J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.39.6.576 on 1 June 1976. Downloaded from

Journal ofNeurology, Neurosurgery, andPsychiatry, 1976, 39, 576-580

Neurological aspects of sinoatrial block

A. J. FAIRFAX AND C. D. LAMBERT From the Departments of and Neurology, St George's Hospital, London

SYNOPSIS The symptoms of 100 patients with chronic cardiac sinoatrial disorder were analysed. The most common presenting features were syncope in 34 cases and dizziness in 22 cases. Over three-quarters of the patients had cerebral ischaemic symptoms at some stage of the disease. Diagnostic difficulties are often encountered and are illustrated by two case histories. Although sinoatrial disorder has been described in association with neuromuscular diseases, only one such example was found in this series. The patient had a limb girdle dystrophy with and diffuse disease of the cardiac conducting system. Muscle biopsy samples taken from 11 patients with idiopathic sinoatrial disorder were normal showing no evidence of subclinical muscular disease. Protected by copyright. The importance of disorders of the sinoatrial In this paper the presenting features, sympto- pacemaker in producing disturbances of cardiac matology, and frequency of neuromuscular asso- rhythm has become increasingly recognized by ciations of a group of patients with sinoatrial cardiologists in recent years (Moss and Davis, disorders are analysed. Diagnostic difficulties 1974). The resulting disturbances of rhythm have which may be encountered are illustrated by two been collectively termed the 'sick sinus' syndrome. case histories. Patients with this disorder may present to a neurologist with recurrent episodes of altered con- sciousness, dizziness, or syncope. Diagnosis may METHODS be difficult unless cardiac monitoring facilities are One hundred patients attending cardiac clinics at available, especially when the routine electrocar- St George's Hospital and the National Heart diogram is normal. Embolism is an important Hospital were studied (Table). All had docu- complication occurring in 15-20% of cases and mented, unexplained sinus (heart rate cerebral infarction is the most common outcome less than 60 beats/minute) or as (Rubenstein et al., 1972; Fairfax, Lambert, and a dominant feature. In some patients, this was Leatham-submitted for publication 1976). associated with attacks of atrial , http://jnnp.bmj.com/ The majority of cases of the sick sinus syn- flutter, and (Rubenstein et al., 1972). drome are of unknown or of ischaemic aetiology. This syndrome occasionally develops in patients with neuromuscular diseases and has been re- ported in dystrophia myotonica (Radford and T A B L E Julian, 1974), facioscapulohumeral dystrophy PRESENTING SYMPTOMS IN 100 PATIENTS WITH SINO- (Bloomfield and Sinclair-Smith, 1965; Caponnetto ATRIAL DISORDER et al., 1968), scapuloperoneal dystrophy (Thomas on September 26, 2021 by guest. et al., 1972), and Friedreich's ataxia (Thery, 1975). Symptom (no.) Sinoatrial disorder is also recognized in the Jervell Neurological and Lange-Nielsen syndrome in which congenital Syncope 34 deafness is associated with syncope, a character- Dizziness 22 istic Altered consciousness 3 electrocardiogram, and sudden death from Cardiac (Schwartz et al., 1975). Palpitation 12 Chest pain 11 Shortness of breath S Address for correspondence: Dr A. J. Fairfax, Department of Cardi- 2 ology, St George's Hospital, Hyde Park Corner, London S.W. 1. Incidental finding 11 (Accepted 22 January 1976.) 576 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.39.6.576 on 1 June 1976. Downloaded from

Neurological aspects of sinoatrial 577

Details of the symptoms and of any possible aetio- were features of cardiomyopathy associated logical factors were obtained from the case re- with a limb-girdle muscular dystrophy which cords. Fifty of the patients were examined per- had become evident in childhood. Further de- sonally by one of the authors (A. J. F.). In 11 tails of this case are reported elsewhere patients with idiopathic sinoatrial disorder, a bi- (Lambert and Fairfax, 1976). opsy specimen was obtained from the deltoid features are summarized in muscle under local anaesthesia during the im- The presenting plantation of a . The muscle the Table. Syncope was the most common pre- sections were examined using conventional mor- senting feature occurring in 34 cases; in ad- phological and histochemical techniques (Du- dition, a further 39 patients subsequently bowitz and Brooke, 1973). developed this symptom. Dizzy attacks were noted by 83 patients at some stage. The most common cardiac symptom was recurrent RESULTS palpitation. In 11 cases a slow pulse had been The series included 51 men and 49 women with found incidentally before any symptoms de- a mean age of 64.7 years at the time of study veloped. To illustrate particular diagnostic (range 17-93 years). The age of onset of the difficulties, two case histories are described in disorder is given in Fig. 1. In 75 patients no detail. cause was found for the . Fifteen patients had symptoms suggesting the presence CASE 1

of ischaemic heart disease. In three cases, Protected by copyright. damage to the sinus node followed heart sur- A healthy 58 year old man presented as an emer- Two of the youngest patients, aged 17 gency after a series of five blackouts on the gery. morning of admission. Three months previously, and 20 years, were brothers. Although no other episodes of light-headedness with facial pallor had members of the family were apparently af- developed; these became more severe, sometimes fected, it was thought that the disorder was resulting in loss of consciousness. A similar black- hereditary (Spellberg, 1971). out 15 years earlier had been regarded as epileptic In one patient, a 40 year old woman, sino- and treatment with phenobarbitone instituted. atrial disorder and atrioventricular heart block There was no history of pectoris.

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4 2 I 0-4 5-9 10- 15- 20- 25- 30- 35- 40- 45- 50- 55- 60- 65- 70- 75- 80- 85- 90- 14 19 24 29 34 39 44 49 54 59 64 69 74 79 84 89 94

Age Group (years)

FIG. 1 Age at onset of symptoms of sinoatrial disorder. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.39.6.576 on 1 June 1976. Downloaded from

578 A. J. Fairfax and C. D. Lambert

On examination, the patient was normotensive benzhexol and amantidine. Two years later he with no postural hypotension. There were no developed sudden shakiness during which his abnormal cardiological or neurological signs. The vision became purple. Some attacks were associ- resting electrocardiogram was unremarkable apart ated with a loss of consciousness but were not from . Unlike many cases of related to posture. Facial flushing was noticed at sinoatrial disorder where constant sinus brady- the end of an attack. cardia is a feature (Fig. 2), the resting heart rate Examination disclosed tremor and rigidity of was 75 beats/minute, accelerating normally with Parkinsonism affecting all limbs. Postural hypo- exercise and infusions of isoprenaline and atro- tension was present with a fall from 130/80 mmHg pine, and slowing with carotid sinus massage. lying to 80/60 mmHg standing. The resting pulse An attack was documented in the cardiac was 80 beats/minute with intervals of missed monitoring unit: at the onset, there was pro- beats. Of the several possible causes of syncope gressive slowing of the heart to 37 beats/minute, present, the cardiac arrhythmia was thought to followed by complete atrial and ventricular be the dominant feature. There had been evidence producing transient loss of consciousness. of sinoatrial dysfunction secondary to ischaemic Treatment by temporary endocardial pacing was heart disease for the previous four years with instituted and a paced-beat counter showed that episodes of and short periods of the heart rate was falling below 40 beats/minute sinus arrest. Left was also between 10 to 15 times in a 24 hour period, mainly shown on the electrocardiogram. The pulse rate at night. was not speeded by either isoprenaline or , In view of a family history of ischaemic heart and periods of sinus arrest of up to two seconds disease, coronary arteriography was performed. continued despite drug therapy. The symptoms Protected by copyright. The angiogram showed a normally functioning were abolished by the implantation of a pace- left and there was no sign of cardio- maker. myopathy or of . A diagnosis of idiopathic sinoatrial disorder was made, and a permanent demand pacemaker in- RESULTS OF MUSCLE BIOPSY No evidence of stalled, since which time the patient has been significant muscle pathology was found in the 11 asymptomatic. skeletal muscle samples obtained by biopsy from patients with idiopathic sinoatrial disorder includ- 2 ing the two brothers with familial sinus node CASE disease. Three biopsy specimens, all from elderly A 73 year old man was referred to the neurology patients, showed minor changes, namely mild clinic for the treatment of Parkinson's disease. In predominance of type 1 fibres in one case, changes view of a long history of angina pectoris, he was of denervation in the second, and occasional not given L-dopa, but improved substantially on atrophic fibres in the third. http://jnnp.bmj.com/

BEFORE EXERCISE on September 26, 2021 by guest.

AFTER EXERCISE

FIG. 2 Characteristic electrocardiogram of a case of sinoatrial disorder showing sinus bradycardia (rate 52/min) with little change of heart rate after maximal exercise. Time calibration 0.2 s. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.39.6.576 on 1 June 1976. Downloaded from

Neurological aspects of sinoatrial heart block 579

DISCUSSION is a feature of sinus The symptoms observed in sinoatrial disorder node dysfunction (but not of atrioventricular are predominantly episodes of disturbance or heart block) and this accounts for the fre- loss of consciousness, and are similar to those quency of palpitation in these patients. The which occur in atrioventricular conduction alternation of slow and fast heart rates has defects. Both disorders predominantly affect given the disorder the alternative name of patients in the sixth to eight decades of life, 'brady-tachy' syndrome (Short, 1954). and both are now readily treatable by cardiac The majority of cases of sinoatrial disorder pacemaker implantation. The differential diag- are of unknown aetiology (Pomerance and nosis in the elderly includes vertebrobasilar Davies, 1975), and there are few published ischaemia, epilepsy, transient cerebral postmortem studies. Ischaemic heart disease ischaemic attacks, and carotid sinus syncope. accounts for those cases in which the sinus Van Durme (1975) has provided evidence node artery (an end-artery) is occluded during that many cases of cardiac rhythm disturbance (Rossi, 1962; Lippestad are undetected by conventional means. He and Marton, 1967), but no vascular abnor- studied 95 patients who had presented mality was found in a recent postmortem series with dizzy spells or syncope for which no cause (Brownlee et al.. 1975). Davies and Pomerance was found on neurological or cardiological (1972) have shown that the sinus node and examination. The resting electrocardiogram atrial musculature undergo degenerative aging

showed a normal sinus rhythm in two-thirds of changes, and these may explain some cases of Protected by copyright. these patients. A portable, continuously re- in the elderly. Thery (1975) has cording electrocardiogram (Holter, 1961), how- pointed out that in his cases of sinoatrial block ever, showed that disturbances of cardiac there was always complete destruction of the rhythm, including unsuspected sinoatrial dis- sinus node at necropsy. His series included one order, accounted for the symptoms of half of patient with Friedreich's ataxia and cardio- this group of patients. The normal electro- myopathy in whom the sinus node was de- cardiogram between attacks in some cases of stroyed by haemorrhage, fatty degeneration, sinoatrial disorder contrasts with that seen in and fibrosis. A high incidence of sinoatrial intermittent atrioventricular heart block in dysfunction has been reported in the cardio- which evidence of a peripheral conduction myopathy of dystrophia myotonica (Perloff, disturbance is usually present in the periods 1973). The patient in our series with limb of sinus rhythm. girdle muscular dystrophy also had evidence of Although the hallmark of sinoatrial disorder a diffuse cardiomyopathy, with impairment of

is a sinus bradycardia refractory to drugs or function both of the contractile myocardium http://jnnp.bmj.com/ exercise, case 1 illustrates that in the early and of the sinoatrial pacemaker and peripheral stages of the disease bradycardia may be inter- conducting tissues. It is evident from this study mittent, and the heart may respond normally that neuromuscular disease accounts for a very to chronotropic stimulation. Sinoatrial arrest small minority of patients with sinoatrial dis- may oCcur in isolation, or, characteristically, order, and that in the remainder of cases there after a run of tachycardia (Fig. 3). Supra- is no evidence of skeletal muscle pathology. on September 26, 2021 by guest.

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- j p i FIG. 3 Electrocardiogram recorded from a patient with the 'brady-tachy' syndrome, showing a run of supraventricular tachycardia followed by a period of cardiac asystole. Time calibration 0.2 s. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.39.6.576 on 1 June 1976. Downloaded from

580 A. J. Fairfax and C. D. Lambert

These patients, with a primary cardiac path- Lippestad, C. T., and Marton, P. F. (1967). Sinus ology, are still likely to have a neurological arrest in proximal coronary artery occlusion. presentation with giddiness and syncope. American Heart Journal, 74, 551-556. Moss, A. J., and Davis, R. J. (1974). Brady-tachy syndrome. Progress in Cardiovascular Diseases, 16, 439-454. We wish to thank Dr A. Leatham and Dr P. Gautier- Perloff, J. K. (1973). The myocardial disease of Smith for permission to study patients under their heredofamilial neuromyopathies. In Myocardial case, and for helpful criticism, and Miss H. Fischler Diseases, pp. 319-335. Edited by N. 0. Fowler. for secretarial assistance. A.J.F. is in receipt of a Grune and Stratton: New York. grant generously provided from the St George's Hospital Research Fund. Pomerance., A., and Davies, M. J. (1975). The Path- ology of the Heart, p. 403. Blackwell: Oxford. Radford, D. J., and Julian, D. G. (1974). Sick sinus syndrome: Experience of a cardiac pacemaker REFERENCES clinic. British Medical Journal, 3, 504-507. Rossi, L. (1962). Infarction of the sinu-atrial node. Bloomfield, D. A., and Sinclair-Smith, B. C. (1965). British Medical Journal, 2, 927. Persistent atrial standstill. A merican Journal of Medicine, 39, 335-340. Rubenstein, J. J., Schulman, C. L., Yurchak, P. M., and De Sanctis, R. W. (1972). Clinical spectrum of Brownlee, W. C., Evans, R. C., and Shaw, D. B. the sick sinus syndrome. Circulation, 46, 5-13. (1975). Pathology of conducting system in sino- Schwartz, P. J., Periti, M., and Malliani, A. (1975). atrial disease. British Heart Journal, 37, 779. The long Q-T syndrome. American Heart Journal, Caponnetto, S., Pastorini, C., and Tirelli, G. (1968). 89, 378-390. Protected by copyright. Persistent atrial standstill in a patient affected with Short, D. S. (1954). The syndrome of alternating facioscapulohumeral dystrophy. Cardiologia, 53, bradycardia and tachycardia. British Heart Journal, 341-350. 16, 208-214. Davies, M. J., and Pomerance, A. (1972). Quantitative Spellberg, R. D. (1971). Familial sinus node disease. study of ageing changes in the human sinuatrial Chest, 60, 246-251. node and internodal tracts. British Heart Journal, 34, 150-152. Thery, C. (1975). Pathology of sinoatrial disease. British Heart Foundation First European Sym- Dubowitz, V., and Brooke, M. H. (1973). Muscle posium on Cardiac (unpublished). A London. Biopsy. Modern Approach. Saunders: Thomas, P. K., Calne, D. B., and Elliott, C. F. (1972). Holter, N. J. (1961). New methods for heart studies. X-linked scapuloperoneal syndrome. Journal of Science, 134, 1214-1220. Neurology, Neurosurgery, and Psychiatry, 35, 208- Lambert, C. D., and Fairfax, A. J. (1976). The neuro- 215. logical associations of chronic heart block. Journal Van Durme, J. P. (1975). Tachyarrhythmias and of Neurology, Neurosurgery, and Psychiatry, 39, transient cerebral ischaemic attacks. A merican 571-575. Heart Journal, 89, 538-540. http://jnnp.bmj.com/ on September 26, 2021 by guest.