Long-term atrial pacing for sinus node disease with output-terminal programmable pacemakers

Long-term atrial pacing for sinus node disease with output-terminal programmable pacemakers Long-term transvenous atrial pacing for symptomatic sinus node disease. in the absence of atrioventricular conduction disease. confers the advantages of increased cardiac performance and probable freedom from systemic thromboembolism. Conventional ventricular pacing has been preferred. however. because of the complications of atrial pacing, mainly those of electrical and mechanical instability of currently available atrial electrodes. These complications have been circumvented with a new pacemaker. programmable for output terminal. This has allowed the institution of atrial pacing in seven patients. with its attendant advantages and the ability to reprogram noninvasively to ventricular pacing should atrial pacing fail. Such reprogramming has been accomplished without difficulty in one patient who developed second-degree atrioventricular block and one with electrode microdisplacement.

Simon P. Joseph, M.A., B.M., M.R.C.P., and James White, London, England

VentriCUlar pacing is still the preferred method of cardiac stimulation for the treatment of symptomatic disease of the sinus node. Although at present more than 20% of permanent pacemaker implantations are for sinus node disease,":" atrial pacing accounts for only 1% to 3% of implanted pacing systems.P: 6 The reasons for this are threefold: P-wave sensing is less reliable than QRS sensing"; atrial electrodes are less stable than ventricular electrodesv "; and the association of sinus node disease with distal conduction disease implies the possibility of supervening heart block.": 13-16 The recent advent of long-life lithium batteries'? has alleviated problems associated with the greater energy needed for atrial stimulation. 18 Although successful series have been reported ,6, 10-12, 19, 20 the use of atrial pacing has not been widespread because of these problems and the greater technical demands made on the implanting physician or surgeon. The use of ventricular pacing for patients with intact distal conduction systems deprives them of the hemodynamic advantage of atrial systole 2 1- 25 and physiological ventricular contraction'" and does not diminish the high risk of systemic thromboembolism. 3, 14. 15. 27 A new pacemaker has been developed to combat all these From the Middlesex Hospital and Medical School, London, W.l, England. Received for publication Jan. 22, 1979. Accepted for publication March 20, 1979. Address for reprints: Dr. S. P. Joseph, Department of Cardiology, Mayday Hospital, Croydon, Surrey, England.

292

difficulties and to allow atrial pacing in appropriate cases.

Material and methods The new pulse generator* is programmable for energy output and output terminal. Variability of energy output meets changing energy requirements during the 2 weeks after implantation, when the energy threshold is known to rise, t8 and also allows minimum energy output in long-term use when the threshold has stabilized. In addition, the pacemaker has two output terminals connected to the atrial electrode and ventricular electrode, respectively, and it is programmable for either. Thus it may be programmed by external means for atrial sensing and pacing (AAl) via the atrial electrode or for ventricular pacing and sensing (VVl) via the ventricular electrode. Therefore, the pacemaker can be programmed for atrial pacing, with its attendant advantages, or, in the event of loss of atrial capture, problematic P-wave sensing, or development of significant atrioventricular block, the pacemaker can be programmed for ventricular pacing. The sensitivity of the pacemaker has been slightly increased to 0.7 to 0.8 m V to allow P-wave sensing but to avoid T-wave sensing. The programming of the output terminal is achieved by a modification of the Cordis Omni-Stanicor system whereby the semiconductor switches normally used to set the programmed rate are utilized to select the output terminal. *Cordis Europa N. V., Roden, The Netherlands.

0022-5223/79/080292+06$00.60/0 © 1979 The C. V. Mosby Co.

Volume 78

Long-term atrial pacing for sinus node disease

Number 2

293

August, 1979

Table I Electrophysiology

Additional cardiac diagnoses

Months after implant

Outcome

19

VP

Prolonged SNRT

Mitral regurgitation,CCF CCF

16

VP

Prolonged SNRT

CCF

15

AP

SA block

Prolonged SNRT

LVF, hypertension

15

AP

Sinus brady

Prolonged SNRT Prolonged SNRT

10 7

AP AP

7

AP

Electrocardiogram Patient (age, sex)

Symptoms, signs

Resting Sinus brady, sinus arrest, LBBB Sinus brady, sinus arrest Sinus brady, SA block SA block

5 (66, M) 6 (88, M)

Syncope, dyspnea,edema Syncope, dyspnea Syncope, dyspnea Near-syncope, dyspnea Syncope Near-syncope

7 (82, F)

Near-syncope

I (87, F) 2 (72, F) 3 (88, M) 4 (57, F)

Sinus brady Atrial fib., sinus brady Sinus brady, LBBB

I

Ambulatory

Hypertension CCF

Legend: Sinus brady, Sinus bradycardia. SA block, Sinoatrial block. Atrial fib, Atrial fibrillation. SNRT, Sinus node recovery time. CCF, Congestive cardiac failure.

LVF, Left ventricular failure. VP, Ventricular paced. AP, Atrial paced.

The criteria for the implantation of this pulse generator were that the patient be adult and symptomatic, that drugs be contraindicated or ineffective in controlling symptoms, and that there be impairment of cardiac performance, evidenced by the presence or history of cardiac failure, cardiomegaly, or diminished exercise tolerance. The presence of conduction disease, normally a contraindication to atrial pacing, was regarded as such only if there was evidence to suggest that it was contributing to the patient's symptoms. The presence of sinus bradycardia for a major part of the time was a relative indication, and, because many patients with sinus node disease are prone to supraventricular tachycardia, the possibility of an inducible tachycardia at the site of permanent atrial stimulation was eliminated by scanning the atrial diastolic period with a programmable external pacemaker at the time of implantation." Seven patients with syncope or near-syncope were diagnosed as having sinus node disease on the basis of resting or ambulatory electrocardiographic monitoring that showed sinus arrest, sinoatrial block, or sinus bradycardia (Table I). The diagnosis of sinus node disease was confirmed by electrophysiological investigation in five patients. In one patient (No.4) in whom there was doubt concerning the relationship between sinus arrest and near-syncope, a trial of pacing relieved symptoms. Five patients had dominant bradycardia, all had cardiomegaly, five had recent cardiac failure, and all were severely handicapped by their symptoms. One had a previous instance of cerebral embolism. Electrocardiographic and electrophysiological investigation excluded the presence of conduction disease in all ex-

cept two (Nos. 1 and 7) who had left bundle branch block. The pulse generator was implanted in the pectoral region in all seven patients. In three patients, both ventricular and atrial electrodes were introduced into the heart via a single cephalic vein; in four the atrial electrode necessitated a second vein, being introduced via the subclavian vein by means of a percutaneous technique with a No.9 Fr. introducer. 29 The atrial terminal was connected in four patients to a Cordis unipolar coronary sinus electrode, introduced into the coronary sinus by the method of Moss and associates.s" A Vitatron Helifix electride was inserted into the right atrial appendage of three patients. In all seven cases, the ventricular terminal was connected to a Cordis unipolar electrode with a 2 mm tip. Results

The seven pulse generators have been implanted for an average of 13 months (7 to 19 months). Two have required permanent and two have required transient programming from atrial to ventricular pacing (Fig. 1). Patient 1, with left bundle branch block, developed intermittent, Mobitz type 1, second degree atrioventricular block; although syncope did not recur, the pacemaker has been programmed to ventricular pacing noninvasively, In a second patient, loss of atrial capture developed 3 days after implantation because of electrode microdisplacement, and the pacemaker was programmed to ventricular stimulation in the same manner. In two patients, transient loss of atrial capture resulted from a rise in threshold above the output of the pacemaker, between the sixth and seventh days after

The Journal of

294 Joseph and White

Thoracic and Cardiovascular Surgery

Fig. 1. Patient 3. External programming of output-terminal programmable pacemaker from atrial to ventricular pacing.

implantation in one patient and between the third and forty-seventh days in the other. During these periods the pacemakers were programmed for ventricular pacing, and subsequently atrial pacing was resumed. All patients remain free from syncope or nearsyncope. The five patients with a history of cardiac failure remain free of recurrence, but the three now atrially paced require reduced medication; e.g., Patient 3 requires a daily dose of 40 mg of furosemide instead of 120 mg. There have been no systemic thromboembolic events since pacing was instituted. Discussion The inability of ventricular pacing to control cardiac failure in complete heart block is well known.": 32 Equally well established is the ability of atrial systole to improve cardiac output in the resting state, although the degree of improvement is disputed. 21-25. 33 The contribution of atrial systole is greatest in the presence of left ventricular impairment. 34-37 In addition, the abnormal pattern of ventricular contraction produced by artificial ventricular stimulation results in lower stroke volume than that produced by a physiological pattern of

ventricular activation.t" As many patients with sinus node disease do not require artificial ventricular stimulation, it seems logical to strive for atrial stimulation in the presence of cardiac failure. Although these patients still require medication, experience at this center has shown that cardiac failure is more readily controlled. In some patients retrograde atrial activation following ventricular stimulation causes atrial contraction against closed atrioventricular valves; this may reduce stroke volume sufficiently to cause serious hemodynamic impairment. 3. 13. 38. 39 The reported high incidence of systemic thromboembolism in this disease is an additional reason for favoring atrial stimulation." Thrombus probably forms in akinetic left atria, and maintenance of regular atrial systole may reduce this serious cause of morbidity and death. Thromboembolism does not appear to be modified by ventricular pacing": 14. 15, 27 and is sufficiently serious to have elicited the suggestion of anticoagulation for all patients with this disorder. 40 There have been no cases of systemic thromboembolism in 13 atrially paced patients at this hospital over a period of 2 years.

Volume 78 Number 2

Long-term atrial pacing for sinus node disease

295

August, 1979

Of the seven patients given this output terminal programmable pacemaker so far, five continue with satisfactory atrial pacing. Two patients permanently and two temporarily have required ventricular pacing because of the problems known to be associated with atrial pacing. Although atrial pacing has failed in two patients, they have not required surgical intervention to effect reversion to conventional ventricular pacing. The failure rate of permanent atrial pacing varies between 6% and 20%6, 8-12 and is, in most series, higher than would be considered acceptable for ventricular pacing.P- 41 The main reason for failure is the inherent instability of atrial electrodes so far introduced. Because the hemodynamic benefit which accrues from atrial pacing is not always considered sufficiently great, and because the improvement in thromboembolic risk remains theoretical, there will continue to be an ethical argument against the use of transvenous atrial electrodes until they are mechanically and electrically as stable as currently used ventricular transvenous electrodes. Furthermore, any new atrial electrode not only must be comparable to ventricular electrodes for stability in long-term use, but also must be as easy to manipulate and position during implantation. If it is not, implanting physicians will be reluctant to enter a learning phase during which the failure rate will be high. In view of these problems, it seems unlikely that long-term atrial pacing will be used more commonly in the near future unless a way can be found to avoid the problems. The concept of a programmable outputterminal pulse generator allows effective circumvention of all these problems, including the onset of atrioventricular block known to be associated with sinus node disease in 10% to 50% of cases. 3. 13-16 The implanting surgeon can now embark on atrial pacing with limited previous experience with atrial electrodes and their manipulation, secure that he can revert to standard ventricular pacing if he fails. He will then be able to enter a learning phase without detriment to the patient, and the patient can accept the idea without also having to accept the possibility of surgical intervention in the event of failure. Sudden loss of atrial pacing could lead to the original symptoms of syncope or near-syncope, although this is unlikely to be fatal as in conduction disease. Further development, however, could lead to automatic switching from atrial to ventricular pacing in the event of loss of ventricular capture due to either atrioventricular block or loss of atrial capture. Atrioventricular sequential pacing": 42 is an alternative method of maintaining the normal sequence of atrioventricular synchrony and

allowing continued ventricular pacing if atrial capture should be lost. It is illogical, however, to pace both atria and ventricles when atrioventricular conduction is normal, if only because the two pulses required for each cardiac cycle halve the life of the pacemaker. These expensi ve pacemakers are best restricted for the few patients who require atrioventricular synchrony in the presence of both sinus node disease and atrioventricular block. Additional externally programmable modes of pacing, including atrioventricular sequential pacing and atrial synchronous ventricular pacing, eventually will be incorporated in a single pulse generator. The programmable output-terminal pacemaker also allows other applications. For example, as reliable and long-lived lithium-powered pacemakers become widely used, the electrode is becoming the major limiting factor for the longevity of pacing systems. Despite careful design, the motion imposed by continuing cardiac movement for many years causes lead fracture.:" Although attempts to solve this problem are being made, it may be some years before they can be proved in vivo. The use of a programmable output-terminal pulse generator would allow the redundancy of a second electrode, and this may avoid surgical intervention if the first electrode fails. In addition, it would allow the ethical use of unproved or experimental electrodes in the clinical situation. Many parameters of pacemaker function are now programmable noninvasively using externally pulsed electromagnetic fields with decoding devices within the pacemaker; these include energy output, stimulus width and rate, sensitivity, and refractory period. The ability to program for output terminal, a simple and logical adaptation of negligible cost, will allow wider use of an additional mode of cardiac pacing, with advantage to the patient and without detriment to the patient or physician. We wish to thank Drs. W. Somerville, R. W. Emanuel, 1. D. H. Slater, J. Wedgwood, and G. Beynon for permission to investigate and pace their patients. REFERENCES Jensen G, Sigurd B, Meibom J, Sandoe E: Adams-Stokes syndrome caused by paroxysmal third-degree atrioventricular block. Br Heart J 35:516-520, 1973 2 Rockseth R, Hatle L: Prospective study on the occurrence and management of chronic sinoatrial disease with follow-up. Br Heart J 36:582-587, 1974 3 Hartel G, Talvensaari T: Treatment of sino-atrial syndrome with permanent cardiac pacing in 90 patients. Acta Med Scand 198:341-347, 1975 4 Kaul TK, Kumar EB, Thomson RM, Bain WH: Sinoatrial disorders (the "sick sinus" syndrome). Experience

The Journal of

296 Joseph and White

Thoracic and Cardiovascular Surgery

5

6 7 8

9 10

II

12

13

14

15

16

17

18

19

20

21

22

with implanted cardiac pacemakers. Abstracts of the Seventh European Congress of Cardiology 1:359, 1976 Parsonnet V, Furman S, Bilitch M, Escher D: Permanent cardiac pacemaker leads (abstr). Circulation 55, 56:Suppl 3: 12, 1977 Kleinert M, Bock M, Wilhemi F: Clinical use of a new transvenous atrial lead. Am J Cardiol 40:237-242, 1977 Furman S, DeCaprio V, Hurzeler P: The atrial signal and pacer sensing (abstr). Med Instrum 10:47-48, 1976 Chokshi DS, Mascarenhas E, Samet P, Center S: Treatment of sino-atrial rhythm disturbances with permanent cardiac pacing. Am J Cardiol 32:215-220, 1973 Cappelan C, Hall K V: Pervenous atrial electrodes. Scand J Thorac Cardiovasc Surg 8:1l5-118, 1974 Smyth NPD, Citron P, Keshishian JM, Garcia JM, Kelly LC: Permanent pervenous atrial sensing and pacing with a new J-shaped lead. J THORAC CARDIOVASC SURG 72: 565-570, 1976 Greenberg P, Castellanet M, Messenger J, Ellestad MH: Coronary sinus pacing. Clinical follow-up. Circulation 57:98-103, 1978 Moss AJ, Rivers RJ: Atrial pacing from the coronary vein. Ten year experience in 50 patients with implanted pervenous pacemakers. Circulation 57: 103-106, 1978 Rubenstein JJ, Shulman CL, Jurchak PM, DeSanctis RW: Clinical spectrum of the sick sinus syndrome. Circulation 46:5-13, 1972 Areosty JM, Cohen SI, Morkin E: Bradycardia-tachycardia syndrome. Results in twenty-eight patients treated by combined pharmacologic therapy and pacemaker implantation. Chest 66:257-263, 1974 Krishnaswami V, Geraci A: Permanent pacing in disorders of sinus node function. Am Heart J 89:579-585, 1975 Conde CA, Leppo J, Lipski J, Stimmel B, Litwak R, Donoso E, Dack S: Effectiveness of pacemaker treatment in the bradycardia-tachycardia syndrome. Am J Cardiol 32:209-214, 1973 Parsonnet V: Cardiac pacing and pacemakers VII. Power sources for implantable pacemakers. Part II. Am Heart J 94:658-664, 1977 Joseph SP, Jenkins P: Acute and chronic energy thresholds in permanent atrial pacing via the coronary sinus, Troubles du rythme et Electrostimulation. P Puel, ed., Toulouse, 1977, University, Paul-Sabatier, pp 351-358 Witte J, Dressler C, Schroder G, Von Knorre GH: Transvenous atrial synchronized pacing, Advances in Pacemaker Technology, M Schaldach, S Furman, eds., Berlin, 1975, Springer- Verlag, p 99 Geddes JS, Webb SW, Clements IP: Clinical experience with transvenous atrial pacing. Br Heart J 40:589-595, 1978 Brockman SK: Dynamic function of atrial contraction in regulation of cardiac performance. Am J Physiol 204: 597-603, 1963 Burchall HB: A clinical appraisal of atrial transport function. Lancet 1:775-779, 1964

23 Leinbach RC, Chamberlain DA, Kastor JA, Harthome JW, Sanders CA: A comparison of the hemodynamic effects of ventricular and sequential A- V pacing in patients with heart block. Am Heart J 78:502-508, 1969 24 Deal CW, Fielden P, Monk I: Hemodynamic effects of differing pacemaker sites and demand pacing. J THORAC CARDIOVASC SURG 66:454-457, 1973 25 Westermann KW, Fink HG, Priester G, Eggert R: Orthostatic circulatory adaptation in patients with cardiac pacemakers. Herz/Kreislauf 6:323-327, 1974 26 Kosowsky BD, Scherlag BJ, Damato AN: Re-evaluation of the atrial contribution to ventricular function. Study using His bundle pacing. Am J CardioI21:518-524, 1968 27 Radford DJ, Julian DG: Sick sinus syndrome. Experience of a cardiac pacemaker clinic. Br Med J 3:504-507, 1974 28 Wellens HJJ: Electrical Stimulation of the Heart in the Study and Treatment of Tachycardias, Leiden, 1971, H. E. Stenfert Kroesse N. V. 29 Jachuck SJ, Gill BS, Petty AH: Permanent cardiac pacing through the subclavian vein. Br J Surg 61:373-376, 1974 30 Moss AJ, Rivers RJ, Kramer DH, Resnicoff S: Permanent pervenous atrial synchronized ventricular pacing. Circulation 48:37-40, 1973 31 Davidson D, Braak C, Preston T, Judge R: Permanent ventricular pacing. Effect on long term survival, congestive cardiac failure and subsequent myocardial infarction and stroke. Ann Intern Med 77:345-351, 1972 32 Hetzel MR, Ginks WR, Pickersgill AJ, Leatham A: Value of pacing in cardiac failure associated with chronic atrio-ventricular block. Br Heart J 40:864-869, 1978 33 Snyder JH, Bender F, Kitchin AH, Zitnik RS, Donald DE, Wood EH: Atrial contribution to stroke volume in dogs with chronic heart block. Circ Res 19:33-41, 1966 34 Friesen WG, Woodson RD, Ames AW, Herr RH, Starr A, Kassebaum DG: A hemodynamic comparison of atrial and ventricular pacing in postoperative cardiac surgical patients. J THoRAc CARDIOVASC SURG 55:271-279, 1968 35 Gilgenkrantz JM, Groussin P, Witz F, Cherrier F, Saulnier JP, Dodinot B: Role hemodynamique de la contraction auriculaire dans I'infarctus du myocarde a la phase aigue. Arch Mal Coeur 68:1021-1028, 1975 36 Cherrier F, Groussin P, Witz F, Aliot E, Gilgenkrantz JM: La systole auriculaire. Etude de son role Ie sujet normal et dans I'insuffisance ventriculaire gauche. Arch Mal Coeur 68:1013-1020, 1975 37 Rahimtoola SH, Ehsani A, Sinno MZ, Loeb HS, Rosen KM: Left atrial transport function in myocardial infarction. Importance of its booster pump function. Am J Med 59:686-694, 1975 38 Alicandri C, Fouad FM, Tarazi RC, Castle L, Morant V: Three cases of hypotension and syncope with ventricular pacing. Possible role of atrial reflexes. Am J Cardiol 42:137-142, 1978 39 Johnson AD, Laiken SL, Engler RL: Hemodynamic compromise associated with ventriculo-atrial conduction following transvenous pacemaker placement. Am J Med 65:75-79, 1978

Volume 78 Number 2

Long-term atrial pacing for sinus node disease

297

August, 1979

40 Fairfax AJ, Lambert CD, Leatham A: Systemic embolism in chronic sino-atrial disorder. N Engl J Med 295: 190192, 1976 41 Grendahl H, Sivertssen E: Pacemaker wires and electrodes. A follow-up study. Acta Med Scand Suppl 596:12-21, 1976 42 Levy S, Jausseran JM, Boyer C, Luccioni R, Monties JR,

Gerard R: La stimulation 'sequentielle ' auriculoventriculaire par stimulateur 'bifocal' implantable. Arch Mal Coeur 69: 1285-1292, 1976 43 Mantini EL, Majors RK, Kennedy JR, Lebo GR: A recommended protocol for pacemaker follow-up. Analysis of 1705 implanted pacemakers. Ann Thorac Surg 24:6267, 1977