CASE REPORT supraventricular tachycardia, pediatric
Evaluation and Management of Supraventricular Tachycardia in Children Emergency physicians m a y be called on to resuscitate acute complications in pediatric patients w i t h congenital heart disease. Supraventricular tachycardia, with or w~thout hemodynamic decompensation, is one of the most serious complications. We present the case of a 22-month-old boy with a history of single ventricle who presented to our institution with a history of syncope and hemodynamically stable supraventricular tachycardia. Initial attempts at pharmacologic conversion with propranolol and verapamil failed. The arrhythmia was terminated in response to an IV fluid bolus and dopamine infusion and probably resulted from a combination of anemia, hypovolemia, and impaired contractility. Appropriate evaluation and management relating to the care of acute supraventricular tachycardia in children are discussed. [Binder LS, Boeche R, Atkinson D: Evaluation and management of supraventricular tachycardl"a in children. Ann Emerg Med January 1991;20:51-54.]
INTRODUCTION Complications occurring in pediatric patients with congenital heart disease are important but infrequently encountered emergency department problems. A diverse spectrum of pediatric congenital heart disease exists, and patients with these disease entities may present with various cardiac complications, including acute syncope, arrhythmias, congestive heart failure, or acute cyanosis. 1 Emergency physicians may be called on to undertake stabilization of these patients. We present the case of a toddler with single ventricle who presented with supraventricular tachycardia and discuss the management of supraventricular tachycardia in children.
Louis S Binder, MD Renee Boeche, DO Darryl Atkinson, DO El Paso, Texas From the Department of Emergency Medicine, Texas Tech University Health Sciences Center at El Paso. Received for publication April 16, 1990. Revision received July 30, 1990. Accepted for publication August 17, 1990. Address for reprints: Louis S Binder, MD, Department of Emergency Medicine, Texas Tech University Health Sciences Center at El Paso, 4800 Alberta Avenue, El Paso, Texas 79905.
CASE REPORT A 22-month-old boy with a diagnosis of single ventricle who had pulmonary arterial banding at 6 months of age presented with a chief complaint of syncope and tachycardia. The mother reported that the child sustained a syncopal episode of five minutes' duration while playing in the backyard one to two hours before arrival. The event was associated with apnea and pallor, prompting m0uth-to-mouth ventilation by the mother until recovery. The child was initially taken to a neighborhood clinic and treated with an ammonia capsule inhalant and a "shot to help his breathing." He was then brought to the ED for further evaluation. Medications included lanoxin 0.9 mg twice daily. On examination, the child appeared alert but agitated and cried and thrashed about intermittently. There was no cyanosis or respiratory distress. Vital signs were systolic blood pressure of 75 to 85 m m Hg by Doppler; pulse, 210 to 220; respirations, 30; and temperature, 37.2 C; his weight was 10 kg. Monitor and 12-lead ECGs each revealed a supraventricular tachycardia of 210 to 220 with no other ectopy (Figure}. Head, eyes, ears, nose, and throat examinations were normal. The neck was suppie with no nodes or jugular venous distension, and the trachea was midline. The lungs were clear to auscultation. Cardiac examination revealed a rapid rhythm with a grade 4/6 holosystolic precordial murmur. Abdominal and urogenital examinations were normal. Extremities revealed bilateral femoral cutdown scars but no cyanosis or edema, and pulses were intact.
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Neurologic examination was unremarkable. O x y g e n w a s g i v e n by n o n rebreather mask, a left tibial interosseous IV line "was placed, and normal saline was begun at keep-open rate. Attempts at peripheral and central venous c a n n u l a t i o n were initially unsuccessful. A supine portable chest radiograph was within normal limits. Capillary blood gases on 8 L/rain oxygen by nonrebreather mask revealed Po 2 of 70; Pco2, 20; and pH 7.40. A CBC revealed a hemoglobin of 9.6; hematocrit, 27.6; white blood cells, 18,800/ram 3 with 45 polymorphonuclear leukocytes, 45 lymphocytes, and seven bands; sodium, 138 mEq/L; potassium, 3.1 mEq/L; chloride, 109 mEq/L; carbon dioxide, 6 mEq/L; blood urea nitrogen, 19 rag%; glucose, 249 mg/dL; and creatinine, 1.0 mg%. Digoxin level was 1.0 ~g/dL (normal range, 0.8 to 2.0 ~g/mL). Pediatrics was immediately consulted, and a preliminary diagnosis of congenital single ventricle with cardiogenic supraventricular tachycardia in a n o r m o t e n s i v e infant was made. Propranolol 0.25 mg was given by the interosseous route four times at five-minute intervals, and 1 mg verapamil was given by the interosseous r o u t e two t i m e s at nineminute intervals; this resulted in no change in the rhythm. The failure to respond to pharmaceutical intervention led to a suspected diagnosis of acquired subaortic outflow obstruction secondary to pulmonary arterial banding. A right subclavian IV line was established, and dopamine was begun at 10 txg/kg/min. At hospitalization, additional information became available that the child had been to the ED 11 days earlier with bilateral otitis media and croup, had had watery yellow diarrhea for two days, and had been playing outside all day in 90 to 100 F weather before the syncopal episode. A 200-mL bolus of normal saline was administered. The child improved sequentially and hemodynamically to both therapeutic interventions. Following an additional 100 mL of normal saline and 100 mL of packed red blood cells, the heart r h y t h m corrected to sinus tachycardia at a rate of 150 with a blood pressure of 76/40 mm Hg. The child was admitted to the pediatric ICU with diagnoses of corn20:1 January 1991
bined cardiogenic and hypovolemic hypotension from suspected concomitant aortic outflow obstruction and dehydration, secondary supraventricular tachycardia, and anemia of unclear etiology. The dopamine infusion was weaned over eight hours, and the systolic blood pressure increased to and remained at more than 100 m m Hg. The pulse rate remained at 120 to 130 throughout the remainder of the patient's ten-day hospital stay. A two-dimensional echocardiogram performed on admission revealed ventricular hypertrophy with a dilated single ventricular cavity, normal great vessel relationship, and no pericardial effusion. No subaortic stenosis was visualized. The anemia was found to be secondary to iron deficiency, and the child was begun on ferrous sulfate. He had occasional febrile episodes to 39 C, which were thought to be secondary to otitis media and urinary tract infection, and he was treated with cefotaxime and trimethoprim/ sulfisoxazole. On the seventh hospital day, stool cultures were positive for Salmonella enteritidis. At discharge, he returned to the care of his pediatric cardiologist in another city and was reportedly doing well at 6 months' follow-up.
DISCUSSION Paroxysmal supraventricular tachycardia (PSVT) is the most common significant arrhythmia seen in pediatric practice. The most frequent presentation is infantile PSVT (occurring in infants less than 5 months old) presenting with poor feeding, fussiness, and pallor; less often seen is hypotension or acute syncope. 2 The range of tachycardia is 220 to 320 in younger infants (less than 6 months old), 180 to 300 in children 1 to 2 years old, and 150 to 250 in older children. 3 Fifty percent of infantile PSVT is idiopathic, 20% can be related to associated conditions (eg, infection, fever, sympathomimetic use, volume or electrolyte depletion; or acid-base derangement), 20% is related to congenital heart disease, and 10% occurs in infants with pre-exciration syndrome. 4 Electrophysiologic characterization of pediatric PSVT has established that both enhanced automaticity (eg, metabolic, pharmacologic, atrial fibrillation, or flutter) and re-entrant circus dysrhythmias may result in Annals of Emergency Medicine
this dysrhythmia, similar to adult patients.3, s Clinically, infants with PSVT present with signs of early hypotension and congestive heart failure, poor feeding, irritability or lethargy, pallor, and tachypnea. 4,6y Infants and children with acute PSVT are treated as determined by the severity of hemodynamic decom'pensation. Toxic or unstable patients (eg, shock, acidosis, severe heart failure or pulmonary edema, or pulseless) should undergo immediate, sync h r o n i z e d DC c a r d i o v e r s i o n at 1 W/sec/kg, despite possible antecedent treatment with digitalis. 1-3 Pretreatment with IV phenytoin {10 to 15 mg/kg) may be advisable if digitalization was instituted before cardioversion. In moderately hypotensive children, increasing the blood pressure with c~-adrenergic agents such as phenylephrine (0.01 mg/kg) may terminate PSVT by baroreceptor stimulation of increased parasympathetic (vagal) tone. ~-Adrenergic agents are not efficacious in children less than 18 months old and may acutely precipitate hypertension or heart failure.8 The management of children who are minimally symptomatic is cont r o v e r s i a l . Vagal m a n e u v e r s , although suggested as initial treatment, are frequently unsuccessful in children.8, 9 Some authors advocate synchronized cardioversion for these patients, whereas others believe t h e s e i n f a n t s m a y be m e d i c a l l y treated, as m o s t p a t i e n t s treated pharmacologically will convert rapidly. If pharmacologic treatment is undertaken, a number of different agents have been advocated, each with its inherent therapeutic benefits and risks. Historically, digitalization (25 to 50 txg/kg) has been advocated as the drug of choice 1 3 and is effective at t e r m i n a t i o n of pediatric PSVT by prolonging atrioventricular nodal conduction in both the fast (f3) and slow (~) pathways. However, termination of PSVT with digitalis may be delayed, its use with misidentified ventricular tachycardia may provoke progression to ventricular fibrillation, m and its use with unsuspected Wolfe-Parkinson-White s y n d r o m e may increase conduction through accessory atrioventricular pathways, resuiting in 1:1 atrioventricular conduction. 3 Propranolol (0.1 mg/kg IV bolus), w h i c h s i m i l a r l y prolongs 52/75
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FIGURE. Rhythm strip showing supraventricular tachycardia. secondary cardiogenic PSVT, and suspected subaortic outflow obstruction. The suspected diagnosis was refuted by echocardiography. We surmise that the supraventricular tachycardia in this child with single ventricle occurred secondary to a combination of anemia, hypovolemia, and impaired ionotropism. Correction of metabolic etiologies t h r o u g h h y d r a t i o n and transfusion and improvement in ionotropism from dopamine infusion resulted in clinical improvement and termination of the arrhythmia.
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SUMMARY
atrioventricular nodal conduction, may be used in infants and children unresponsive to digitalis. 1-3 However, propranolol bolus may precipitate hemodynamically significant hypotension and bradycardia in children. 8 Intravenous verapamil (0.1 mg/kg tV bolus) has been used successfully to treat pediatric PSVT u-13 but can cause bradydysrhythmias and hypotension, especially in infants.gJ 4q6 I m m a t u r i t y of the autonomic nervous system, 17 the greater dependence of pediatric cardiac output on heart rate than on stroke volume, 18 and increased myocardial sensitivity t o the negative ionotropic effects of verapamil in immature animals 19 are potential mechanisms for the greater hemodynamic effect of verapamil in infants. Pretreatment with IV calcium chloride or calcium gluconate decreases the hemodynamic depression of verapamil in adults without compromising its antiarrhythmic effect,2o,21 but this has not been studied in children. With these data, some authors have recommended verapamil as safe and effective for treatment of pediatric PSVT, ~2 whereas others have recommended against its use, especially in infants less than 12 months old. 9 The most recent development in the pharmacologic m a n a g e m e n t of PSVT has been the Food and Drug Administration approval of adenosine (0.05 to 0.25 mg/kg IV bolus), a short-acting purine nucleoside, for IV treatment of PSVT. Adenosine slows atrioventricular nodal conduction 2~ 76/53
and has a 90% success rate in adults in terminating atrioventricular node re-entrant tachycardia and re-entrant PSVT in the Wolfe-Parkinson-White syndrome, including some patients unresponsive to verapamil. 23 Advantages of the use of adenosine in children include a lack of substantial adverse h e m o d y n a m i c effects,24, 25 a lack of pharmacologic i n t e r a c t i o n w i t h other cardiac drugs, 26 safety when used with wide-complex tachycardia, 24 and a very short half-life (five to 15 seconds) due to metabolism by circulating adenosine deami n a s e s and rapid t r a n s p o r t i n t o cells. ~2 This results in a short interval (less than 20 seconds) to PSVT termination and short duration of any adverse effects. Transient bradycardia and heart block have occurred after arrhythmia termination, and frequent atrial flutter, atrial fibrillation, premature ventricular complexes, and transient asystole have been reported. 26 Des p i t e this, a d e n o s i n e has b e e n deemed safe for use in severely ill children and advocated as an effective first-line agent for acute termination of PSVT in children.24, 25 Rapid atrial or esophageal overdrive pacing may result in a 2:1 atriqventricular block and a reduced ventricular rate with hemodynamic imp r o v e m e n t . 2,3,27,28 In addition, if evidence exists for metabolic etiologies of PSVT, treatment of these etiologies should be undertaken (as occurred in our patient). This infant's initial clinical picture was one of congenital heart disease, Annals of Emergency Medicine
The case of a 22-month-old boy with single ventricle who presented with supraventricular tachycardia is presented. The arrhythmia did not convert with standard pharmacologic therapy and was ultimately terminated by correction of underlying metabolic causes and ionotropic support. This case illustrates the importance of searching for u n d e r l y i n g metabolic etiologies (fever, acid-base, volume, or electrolyte depletion) in the precipitation of pediatric PSVT and the important similarities and differences in the m a n a g e m e n t of PSVT between adult and pediatric patients.
REFERENCES 1. McCrory JH, Heart disease, in Tintinalli JE, Krome RL, Ruiz E [eds}: Emergency Medicine: A Comprehensive Study Guide, ed 2. New York, McGraw-Hill Books, 1988, p 412-415. 2. Gillette PC, Carson A, Crawford F, et al: Supraventricular tachycardia, in Adams FH, Emmanouilides GC, Riemenschneider TA (eds}: Moss's Heart Disease in Infants, Children and Adolescents, ed 4. Baltimore, Williams & Wilkins, 1989, p 931-935. 3. Gewotz MH, Vetter VL: Supraventricular tachycardia, in l~Ieisher GR, Ludwig S, Henretig FM, et al (eds}: Textbook of Pediatric Emergency Medicine, ed 2. Baltimore, Williams & Wilkins, 1988, p 367-376. 4. Garson A, Gillette PC r M c N a m a r a DG: Supraventricular tachycardia in children: Clinical features, response to treatment, and long term follow up in 217 patients. J Pediatr 1981;98:875-880. 5. Gillette PC: The mechanism of supraventricular tachycardia in children. Circalation 1976;54:133-139. 6. Anderson ED, Jacobsen JR, Sandoe E: Paroxysmal tachycardia in infancy and childhood. Acta Pediatr Scand 1973;62:341-345. 7. Nadas AS: Paroxysmal tachycardia in infants and children. Pediatrics 1952;9:167-172. 8. Ludominski A, Garson A: Supraventricular tachycardia, in Garson A, Bricker JT, McNamara DG (eds): The Service and Practice of Pediatric Cardiology Philadelphia, Lea & Febiger, 1990, p 1809-1948. 9. Garson A: Medicolegal problems in the management of cardiac arrhythmias in children. Pediatrics 1987;79: 84-87. 10. Greco R, Musto B, Ariezo V, et ai: Treatment of par-
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oxysmal supraventricular tachycardia in infancy with digitalis, adenosine-5'-triphosphate, and verapamil: A comparative study. Circtdetion 1982;66:504-508. 11. Silberbach M, Dunnigan A, Benson DW: Effect of intravenous propranolol or verapamil on infant orthodromic reciprocating tachycardia. A m J Cardiol 1989; 63:438 441. 12. Sapire DW, O~Riordan AC, Black AFS: Safety and efficacy of short and long term verapamil therapy in children with tachycardia. Am J Cardiol 1981;48:1091-1096. 13. Porter CJ, Gillette DC, Garson A, et al: Effect of verapamil on supraventricular tachycardia in children. Arn [ Cardiof i98I;48:487-491. 14. Epstein ML, Kiel EA, Victorica BE: Cardiac decompensation following verapamil therapy in infants with supraventricular tachycardia. Pediatrics 1985;75: 737-740. 15. Kirk CR, Gibbs JL, Thomas R, et al: Cardiovascular collapse after verapamil in supraventricular tachycardia. Arch Dis Child 1987;62:1265-1266.
16. Porter C L Garson A, Gillette PC: Verapamil: An ef-
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fective calcium blocking agent for pediatric patients• Pediatrics 1983~7l:748-755.
22. Bellardinelli L, Linden l, Berne RM: The cardiac effects of adenosine. Prog Cardiovasc Dis 1989;32:73-97.
17. Friedman WF, Pool PE, lacobowitz D, et al: Sympa thetic innervation of the developing rabbit heart: Bio chemical and histochemical comparisons of fetal neonatal, and adult myocardium. Circ Res 1958;23:25-30.
23. Adenosine Study Group, University of Virginia: Adenosine for termination of supraventricular tachycardis: Dose ranging and comparison with verapamil. Circulation (Suppl II) 1989;80:631.
18. Klopfenstein HS, Rudolph AM: Postnatal changes in the circulation and responses to volume loading in sheep. Circ Res 1978;42:839-843.
24. Till J, Shirlebourne EA, Rigby ML, et al: Efficacy and safety of adenosine in the t r e a t m e n t of supraventricular tachycardia in infants and children. Br Heart [ 1989;62:204-211.
19. Gibson R, Driscoll D, Gillette 12,et al: The comparative electrophysiologic and hemodynamic effects of verapamil in puppies and adult dogs. Dev Pharmacol Ther 1981;2:104-110. 20. Haft JI, Habbab MA: T r e a t m e n t of atrial arrhythmias: Effectiveness of verapamil when preceded by c a l c i u m in[usion. Arch Intern Med 1986;146: I085-1089. 21. Weiss AT, Lewis B8, Hafon DA, et al: The use of calcium with verapamil in the management of supraventricular tachyarrhythmias. Int J Cardiol 1983, 4:275-280.
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25. Overholt ED, Rheuban KS, Gntgesell HP, et al: Usefulness of adenosine for arrhythmias in infants and children. A m J Cardiol 1988;61:336-340. 26. Adenosine. Med Lett Drugs Ther 1990~32:63. 27. Benson DW, Sanford M, Dnnnigan A, et al: Transesophageal pacing threshold: Role of interelectrode spacing, pulse width, and catheter insertion depth. A m 1 Cardiol 1984;53:6666. 28. Gillette PC, Shannon C, Blair H, et al: Transvenous pacing in pediatric patients. A m Heart ! 1983;105: 843-849.
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