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THE CLINICAL OCCURRENCE OF SINO-AURICULAR BLOCK.
65
THE CLINICAL
OCCURRENCE
SINO-AURICULAR BY PHILIP
days. Typhoid aged 12. Life-long non-smoker and abstainer. Complained of headache on walking. Not fond of exercise. Examination.—No abnormal cardiac signs. No enlargement (radioscopy). Blood pressure : systolic 120, diastolic 80. Urine normal. Polygram showed sino-auricular Hock, confirmed by electrocardiogram (Fig. 2).
OF
BLOCK.
BARLOW, M.D. EDIN.,
BARRISTER-AT-LAW ; OUT-PATIENT
MEDICAL OFFICER, NATIONAL HOSPITAL FOR DISEASES OF THE HEART, LONDON.
Fin. 2. ALTHOUGH in vast majority of cases an intermission of the pulse is due to an extrasystole, or in a minority to a slight heart-block with dropped beat, there have proved to be occasional intermissions resulting from neither of these irregularities. In some of these exceptional cases a characteristic polygram In this instance the pause. II.—Sino-auricular block. and electrocardiogram has been found and the term Case which measures nearly two normal cycles, is not preceded sino-auricular block has been applied to the condition. by any quickening of the heart, though the cycle immediately It was first used by Wenckebach in 190732 in succeeding the intermission is longer than normal. describing a phenomenon comparable with auriculo-’ ventricular block, but where instead of an auricular CASE III.—Male, aged 51 ; warehouseman. Influcnza one beat failing to influence the ventricle (missed year ago, not well since. Two months ago felt suddenly ill ventricular beat), the auricular, as well as the and fainted ; two weeks ago fainted again. Absent from ventricular contraction, failed to appear on the work eleven weeks. Shortness of breath and slight pain polygram-a whole heart beat was missed. In over left margin and lower end of sternum. No history of other words, there was a pause in the record equal to rheumatic fever. Abstainer and moderate smoker. two cycles, suggesting that the sinus had produced Examination.—Pulse irregular showing dropped beats ; varied between 60 and 70 beats a minute (Fig. 3). an impulse which had been blocked and a whole heart Heart not enlarged. No symptoms and no signs of failure. beat had been lost (sino-auricular block). Blood pressure, systolic 1:35, diastolic 100. After one month’s Four cases will now be described to illustrate the condition. Fin. 3. Clinical Records. CASE I.—Male, aged 65; tailor. Three years ago giddiness a
rate
one morning on rising ; consulted doctor, who remarked that pulse was slow. Pain in the back and in the right shoulder, induced by exertion, worse last six months ; slight palpita-
tion, some breathlessness and exhaustion.
Moderate smoker, history of previous illness or infection. Pulse intermittent. Examination.—Moderate obesity. block. The pause is almost exactly Heart sounds distant. Short svstolic murmur at aortic area. Case III.-Sino-auricular equal to the two cycles preceding it. The P.-Il. interval is Blood pressure, 190 systolic, 90 diastolic. Slight oedema shorter after the pause. of ankles. Urine normal. Wassermann reaction negative. Radioscopy, globular heart, apex just external to nipple line, slight enlargement to the right ; aorta normal. Pulse observation an electrocardiogram showed no arrhythmia and was not always irregular, but if so it showed frequent at this time patient was at work and feeling well. Two months later still slight irregularity was present ; rate
abstainer ;
no
62 beats
a
minute.
cardiogram showed no complaints.
(’ase I.—Sino-auricular block.
In (a) the pause, which is almost exactly double two normal cycles, is ushered in by a slight quickening of the whole heart. Thereafter there is a succession of long cycles of the same length. In (b) bigeminydtie to 3 : 2
One year after the first visit an electropauses and no arrhythmia and he had
no
CASE IV.—Male, aged 41; furniture packer. Pain under left breast, some breathlessness, faintness, palpitation and exhaustion, all for two years. Examination.—Heart not enlarged (radioscopy). Blowing murmur at the apex, pulse irregular, occasional systolic " dropped beats," varying between 60 and 70 beats a minute (Fig. 4). Blood pressure, ’systolic 140, diastolic 70. Wassermann reaction positive. No symptoms and signs of failure. Moderate smoker and moderate drinker. Atropin
FIG. 4.
sino-auricular block.
dropped beats." Rate varied between 56 and 72beats a minute. Patient at no time was conscious of these intermissions and suffered no inconvenience from them. His symptoms were ascribed to chronic arthritis, with a moderate Ilegree of hyperpiesis. When the pulse was irregular the electrocardiogram was as in Fig. 1. During the 14 months of subsequent observation several electrocardiograms were taken, all of which were similar to Fig. 1, with exception of the last, which showed sinus bradycardia only. The same minor symptoms and signs were present and the blood pressure was systolic 170, diastolic 80, CASE II.—Male, aged 31 ;medical man. Had noticed of the heart for some ten years, since student
irregularity
Case IV.-Triple record of sino-auricular block. Rlectrocardiograni shows a pause nearly equalling two normal cycles. The P.R. and A.-C. intervals are lengthened in successive beats before the pause. This record was taken while respiration was
held.
Adaptability
in Disease: References.
Adami, J. G.: Brit. Med. Jour., 1917, i., 837. Thiele, F. H., and Embleton, D. : Zeits. f. Imm. forsch. exp. Ther., Nov. 12th, 1923. 3. Andrewes, Sir F. W. : THE LANCET, 1926, i., 1075. 4. Leathes, J. B. : THE LANCET, 1926, ii., 268. 5. Bramwell, E.: Northern Counties Med. Jour., vi., No. 3. 6. Cowan, J.: Edin. Med. Jour., 1926, xxxiii., 547. 7. Mark, L. : Acromegaly, a Personal Experience, 1912. 1. 2.
gr. u.
1/100
subcut. reduced the number of pauses.
After two
years’ observation condition was much the same. After five years’ observation patient complained of nothing more than lassitude. Electrocardiograms still showed sino-auricular block.
The cases recorded in the literature before 1916, 14 in number, are fully dealt with by Levine 114 who
66
gives
a
table of them, together with His collected cases are one of
comprehensive
four of his
own.
the auricle. Cushny,33 employed aconitine and electrical stimulation, Eyster and Meek,7 with textile leads worked out with great care the course of negativity which passes over the heart of a tortoise, and the same authors in another paper describe a great number of experiments which seem to show, among other things, that special paths of conduction exist in the auricles. Rothberger 24 concludes from some recent experiments that there are two such paths from the lower end of the node, and Poulton and Dowling 19believe that there is some direct connexion between node and ventricle, irrespective of the contracting auricle. The existence of any such tissues of conduction between sinus and auricle is strenuously denied by Lewis on both anatomical and
Joachim,"2 two of Wenckeback,32 of Gibson,9 one of Rihl,22 one of Laslett,13 two of Riebold,21 and one of Schott.26 He points out that the arrhythmia occurred after digitalis in ten cases, disappearing when its administraIn four of the eight others this drug tion ceased. was not given and in the remaining four there is no note on the subject, though in two it may have been given, as heart failure was present. Four cases were subject to paroxysmal auricular fibrillation (two of Levine,14 Laslett,13 and Riebold 21). His own cases showed pauses equal in length to multiples of the normal heart cycle. He thinks that the variation in length of the normal physiological grounds. Resnik,20 in December, 1925, conducted some cycle is due to a change in the rate of the pacemaker or in the time the impulse takes to reach the auricular experiments at the Johns Hopkins Hospital on musculature. It is not due entirely to the latter, for dogs with 0-5 to 1 c.cm. of pituitrin, taking one lead the P-P interval would become gradually longer until from the sino-auricular node itself, the other being one sinus beat would be blocked ; in one of his cases, the ordinary lead II. From these (three are the P-P intervals become shorter before the pause published) he deduces that instead of there being a (cf. Lewis), as if the conduction of the impulse block between the node and auricle, the former fails improves. Sometimes the intervals lengthen and to originate an impulse at all, the result of vagal then shorten without any blocked beats, and in one influence. He suggests the name sino-auricular instance of his an impulse is blocked after a short standstill." beat. The block depends on slight sinus arrhythmia. Ætiology. Whenever the sinus rate increases beyond a certain The aetiology of sino-auricular block is ’often point the node fails to conduct the impulse to the uncertain. Digitalis has been cited as one of auricles. the causes by many authors (Levine,14 Lewis,15 Forms of the Irregularity. Parkinson,18 Whiter and Cases 2, 4, 6, 7, 8, 14. The irregularity may take several forms ; () the 15, 16, 18). In the cases collected by Levine JJ it heart may intermit occasionally as described above ; is to be noted that the use of digitalis was recorded or (b) beats may be separated into groups by regular definitely in 56 per cent. of them, whereas in thos recurrence (as in Cases 1, 2, 5, 9, 10, 32, 1.) ; or (c) included here the use of the drug was noted in onl) there may be abrupt slowing or quickening (Case 12, 25 per cent. In the last figure are included Whites also reference 16, Fig. 368 3). Sometimes the three cases (Cases 14, 15, and 16) of complete ninorhythm is abruptly halved, but more often the rate is auricular block at Massachusetts General Hospital, slightly more than half the rapid rate, each of the but in a later publication3-l he mentions that lie has long cycles being less than two of the short ones observed six cases in which digitalis was prirnarily taken together ; or there may be rarely a continuous responsible. Other occasional causes reported are tobacco bradycardia of perhaps 30 beats per minute (Case 11 ), which is distinguished from other forms of slow action (Neuhof, 17 Cases 30, 31), atropine (Smith,28Case 20), by the way in which it accelerates in response to salicylates (Sicard and Meara,27 Cases 3 and 4), and Levine 14 adds febrile exercise, doubling at once, then quickening gradually, obscure vagal influences. then after exertion slowly decreasing to 80 or 70, and conditions, particularly rheumatic fever and chronic then halving suddenly to its original rate. The most myocarditis, to the list, and White arteriosclerosis and
Mackenzie,16 one
four of
of Hewlett,l1
one
"
recent
discussion
of
the
several forms of this Levine 14 describes a
hypertension.
irregularity is that of Lewis.15
Frequency.
in which the intervals were usually approximately i There is no doubt that the condition is infrequent. double, but sometimes simple multiples of the normal Smith 211 says that is not so rare as the paucity of the beats and occasionally longer than two normal literature would have us believe ; Levine 14 states that cycles, once equalling five cycles ; this appears to be its frequency is greater than is recognised, and this a parallel instance to three cases mentioned by White,33 view is shared by White.33 Some observers have too (his Cases 14, 15, and 16) of complete auricular readily accepted the pauses so common in pronounced standstill, which he terms complete sino-auricular sinus arrhythmia as due to sino-auricular block. block (from digitalis) ; this appears to be the only Smith 28 is careful to emphasise this and admits that reference to complete blocking. Long pauses of at least two of his cases (Cases 25 and 26) might be similar nature can be produced by pressure on the interpreted as examples of the former. vagus nerve in the neck and in morphinised dogs with It is certain that cases are rarely seen at a clinic (Robinson and Draper 23), and in dogs such as that of the National Hospital for Diseases excised vagus injected with pituitrin (Resnik 20). of the Heart, though practically all irregular rhythms are investigated by the electrocardiograph. Not more Association with Auriculo-ventricular Block. than 11 cases at most had been observed at the The frequent association of sino-auricular with Massachusetts General Hospital from 1914 to 1922.34 auriculo-ventricular block is emphasised by Lewis,15 who says that it is too frequent to be accidental. In S’ymptoms and Associated Conditions. three of his four electrocardiograms conduction is There are no symptoms indicative of sino-auricular distinctly impaired as shown by the prolonged P-R block, and patients are not conscious of the interinterval, shortening after each long diastole (also missions. In Case 9 (Straub10) alcoholic neuritis was Cases 6, 8, and IV. (Fig. 4)). In my four cases there present, and this is the only mention of alcohol as a is no auriculo-ventricular block, except in Case IV., concomitant. In the author’s Case 2 the patient where the P-R interval is prolonged (Fig. 4). was a life-long abstainer. Smith’s28 cases (19, 20, 21) There have been a great many experiments on were from diphtheria wards, Schirmer’s25 (Case 32) various types of animals, both warm-blooded and had diphtheria bacilli in the throat, and Andersen ’81 cold, designed to solve the problem of the origin of (Case 29) had a history of diphtheria. Some, however, the impulse and the causation of sino-auricular block. of Smith’s cases were suffering from other zymotic Thus, in 1910 Hering 10 cooled the sinus region in dogs diseases-mumps (Case 23) and pertussis (Case 24). and since then the node has been injured, Stannius Venereal disease’is mentioned in Straub’s cases and ligatures have been applied and various procedures in Case 4, and also in the former the fact of treatment have been adopted to cut off communication between with mercury, the Wassermann reaction was negative, the whole node or different portions of the node In Case 4 the but the Sachs Gorgi positive. case
I
and
67 Wassermann reaction was positive, though were there no clinical signs of syphilis. There was a history of rheumatic fever in seven (Cases 1, 2, 3, 4, 6, 9, 27) and of typhoid in three (Cases 1, 6, 11). The general association is very much as outlined by Levinel4
and
White34—(supra) myocarditis, rheumatism, general cardiosclerosis, and febrile conditions, but in many there is of
no
irnportance. Atropin is shown
block in five
discoverable
to have
cause or
association
temporarily abolished
the
(1, 2, 5, 6, 27), swallowing in three (2, 5, 11), quinidine in two (9, 29). Pressure on the vagi increased the irregularity in three cases (5, 27, 28) It is noted that and on the eyeball in two (11, 27).
in
cases
case’-pressure on vagi and on the eyeball had effect. Exertion, physical or mental, increased the arrhythmia in four cases (6, 22, 25, 26), and in one 21 In one casell the heart-rate caused it to disappear. doubled on exertion and in one12 it halved one minute after violent exercise. one
no
Diagnosis. The condition can only be diagnosed by graphic methods. A slight preparatory quickening of the whole heart, followed by a pause equalling approximately two normal heart cycles with a total absence of " P " or "a" waves, occurring either alone or grouped, as above, is seen on the record. Sinoauricular block must be differentiated from (a) the extrasystole, (b) the occasional dropped beats of auricular-ventricular heart-block, (c) sinus bradycardia with ventricular escape, (d) a blocked premature auricular contraction, and (e) sinus arrhythmia, which often simulates sino-auricular block very closely. Resnik 20 obtained in his experiments practically " complete transitions between sino-auricular standstill " and sinus arrhythmia. He regards the condition as a special form of sinus arrhythmia.
Prognosis and Treatment. There is little or nothing in the literature on the subject of prognosis. Schirtner’s case (Case 32) was reported as recovered and the four cases here described have shown no serious signs. No treatment is necessary. The condition is not pathological, is present in a few hearts, and may be regarded as physiological. It does not by itself necessitate any interference with the patient’s mode of life and can be neglected in considering his future. Summary. 1. Four cases of sino-auricular block are described and a tabular summary of published cases since 1916 is furnished. 2. It is a rare cause of intermission of the pulse, in which a whole heart beat fails to appear, and it is only recognisable by graphic methods. 3. Atropin usually abolishes the block temporarily. Pressure on the bulbus oculi and also on the vagus has varied effects. 4. Ætiologically no one factor is responsible, though many cases are definitely due to digitalis administration. Other suggested causes are the use of tobacco, salicylates, and infective conditions. 5. There are no characteristic symptoms in association, 6. The condition may be and it produces none. present without any symptoms or signs of cardiovascular disease, but it is often accompanied by slight grades of auriculo-ventricular block or other signs which indicate associated myocardial disease. I wish to express my thanks to Dr. John Parkinson, physician to the hospital, for permission to use the four cases shown and for his help.
Bibliography. 1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11.
Andersen, Siggard: Acta. Med. Scand., 1923, lviii., 151. Brown, N. W. : Archiv. Int. Med., 1919, xxiv., 458. Cushny, A. R. : Heart, 1909-10, i., 1. Daniclopolu, D. : Archiv. des Mal. du Cœur., 1913, vi., 792. Eyster, J. A. E., and Evans, J. S. : Archiv. Int. Med., 1915, xvi., 832. Eyster and Meek, W. J. : Ibid., 1917, xix., 116. Same authors : Amer. Jour. Phys., 1912-13, xxxi., 31. Gallavardin, L., and Dumas, A. : Archiv. des Mal. du Cœur, 1920, xiii., 63. Gibson, G. A. : Pract., Lond., 1907, lxxviii., 589. Hering, H. E. : Archiv. f. d. ges. Physiol., 1900, lxxxii., 1. Hewlett, A. W. : Jour. Amer. Med. Assoc., 1907, xlviii., 47. (Continued at foot of next page.)
THE CLINICAL
OCCURRENCE
SINO-AURICULAR BY PHILIP
days. Typhoid aged 12. Life-long non-smoker and abstainer. Complained of headache on walking. Not fond of exercise. Examination.—No abnormal cardiac signs. No enlargement (radioscopy). Blood pressure : systolic 120, diastolic 80. Urine normal. Polygram showed sino-auricular Hock, confirmed by electrocardiogram (Fig. 2).
OF
BLOCK.
BARLOW, M.D. EDIN.,
BARRISTER-AT-LAW ; OUT-PATIENT
MEDICAL OFFICER, NATIONAL HOSPITAL FOR DISEASES OF THE HEART, LONDON.
Fin. 2. ALTHOUGH in vast majority of cases an intermission of the pulse is due to an extrasystole, or in a minority to a slight heart-block with dropped beat, there have proved to be occasional intermissions resulting from neither of these irregularities. In some of these exceptional cases a characteristic polygram In this instance the pause. II.—Sino-auricular block. and electrocardiogram has been found and the term Case which measures nearly two normal cycles, is not preceded sino-auricular block has been applied to the condition. by any quickening of the heart, though the cycle immediately It was first used by Wenckebach in 190732 in succeeding the intermission is longer than normal. describing a phenomenon comparable with auriculo-’ ventricular block, but where instead of an auricular CASE III.—Male, aged 51 ; warehouseman. Influcnza one beat failing to influence the ventricle (missed year ago, not well since. Two months ago felt suddenly ill ventricular beat), the auricular, as well as the and fainted ; two weeks ago fainted again. Absent from ventricular contraction, failed to appear on the work eleven weeks. Shortness of breath and slight pain polygram-a whole heart beat was missed. In over left margin and lower end of sternum. No history of other words, there was a pause in the record equal to rheumatic fever. Abstainer and moderate smoker. two cycles, suggesting that the sinus had produced Examination.—Pulse irregular showing dropped beats ; varied between 60 and 70 beats a minute (Fig. 3). an impulse which had been blocked and a whole heart Heart not enlarged. No symptoms and no signs of failure. beat had been lost (sino-auricular block). Blood pressure, systolic 1:35, diastolic 100. After one month’s Four cases will now be described to illustrate the condition. Fin. 3. Clinical Records. CASE I.—Male, aged 65; tailor. Three years ago giddiness a
rate
one morning on rising ; consulted doctor, who remarked that pulse was slow. Pain in the back and in the right shoulder, induced by exertion, worse last six months ; slight palpita-
tion, some breathlessness and exhaustion.
Moderate smoker, history of previous illness or infection. Pulse intermittent. Examination.—Moderate obesity. block. The pause is almost exactly Heart sounds distant. Short svstolic murmur at aortic area. Case III.-Sino-auricular equal to the two cycles preceding it. The P.-Il. interval is Blood pressure, 190 systolic, 90 diastolic. Slight oedema shorter after the pause. of ankles. Urine normal. Wassermann reaction negative. Radioscopy, globular heart, apex just external to nipple line, slight enlargement to the right ; aorta normal. Pulse observation an electrocardiogram showed no arrhythmia and was not always irregular, but if so it showed frequent at this time patient was at work and feeling well. Two months later still slight irregularity was present ; rate
abstainer ;
no
62 beats
a
minute.
cardiogram showed no complaints.
(’ase I.—Sino-auricular block.
In (a) the pause, which is almost exactly double two normal cycles, is ushered in by a slight quickening of the whole heart. Thereafter there is a succession of long cycles of the same length. In (b) bigeminydtie to 3 : 2
One year after the first visit an electropauses and no arrhythmia and he had
no
CASE IV.—Male, aged 41; furniture packer. Pain under left breast, some breathlessness, faintness, palpitation and exhaustion, all for two years. Examination.—Heart not enlarged (radioscopy). Blowing murmur at the apex, pulse irregular, occasional systolic " dropped beats," varying between 60 and 70 beats a minute (Fig. 4). Blood pressure, ’systolic 140, diastolic 70. Wassermann reaction positive. No symptoms and signs of failure. Moderate smoker and moderate drinker. Atropin
FIG. 4.
sino-auricular block.
dropped beats." Rate varied between 56 and 72beats a minute. Patient at no time was conscious of these intermissions and suffered no inconvenience from them. His symptoms were ascribed to chronic arthritis, with a moderate Ilegree of hyperpiesis. When the pulse was irregular the electrocardiogram was as in Fig. 1. During the 14 months of subsequent observation several electrocardiograms were taken, all of which were similar to Fig. 1, with exception of the last, which showed sinus bradycardia only. The same minor symptoms and signs were present and the blood pressure was systolic 170, diastolic 80, CASE II.—Male, aged 31 ;medical man. Had noticed of the heart for some ten years, since student
irregularity
Case IV.-Triple record of sino-auricular block. Rlectrocardiograni shows a pause nearly equalling two normal cycles. The P.R. and A.-C. intervals are lengthened in successive beats before the pause. This record was taken while respiration was
held.
Adaptability
in Disease: References.
Adami, J. G.: Brit. Med. Jour., 1917, i., 837. Thiele, F. H., and Embleton, D. : Zeits. f. Imm. forsch. exp. Ther., Nov. 12th, 1923. 3. Andrewes, Sir F. W. : THE LANCET, 1926, i., 1075. 4. Leathes, J. B. : THE LANCET, 1926, ii., 268. 5. Bramwell, E.: Northern Counties Med. Jour., vi., No. 3. 6. Cowan, J.: Edin. Med. Jour., 1926, xxxiii., 547. 7. Mark, L. : Acromegaly, a Personal Experience, 1912. 1. 2.
gr. u.
1/100
subcut. reduced the number of pauses.
After two
years’ observation condition was much the same. After five years’ observation patient complained of nothing more than lassitude. Electrocardiograms still showed sino-auricular block.
The cases recorded in the literature before 1916, 14 in number, are fully dealt with by Levine 114 who
66
gives
a
table of them, together with His collected cases are one of
comprehensive
four of his
own.
the auricle. Cushny,33 employed aconitine and electrical stimulation, Eyster and Meek,7 with textile leads worked out with great care the course of negativity which passes over the heart of a tortoise, and the same authors in another paper describe a great number of experiments which seem to show, among other things, that special paths of conduction exist in the auricles. Rothberger 24 concludes from some recent experiments that there are two such paths from the lower end of the node, and Poulton and Dowling 19believe that there is some direct connexion between node and ventricle, irrespective of the contracting auricle. The existence of any such tissues of conduction between sinus and auricle is strenuously denied by Lewis on both anatomical and
Joachim,"2 two of Wenckeback,32 of Gibson,9 one of Rihl,22 one of Laslett,13 two of Riebold,21 and one of Schott.26 He points out that the arrhythmia occurred after digitalis in ten cases, disappearing when its administraIn four of the eight others this drug tion ceased. was not given and in the remaining four there is no note on the subject, though in two it may have been given, as heart failure was present. Four cases were subject to paroxysmal auricular fibrillation (two of Levine,14 Laslett,13 and Riebold 21). His own cases showed pauses equal in length to multiples of the normal heart cycle. He thinks that the variation in length of the normal physiological grounds. Resnik,20 in December, 1925, conducted some cycle is due to a change in the rate of the pacemaker or in the time the impulse takes to reach the auricular experiments at the Johns Hopkins Hospital on musculature. It is not due entirely to the latter, for dogs with 0-5 to 1 c.cm. of pituitrin, taking one lead the P-P interval would become gradually longer until from the sino-auricular node itself, the other being one sinus beat would be blocked ; in one of his cases, the ordinary lead II. From these (three are the P-P intervals become shorter before the pause published) he deduces that instead of there being a (cf. Lewis), as if the conduction of the impulse block between the node and auricle, the former fails improves. Sometimes the intervals lengthen and to originate an impulse at all, the result of vagal then shorten without any blocked beats, and in one influence. He suggests the name sino-auricular instance of his an impulse is blocked after a short standstill." beat. The block depends on slight sinus arrhythmia. Ætiology. Whenever the sinus rate increases beyond a certain The aetiology of sino-auricular block is ’often point the node fails to conduct the impulse to the uncertain. Digitalis has been cited as one of auricles. the causes by many authors (Levine,14 Lewis,15 Forms of the Irregularity. Parkinson,18 Whiter and Cases 2, 4, 6, 7, 8, 14. The irregularity may take several forms ; () the 15, 16, 18). In the cases collected by Levine JJ it heart may intermit occasionally as described above ; is to be noted that the use of digitalis was recorded or (b) beats may be separated into groups by regular definitely in 56 per cent. of them, whereas in thos recurrence (as in Cases 1, 2, 5, 9, 10, 32, 1.) ; or (c) included here the use of the drug was noted in onl) there may be abrupt slowing or quickening (Case 12, 25 per cent. In the last figure are included Whites also reference 16, Fig. 368 3). Sometimes the three cases (Cases 14, 15, and 16) of complete ninorhythm is abruptly halved, but more often the rate is auricular block at Massachusetts General Hospital, slightly more than half the rapid rate, each of the but in a later publication3-l he mentions that lie has long cycles being less than two of the short ones observed six cases in which digitalis was prirnarily taken together ; or there may be rarely a continuous responsible. Other occasional causes reported are tobacco bradycardia of perhaps 30 beats per minute (Case 11 ), which is distinguished from other forms of slow action (Neuhof, 17 Cases 30, 31), atropine (Smith,28Case 20), by the way in which it accelerates in response to salicylates (Sicard and Meara,27 Cases 3 and 4), and Levine 14 adds febrile exercise, doubling at once, then quickening gradually, obscure vagal influences. then after exertion slowly decreasing to 80 or 70, and conditions, particularly rheumatic fever and chronic then halving suddenly to its original rate. The most myocarditis, to the list, and White arteriosclerosis and
Mackenzie,16 one
four of
of Hewlett,l1
one
"
recent
discussion
of
the
several forms of this Levine 14 describes a
hypertension.
irregularity is that of Lewis.15
Frequency.
in which the intervals were usually approximately i There is no doubt that the condition is infrequent. double, but sometimes simple multiples of the normal Smith 211 says that is not so rare as the paucity of the beats and occasionally longer than two normal literature would have us believe ; Levine 14 states that cycles, once equalling five cycles ; this appears to be its frequency is greater than is recognised, and this a parallel instance to three cases mentioned by White,33 view is shared by White.33 Some observers have too (his Cases 14, 15, and 16) of complete auricular readily accepted the pauses so common in pronounced standstill, which he terms complete sino-auricular sinus arrhythmia as due to sino-auricular block. block (from digitalis) ; this appears to be the only Smith 28 is careful to emphasise this and admits that reference to complete blocking. Long pauses of at least two of his cases (Cases 25 and 26) might be similar nature can be produced by pressure on the interpreted as examples of the former. vagus nerve in the neck and in morphinised dogs with It is certain that cases are rarely seen at a clinic (Robinson and Draper 23), and in dogs such as that of the National Hospital for Diseases excised vagus injected with pituitrin (Resnik 20). of the Heart, though practically all irregular rhythms are investigated by the electrocardiograph. Not more Association with Auriculo-ventricular Block. than 11 cases at most had been observed at the The frequent association of sino-auricular with Massachusetts General Hospital from 1914 to 1922.34 auriculo-ventricular block is emphasised by Lewis,15 who says that it is too frequent to be accidental. In S’ymptoms and Associated Conditions. three of his four electrocardiograms conduction is There are no symptoms indicative of sino-auricular distinctly impaired as shown by the prolonged P-R block, and patients are not conscious of the interinterval, shortening after each long diastole (also missions. In Case 9 (Straub10) alcoholic neuritis was Cases 6, 8, and IV. (Fig. 4)). In my four cases there present, and this is the only mention of alcohol as a is no auriculo-ventricular block, except in Case IV., concomitant. In the author’s Case 2 the patient where the P-R interval is prolonged (Fig. 4). was a life-long abstainer. Smith’s28 cases (19, 20, 21) There have been a great many experiments on were from diphtheria wards, Schirmer’s25 (Case 32) various types of animals, both warm-blooded and had diphtheria bacilli in the throat, and Andersen ’81 cold, designed to solve the problem of the origin of (Case 29) had a history of diphtheria. Some, however, the impulse and the causation of sino-auricular block. of Smith’s cases were suffering from other zymotic Thus, in 1910 Hering 10 cooled the sinus region in dogs diseases-mumps (Case 23) and pertussis (Case 24). and since then the node has been injured, Stannius Venereal disease’is mentioned in Straub’s cases and ligatures have been applied and various procedures in Case 4, and also in the former the fact of treatment have been adopted to cut off communication between with mercury, the Wassermann reaction was negative, the whole node or different portions of the node In Case 4 the but the Sachs Gorgi positive. case
I
and
67 Wassermann reaction was positive, though were there no clinical signs of syphilis. There was a history of rheumatic fever in seven (Cases 1, 2, 3, 4, 6, 9, 27) and of typhoid in three (Cases 1, 6, 11). The general association is very much as outlined by Levinel4
and
White34—(supra) myocarditis, rheumatism, general cardiosclerosis, and febrile conditions, but in many there is of
no
irnportance. Atropin is shown
block in five
discoverable
to have
cause or
association
temporarily abolished
the
(1, 2, 5, 6, 27), swallowing in three (2, 5, 11), quinidine in two (9, 29). Pressure on the vagi increased the irregularity in three cases (5, 27, 28) It is noted that and on the eyeball in two (11, 27).
in
cases
case’-pressure on vagi and on the eyeball had effect. Exertion, physical or mental, increased the arrhythmia in four cases (6, 22, 25, 26), and in one 21 In one casell the heart-rate caused it to disappear. doubled on exertion and in one12 it halved one minute after violent exercise. one
no
Diagnosis. The condition can only be diagnosed by graphic methods. A slight preparatory quickening of the whole heart, followed by a pause equalling approximately two normal heart cycles with a total absence of " P " or "a" waves, occurring either alone or grouped, as above, is seen on the record. Sinoauricular block must be differentiated from (a) the extrasystole, (b) the occasional dropped beats of auricular-ventricular heart-block, (c) sinus bradycardia with ventricular escape, (d) a blocked premature auricular contraction, and (e) sinus arrhythmia, which often simulates sino-auricular block very closely. Resnik 20 obtained in his experiments practically " complete transitions between sino-auricular standstill " and sinus arrhythmia. He regards the condition as a special form of sinus arrhythmia.
Prognosis and Treatment. There is little or nothing in the literature on the subject of prognosis. Schirtner’s case (Case 32) was reported as recovered and the four cases here described have shown no serious signs. No treatment is necessary. The condition is not pathological, is present in a few hearts, and may be regarded as physiological. It does not by itself necessitate any interference with the patient’s mode of life and can be neglected in considering his future. Summary. 1. Four cases of sino-auricular block are described and a tabular summary of published cases since 1916 is furnished. 2. It is a rare cause of intermission of the pulse, in which a whole heart beat fails to appear, and it is only recognisable by graphic methods. 3. Atropin usually abolishes the block temporarily. Pressure on the bulbus oculi and also on the vagus has varied effects. 4. Ætiologically no one factor is responsible, though many cases are definitely due to digitalis administration. Other suggested causes are the use of tobacco, salicylates, and infective conditions. 5. There are no characteristic symptoms in association, 6. The condition may be and it produces none. present without any symptoms or signs of cardiovascular disease, but it is often accompanied by slight grades of auriculo-ventricular block or other signs which indicate associated myocardial disease. I wish to express my thanks to Dr. John Parkinson, physician to the hospital, for permission to use the four cases shown and for his help.
Bibliography. 1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11.
Andersen, Siggard: Acta. Med. Scand., 1923, lviii., 151. Brown, N. W. : Archiv. Int. Med., 1919, xxiv., 458. Cushny, A. R. : Heart, 1909-10, i., 1. Daniclopolu, D. : Archiv. des Mal. du Cœur., 1913, vi., 792. Eyster, J. A. E., and Evans, J. S. : Archiv. Int. Med., 1915, xvi., 832. Eyster and Meek, W. J. : Ibid., 1917, xix., 116. Same authors : Amer. Jour. Phys., 1912-13, xxxi., 31. Gallavardin, L., and Dumas, A. : Archiv. des Mal. du Cœur, 1920, xiii., 63. Gibson, G. A. : Pract., Lond., 1907, lxxviii., 589. Hering, H. E. : Archiv. f. d. ges. Physiol., 1900, lxxxii., 1. Hewlett, A. W. : Jour. Amer. Med. Assoc., 1907, xlviii., 47. (Continued at foot of next page.)