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Clinical analysis of right bundle branch block
Clifford S. Reach, M.D., and Josefih R. Vivas, Colmtel, MC, USA Balboa Heights, Can&t Zone In the fields of clinical medicine, established criteria need constant re-evaluation. It may be stated that the prognostic significance of any form of bridle branch block rests on the nature of the underlying path&gic entity involving the heart, and it may be further stated that once the nature of th tit dti is known, there is no prognostic significance to the presence of but&e branch block. However, the finding of bundle branch Mock in routine eiectrocardiograms, not accompanied by clinical symptomatology and x-ray findi, puzeks the physician and confronts hini with the question of the prognoactic @&&ance of the electrocardiographic finding. In the search for an antier to this qeeaaion and in order to re-evaluate previotisly established dicta, it was de&A& to analyze all cases of bundle branch block recorded in the electrocardiagmphic &B of Gorgas Hospital in the years 1952 through 1958. This first paper deals with complete right bundle branch block. CRITERIA
FOR
DIAGNOSIS
The criteria for the diagnosis of complete right bundle branch block have changed little since originally set forth by Wilson, in 1931. The duration of the QRS complex must be 0.12 second or greater, as measured in the chest l&s of a twelve-lead electrocardiographic tracing. While the rSR or rR’ patterns are usually seen in Leads Vi-V2 and avR, together with a broad S in Lead I and secondary ST-T wave changes in these leads, they are secondary critetia estab&hing the site rather than the extent of the block, and are subject to positional variations. Most often the diagnosis of complete right bundle branch block is not made until the time of electrocardiography; however, it may be suspected in casee which have splitting of either the first or second heart sounds. The absence of a characteristic mean vector or QRS loop is reported by both Sodi-Pallarea and Lasser, leaving the diagnosis in the realm of “pattern” or standard efectrocardiography. From the D@mrtmt Received for publication
of Medicine. Gorfmz? June 1, 1969.
Hospdtal, 543
Bdboa
He&hts.
Canal
Irwe.
544
REUSCH
MECHANISM
OF
AND
VIVAS
Am. Heart J. October, 1959
PRODUCTION
The electrocardiographic tracing of complete right bundle branch block is produced when the duration of the electrical activity of depolarization of the combined ventricular muscle mass exceeds 0.12 second and the terminal vectors are directed toward the right. The separate investigations of Sodi-Pallares and Dickens and Goldberg, using intracardiac and epicardial electrodes, have demonstrated this electrical pattern to be the result of two-phase septal depolarization. The upper septum is depolarized as usual, but there is a delay in the depolarization of the lower septum, which occurs terminally, resulting in a terminal vector directed to the right, with an R’ in Leads VI, V~R, and aVa. The ST-T changes are of the secondary rather than the primary type, except in cases of coronary vascular disease. CASE
PRESENTATIONS
The population represented in these studies is composed of three groups: (1) Panamanian nationals and their dependents, (2) U. S. civil service employees and their dependents, and (3) U. S. military personnel and their dependents. The first two of these three groups are comparable to a cross-section of an average American community. The third group contains an abnormally high number of young healthy males, which may, in some degree, affect the following figures. In the ‘I-year period from January, 1952, through December, 1958, there were 17,750 twelve-lead electrocardiograms taken in Gorgas Hospital. These examinations represent 8,770 individuals, because our re-examination rate is 50 per cent. In these tracings there were 179 instances of complete right bundle branch block, representing 100 separate cases. This produces an incidence of 1.15 per cent or a prevalence of 11.5 per 1,000 patients examined. Our 100 cases of right bundle branch block are tabulated in Table I according to disease process, age at the time of discovery, and sex. Summarizing Table I, we can say that in 62 per cent of our cases of complete right bundle branch block there was evidence of heart disease, of which arteriosclerotic heart disease was the most prevalent. It is interesting to note that there is a 3:l prevalence of males in our group in which no heart disease was found; however, the prevalence of males is reduced to 2:l in the group with diagnosed heart disease. There were 23 fatalities in the 100 cases of right bundle branch block recorded in this ‘I-year period. These fatalities are tabulated in Table II. In the three cases in which there was no heart disease the deaths were due to carcinoma of the lung, pulmonary tuberculosis, and amyotrophic lateral sclerosis. DISCUSSION
AND
CONCLUSIONS
In an attempt to verify the frequently heard statement that right bundle branch block is often of little clinical significance, we have collected the aforementioned material. Our findings are basically in agreement with those of Bayley, who reported that in 24 per cent of his cases there was no evidence of heart disease. While we find that in one out of three of our cases of right bundle branch
%t%E: “4”
CLINICAL
ANALYSIS
OF
RIGHT
BUNDLE
BRANCH
545
BLOCK
block there is no heart disease, the probability is that if these persons were properly followed up and investigated, many would be diagnosed as having some form of cardiac abnormality. Table II further demonstrates that the coincidence of right bundle branch block and diagnosed heart disease indicate a poorer subjects out of a prognosis than does right bundle branch block alone. Twenty group of 62 died when right bundle branch block and heart disease were present, but only 3 out of 38 who had right bundle branch block died when no heart disease was diagnosed. TABLE
I ___-.-.--.-_ --_______---AVERAGE AGE (YR.)
TOTAL
TYPEOF
CARDIAC
CASES __-
DISEASE
Hypertensive cardiovascular disease Arterimclerosis Rheumatic heart disease CongenitaI heart disease Heart disease of unknown etiology
MALE
22 30
FEMALE ___
14 22
---_-
ii
-.-
x:
33
5 ;: 1
i
;
2
:o” -
Total with heart disease No heart disease
2:
40 29
229
::
100
69
31
-
-I
Grand total
TABLE
II DEATHS
DISEASE
TOTAL CASES
TOTAL DEATHS o-1
1-12 MO.
MO.
12-48
PER CENT
MO. --__
Hypertension Arteriosclerosis Rheumatic heart disease Congenital heart disease Undiagnosed heart disease
3,-'___-
--'
0
--
-
Total with heart disease No heart disease Grand total *All
of these
were
due
to acute
myocwdialinfasction.
The interesting predominance of this condition in maIes, as compared to females, has led us to re-examine our cases and the population from which we have obtained the tracings. Although at first the presence of a military segment in our population might seem to explain this finding, the average age of our subjects is far above the usual retirement age of military personnel and probably is not grossly affected by this group. Another point of potential error is due to the fact that a number of our tracings are taken as annual physical examinattis and ore-employment examinations, in both of which instances males predominate;
546
REUSCH
AND
VIVAS
Am. Heart J. October, 1959
however, this would fail to explain the prevalence in those subjects with disease, since they, in general, fall outside these groups of pre-employment young military personnel.
heart and
SUMMARY
1. Complete right bundle branch block is associated with heart disease in 62 per cent of our cases. 2. Arteriosclerotic heart disease is the most common variety of heart disease associated with right bundle branch block. 3. The prognosis for right bundle branch block is considerably more grave when associated with diagnosed heart disease. 4. There is an unexplained predominance of males in both the group with and the group without detectable heart disease. REFERENCES
Bayley, R. H.: The Frequency and Significance of Right Bundle Branch Block, Am. J. M. SC. 188:236. 1934. 2. Dickens, J., and Goldberg, H.: The Endocardial Lead in Complete Right Bundle Branch 1.
B&k,
3.
4. 5. 6. 7.
AM.
HEART
1.
Sfir372.
1958.
Lasser, et al.: Vector Car;iiographlcAnalysis of RsR’ Complex, AM. HEART J. 418667, 1951. Miguel, C., Sodi-Pallal res. et al. : Right Bundle Branch Block and Right Ventricular Hyper__ ophy, Am. J. Cardiology 187, 1958. Sodi-P: hares, D., et al.: New Contributions to the Study of the Intra-Cavitary Potential in Cases of Right Bundle Branch Block in the Human Heart, AY. HEART J. 36~1, 1948. Wilson, F. N., et al.: The Precordial Electrocardiogram, AM. HEART J. 27:19, 1944. Wilson, F. N., MacLeod, A. G., and Baker, P. S.: The Order of Ventricular Excitation in Human Bundle Branch Block, AK HEART J. 7:305, 1932.
FOR
DIAGNOSIS
The criteria for the diagnosis of complete right bundle branch block have changed little since originally set forth by Wilson, in 1931. The duration of the QRS complex must be 0.12 second or greater, as measured in the chest l&s of a twelve-lead electrocardiographic tracing. While the rSR or rR’ patterns are usually seen in Leads Vi-V2 and avR, together with a broad S in Lead I and secondary ST-T wave changes in these leads, they are secondary critetia estab&hing the site rather than the extent of the block, and are subject to positional variations. Most often the diagnosis of complete right bundle branch block is not made until the time of electrocardiography; however, it may be suspected in casee which have splitting of either the first or second heart sounds. The absence of a characteristic mean vector or QRS loop is reported by both Sodi-Pallarea and Lasser, leaving the diagnosis in the realm of “pattern” or standard efectrocardiography. From the D@mrtmt Received for publication
of Medicine. Gorfmz? June 1, 1969.
Hospdtal, 543
Bdboa
He&hts.
Canal
Irwe.
544
REUSCH
MECHANISM
OF
AND
VIVAS
Am. Heart J. October, 1959
PRODUCTION
The electrocardiographic tracing of complete right bundle branch block is produced when the duration of the electrical activity of depolarization of the combined ventricular muscle mass exceeds 0.12 second and the terminal vectors are directed toward the right. The separate investigations of Sodi-Pallares and Dickens and Goldberg, using intracardiac and epicardial electrodes, have demonstrated this electrical pattern to be the result of two-phase septal depolarization. The upper septum is depolarized as usual, but there is a delay in the depolarization of the lower septum, which occurs terminally, resulting in a terminal vector directed to the right, with an R’ in Leads VI, V~R, and aVa. The ST-T changes are of the secondary rather than the primary type, except in cases of coronary vascular disease. CASE
PRESENTATIONS
The population represented in these studies is composed of three groups: (1) Panamanian nationals and their dependents, (2) U. S. civil service employees and their dependents, and (3) U. S. military personnel and their dependents. The first two of these three groups are comparable to a cross-section of an average American community. The third group contains an abnormally high number of young healthy males, which may, in some degree, affect the following figures. In the ‘I-year period from January, 1952, through December, 1958, there were 17,750 twelve-lead electrocardiograms taken in Gorgas Hospital. These examinations represent 8,770 individuals, because our re-examination rate is 50 per cent. In these tracings there were 179 instances of complete right bundle branch block, representing 100 separate cases. This produces an incidence of 1.15 per cent or a prevalence of 11.5 per 1,000 patients examined. Our 100 cases of right bundle branch block are tabulated in Table I according to disease process, age at the time of discovery, and sex. Summarizing Table I, we can say that in 62 per cent of our cases of complete right bundle branch block there was evidence of heart disease, of which arteriosclerotic heart disease was the most prevalent. It is interesting to note that there is a 3:l prevalence of males in our group in which no heart disease was found; however, the prevalence of males is reduced to 2:l in the group with diagnosed heart disease. There were 23 fatalities in the 100 cases of right bundle branch block recorded in this ‘I-year period. These fatalities are tabulated in Table II. In the three cases in which there was no heart disease the deaths were due to carcinoma of the lung, pulmonary tuberculosis, and amyotrophic lateral sclerosis. DISCUSSION
AND
CONCLUSIONS
In an attempt to verify the frequently heard statement that right bundle branch block is often of little clinical significance, we have collected the aforementioned material. Our findings are basically in agreement with those of Bayley, who reported that in 24 per cent of his cases there was no evidence of heart disease. While we find that in one out of three of our cases of right bundle branch
%t%E: “4”
CLINICAL
ANALYSIS
OF
RIGHT
BUNDLE
BRANCH
545
BLOCK
block there is no heart disease, the probability is that if these persons were properly followed up and investigated, many would be diagnosed as having some form of cardiac abnormality. Table II further demonstrates that the coincidence of right bundle branch block and diagnosed heart disease indicate a poorer subjects out of a prognosis than does right bundle branch block alone. Twenty group of 62 died when right bundle branch block and heart disease were present, but only 3 out of 38 who had right bundle branch block died when no heart disease was diagnosed. TABLE
I ___-.-.--.-_ --_______---AVERAGE AGE (YR.)
TOTAL
TYPEOF
CARDIAC
CASES __-
DISEASE
Hypertensive cardiovascular disease Arterimclerosis Rheumatic heart disease CongenitaI heart disease Heart disease of unknown etiology
MALE
22 30
FEMALE ___
14 22
---_-
ii
-.-
x:
33
5 ;: 1
i
;
2
:o” -
Total with heart disease No heart disease
2:
40 29
229
::
100
69
31
-
-I
Grand total
TABLE
II DEATHS
DISEASE
TOTAL CASES
TOTAL DEATHS o-1
1-12 MO.
MO.
12-48
PER CENT
MO. --__
Hypertension Arteriosclerosis Rheumatic heart disease Congenital heart disease Undiagnosed heart disease
3,-'___-
--'
0
--
-
Total with heart disease No heart disease Grand total *All
of these
were
due
to acute
myocwdialinfasction.
The interesting predominance of this condition in maIes, as compared to females, has led us to re-examine our cases and the population from which we have obtained the tracings. Although at first the presence of a military segment in our population might seem to explain this finding, the average age of our subjects is far above the usual retirement age of military personnel and probably is not grossly affected by this group. Another point of potential error is due to the fact that a number of our tracings are taken as annual physical examinattis and ore-employment examinations, in both of which instances males predominate;
546
REUSCH
AND
VIVAS
Am. Heart J. October, 1959
however, this would fail to explain the prevalence in those subjects with disease, since they, in general, fall outside these groups of pre-employment young military personnel.
heart and
SUMMARY
1. Complete right bundle branch block is associated with heart disease in 62 per cent of our cases. 2. Arteriosclerotic heart disease is the most common variety of heart disease associated with right bundle branch block. 3. The prognosis for right bundle branch block is considerably more grave when associated with diagnosed heart disease. 4. There is an unexplained predominance of males in both the group with and the group without detectable heart disease. REFERENCES
Bayley, R. H.: The Frequency and Significance of Right Bundle Branch Block, Am. J. M. SC. 188:236. 1934. 2. Dickens, J., and Goldberg, H.: The Endocardial Lead in Complete Right Bundle Branch 1.
B&k,
3.
4. 5. 6. 7.
AM.
HEART
1.
Sfir372.
1958.
Lasser, et al.: Vector Car;iiographlcAnalysis of RsR’ Complex, AM. HEART J. 418667, 1951. Miguel, C., Sodi-Pallal res. et al. : Right Bundle Branch Block and Right Ventricular Hyper__ ophy, Am. J. Cardiology 187, 1958. Sodi-P: hares, D., et al.: New Contributions to the Study of the Intra-Cavitary Potential in Cases of Right Bundle Branch Block in the Human Heart, AY. HEART J. 36~1, 1948. Wilson, F. N., et al.: The Precordial Electrocardiogram, AM. HEART J. 27:19, 1944. Wilson, F. N., MacLeod, A. G., and Baker, P. S.: The Order of Ventricular Excitation in Human Bundle Branch Block, AK HEART J. 7:305, 1932.