Clinical
communications
Prognosis of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot John A. Cairns, M.D., F.R.C.P.(C) Anthony R. C. Dobell, M.D., C.M., F.R.C.S.(C), F.A.C.S. James E. Gibbons, M.D., C.M., F.A.A.P., F.A.C.C. Irving Tessler, M.D. Montreal,
Que.,
Canada
Right bundle branch block and left anterior hemiblock may be caused by intracardiac repair of tetralogy of Fallot. This was first reported by Kulbertus,‘. z in 1968; 8 per cent of his patients developed the combined lesion postoperatively, and he expressed concern about the possibility of late complete heart block and death in these patients. In 1972, papers by Wolff and associates” and by Moss and co-workers* drew attention to an alarming incidence of complete heart block of late onset and sudden death in these patients. This article reports on a series of patients who underwent intracardiac repair of tetralogy of Fallot, 22 per cent of whom developed right bundle branch block and left anterior hemiblock postoperatively. The purpose of the article is to document the benign prognosis in these patients postoperatively and in late follow-up, and to discuss these findings in relation to contrary reports in the literature. Methods
A review was made of clinical records and ECG’s of all patients who underwent open intracardiac repair of tetralogy of Fallot at the Montreal Children’s Hospital from January, 1958, to June, 1972. Patients who died within 1 month of operation were considered to be operaFrom the Department and McGill University, Originally presented College of Cardiology, Received
for publication
Reprints Victoria Canada.
requests: Hospital,
November,
of Cardiology, Montreal Montreal, Que., Canada.
Children’s
Hospital,
at the Annual Scientific Session, New York, N. Y., Feb. 11-14, 1974.
American
Sept. 20, 1974.
J. A. Cairns, M.D., Division of Cardiology, Royal 687 Pine Ave. West, Montreal H3A lA1, Que.,
1975, Vol. 90, NO. 5, pp. 549-554
tive deaths. On the basis of the ECG on hospital discharge, operative survivors were divided into four groups: (1) no bundle branch block-QRS width 0.08 second or less; (2) right bundle branch block-terminal slurred S wave in Lead I, R’ in Lead V, with QRS widening (incomplete 0.09 to 0.011 second, complete 0.12 second or greater); (3) right bundle branch block and left anterior hemiblock-right bundle branch block plus Q waves of 0.02 second in Leads I and aVL, mean QRS axis of unblocked forces -30 to -120 degrees, counterclockwise frontal plane vector loop (Figs. 1 and 2); (4) complete heart block-idioventricular pacemaker, with no conduction of supraventricular impulses, rate under 50 per minute. The post-hospital course and current status of patients were determined from review of clinic charts and ECG’s and by letter and telephone contact with doctors of patients not. followed in our clinic. The information was augmented by telephone contact with the family or patient. Results
A total of 178 patients underwent open operation; of these, 25 died, an operative mortality of 14 per cent (Table I). Of the 153 survivors, the preoperative and postoperative ECG’s were available for review on 141 (92 per cent). The 141 patients were distributed as outlined in Table II. The focus of this report is on the 31 patients (22 per cent) who developed right bundle branch block and left anterior hemiblock postoperatively. Among these 31 patients, only 2 developed a postoperative arrhythmia; in each it was complete heart block while coming off cardiopul-
American
Heart
FJournal
549
Cairns
et al.
AVL
I
Fig. 1. Selected ECG leads from Patient J. P. with tetralogy Postoperatively, age 4 years, now showing right bundle branch Q waves in Leads I and aV,, left axis deviation of unblocked loop.
I. Tetralogy of Fallot-intracardiac at Montreal Children’s Hospital, January, June, 1972
repair 195%
Table
Total patients Operative deaths survivolx survivors ECGs available
Table
178 25 (14%) 153 (86%) 153 141 (92%)
ECG one month
II.
postoperatively-141
patients No bundle branch block Right bundle branch block Right bundle branch block left anterior hemiblock Complete heart block
Table
Ill.
anterior
and
Right bundle branch hemiblock-31 patients
Postoperative arrhythmia Complete heart block-6 days Complete heart block, Nodal rhythm-7 days Late deaths Right ventricular failure-4 months Repeat operation-20 months survivors Average survival 67 months Range (148-12) Late arrhythmias-O CHB
550
= complete
heart
block.
27 (19%) 82 (58%) 31 (22%) l(
1%)
block and left 2
2
29
Ill
Vl
of Fallot. A, Preoperatively, age 4% months. B, block and left anterior hemiblock. Note 0.02-second forces, and counterclockwise frontal plane vector
monary bypass. In one, a 13-year-old girl, normal sinus rhythm with right bundle branch block and left anterior hemiblock returned after 6 days. In the other, a &year-old boy, complete heart block was present intermittently for only a few hours, to be replaced by a probable nodal rhythm, which resolved after 7 days. Both children had epicardial pacing wires and were paced as indicated until reliable normal sinus rhythm returned. Of the 31 patients with right bundle branch block and left anterior hemiblock postoperatively, 29 are alive at present (Table III), an average of 67 months after operation (range 148 to 12 months). There have been no reports of arrhythmias and no ECG evidence of complete heart block. All are doing well in terms of cardiac function as evidenced by physical examination and level of activities. Two patients have died late (Table III). The first of these was the 13-year-old girl who developed transient complete heart block postoperatively in 1960. Although normal sinus rhythm returned, digitalis was required for control of congestive heart failure. Digitalis was stopped before discharge 2 months postoperatively, but congestive heart failure returned after another 2 months. She was rehospitalized and died 3 weeks later of progressive congestive heart failure. There was no evidence of recurrence of complete heart block. This death was considered to be related to an incomplete intracardiac repair. The other patient was a boy, age 4 years at his initial
November,
1975, Vol. 90, No. 5
RBBB
Fig. 2. Complete Postoperatively,
ECG’s from age 4 years.
Patient
J. P. with
operation when severe infundibular stenosis was noted. Twenty months later, in 1966, reoperation was undertaken because of a persistent infundibular pressure gradient and a ventricular septal defect. He died during this second open operation. Thus, although two late deaths have occurred in this series of 31 patients, neither could be attributed to the presence of right bundle branch block and left anterior hemiblock. Discussion
The combined lesion of right bundle branch block and left anterior hemiblock has been well described and widely reported in the adult cardiology literature. In 1921, Wilson and Herrmann” reported that the pattern now recognized as right bundle branch block and left anterior hemiblock could be produced by interruption of the right bundle branch and the anterior fascicle of the left bundle branch. Subsequent reports have developed the diagnostic criteria,fi examined the
American
Heart
Journal
tetralogy
of Fallot.
A, Preoperatively,
and
left
mtericx
age 4% months.
hemiblock
B,
pathologic basis,i-l” discussed the etiologies,‘. I” and outlined the prognosis for this lesion.‘~ I*. l2 Two recent reports have reviewed all of these aspects of the combined lesion. There has been controversy over the exact diagnostic criteria for right bundle branch block and left anterior hemiblock. Criteria have applied to the initial 0.02-second vector, the mean QRS axis, the axis of unblocked forces, and the inscription of the frontal plane vector loop. The criteria chosen in the present study are adapted from those of Rosenbaum” and are consistent with those of many other reports in the literature. In general, there has been good correlation between the ECG evidence for right bundle branch block and left anterior hemiblock and the experimental interruption of the right bundle branch and left anterior fascicle in dogs’:‘-‘” and in primates.‘” I’: Postmortem human studies have revealed appropriately located lesions to explain antemortem right bundle branch block and left anterior hemiblock.‘, *. !‘. Ii
551
Cairns
et al.
Table IV. Prognosis of RBBB
and LAH
Transient postoperative CHB
t-
Author Cairns et al. Downing et al. Wolff et al. Moss et al.
Late CHB or SD
I
RBBB and LAH
Total
31
2
14
2
24
9
6 (67%)
3
3
3 (100%)
0
0
0
0
0
0
3 CHB 6SD 3 CHB
-
6 (67%) > 3 (100%)
12
9 (75%)
CHB = complete heart block; LAH = left anterior hemiblock; RBBB = right bundle branch block: SD = sudden death.
There are a number of etiologies of right bundle branch block and left anterior hemiblock in adults. The reported frequency of each etiology varies widely among several large series in the literature. Some authors have reported a high incidence of atherosclerotic coronary artery disease, postulating chronic ischemia and fibrosis of the conducting system.‘, *I. I*. I** I9 Others have found coronary artery disease is less common in these patients and attribute the block to a primary “sclero degenerative disease” of the bundle branches and Purkinje networkg. *O or to “sclerosis of the left side of the cardiac skeleton.“2’ Still others have considered the etiological roles of hypertension,“* I2 aortic valve disease,G previous myocarditis,‘, z0 and cardiomyopathy.” The prognosis of these patients has not yet been fully delineated. However, when combined right bundle branch block and left anterior hemiblock develops outside the setting of acute myocardial infarction, the prognosis is reasonably good. The incidence of complete heart block has been reported at 10 per cent during an unspecified period of follow-up by Lasser and associates,” 6 per cent by Rosenbaum and associates,7 and 13.6 per cent during an average 18.9-month follow-up by Scanlon and associates.‘* The life expectancy for this group may be no different from that of other patients in this age group who require an electrocardiogram.”
552
The surgical creation of right bundle branch block was first reported by Kittle and co-workersz3 in 1956, after repair of pulmonic stenosis, whereas left anterior hemiblock (then described as left ventricular parietal block) was first reported by Samson and Bruce2’ in 1962, after transventricular aortic commissurotomy. The combined lesion of right bundle branch block and left anterior hemiblock (then described as left superior intraventricular block) was first documented by Kulbertus’ in 1968, after repair of ventricular septal defect and tetralogy of Fallot. Several authors have since drawn attention to the occurrence of the combined lesion after intracardiac repair of tetralogy of Fallot.‘?, z,. X. y7 Lev”” and Rosenbaum and associatesz6 have described the conduction system and its relation to the ventricular septal defect in tetralogy of Fallot. The left posterior fascicle separates from the A-V bundle at the posterior angle of the defect relatively well removed from the vicinity of the repair. The left anterior fascicle and right bundle branch continue along the inferior margin of the defect and are at risk of damage from edema, inflammation, hemorrhage, or suture. The combined lesion of right bundle branch block and left anterior hemiblock develops with a reported incidence that varies from 7 per cent” to 10.7 per cent,29 and 22 per cent in the present series. There are only three previously published series which report late follow-up of right bundle branch block and left anterior hemiblock after open operation for tetralogy of Fallot. In two of theses, 4 there was a high incidence of complete heart block and sudden death. In the third,‘” as in the present series, neither occurred. We have analyzed these reports in an attempt to explain these differences. In the adult, complete heart block occurs when the progressive disease which involves the right bundle branch and left anterior fascicle extends into the distal His bundle or left posterior fascicle. In the child undergoing intracardiac repair of tetralogy, the right bundle branch and left anterior fascicle are at risk of damage, and right bundle branch block and left anterior hemiblock may appear. However, once healing of the operative wound has occurred and there has been no evidence of trifascicular damage, one might reasonably expect no progression of the conduction disorder-since no progressive disease is present. We considered whether some of these patients might have trifascicular
November,
1975, Vol. 90, No. 5
RBBB
disease in the postoperative period, and whether these were the patients at high risk for late complete heart block and sudden death. The four series are analyzed in Table IV. In the present series, and in that of Downing and associates,z!’ transient postoperative complete heart block developed in only 2 of 31 and 2 of 14 patients, respectively. There were no episodes of late complete heart block or sudden death. In Wolff and associates’ series” of 24 patients, transient postoperative complete heart block occurred in 9, 6 of whom went on to develop late complete heart block or to die suddenly. A total of 9 patients developed late complete heart block or died suddenly: 6 had had transient complete heart block postoperatively, and 3 had had no previous arrhythmias. Moss and associates4 in their series had 10 patients with tetralogy of Fallot in whom complete heart block of late onset developed. Of these 10, only 3 had had right bundle branch block and left anterior hemiblock, and all 3 had had transient postoperative complete heart block. Thus, of 12 reported cases of complete heart block of late onset or sudden death in patients with right bundle branch block and left anterior hemiblock, in 9 (75 per cent), transient complete heart block was noted in the postoperative period. The process by which complete heart block resolves, only to recur at some later date, can only be postulated. However, it is reasonable to suppose that once the left posterior fascicle is damaged and complete heart block occurs, even though resolution of acute inflammation and edema allows conduction to resume through this fascicle, an ongoing process of fibrosis may be initiated which will eventually lead to permanent complete heart block. The electrophysiologic correlate of such a sequence would be prolongation of the HV interval during normal sinus rhythm, and block distal to the His deflection after development of late complete heart block. Clearly, those children with transient postoperative complete heart block and residual right bundle branch block and left anterior hemiblock require close clinical and ECG follow-up. Consideration should be given to studies of the bundle of His in order to delineate the conduction status of the left posterior fascicle. The documentation of HV conduction delay would suggest a high risk for the development of late-onset complete heart block. However, the magnitude of this risk and,
American
Heart
Journal
and kjt onterror’
hemibloch
consequently, the role for prophylactic pacing in such children remain to be more clearly defined. The present series and that of Downing and associates indicate that the occurrence of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot does not of itself carry a high risk of late complete heart block or sudden death. Our conclusion from the series of Wolff and of Moss and co-workers is that the critical factor in a bad late prognosis in patients with postoperative ECG evidence of right bundle branch block and left anterior hemiblock may be the history of transient postoperative complete heart block-indicative: of trifascicular disease in this setting. Summary
One hundred and forty-one survivors of intracardiac repair of tetralogy of Fallot, (TOF), operated on between 1958 and 1972, were studied in order to document the incidence of right bundle branch block and left anterior hemiblock (RBBB and LAH) and to define the late prognosis. RBBB and LAH occurred in 31 patients (22 per cent), all of whom have had complete follow-up. Transient complete heart block (CHB) occurred postoperatively in 2 patients; there were no other significant arrhythmias. Two late deaths have occurred, neither from arrhythmia (one from progressive congestive heart failure, and the other from attempted reclosure of a ventricular septal defect). The remainder of the patients are well an average of 76 months postoperatively (range, 144 to 12 months). The absence of late-onset CHB or sudden death in this series contrasts with the relatively high incidence of these events in some studies of RBBB and LAH after intracardiac repair of TOF. However, in those reports a history of transient postoperative CHB (indicative of trifascicular disease in this setting) can be found in 75 per cent of those who developed late-onset CHB or died suddenly. We conclude that the occurrence of RBBB and LAH after intracardiac repair of TOF does not of itself carry a bad late prognosis. The critical factor in a bad late prognosis in patients with ECG evidence of RBBB and LAH may be the history of transient postoperative CHB. Addendum
Since the preparation of this report and its presentation in abstract form, Godman and asso-
553
Cairns
et al.
ciates have published similar conclusions (Circulation 49:214-221, 1974). They studied 14 patients with postoperative right bundle branch block and left anterior hemiblock. Four of those patients developed late-onset complete heart block, all 4 of them having had transient postoperative complete heart block. Studies of the bundle of His placed the block distal to the bundle of His in all 4. Six additional patients of the group had had transient postoperative complete heart block, and in 5 of the 6 the HV time was prolonged. Transient postoperative complete heart block was judged to identify a group of patients with postoperative right bundle branch block and left anterior hemiblock at particularly high risk of developing late-onset complete heart block.
12.
13.
14. 15.
16.
HEARTJ. 70:381, 1965. 17.
We thank Miss Lorraine Brown for secretarial assistance and help with translation and interviews of families and patients. We also thank Mrs. Ellen Simon for secretarial assistance during the initial phases of the study.
ia.
REFERENCES
19.
2.
K. A.: surgical
20.
J. 77:123,
21.
Wolff, G. S., Rowland, T. W., and Ellison, R. C.: Surgically induced right bundle-branch block with left anterior hemiblock: an ominous sign in postoperative tetralogy of Fallot, Circulation 46:587, 1972. Moss, A. J., Klyman, G., and Emmanouilides, G. C.: Late onset complete heart block: newly recognized sequela of cardiac surgery, Am. J. Cardiol. 30:884, 1972. Wilson, F. N., and Herrmann, G.: Experimental study of incomplete bundle branch block and of the refractory period of the heart of the dog, Heart 8:229, 1921. Rosenbaum, M. R.: The hemiblocks: diagnostic criteria and clinical significance, Mod. Concepts Cardiovasc. Dis. 39:141, 1970. Rosenbaum, M. B., Elizari, M. V., and Lazzari, J. 0.: The hemiblocks, Oldsmar, Florida, Tampa Tracings, 1970. Unger, P. N., Lesser, M. E., Kugel, V. H., and Lev, M.: The concept of “masquerading” bundle-branch block: an electrocardiographic-pathologic correlation, Circulation i 7:397, 1958. Lenegre, J.: Etiology and pathology of bilateral bundle branch block in relation to complete heart block, Prog. Cardiovasc. Dis. 6:409, 1964. Trevino, A. J., and Beller, B. M.: Conduction disturbances of the left bundle branch system and their relationship to complete heart block, Am. J. Med. 51:362, 1971. Lasser, R. P., Haft, J. I., and Friedberg, C. K.: Relationship of right bundle-branch block and marked left axis deviation (with left parietal or peri-infarction block) to
22.
1969.
4.
5.
6.
7. a.
9.
IO.
11.
554
The clinical intraventricular
significance blocks,
Watt, T. B., Jr., and Pruitt, R. D.: Character, cause and consequence of combined left axis deviation and right bundle branch block in human electrocardiograms, AM.
HEART J. 77:460,1969. K. A.: block in closure,
3.
Pryor, R., and Blount, S. G., Jr.: of true left axis deviation. Left
AM. HEART J. 72:391,1966.
1. Kulbertus,
H. E., Coyne, J. J., and Hallidie-Smith, Left axis deviation with right bundle-branch ventricular septal defect before and after surgical Br. Heart J. 30:422, 1968. Kulbertus, H. E., Coyne, J. J., and Hallidie-Smith, Conduction disturbances before and after closure of ventricular septal defect, AM. HEART
complete heart block and syncope, Circulation 37:429, 1968. Scanlon, P. J., Pryor, R., Blount, S. G., Jr.: Right bundlebranch block associated with left superior or inferiol intraventricular block. Clinical setting, prognosis, and relation to complete heart block, Circulation 42:1123, 1970. Uhley, H. N., and Rivkin, L. M.: Electrocardiographic patterns following interruption of the main and peripheral branches of the canine left bundle of His, Am. J. Cardiol. 13:41, 1964. Watt, T. B., Jr., and Pruitt, R. D.: Electrocardiographic findings associated with experimental arborization block in dogs, AM. HEARTJ. 69:642,1965. Watt, T. B., Jr., Freud, G. E., Durrer, D., and Pruitt, R. D.: Left anterior arborization block in canine and primate hearts: an electrocardiographic study, Circ. Res. 22:57, 1968. Watt, T. B., Jr., Murao, S., and Pruitt, R. D.: Left axis deviation induced experimentally in a primate heart, AM.
23.
24.
25.
26.
27.
28. 29.
Kulbertus, H., and Collington, P.: Association of right bundle-branch block with left superior or inferior intraventricular block. Its relation to complete heart block and Adams-Stokes syndrome, Br. Heart J. 31:435, 1969. Davies, M., and Harris, A.: Pathological basis of primary heart block, Br. Heart J. 31:219, 1969. Lev, M.: Anatomic basis for atrioventricular block, Am. J. Med. 37:742, 1964. Lainesse, A., Singson, C., and Alexander, S.: Prognosis of right bundle branch block and marked axis deviation in an outpatient population, (Abst.) Am. J. Cardiol. 31:143, 1973. Kittle, C. F., Santos, E. M., and Dimond, E. G.: Persistent right bundle branch block due to pulmonic valvotomy and infundibulectomy, Am. Surg. 22:80, 1956. Samson, W. E., and Bruce, R. A.: Left vent,ricular parietal block produced by transventricular aortic commissurotomy, AM. HEART J. 63:41, 1962. Landtman, B., and Wolff, M. D.: Total correction of tetralogy of Fallot. II. Changes in the electrocardiogram following surgery, Circulation 3 1:394, 1965. Rosenbaum, M. B., Corrado, G., Oliveri, R., Castellanos, A., Jr., and Elizari, M. V.: Right bundle branch block with left anterior hemiblock surgically induced in tetralogy of Fallot. Relation to the mechanism of electrocardiographic changes in endocardial cushion defects, Am. J. Cardiol. 26:12, 1970. Chesler, E., Bick, W., and Schrire, V.: Left anterior hemiblock and right bundle branch block before and after surgical repair of tetralogy of Fallot, AM. HEART J. 84:45, 1972. Lev, M.: The architecture of the conduction system in congenital heart disease. II. Tetralogy of Fallot, Arch. Pathol. 67:572, 1959. Downing, J. W., Jr., Kaplan, S., and Bove, K. E.: Postsurgical left anterior hemiblock and right bundle-branch block, Br. Heart J. 34:263, 1972.
November,
1975, Vol. 90, No. 5
communications
Prognosis of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot John A. Cairns, M.D., F.R.C.P.(C) Anthony R. C. Dobell, M.D., C.M., F.R.C.S.(C), F.A.C.S. James E. Gibbons, M.D., C.M., F.A.A.P., F.A.C.C. Irving Tessler, M.D. Montreal,
Que.,
Canada
Right bundle branch block and left anterior hemiblock may be caused by intracardiac repair of tetralogy of Fallot. This was first reported by Kulbertus,‘. z in 1968; 8 per cent of his patients developed the combined lesion postoperatively, and he expressed concern about the possibility of late complete heart block and death in these patients. In 1972, papers by Wolff and associates” and by Moss and co-workers* drew attention to an alarming incidence of complete heart block of late onset and sudden death in these patients. This article reports on a series of patients who underwent intracardiac repair of tetralogy of Fallot, 22 per cent of whom developed right bundle branch block and left anterior hemiblock postoperatively. The purpose of the article is to document the benign prognosis in these patients postoperatively and in late follow-up, and to discuss these findings in relation to contrary reports in the literature. Methods
A review was made of clinical records and ECG’s of all patients who underwent open intracardiac repair of tetralogy of Fallot at the Montreal Children’s Hospital from January, 1958, to June, 1972. Patients who died within 1 month of operation were considered to be operaFrom the Department and McGill University, Originally presented College of Cardiology, Received
for publication
Reprints Victoria Canada.
requests: Hospital,
November,
of Cardiology, Montreal Montreal, Que., Canada.
Children’s
Hospital,
at the Annual Scientific Session, New York, N. Y., Feb. 11-14, 1974.
American
Sept. 20, 1974.
J. A. Cairns, M.D., Division of Cardiology, Royal 687 Pine Ave. West, Montreal H3A lA1, Que.,
1975, Vol. 90, NO. 5, pp. 549-554
tive deaths. On the basis of the ECG on hospital discharge, operative survivors were divided into four groups: (1) no bundle branch block-QRS width 0.08 second or less; (2) right bundle branch block-terminal slurred S wave in Lead I, R’ in Lead V, with QRS widening (incomplete 0.09 to 0.011 second, complete 0.12 second or greater); (3) right bundle branch block and left anterior hemiblock-right bundle branch block plus Q waves of 0.02 second in Leads I and aVL, mean QRS axis of unblocked forces -30 to -120 degrees, counterclockwise frontal plane vector loop (Figs. 1 and 2); (4) complete heart block-idioventricular pacemaker, with no conduction of supraventricular impulses, rate under 50 per minute. The post-hospital course and current status of patients were determined from review of clinic charts and ECG’s and by letter and telephone contact with doctors of patients not. followed in our clinic. The information was augmented by telephone contact with the family or patient. Results
A total of 178 patients underwent open operation; of these, 25 died, an operative mortality of 14 per cent (Table I). Of the 153 survivors, the preoperative and postoperative ECG’s were available for review on 141 (92 per cent). The 141 patients were distributed as outlined in Table II. The focus of this report is on the 31 patients (22 per cent) who developed right bundle branch block and left anterior hemiblock postoperatively. Among these 31 patients, only 2 developed a postoperative arrhythmia; in each it was complete heart block while coming off cardiopul-
American
Heart
FJournal
549
Cairns
et al.
AVL
I
Fig. 1. Selected ECG leads from Patient J. P. with tetralogy Postoperatively, age 4 years, now showing right bundle branch Q waves in Leads I and aV,, left axis deviation of unblocked loop.
I. Tetralogy of Fallot-intracardiac at Montreal Children’s Hospital, January, June, 1972
repair 195%
Table
Total patients Operative deaths survivolx survivors ECGs available
Table
178 25 (14%) 153 (86%) 153 141 (92%)
ECG one month
II.
postoperatively-141
patients No bundle branch block Right bundle branch block Right bundle branch block left anterior hemiblock Complete heart block
Table
Ill.
anterior
and
Right bundle branch hemiblock-31 patients
Postoperative arrhythmia Complete heart block-6 days Complete heart block, Nodal rhythm-7 days Late deaths Right ventricular failure-4 months Repeat operation-20 months survivors Average survival 67 months Range (148-12) Late arrhythmias-O CHB
550
= complete
heart
block.
27 (19%) 82 (58%) 31 (22%) l(
1%)
block and left 2
2
29
Ill
Vl
of Fallot. A, Preoperatively, age 4% months. B, block and left anterior hemiblock. Note 0.02-second forces, and counterclockwise frontal plane vector
monary bypass. In one, a 13-year-old girl, normal sinus rhythm with right bundle branch block and left anterior hemiblock returned after 6 days. In the other, a &year-old boy, complete heart block was present intermittently for only a few hours, to be replaced by a probable nodal rhythm, which resolved after 7 days. Both children had epicardial pacing wires and were paced as indicated until reliable normal sinus rhythm returned. Of the 31 patients with right bundle branch block and left anterior hemiblock postoperatively, 29 are alive at present (Table III), an average of 67 months after operation (range 148 to 12 months). There have been no reports of arrhythmias and no ECG evidence of complete heart block. All are doing well in terms of cardiac function as evidenced by physical examination and level of activities. Two patients have died late (Table III). The first of these was the 13-year-old girl who developed transient complete heart block postoperatively in 1960. Although normal sinus rhythm returned, digitalis was required for control of congestive heart failure. Digitalis was stopped before discharge 2 months postoperatively, but congestive heart failure returned after another 2 months. She was rehospitalized and died 3 weeks later of progressive congestive heart failure. There was no evidence of recurrence of complete heart block. This death was considered to be related to an incomplete intracardiac repair. The other patient was a boy, age 4 years at his initial
November,
1975, Vol. 90, No. 5
RBBB
Fig. 2. Complete Postoperatively,
ECG’s from age 4 years.
Patient
J. P. with
operation when severe infundibular stenosis was noted. Twenty months later, in 1966, reoperation was undertaken because of a persistent infundibular pressure gradient and a ventricular septal defect. He died during this second open operation. Thus, although two late deaths have occurred in this series of 31 patients, neither could be attributed to the presence of right bundle branch block and left anterior hemiblock. Discussion
The combined lesion of right bundle branch block and left anterior hemiblock has been well described and widely reported in the adult cardiology literature. In 1921, Wilson and Herrmann” reported that the pattern now recognized as right bundle branch block and left anterior hemiblock could be produced by interruption of the right bundle branch and the anterior fascicle of the left bundle branch. Subsequent reports have developed the diagnostic criteria,fi examined the
American
Heart
Journal
tetralogy
of Fallot.
A, Preoperatively,
and
left
mtericx
age 4% months.
hemiblock
B,
pathologic basis,i-l” discussed the etiologies,‘. I” and outlined the prognosis for this lesion.‘~ I*. l2 Two recent reports have reviewed all of these aspects of the combined lesion. There has been controversy over the exact diagnostic criteria for right bundle branch block and left anterior hemiblock. Criteria have applied to the initial 0.02-second vector, the mean QRS axis, the axis of unblocked forces, and the inscription of the frontal plane vector loop. The criteria chosen in the present study are adapted from those of Rosenbaum” and are consistent with those of many other reports in the literature. In general, there has been good correlation between the ECG evidence for right bundle branch block and left anterior hemiblock and the experimental interruption of the right bundle branch and left anterior fascicle in dogs’:‘-‘” and in primates.‘” I’: Postmortem human studies have revealed appropriately located lesions to explain antemortem right bundle branch block and left anterior hemiblock.‘, *. !‘. Ii
551
Cairns
et al.
Table IV. Prognosis of RBBB
and LAH
Transient postoperative CHB
t-
Author Cairns et al. Downing et al. Wolff et al. Moss et al.
Late CHB or SD
I
RBBB and LAH
Total
31
2
14
2
24
9
6 (67%)
3
3
3 (100%)
0
0
0
0
0
0
3 CHB 6SD 3 CHB
-
6 (67%) > 3 (100%)
12
9 (75%)
CHB = complete heart block; LAH = left anterior hemiblock; RBBB = right bundle branch block: SD = sudden death.
There are a number of etiologies of right bundle branch block and left anterior hemiblock in adults. The reported frequency of each etiology varies widely among several large series in the literature. Some authors have reported a high incidence of atherosclerotic coronary artery disease, postulating chronic ischemia and fibrosis of the conducting system.‘, *I. I*. I** I9 Others have found coronary artery disease is less common in these patients and attribute the block to a primary “sclero degenerative disease” of the bundle branches and Purkinje networkg. *O or to “sclerosis of the left side of the cardiac skeleton.“2’ Still others have considered the etiological roles of hypertension,“* I2 aortic valve disease,G previous myocarditis,‘, z0 and cardiomyopathy.” The prognosis of these patients has not yet been fully delineated. However, when combined right bundle branch block and left anterior hemiblock develops outside the setting of acute myocardial infarction, the prognosis is reasonably good. The incidence of complete heart block has been reported at 10 per cent during an unspecified period of follow-up by Lasser and associates,” 6 per cent by Rosenbaum and associates,7 and 13.6 per cent during an average 18.9-month follow-up by Scanlon and associates.‘* The life expectancy for this group may be no different from that of other patients in this age group who require an electrocardiogram.”
552
The surgical creation of right bundle branch block was first reported by Kittle and co-workersz3 in 1956, after repair of pulmonic stenosis, whereas left anterior hemiblock (then described as left ventricular parietal block) was first reported by Samson and Bruce2’ in 1962, after transventricular aortic commissurotomy. The combined lesion of right bundle branch block and left anterior hemiblock (then described as left superior intraventricular block) was first documented by Kulbertus’ in 1968, after repair of ventricular septal defect and tetralogy of Fallot. Several authors have since drawn attention to the occurrence of the combined lesion after intracardiac repair of tetralogy of Fallot.‘?, z,. X. y7 Lev”” and Rosenbaum and associatesz6 have described the conduction system and its relation to the ventricular septal defect in tetralogy of Fallot. The left posterior fascicle separates from the A-V bundle at the posterior angle of the defect relatively well removed from the vicinity of the repair. The left anterior fascicle and right bundle branch continue along the inferior margin of the defect and are at risk of damage from edema, inflammation, hemorrhage, or suture. The combined lesion of right bundle branch block and left anterior hemiblock develops with a reported incidence that varies from 7 per cent” to 10.7 per cent,29 and 22 per cent in the present series. There are only three previously published series which report late follow-up of right bundle branch block and left anterior hemiblock after open operation for tetralogy of Fallot. In two of theses, 4 there was a high incidence of complete heart block and sudden death. In the third,‘” as in the present series, neither occurred. We have analyzed these reports in an attempt to explain these differences. In the adult, complete heart block occurs when the progressive disease which involves the right bundle branch and left anterior fascicle extends into the distal His bundle or left posterior fascicle. In the child undergoing intracardiac repair of tetralogy, the right bundle branch and left anterior fascicle are at risk of damage, and right bundle branch block and left anterior hemiblock may appear. However, once healing of the operative wound has occurred and there has been no evidence of trifascicular damage, one might reasonably expect no progression of the conduction disorder-since no progressive disease is present. We considered whether some of these patients might have trifascicular
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1975, Vol. 90, No. 5
RBBB
disease in the postoperative period, and whether these were the patients at high risk for late complete heart block and sudden death. The four series are analyzed in Table IV. In the present series, and in that of Downing and associates,z!’ transient postoperative complete heart block developed in only 2 of 31 and 2 of 14 patients, respectively. There were no episodes of late complete heart block or sudden death. In Wolff and associates’ series” of 24 patients, transient postoperative complete heart block occurred in 9, 6 of whom went on to develop late complete heart block or to die suddenly. A total of 9 patients developed late complete heart block or died suddenly: 6 had had transient complete heart block postoperatively, and 3 had had no previous arrhythmias. Moss and associates4 in their series had 10 patients with tetralogy of Fallot in whom complete heart block of late onset developed. Of these 10, only 3 had had right bundle branch block and left anterior hemiblock, and all 3 had had transient postoperative complete heart block. Thus, of 12 reported cases of complete heart block of late onset or sudden death in patients with right bundle branch block and left anterior hemiblock, in 9 (75 per cent), transient complete heart block was noted in the postoperative period. The process by which complete heart block resolves, only to recur at some later date, can only be postulated. However, it is reasonable to suppose that once the left posterior fascicle is damaged and complete heart block occurs, even though resolution of acute inflammation and edema allows conduction to resume through this fascicle, an ongoing process of fibrosis may be initiated which will eventually lead to permanent complete heart block. The electrophysiologic correlate of such a sequence would be prolongation of the HV interval during normal sinus rhythm, and block distal to the His deflection after development of late complete heart block. Clearly, those children with transient postoperative complete heart block and residual right bundle branch block and left anterior hemiblock require close clinical and ECG follow-up. Consideration should be given to studies of the bundle of His in order to delineate the conduction status of the left posterior fascicle. The documentation of HV conduction delay would suggest a high risk for the development of late-onset complete heart block. However, the magnitude of this risk and,
American
Heart
Journal
and kjt onterror’
hemibloch
consequently, the role for prophylactic pacing in such children remain to be more clearly defined. The present series and that of Downing and associates indicate that the occurrence of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot does not of itself carry a high risk of late complete heart block or sudden death. Our conclusion from the series of Wolff and of Moss and co-workers is that the critical factor in a bad late prognosis in patients with postoperative ECG evidence of right bundle branch block and left anterior hemiblock may be the history of transient postoperative complete heart block-indicative: of trifascicular disease in this setting. Summary
One hundred and forty-one survivors of intracardiac repair of tetralogy of Fallot, (TOF), operated on between 1958 and 1972, were studied in order to document the incidence of right bundle branch block and left anterior hemiblock (RBBB and LAH) and to define the late prognosis. RBBB and LAH occurred in 31 patients (22 per cent), all of whom have had complete follow-up. Transient complete heart block (CHB) occurred postoperatively in 2 patients; there were no other significant arrhythmias. Two late deaths have occurred, neither from arrhythmia (one from progressive congestive heart failure, and the other from attempted reclosure of a ventricular septal defect). The remainder of the patients are well an average of 76 months postoperatively (range, 144 to 12 months). The absence of late-onset CHB or sudden death in this series contrasts with the relatively high incidence of these events in some studies of RBBB and LAH after intracardiac repair of TOF. However, in those reports a history of transient postoperative CHB (indicative of trifascicular disease in this setting) can be found in 75 per cent of those who developed late-onset CHB or died suddenly. We conclude that the occurrence of RBBB and LAH after intracardiac repair of TOF does not of itself carry a bad late prognosis. The critical factor in a bad late prognosis in patients with ECG evidence of RBBB and LAH may be the history of transient postoperative CHB. Addendum
Since the preparation of this report and its presentation in abstract form, Godman and asso-
553
Cairns
et al.
ciates have published similar conclusions (Circulation 49:214-221, 1974). They studied 14 patients with postoperative right bundle branch block and left anterior hemiblock. Four of those patients developed late-onset complete heart block, all 4 of them having had transient postoperative complete heart block. Studies of the bundle of His placed the block distal to the bundle of His in all 4. Six additional patients of the group had had transient postoperative complete heart block, and in 5 of the 6 the HV time was prolonged. Transient postoperative complete heart block was judged to identify a group of patients with postoperative right bundle branch block and left anterior hemiblock at particularly high risk of developing late-onset complete heart block.
12.
13.
14. 15.
16.
HEARTJ. 70:381, 1965. 17.
We thank Miss Lorraine Brown for secretarial assistance and help with translation and interviews of families and patients. We also thank Mrs. Ellen Simon for secretarial assistance during the initial phases of the study.
ia.
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