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Communications Lithium-Induced Dysrhythmias As a Marker for Sick Sinus Syndrome

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Communications Lithium-Induced Dysrhythmias As a Marker for Sick Sinus Syndrome Communications Lithium-Induced Dysrhythmias as a Marker for Sick Sinus Syndrome Wm. MacMillan Rodney, MD, Peter Chopivsky, MD, and Jim H. Hara, MD Los Angeles, California Lithium treatment has been associated with an were 1.3 mEq/L, 1.1 mEq/L, 0.2 mEq/L, and 0.1 increasing number of cardiac complications.1'4 mEq/L, respectively. Cardiac ambulatory (Holter) Emerging among these is cardiac sinus node dys­ monitor on the second hospital day continued to function.5'7 Other investigators have reported show a junctional rhythm with ventricular bigem- cases of sinus node dysfunction that reversed iny (Figure 1). Rates ranged from 40 to 65 beats/ upon withdrawal of lithium.8 Reported here is a min at rest to 50 to 100 beats/min with activity. case of sinus node dysfunction associated with Sinoatrial blocks of up to 2.92 seconds were re­ lithium therapy that did not reverse to normal after corded (Figure 2). By the third hospital day, the cessation of lithium. Lithium may play a role in predominant rhythm was sinus, but sinoatrial inducing dysrhythmias, including sinoatrial node blocks of up to 2 seconds continued to occur. On dysfunction. hospital day 8, Holter monitor showed sinus rhythm of 60 to 85 beats/min, PR intervals of 180 Case Report ms, and QRS duration of 80 ms. Yet, frequent A 59-year-old retired opera singer followed at premature atrial contractions and supraventricular the UCLA Family Medicine Clinic since No­ and ventricular tachycardia were also recorded. vember 1979 was admitted to UCLA Hospital Reinstitution of lithium therapy was advised by in January 1980 for asymptomatic bradycardia. the psychiatrist, but after consideration of the She had been treated with 750 mg of lithium car­ above Holter findings, it was decided to proceed bonate twice daily since 1977 for manic-depressive with discontinuation of all medications. Asymp­ illness. There was no history of ischemic heart tomatic sinus rhythm continued, and the patient disease, rheumatic fever, or diphtheria. was discharged on no medications on the 11th On the day of her admission, she was seen in hospital day. routine follow-up by her psychiatrist, who noted Two weeks after discharge, repeat Holter moni­ an irregularly irregular slow pulse. He referred the tor showed evidence of sinoatrial node disease: patient to her family physician, who obtained an paired atrial extrasystoles, occasional one- to four- electrocardiogram showing a junctional rhythm of beat junctional escape rhythm, one episode of su­ 30 beats/min. P wave activity was random with praventricular tachycardia, and two premature ven­ intermittent gaps greater than 20 seconds. Atro­ tricular contractions. Five months after discharge, pine, 0.5 mg intravenously, was given twice within the Holter revealed sinus rhythm with periods of 5 minutes without effect. The patient was admitted first-degree and second-degree Wenckeback-type to the coronary observation unit and all medica­ atrioventricular block. tions were withdrawn. Lithium levels on hospital days 1, 2, 5, and 7 Comment Reversible cardiac sinus node dysfunction in­ From the Division of Family Practice, School of Medicine, University of California, Los Angeles, California. Requests duced by lithium carbonate has been reviewed re­ for reprints should be addressed to Dr. Peter Chopivsky, cently.7,8 Sinus bradycardia has been found to be UCLA Family Health Center, CHS-BH-134, Los Angeies, CA 90024. the most frequent dysrhythmia; however, sinus ® 1983 Appleton-Century-Crofts THE JOURNAL OF FAMILY PRACTICE, VOL. 16, NO. 4: 797-799, 1983 797 LITHIUM-INDUCED DYSRHYTHMIAS Figure 1. Flolter monitor tracing showing junctional rhythm with ven­ tricular bigeminy pauses of up to 4.6 seconds have been reported.5 from 10 to 31 years have been reported.12 These European investigators have reported two cases of cases confirm earlier descriptions of an erratic, nodal rhythm with sinoatrial block.9,10 It has been slowly progressive course in which escape postulated that lithium alone is not sufficient to rhythms occur with increasing frequency.13,14 Ini­ cause the above dysfunction.5 tially these rhythms may be only escape rhythms, This case report describes a prolonged period of but eventually they can become the basic pace­ junctional rhythm with sinoatrial node activity makers with increased risk of sudden death.15 suppressed to the point of sinoatrial arrest. Nei­ Because of the reported linkage of sinus node ther this degree of sinoatrial dysfunction in asso­ dysfunction to lithium therapy, Roose et al8 have ciation with the use of lithium nor the persistence suggested regular pulse readings with semiannual of sinoatrial node dysfunction following cessation electrocardiogram rhythm strips for “ all lithium- of lithium has been reported previously. As in a treated patients who are over the age of 50 or who majority of similar cases, this case raises the sus­ have a history of heart disease.” Though the idea picion of underlying organic heart disease aggra­ of a pulse diary is laudable, there is strong vated by lithium. As in many of the previously evidence to support Holter monitoring in contrast reported cases, this patient was originally asymp­ to rhythm strip recording because of the Holter tomatic in spite of the existence of impressive dys­ monitor’s greater sensitivity in detecting dys­ rhythmia. In this case, the persistence of sinoatrial rhythmias.16,17 and atrioventricular node dysfunction, despite the This case suggests that lithium may play a role cessation of lithium, raises the possibility that in inducing dysrhythmias, especially those due to lithium unmasked an ongoing but silent (asympto­ sinoatrial node dysfunction. Physicians should be matic) sinus node dysrhythmia. alert to this possible association. Patients in whom The natural history and etiology of sinoatrial the use of lithium is contemplated warrant careful disorder (sick sinus syndrome) are not well pretherapy cardiac investigation. Medical history known. A prospective eight-year survey revealed and physical examination may suffice for the major­ that 47 percent of patients with this disorder were ity. High-risk subsets include those with a history free of significant complication.11 The long-term of syncope, dizziness, transient ischemic attacks, prognosis cannot be stated with certainty, but palpitations, and recent worsening of cardiac cases that have been studied over periods ranging symptoms such as angina or dyspnea on exertion. 798 THE JOURNAL OF FAMILY PRACTICE, VOL. 16, NO. 4, 1983 RICKETS AND BREAST-FEEDING Age itself is a relative risk marker, since the mean References age of presentation for sinoatrial disorder in the 1. Tangedahl TN, Gan GT: Myocardial irritability as­ Shaw and Kekwick study11 was 62 years. Because sociated with lithium carbonate therapy. N Engl J Med 287: 867, 1972 of their frequency in this population, spells of 2. Demers RG, Heninger GR: Electrocardiographic lightheadedness, momentary lapses of memory, T-wave changes during lithium carbonate treatment. JAMA 218:381, 1971 nocturnal awakening, and generalized fatigue are 3. Tseng HL: Interstitial myocarditis probably related probably of insufficient sensitivity to warrant ex­ to lithium carbonate intoxication. Arch Pathol 92:444, 1971 4. Tilkian AG, Schroeder JS, Kao JJ, et al: The car­ tensive routine investigation; nevertheless, these diovascular effect of lithium in man. Am J Med 61:665, may also be markers for sick sinus syndrome.15 1976 5. Wilson JR, Kraus ES, Bailas MM, et al: Reversible High-risk patients should receive 24-hour ambu­ sinus node abnormalities due to lithium carbonate therapy. latory cardiac monitoring prior to and after the N Engl J Med 294:1223, 1975 6. Wellens HJ, Cats VM, Duren DR: Symptomatic sinus initiation of lithium therapy. Atrial pacing and node abnormalities following lithium carbonate therapy. measurement of sinus node recovery time is felt to Am J Med 59:285, 1975 7. Rector WG, Jarzobski JA, Levin HS: Sinus node dys­ be the most reproducible diagnostic evaluation for function associated with lithium therapy: Report of a case sinus node disease.12 This invasive procedure is and review of the literature. Nebr Med J, July 1979, pp 193- 196 not a reasonable screening test, however, and car­ 8. Roose SP, Nurnberger J I, Dunner DL, et al: Cardiac diology consultation would be required for its use. sinus node dysfunction during lithium treatment. Am J Psychiatry 136:804, 1979 The intervals needed for periodic ambulatory car­ 9. Kleinert M: Myokardiopathie unter lithiumtherapie. diac monitoring for the best cost-benefit ratio are Med Klin 69:494, 1974 10. Humbert G, Fillastre JP, Leroy J, et al: Intoxication unknown. Further study will be required. At pres­ par le lithium. Sem Hop Paris 50:509, 1974 ent, however, monitoring is recommended once 11. Shaw DB, Kekwick CA: Potential candidates for pacemakers: Survey of heart block and sinoatrial disorder when therapeutic levels are established, then an­ (sick sinus syndrome). Br Heart J 40:99, 1978 nually in follow-up. Holter monitoring should be 12. Ferrer Ml: The heart's primary pacemaker: Types of dysfunction. Hosp Physician, June 1980, pp A15-A30 performed immediately if the patient reports 13. Ferrer Ml: The sick sinus syndrome in atrial disease. symptoms associated with increased incidence of JAMA 206:645, 1968 14. Rubenstein JJ, Schulman CL, Yurchak PM, et al: sick sinus syndrome. When cardiac dysfunction is Clinical spectrum of sick sinus syndrome. Circulation 41:5, diagnosed, cardiology consultation is suggested. 1972 15. Ferrer Ml: The sick sinus syndrome. Circulation In sinoatrial disorder, pacemaker implantation is 47:635, 1973 indicated in symptomatic bradycardiac patients.12-18 16. Schultze RA, Strauss HW, Pitt B: Sudden death in the year following myocardial infarction. Am J Med 62:192, It is hoped that health care providers involved 1977 with disorders requiring lithium therapy will col­ 17. Zomeraich S: Ambulatory ECG in the detection of arrhythmias. Practical Cardiol 6(4):43, 1980 laborate with colleagues in cardiology in the study 18.
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