complexes and the presence of RBBB was shown by recording high V1 and right-sided chest leads. The vectorcardiogram was also useful in several cases. The clinical course of this type of bifascicular block was transient and benign, with an in-hospital mortality of 6.7%. No patient developed trifascicular or complete atrioventricular block and, therefore, we conclude that prophylactic installation of a temporary pacemaker is not indicated in this type of bifascicular block. The possible role of extracellular potassium released during acute myocardial necrosis in the pathophysiological mechanism of these blocks is discussed.

Vectorcardiographic features of left anterior hemiblock combined with complete right bundle branch block

Summary The vectorcardiographic features of left anterior hemiblock (LAHB) combined with right bundle branch block (RBBB) were characterized using the Frank lead system. In the presence of RBBB, the following criteria appeared to be most useful for the additional diagnosis of coexisting LAHB: Superior displacement and counterclockwise inscription of the frontal plane QRS loop, and QRS duration of 120 msec or more, with delayed inscription of the terminal 60 msec vectors. LAHB combined with RBBB results in a more superior frontal plane maximum QRS vector than does isolated RBBB or LAHB.

The correlation between the electrocadiographic patterns of ventricular hypertrophy and the anatomic findings.

The correlation of the electrocardiogram with anatomic evidence of ventricular hypertrophy, while laden with numerous pitfalls, still remains the best available means of determining the accuracy of the electrocardiographic diagnosis of ventricular hypertrophy. In 100 instances of isolated left ventricular hypertrophy (LVH) demonstrated at autopsy, a positive electrocardiographic diagnosis was made in 85 per cent by use of conventional criteria. However, in other studies designed to test the reliability of these criteria, it was found that a false-positive diagnosis was made in 10 to 15 per cent of the cases. The electrocardiographic diagnosis of right ventricular hypertrophy (RVH) is more difficult. In electrocardiographic studies, confirmed by autopsies, the correlation has ranged from 23 to 100 per cent, while the number of false-positive diagnoses has been as high as 33 per cent. The correct electrocardiographic diagnosis is more frequent in RVH due to congenital heart disease than to acquired heart disease. The significance of the rSR' pattern in right precordial leads is discussed. Its occurrence in anatomic RVH and the problem of the electrocardiographic diagnosis of RVH in the presence of right bundle-branch block (RBBB) are reviewed. Combined ventricular hypertrophy (CVH) is frequently missed in the electrocardiogram, the diagnosis having been made in only 8 to 26 per cent of cases proved at autopsy. The unreliability of the electrocardiographic diagnosis of LVH in the presence of left bundle-branch block (LBBB) is documented. The precise electrophysiologic phenomena that occur in ventricular hypertrophy are still largely conjectural. The more commonly accepted hypotheses are reviewed. The lack of close correlation between ventricular wall thickness or respective ventricular muscle mass and the individual electrocardiographic patterns is emphasized. The possible explanations for some of these discrepancies are presented.

Electrocardiographic Diagnosis of Ventricular Hypertrophy in the Presence of Right Bundle-Branch Block

Forty-nine autopsied cases of complete and incomplete right bundle-branch block were studied with correlation of the electrocardiographic and anatomic diagnosis of ventricular hypertrophy. Twenty-six (53 per cent) of the cases showed anatomic evidence of right ventricular hypertrophy. The cases were studied for right ventricular hypertrophy according to the criteria of Barker and Valencia and of Milnor. Milnor's criteria resulted in frequent overdiagnosis while those that met Barker and Valencia's criteria usually but not invariably showed anatomic right ventricular hypertrophy. The electrocardiographic diagnosis of left ventricular hypertrophy was masked by the bundle-branch block in anatomically proved cases.