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Unusual forms of second-degree atrioventricular block, including Mobitz Type-II block, associated with the Morgagni-Adams-Stokes syndrome
Clinic al c ommunic
ations
Unusual forms of second-degree atrioventri+uiar block, including Mobitr Type-II block, associated with the Morgqpri-Adams-Stokes syndrome Ephraim Donoso, M.D.* Lawrence N. Adler, M.D.** Charles K. Friedberg, M.D. New York, N. Y.
T
he Morgagni-Adams-Stokes (M-A-S) syndrome occurs most frequently with complete heart block’-4 and rarely with sinus bradycardia.4-6 However, between attacks the electrocardiogram often discloses varying degrees of second-degree heart block, especially 2:l block, or only first-degree heart block with bundle branch block. In a review of 100 consecutive cases of M-A-S syndrome over a period of 15 years from 1946 to 1961, at The Mount Sinai Hospital, New York, several forms of second-degree atrioventricular (A-V) block were noted which are generally regarded as being unusual. There were 3 cases of Mobitz Type-II block in our series, and 7 additional cases were reviewed from the literature.7-10 Two patients in our series demonstrated 2:l A-V block with A-V interference associated with the M-A-S syndrome, and 8 patients had advanced or high degrees of A-V block. This report deals with the clinical and electrocardiographic manifestations and the prognostic significance of these uncommon forms of second-degree heart block. From The Received *Address Sinai **Present Medical
Mobitr Type-II block There are two forms of Mobitz atrioventricular block. Mobitz Type I is commonly termed the “Wenckebach phenomenon.” Mobitz Type II has not been consistently defined since the original publications of Mobitz on this subject.7,i1 The classification into Types I and II actually corresponded to Wenckebach’s division of second-degree block. l2 In Type I, according to Wenckebach’s concept, dropped beats were presumed to be due to impaired atrioventricular conduction, as indicated by a prolonged P-R interval (actually a prolonged a-c interval in the jugular pulse). In Type II, dropped beats were presumed to be due to impairment of ventricular excitability, since the P-R interval was within normal limits. Subsequent evidence revealed that, despite the normal P-R interval, cases of Type-II second-degree heart block were also associated with lesions in the bundle of His and presumably with impaired atrioventricular conduction. In the original reports of Mobitz,‘,” Type II included second-degree block of varied severity, e.g., 2:l and more advanced heart
Division of Cardiology, The Department of Medicine, The Mount for publication April 15. 1963. correspondence to Ephraim Donoso, M.D., Division of Cardiology, Hospital, 11 East 100th St., New York 29. N.Y. address: Thorndike Memorial Laboratory, Boston City Hospital. School. Boston, Mass.
Sinai
Hospital,
New
Departmentof and
Department
York,
Medicine. of Medicine,
N. Y. The Mount Harvard
Unusual! forms
of second-degree atrioventricular
block
151
Fig. 1. Mobitz Type-II block. S,B,C, Patient No. 1, J. H. (Table I): A demonstrates 3:2 Mobitz Type-II block in which the P-P and P-R intervals are fixed. Following every third P wave the ventricular beat is dropped. B demonstrates a 65 Mobitz Type-II block in Lead VS and 7:6 ventricular response in Lead Vs. C was taken 20 days later, and again shows 3:2 and 5:4 Mobitz Type-II block. D, Patient No. 2, G. K. (Table I): Demonstrates regular sinus rhythm before development of 3:2 and a 2:l Mobitz Type-II block. E, Patient No. 3, S. S. (Table I): Shows a 4:3 Mobitz Type-II block.
Fig. 2. 2:l A-V block with A-V dissociation. Patient No. 1 (Table II). The bottom tracing is an example of 2:l A-V block with A-V dissociation. The atria1 rate is almost twice the ventricular rate, and the P waves can be noted marching to the right in relation to the QRS complexes. The second and the last QRS complexes are examples of ventricular capture beats. The QRS complexes are supraventricular in form. The tracing at the top shows ventricular fibrillation, followed by ventricular tachycardia in the middle tracing. The third complex from the end in the middle tracing is a ventricular escape beat, and the last one is a ventricular capture beat.
152
Donoso, Adler, and Friedberg
block, provided that the P-R interval was normal. In recent times,s-10 and in this communication, Mobitz Type-II block has been more strictly delimited to that form of second-degree A-V block in which the P-R and P-P intervals are fixed and a single ventricular beat is dropped at intervals without warning, resulting in a 3:2 or 4:3 or 65, etc., ventricular response.’ This unusual form of atrioventricular block is of special interest because of the consistent occurrence of Adams-Stokes syndrome in patients with this type of conduction disturbance, and because an ominous prognosis has been attributed to it.g Data on the 3 patients in our series who manifested Mobitz Type-II block transiently are presented in Table I. In only 1 patient (No. 1, J.H.) did the 3:2 block persist throughout the entire electrocardiogram. In subsequent records in this case there were 5:4, 6:5, and 7:6 ratios of Mobitz block (Fig. l,A, B, C) before complete heart block developed. This patient had a severe form of the M-A-S syndrome with frequently changing degrees of heart
Table I. ill obitz Type-II
Author
I
Mobitz’ Spang* Kaufman,
et aLg
D.C.
KatzlO
This
NSR:
(a) (b) (cl series No. 1
J.H.
No.
2
G.K.
No.
3
S.S.
Normal
sinus
rhythm.
1). In Patient No. 3 (S.S., Table I) there was a regular sinus rhythm with right
A- V block
ECG
~ Mobi~o?pe-II
~
55, M 3:2 A-V block to CHB 45, M 2:l and 3:2 A-V block 41, M CHB to 3:2 Mobitz with diaphragmatic myocardial infarction and RBBB 67, M NSR with tall Rvl and wide QRS plus left axis deviation (on admission) to Mobitz Type-II block Not demonstrated Not demonstrated Not demonstrated
312, 4:3 312 3:2
NSR NSR 3:2 Mobitz persisted
62, M NSR with RBBB to Mobitz 67, F NSR with RBBB to 3:2 Mobitz with RBBB
3:2, 5:4, 65,
Patied
J.C.R.
block, and he remained in the hospital 6 months. He died suddenly 1 year later at home. Patient No. 2 (G.K., Table I) had a transient 3:2 Mobitz Type-II block (Fig. 1,D). Her electrocardiogram returned to regular sinus rhythm before complete heart block developed. She had frequent M-A-S attacks, but the electrocardiogram eventually returned to regular sinus rhythm after periods of incomplete and complete ,‘2-V block. Her disease became so severe that it was necessary to implant an internal cardiac pacemaker. She is still alive 2 years after the onset of the M-A-S syndrome, and 7 months after the pacemaker was installed. Before the development of complete heart block, both Patients No. 1 and Ko. 2 had a right bundle branch block. With complete heart block their electrocardiograms showed QRS patterns of both right and left bundle branch block. The characteristic similarity in these 2 cases was the frequently changing block (Table
68, M NSR with RBBB to 2:l with RBBB to Mobitz CHB:
Complete
heart
block.
ASHD:
5~4, 4~3, 3~2
Changed
to
1 :if)
0.36 0.16
0.20
CHB
0.24 0.26 0.24
3~2, 4:3 65 2~1, 312, 4~3 7:6
3:2
4:3
Atherosclerotic
heart
disease.
0.20
NSR to CHB with LBBB 2 :l to NSR to CHB with RBBB and LBBB NSR with RBBB
RBBB:
Right
bundle
0.20
0.12
branch
block.
i~‘ol~tme 67 Nurnbcr 2
Unusuab forms
bundle branch block, 2:l A-V block, and 4:3 Mobitz Type-II block on different occasions (Fig. 1,E). Regular sinus rhythm reappeared and persisted. This patient has had a milder course than did the other 2 patients, and he is still alive 6 months after discharge from the hospital. All 3 patients with Mobitz Type-II block demonstrated other forms of incomplete A-V block, and in no instance did the second-degree A-V block persist. The etiology in Patient No. 1 was coronary heart disease. The other 2 patients, one aged 67 years and the other 68, had no evidence of angina pectoris, myocardial infarction, hypertension, or valvular heart disease and, therefore, are classified as having heart block of unknown etiology. Seven cases of Mobitz Type-II block have been recorded in the literature available to us.‘-lo In addition, Wenckebach published jugular and radiopulse tracings which indicate occasional dropped beats with a normal, constant a-c interval, but no electrocardiograms and no clinical history are given.12 Three out of 100 patients in our series with M-A-S syndrome
CL:)
)
0.48 0.68-0.74 0.63
(f$
1 $2
0.68-0.70 0.63
0.64
0.64
1 szize
)
of second-degree atrioventricdar
Severity
)
Survived Survived Survived, remained asymptomatic with a 3:2 Mobitz block
Not commented on ASHD ASHD with acute MI
0.16
Yes
Several severe attacks
Died
Cor pulmonale
No clinical No clinical No clinical Yes
Severe
0.60
0.60
0.12
Yes
Severe
0.64
0.64
0.12
Yes
Mild
block.
Etiology
No follow-up Not mentioned 50 attacks in a few days
0.14
branch
1
Yes Yes Yes
0.68
bundle
Course
Wide 0.16 0.13
0.68
Left
153
presented this form of block. The A-V ratios in these 3 cases were 3:2, 4:3, 5:4, 65, and 7:6. None of the Mobitz Type-II blocks observed by us or reported by others persisted, except in the case of 3:2 block reported by Kaufman and associates.g The M-A-S syndrome occurred in 7 of the 10 cases of Mobitz block. In the other 3 cases or electrocardiograms depicted in the monograph on arrhythmias by Katz and PicklO there are no clinical data, and we do not know whether the patients experienced M-A-S attacks. Thus, the M-A-S syndrome has occurred in all cases of Mobitz Type II in which the clinical history was reported, and it would be of interest to observe whether this is an invariable association or whether Mobitz Type-II block occurs independently in patients who never experience M-A-S attacks. No specific pattern for Mobitz Type-II block exists, since the ventricular beats drop out without warning. Eight examples of 3:2, four of 4~3, two of 5:4 and of 65, and one each of 7:6 and 4:3 A-V block occurred in the 10 patients. The patients
0.08 0.12 0.14
LBBB:
block
data data data
Survived hospital. Died 1 year later Survived but required internal pacemaker Survived
Coronary Unknown
Unknown
heart
disease
with 65 and 7:6 A-V block are the first examples of these ratios to be reported. In all but one case the QRS complex was widened. The sudden dropping out of the QRS has been attributed to a prolongation of the absolute refractory period of the A-V bundle; the relative refractory period is unchanged.7r’o The serious prognostic significance which has been attached to this type of A-V conduction7jg is justified to the extent that it has been associated with the M-A-S syndrome. However, we cannot conclude that the outlook differs from that in other cases of A-V block with M-A-S syndrome, since all 3 patients with Mobitz Type-II block survived the period of hospitalization. Two of the 3 patients are still alive 6 and 30 months after the onset of their disease, but 1 patient died within 12 months after the M-A-S syndrome developed. An awareness of this condition, plus more frequent and longer electrocardiographic tracings will probably disclose more esamples of Mobitz Type-II block and provide more definite information as to its clinical and prognostic significance. 2:l A-V block with A-V interference dissociation
III this arrhythmia the atria and ventricles respond to independent pacemakers (A-V dissociation), not because of depressed A-V conduction, as in complete heart block, but because the A-V node or the ventricles are usually refractory when the sinus impulse arrives (interference). Occasionally, the sinus impulse arrives at a nonrefractory period and elicits a ventricular response (capture beat). However, in addition to such interference dissociation, there is a concomitant depression of the atrioventricular bundle which would have resulted in 2:l A-V block if there were not a simultaneous interference with conduction due to the refractory period when the atria1 impulse arrives. The criteria employed for the diagnosis of 2:l A-V block with A-V interference dissociation13 are: (1) a ventricular rate greater than 30 per minute with a constant R-R interval; (2) an atria1 rate which is a multiple of the ventricular rate and almost double its frequency; (3) a “supraventricular” form of QRS of less than O.lO-second
duration; (4) the presence of‘ velrtricular capture beats; (5) a minimum critical R-P interval (absolute refractor)- period) which is constant; and (6) no retrograde V-A conduction. The minimum critical R-P interval is the minimum required time between a conducted sinus impulse and the immediately preceding automatic A-V nodal beat. Two patients out of 100 in our series fulfilled these criteria. Patient No. 1 had a changing heart block with periods of 2:1 A-V block, COIIIplete heart block, and regular sinus rhythm, as well as 2:l A-V block with A-V dissocintion. The atria1 rate was 6.5 per minute, and the ventricular rate was 33 with a minimal critical R-P interval of 1.02 seconds and QRS duration of 0.10 second. Her course was marked b!. recurrent M-A-S attacks due to ventricular tachycardia and fibrillation, but her electrocardiogram continually reverted to regular sinus rhythm (Fig. 2). Patient No. 2 had a milder course. The atria1 and ventricular rates were 83 and 40 per minute, respectively, with an R-P interval of 0.66 second and QRS of 0.10 second. Both patients had ventricular capture beats, but no retrograde conduction. One patient had hypertensive and coronary heart disease,whereas the etiology of the cardiac disease in the second patient was unknown. One patient died 3 years after the onset of the M-A-S syndrome, whereas the other patient is still alive at a 3-year follow-up. .Uthough there is some controversy as to the interpretation of such cases,14s15 we believe that 2:l LA-V block with A-V dissociation is a distinct entity-, and have 2 cases out of 100 in this series which fulfill the criteria. They did not present a clinical picture which differed from that in other forms of heart block. ,L\lthough digitalis is reported to be a cause of 2:l ;\-V block with A-V dissociation,13 neither of these patients had received digitalis. Advanced
atrioventricular
block
Advanced or high-grade atrioventricular block is a form of second-degree heart block in which several successive atria1 impulses are blocked, resulting in an A-V ratio of more than 2:1, usually 4:l and 6:1, whereas the odd-numbered forms, 3:l and 5 :l, are generally regarded as being
rare. Usually, the ventricular rate is below 50 per minute,6J0 and there may be atria1 flutter or tachycardia. Eight out of 100 patients demonstrated high degrees of A-V block: 3:l A-V block occurred in all 8 ; in 2 there was also 4:l block, and in 1, 5:l A-V block (Table II). These multiples of A-V block were Table II. Advanced A-V
Patient
1. O.P. 2. J.H.
3. ,4.P.
4. R.R. 5. D.S. 6. J.K. 7. E.O. 8. W.L.
block
Severity of M-A-S syndrome
3:l
ASHD
Severe
2%
Yes
3:l
ASHD
Severe
Yes
ASHD
No
3:l 4:l 5:l 3:l 4:l 3:l
NO
BBB
2:1, 3:l A-V block to CHB with LBBB NSR with RBBB, 2:1, 3:l and Mobitz TypeII to CHB to NSR with lst-dgrree block NSR with LBBB to 2:1, 3:1, 4:1, 5:l to CHB to NSR NSR with LBBB to 3:1, 4:l to CHB NSR with RBBB to 2:1, 3:l to CHB to NSR CHB to 2:1, 3:l to NSR with RBBB 2:1, 3:l with RBBB to CHB 2~1, 3:1 with RBBB to CHB
Yes
as in Table
Form of advanced A-V block
Etiology
ECG
*Died 6 months later at home. tDied 12 months later at home. H: Hypertension. Other abbreviations
transient in every case, and each patient demonstrated complete heart block during his course (Fig. 3,A and B). Four patients (50 per cent) remained in complete heart block, and the other 4 (50 per cent) resumed a normal sinus rhythm. In all 8 cases the electrocardiogram showed a bundle branch block pattern: in 3 there
Duration of M-A-S syndrome
Course in hospital
No
Survived
6 mo.
No
Survived*
Severe
4 yr.
No
Survived*
ASHD
Severe
4 wk.
No
Died
Moderate
1 yr.
No
Survived
3:l
H and ASHD ASHD
Moderate
2 wk.
No
‘Survivedt
NO
3:l
Unknown
Severe
1 wk.
Yes
Died
No
3:t
H and ASHD
Moderate
3% yr.
No
Survived for 3 yr. (follow up)
IN0
yr.
Patient on digitalis
I.
Fig. 3. Advanced A-V block. Patient No. 3, A.P. (Table II). A demonstrates a 3:l A-V block which subsequently developed into complete heart block. B shows A-V block starting at 5:1, decreasing to 4:1, and then 3 :t in the same lead.
was left bundle branch block, and in 5, right bundle branch block in association with the high-grade A-V block. In 2 of the patients there was an incomplete A-V block with right bundle branch block, and later a left bundle branch block pattern of the QRS with complete heart block developed. A third patient had left bundle branch block initially, but this changed to a right bundle branch block pattern with complete heart block. Although all of these patients had moderate to severe M-A-S syndrome, only 2 (25 per cent) of the 8 died in the hospital. Three patients died within 1 year after discharge, and the other 3 are still alive after 1 year, 1 year, and 3% years, respectively. With one exception, they all had coronary heart disease, and 2 patients were also hypertensive. In only 1 did advanced A-V block develop as a result of digitalis, which is usually considered to be a common cause of this condition. Although the odd-numbered forms of advanced A-V block are considered to be rare,2Jo 8 patients in our series demonstrated a 3:l A-V block, and 2 of them also had 4:l block, and 1 had 5:l block. Xo example of 6:l A-V block was noted. Therefore, in this series the odd-numbered forms are more common than the evennumbered types. This may be coincidental, but it is also possible that the odd-numbered forms of advanced heart block are unstable, relative to the even-numbered forms, and may be more likely to be complicated by pacemaker failure and M-A-S. These advanced degrees of block were all transient and progressed to complete heart block. All of the patients had a moderate to severe M-A-S syndrome. The prognosis in high-grade A-V block is usually considered to be poor. Two of the 8 patients (2.5 per cent) died in the hospital, and 3 more died at home within 1 year after disof 62.5 per charge, for a total mortality cent in the group with advanced A-V block. Only 1 patient developed this heart block from digitalis, which is a frequent cause of partial block. Summary
Several unusual forms of second-degree atrioventricular block associated with the
.\iIorgagni-Adams-Stokes (M-ALs) S)‘lldrome are discussed. Three out of 100 patients with the M-A-S syndrome demonstrated a transient Mobitz Type-II block. Seven additional cases are reviewed from the literature. All of the patients had frequently changing degrees of heart block, and in only 1 patient did the Mobitz TypeII block persist. In all cases in which a clinical history is available, Mobitz TypeII block was associated with an AdamsStokes syndrome. Although a particularly poor prognosis has been indicated for this type of block, the outlook appeared to be no different from that in other cases of M-il-S syndrome in our series. On the other hand, Mobitz Type-II block is of prognostic importance if it indicates that the M-A-S syndrome is likely to develop. Two patients who had 2:l X-V block with A-V interference dissociation presented with the M-A-S syndrome. Neither of these cases was caused by escessive administration of digitalis. Eight patients had advanced or highgrade A-V block related to their M-A-S syndrome. All of them subsequently developed complete heart block. Although odd-numbered ratios of advanced heart block are said to be rare, such forms were present in all 8 cases, whereas 4:l block was present in only 2 cases. This may indicate that M-A-S syndrome is more likely to occur in the odd-ratio type of advanced heart block. Awareness that these unusual forms of second-degree block are associated with M-A-S syndrome may enable the prediction of later development of complete heart block and M-A-S syndrome. REFERENCES 1. Graybiel, A., and White, P. D.: Complete A-V dissociation, AM. HEART J. 52:369, 1956. 2. Campbell, M.: Complete heart block, Brit. Heart J. 6:69, 1944. 3. Penton, G. B., Miller, H., and Levine, S. A.: Some clinical features of complete heart block, Circulation 13:801, 1956. 4. Adler, L. N., Donoso, E., and Friedberg, C. K.: The clinical and electrocardiographic manifestations of 100 cases of Adams-Stokes syndrome over a lS-year period. (In preparation.) 5. Lawrence, J. S., and Forbes, G. W.: Paroxysmal heart block and ventricular standstill, Brit. Heart J. 6:53, 1944. 6. Gilchrist, M. R.: High-grade heart block, Scottish M. J. 3:158, 1958.
Volume 67
Number
7. 8. 9.
10.
11.
2
Unusual forms of second-degree atrioventricular
Mobitz, W.: Uber den partiellen Herzblock, Ztschr. klin. Med. 107:449. 1928. Spang, K.: Rhythmusstijrungen des Herzens, Stuttgart, 1957, Georg Thieme Verlag. Kaufman, J. G., Wachtel, F. W., Rothfield, E., and Bernstein, A.: The association of complete heart block and Adams-Stokes syndrome in two cases of Mobitz type block, Circulation 22:253, 1961. Katz, L. N., and Pick, A.: Clinical electrocardiography. Part I. The arrhythmias, Philadelphia, 1956, Lea & Febiger. Mobitz, W.: Uber die unvollstandige Storung der ErregungsiiberIeitung zwischen Vorhof und Kammer des menschlichen Herzens, Ztschr. ges. exper. Med. 40-41:180, 1924.
12.
block
157
Wenckebach, K. F.: Beitrage zur Kenntnis der menschlichen Herztatigkeit, Arch. f. Anat. Physiol. Phys. Abt., p. 297, 1906, Supplement. 13. Jacobs, D. R., Donoso, E., and Friedberg, C. K.: A-V dissociation-a relatively frequent arrhythmia, Medicine 40:101, 1961. 14. Dressler, W., Roesler, H., and Specter, L. S.: Dissociation with interference in the presence of 2:l atrioventricular block, AM. HEART J. 44:238, 1952. 15. Magri, G.: Dissociation with interference in the presence of partial A-V block, Acta cardiol. 8:529, 19.53.
ations
Unusual forms of second-degree atrioventri+uiar block, including Mobitr Type-II block, associated with the Morgqpri-Adams-Stokes syndrome Ephraim Donoso, M.D.* Lawrence N. Adler, M.D.** Charles K. Friedberg, M.D. New York, N. Y.
T
he Morgagni-Adams-Stokes (M-A-S) syndrome occurs most frequently with complete heart block’-4 and rarely with sinus bradycardia.4-6 However, between attacks the electrocardiogram often discloses varying degrees of second-degree heart block, especially 2:l block, or only first-degree heart block with bundle branch block. In a review of 100 consecutive cases of M-A-S syndrome over a period of 15 years from 1946 to 1961, at The Mount Sinai Hospital, New York, several forms of second-degree atrioventricular (A-V) block were noted which are generally regarded as being unusual. There were 3 cases of Mobitz Type-II block in our series, and 7 additional cases were reviewed from the literature.7-10 Two patients in our series demonstrated 2:l A-V block with A-V interference associated with the M-A-S syndrome, and 8 patients had advanced or high degrees of A-V block. This report deals with the clinical and electrocardiographic manifestations and the prognostic significance of these uncommon forms of second-degree heart block. From The Received *Address Sinai **Present Medical
Mobitr Type-II block There are two forms of Mobitz atrioventricular block. Mobitz Type I is commonly termed the “Wenckebach phenomenon.” Mobitz Type II has not been consistently defined since the original publications of Mobitz on this subject.7,i1 The classification into Types I and II actually corresponded to Wenckebach’s division of second-degree block. l2 In Type I, according to Wenckebach’s concept, dropped beats were presumed to be due to impaired atrioventricular conduction, as indicated by a prolonged P-R interval (actually a prolonged a-c interval in the jugular pulse). In Type II, dropped beats were presumed to be due to impairment of ventricular excitability, since the P-R interval was within normal limits. Subsequent evidence revealed that, despite the normal P-R interval, cases of Type-II second-degree heart block were also associated with lesions in the bundle of His and presumably with impaired atrioventricular conduction. In the original reports of Mobitz,‘,” Type II included second-degree block of varied severity, e.g., 2:l and more advanced heart
Division of Cardiology, The Department of Medicine, The Mount for publication April 15. 1963. correspondence to Ephraim Donoso, M.D., Division of Cardiology, Hospital, 11 East 100th St., New York 29. N.Y. address: Thorndike Memorial Laboratory, Boston City Hospital. School. Boston, Mass.
Sinai
Hospital,
New
Departmentof and
Department
York,
Medicine. of Medicine,
N. Y. The Mount Harvard
Unusual! forms
of second-degree atrioventricular
block
151
Fig. 1. Mobitz Type-II block. S,B,C, Patient No. 1, J. H. (Table I): A demonstrates 3:2 Mobitz Type-II block in which the P-P and P-R intervals are fixed. Following every third P wave the ventricular beat is dropped. B demonstrates a 65 Mobitz Type-II block in Lead VS and 7:6 ventricular response in Lead Vs. C was taken 20 days later, and again shows 3:2 and 5:4 Mobitz Type-II block. D, Patient No. 2, G. K. (Table I): Demonstrates regular sinus rhythm before development of 3:2 and a 2:l Mobitz Type-II block. E, Patient No. 3, S. S. (Table I): Shows a 4:3 Mobitz Type-II block.
Fig. 2. 2:l A-V block with A-V dissociation. Patient No. 1 (Table II). The bottom tracing is an example of 2:l A-V block with A-V dissociation. The atria1 rate is almost twice the ventricular rate, and the P waves can be noted marching to the right in relation to the QRS complexes. The second and the last QRS complexes are examples of ventricular capture beats. The QRS complexes are supraventricular in form. The tracing at the top shows ventricular fibrillation, followed by ventricular tachycardia in the middle tracing. The third complex from the end in the middle tracing is a ventricular escape beat, and the last one is a ventricular capture beat.
152
Donoso, Adler, and Friedberg
block, provided that the P-R interval was normal. In recent times,s-10 and in this communication, Mobitz Type-II block has been more strictly delimited to that form of second-degree A-V block in which the P-R and P-P intervals are fixed and a single ventricular beat is dropped at intervals without warning, resulting in a 3:2 or 4:3 or 65, etc., ventricular response.’ This unusual form of atrioventricular block is of special interest because of the consistent occurrence of Adams-Stokes syndrome in patients with this type of conduction disturbance, and because an ominous prognosis has been attributed to it.g Data on the 3 patients in our series who manifested Mobitz Type-II block transiently are presented in Table I. In only 1 patient (No. 1, J.H.) did the 3:2 block persist throughout the entire electrocardiogram. In subsequent records in this case there were 5:4, 6:5, and 7:6 ratios of Mobitz block (Fig. l,A, B, C) before complete heart block developed. This patient had a severe form of the M-A-S syndrome with frequently changing degrees of heart
Table I. ill obitz Type-II
Author
I
Mobitz’ Spang* Kaufman,
et aLg
D.C.
KatzlO
This
NSR:
(a) (b) (cl series No. 1
J.H.
No.
2
G.K.
No.
3
S.S.
Normal
sinus
rhythm.
1). In Patient No. 3 (S.S., Table I) there was a regular sinus rhythm with right
A- V block
ECG
~ Mobi~o?pe-II
~
55, M 3:2 A-V block to CHB 45, M 2:l and 3:2 A-V block 41, M CHB to 3:2 Mobitz with diaphragmatic myocardial infarction and RBBB 67, M NSR with tall Rvl and wide QRS plus left axis deviation (on admission) to Mobitz Type-II block Not demonstrated Not demonstrated Not demonstrated
312, 4:3 312 3:2
NSR NSR 3:2 Mobitz persisted
62, M NSR with RBBB to Mobitz 67, F NSR with RBBB to 3:2 Mobitz with RBBB
3:2, 5:4, 65,
Patied
J.C.R.
block, and he remained in the hospital 6 months. He died suddenly 1 year later at home. Patient No. 2 (G.K., Table I) had a transient 3:2 Mobitz Type-II block (Fig. 1,D). Her electrocardiogram returned to regular sinus rhythm before complete heart block developed. She had frequent M-A-S attacks, but the electrocardiogram eventually returned to regular sinus rhythm after periods of incomplete and complete ,‘2-V block. Her disease became so severe that it was necessary to implant an internal cardiac pacemaker. She is still alive 2 years after the onset of the M-A-S syndrome, and 7 months after the pacemaker was installed. Before the development of complete heart block, both Patients No. 1 and Ko. 2 had a right bundle branch block. With complete heart block their electrocardiograms showed QRS patterns of both right and left bundle branch block. The characteristic similarity in these 2 cases was the frequently changing block (Table
68, M NSR with RBBB to 2:l with RBBB to Mobitz CHB:
Complete
heart
block.
ASHD:
5~4, 4~3, 3~2
Changed
to
1 :if)
0.36 0.16
0.20
CHB
0.24 0.26 0.24
3~2, 4:3 65 2~1, 312, 4~3 7:6
3:2
4:3
Atherosclerotic
heart
disease.
0.20
NSR to CHB with LBBB 2 :l to NSR to CHB with RBBB and LBBB NSR with RBBB
RBBB:
Right
bundle
0.20
0.12
branch
block.
i~‘ol~tme 67 Nurnbcr 2
Unusuab forms
bundle branch block, 2:l A-V block, and 4:3 Mobitz Type-II block on different occasions (Fig. 1,E). Regular sinus rhythm reappeared and persisted. This patient has had a milder course than did the other 2 patients, and he is still alive 6 months after discharge from the hospital. All 3 patients with Mobitz Type-II block demonstrated other forms of incomplete A-V block, and in no instance did the second-degree A-V block persist. The etiology in Patient No. 1 was coronary heart disease. The other 2 patients, one aged 67 years and the other 68, had no evidence of angina pectoris, myocardial infarction, hypertension, or valvular heart disease and, therefore, are classified as having heart block of unknown etiology. Seven cases of Mobitz Type-II block have been recorded in the literature available to us.‘-lo In addition, Wenckebach published jugular and radiopulse tracings which indicate occasional dropped beats with a normal, constant a-c interval, but no electrocardiograms and no clinical history are given.12 Three out of 100 patients in our series with M-A-S syndrome
CL:)
)
0.48 0.68-0.74 0.63
(f$
1 $2
0.68-0.70 0.63
0.64
0.64
1 szize
)
of second-degree atrioventricdar
Severity
)
Survived Survived Survived, remained asymptomatic with a 3:2 Mobitz block
Not commented on ASHD ASHD with acute MI
0.16
Yes
Several severe attacks
Died
Cor pulmonale
No clinical No clinical No clinical Yes
Severe
0.60
0.60
0.12
Yes
Severe
0.64
0.64
0.12
Yes
Mild
block.
Etiology
No follow-up Not mentioned 50 attacks in a few days
0.14
branch
1
Yes Yes Yes
0.68
bundle
Course
Wide 0.16 0.13
0.68
Left
153
presented this form of block. The A-V ratios in these 3 cases were 3:2, 4:3, 5:4, 65, and 7:6. None of the Mobitz Type-II blocks observed by us or reported by others persisted, except in the case of 3:2 block reported by Kaufman and associates.g The M-A-S syndrome occurred in 7 of the 10 cases of Mobitz block. In the other 3 cases or electrocardiograms depicted in the monograph on arrhythmias by Katz and PicklO there are no clinical data, and we do not know whether the patients experienced M-A-S attacks. Thus, the M-A-S syndrome has occurred in all cases of Mobitz Type II in which the clinical history was reported, and it would be of interest to observe whether this is an invariable association or whether Mobitz Type-II block occurs independently in patients who never experience M-A-S attacks. No specific pattern for Mobitz Type-II block exists, since the ventricular beats drop out without warning. Eight examples of 3:2, four of 4~3, two of 5:4 and of 65, and one each of 7:6 and 4:3 A-V block occurred in the 10 patients. The patients
0.08 0.12 0.14
LBBB:
block
data data data
Survived hospital. Died 1 year later Survived but required internal pacemaker Survived
Coronary Unknown
Unknown
heart
disease
with 65 and 7:6 A-V block are the first examples of these ratios to be reported. In all but one case the QRS complex was widened. The sudden dropping out of the QRS has been attributed to a prolongation of the absolute refractory period of the A-V bundle; the relative refractory period is unchanged.7r’o The serious prognostic significance which has been attached to this type of A-V conduction7jg is justified to the extent that it has been associated with the M-A-S syndrome. However, we cannot conclude that the outlook differs from that in other cases of A-V block with M-A-S syndrome, since all 3 patients with Mobitz Type-II block survived the period of hospitalization. Two of the 3 patients are still alive 6 and 30 months after the onset of their disease, but 1 patient died within 12 months after the M-A-S syndrome developed. An awareness of this condition, plus more frequent and longer electrocardiographic tracings will probably disclose more esamples of Mobitz Type-II block and provide more definite information as to its clinical and prognostic significance. 2:l A-V block with A-V interference dissociation
III this arrhythmia the atria and ventricles respond to independent pacemakers (A-V dissociation), not because of depressed A-V conduction, as in complete heart block, but because the A-V node or the ventricles are usually refractory when the sinus impulse arrives (interference). Occasionally, the sinus impulse arrives at a nonrefractory period and elicits a ventricular response (capture beat). However, in addition to such interference dissociation, there is a concomitant depression of the atrioventricular bundle which would have resulted in 2:l A-V block if there were not a simultaneous interference with conduction due to the refractory period when the atria1 impulse arrives. The criteria employed for the diagnosis of 2:l A-V block with A-V interference dissociation13 are: (1) a ventricular rate greater than 30 per minute with a constant R-R interval; (2) an atria1 rate which is a multiple of the ventricular rate and almost double its frequency; (3) a “supraventricular” form of QRS of less than O.lO-second
duration; (4) the presence of‘ velrtricular capture beats; (5) a minimum critical R-P interval (absolute refractor)- period) which is constant; and (6) no retrograde V-A conduction. The minimum critical R-P interval is the minimum required time between a conducted sinus impulse and the immediately preceding automatic A-V nodal beat. Two patients out of 100 in our series fulfilled these criteria. Patient No. 1 had a changing heart block with periods of 2:1 A-V block, COIIIplete heart block, and regular sinus rhythm, as well as 2:l A-V block with A-V dissocintion. The atria1 rate was 6.5 per minute, and the ventricular rate was 33 with a minimal critical R-P interval of 1.02 seconds and QRS duration of 0.10 second. Her course was marked b!. recurrent M-A-S attacks due to ventricular tachycardia and fibrillation, but her electrocardiogram continually reverted to regular sinus rhythm (Fig. 2). Patient No. 2 had a milder course. The atria1 and ventricular rates were 83 and 40 per minute, respectively, with an R-P interval of 0.66 second and QRS of 0.10 second. Both patients had ventricular capture beats, but no retrograde conduction. One patient had hypertensive and coronary heart disease,whereas the etiology of the cardiac disease in the second patient was unknown. One patient died 3 years after the onset of the M-A-S syndrome, whereas the other patient is still alive at a 3-year follow-up. .Uthough there is some controversy as to the interpretation of such cases,14s15 we believe that 2:l LA-V block with A-V dissociation is a distinct entity-, and have 2 cases out of 100 in this series which fulfill the criteria. They did not present a clinical picture which differed from that in other forms of heart block. ,L\lthough digitalis is reported to be a cause of 2:l ;\-V block with A-V dissociation,13 neither of these patients had received digitalis. Advanced
atrioventricular
block
Advanced or high-grade atrioventricular block is a form of second-degree heart block in which several successive atria1 impulses are blocked, resulting in an A-V ratio of more than 2:1, usually 4:l and 6:1, whereas the odd-numbered forms, 3:l and 5 :l, are generally regarded as being
rare. Usually, the ventricular rate is below 50 per minute,6J0 and there may be atria1 flutter or tachycardia. Eight out of 100 patients demonstrated high degrees of A-V block: 3:l A-V block occurred in all 8 ; in 2 there was also 4:l block, and in 1, 5:l A-V block (Table II). These multiples of A-V block were Table II. Advanced A-V
Patient
1. O.P. 2. J.H.
3. ,4.P.
4. R.R. 5. D.S. 6. J.K. 7. E.O. 8. W.L.
block
Severity of M-A-S syndrome
3:l
ASHD
Severe
2%
Yes
3:l
ASHD
Severe
Yes
ASHD
No
3:l 4:l 5:l 3:l 4:l 3:l
NO
BBB
2:1, 3:l A-V block to CHB with LBBB NSR with RBBB, 2:1, 3:l and Mobitz TypeII to CHB to NSR with lst-dgrree block NSR with LBBB to 2:1, 3:1, 4:1, 5:l to CHB to NSR NSR with LBBB to 3:1, 4:l to CHB NSR with RBBB to 2:1, 3:l to CHB to NSR CHB to 2:1, 3:l to NSR with RBBB 2:1, 3:l with RBBB to CHB 2~1, 3:1 with RBBB to CHB
Yes
as in Table
Form of advanced A-V block
Etiology
ECG
*Died 6 months later at home. tDied 12 months later at home. H: Hypertension. Other abbreviations
transient in every case, and each patient demonstrated complete heart block during his course (Fig. 3,A and B). Four patients (50 per cent) remained in complete heart block, and the other 4 (50 per cent) resumed a normal sinus rhythm. In all 8 cases the electrocardiogram showed a bundle branch block pattern: in 3 there
Duration of M-A-S syndrome
Course in hospital
No
Survived
6 mo.
No
Survived*
Severe
4 yr.
No
Survived*
ASHD
Severe
4 wk.
No
Died
Moderate
1 yr.
No
Survived
3:l
H and ASHD ASHD
Moderate
2 wk.
No
‘Survivedt
NO
3:l
Unknown
Severe
1 wk.
Yes
Died
No
3:t
H and ASHD
Moderate
3% yr.
No
Survived for 3 yr. (follow up)
IN0
yr.
Patient on digitalis
I.
Fig. 3. Advanced A-V block. Patient No. 3, A.P. (Table II). A demonstrates a 3:l A-V block which subsequently developed into complete heart block. B shows A-V block starting at 5:1, decreasing to 4:1, and then 3 :t in the same lead.
was left bundle branch block, and in 5, right bundle branch block in association with the high-grade A-V block. In 2 of the patients there was an incomplete A-V block with right bundle branch block, and later a left bundle branch block pattern of the QRS with complete heart block developed. A third patient had left bundle branch block initially, but this changed to a right bundle branch block pattern with complete heart block. Although all of these patients had moderate to severe M-A-S syndrome, only 2 (25 per cent) of the 8 died in the hospital. Three patients died within 1 year after discharge, and the other 3 are still alive after 1 year, 1 year, and 3% years, respectively. With one exception, they all had coronary heart disease, and 2 patients were also hypertensive. In only 1 did advanced A-V block develop as a result of digitalis, which is usually considered to be a common cause of this condition. Although the odd-numbered forms of advanced A-V block are considered to be rare,2Jo 8 patients in our series demonstrated a 3:l A-V block, and 2 of them also had 4:l block, and 1 had 5:l block. Xo example of 6:l A-V block was noted. Therefore, in this series the odd-numbered forms are more common than the evennumbered types. This may be coincidental, but it is also possible that the odd-numbered forms of advanced heart block are unstable, relative to the even-numbered forms, and may be more likely to be complicated by pacemaker failure and M-A-S. These advanced degrees of block were all transient and progressed to complete heart block. All of the patients had a moderate to severe M-A-S syndrome. The prognosis in high-grade A-V block is usually considered to be poor. Two of the 8 patients (2.5 per cent) died in the hospital, and 3 more died at home within 1 year after disof 62.5 per charge, for a total mortality cent in the group with advanced A-V block. Only 1 patient developed this heart block from digitalis, which is a frequent cause of partial block. Summary
Several unusual forms of second-degree atrioventricular block associated with the
.\iIorgagni-Adams-Stokes (M-ALs) S)‘lldrome are discussed. Three out of 100 patients with the M-A-S syndrome demonstrated a transient Mobitz Type-II block. Seven additional cases are reviewed from the literature. All of the patients had frequently changing degrees of heart block, and in only 1 patient did the Mobitz TypeII block persist. In all cases in which a clinical history is available, Mobitz TypeII block was associated with an AdamsStokes syndrome. Although a particularly poor prognosis has been indicated for this type of block, the outlook appeared to be no different from that in other cases of M-il-S syndrome in our series. On the other hand, Mobitz Type-II block is of prognostic importance if it indicates that the M-A-S syndrome is likely to develop. Two patients who had 2:l X-V block with A-V interference dissociation presented with the M-A-S syndrome. Neither of these cases was caused by escessive administration of digitalis. Eight patients had advanced or highgrade A-V block related to their M-A-S syndrome. All of them subsequently developed complete heart block. Although odd-numbered ratios of advanced heart block are said to be rare, such forms were present in all 8 cases, whereas 4:l block was present in only 2 cases. This may indicate that M-A-S syndrome is more likely to occur in the odd-ratio type of advanced heart block. Awareness that these unusual forms of second-degree block are associated with M-A-S syndrome may enable the prediction of later development of complete heart block and M-A-S syndrome. REFERENCES 1. Graybiel, A., and White, P. D.: Complete A-V dissociation, AM. HEART J. 52:369, 1956. 2. Campbell, M.: Complete heart block, Brit. Heart J. 6:69, 1944. 3. Penton, G. B., Miller, H., and Levine, S. A.: Some clinical features of complete heart block, Circulation 13:801, 1956. 4. Adler, L. N., Donoso, E., and Friedberg, C. K.: The clinical and electrocardiographic manifestations of 100 cases of Adams-Stokes syndrome over a lS-year period. (In preparation.) 5. Lawrence, J. S., and Forbes, G. W.: Paroxysmal heart block and ventricular standstill, Brit. Heart J. 6:53, 1944. 6. Gilchrist, M. R.: High-grade heart block, Scottish M. J. 3:158, 1958.
Volume 67
Number
7. 8. 9.
10.
11.
2
Unusual forms of second-degree atrioventricular
Mobitz, W.: Uber den partiellen Herzblock, Ztschr. klin. Med. 107:449. 1928. Spang, K.: Rhythmusstijrungen des Herzens, Stuttgart, 1957, Georg Thieme Verlag. Kaufman, J. G., Wachtel, F. W., Rothfield, E., and Bernstein, A.: The association of complete heart block and Adams-Stokes syndrome in two cases of Mobitz type block, Circulation 22:253, 1961. Katz, L. N., and Pick, A.: Clinical electrocardiography. Part I. The arrhythmias, Philadelphia, 1956, Lea & Febiger. Mobitz, W.: Uber die unvollstandige Storung der ErregungsiiberIeitung zwischen Vorhof und Kammer des menschlichen Herzens, Ztschr. ges. exper. Med. 40-41:180, 1924.
12.
block
157
Wenckebach, K. F.: Beitrage zur Kenntnis der menschlichen Herztatigkeit, Arch. f. Anat. Physiol. Phys. Abt., p. 297, 1906, Supplement. 13. Jacobs, D. R., Donoso, E., and Friedberg, C. K.: A-V dissociation-a relatively frequent arrhythmia, Medicine 40:101, 1961. 14. Dressler, W., Roesler, H., and Specter, L. S.: Dissociation with interference in the presence of 2:l atrioventricular block, AM. HEART J. 44:238, 1952. 15. Magri, G.: Dissociation with interference in the presence of partial A-V block, Acta cardiol. 8:529, 19.53.