84 Br Heart3' 1993;70:84-87

CASE REPORTS

of the ventricular response to atrial Acceleration Br J: first published as 10.1136/hrt.70.1.84 on 1 July 1993. Downloaded from flutter by amiodarone in an infant with Wolff- Parkinson-White syndrome

J A Till, Mark Baxendall, A Benetar

Abstract ventilation in 100% oxygen. During the first Amiodarone resulted in a rapid ventricu- 24 hours of life there were two episodes of lar response to atrial flutter in an infant supraventricular with further clin- with Wolff-Parkinson-White syndrome. ical deterioration. A 12 lead electrocardio- gram during tachycardia showed a regular (Br HeartrJ 1993;70:84-87) narrow QRS complex consistent with atrio- ventricular reentry tachycardia. Preexcitation In a patient with Wolff-Parkinson-White was evident on an electrocardiogram record- syndrome the ventricular response to an atrial ed during sinus rhythm (fig 1A). The initial is determined both by the atri- attacks of supraventricular tachycardia oventricular node and the accessory connec- responded to vagal manoeuvres. None the tion. There is a small risk of sudden death in less intravenous amiodarone was started at a the Wolff-Parkinson-White syndrome that is dose of 5 mg/kg. Immediately after amio- thought to result from ventricular darone treatment was started the child sus- arising from a rapid ventricular response to tained a severe cardiovascular collapse with a an atrial arrhythmia through the accessory wide complex that required iso- connection.' 2 and may prenaline and further resuscitation. This increase the risk of in restored supraventricular tachycardia which certain patients and are therefore usually seemed to respond to direct current car- avoided in the management of patients with dioversion but on later inspection the electro- Wolff-Parkinson-White syndrome.3 We des- cardiogram showed atrial flutter with 2:1 cribe an infant with Wolff-Parkinson-White atrioventricular nodal block (fig 1B). The http://heart.bmj.com/ syndrome in whom amiodarone resulted in a infant's haemodynamic condition again sta- rapid ventricular response to atrial flutter. bilised but during the next 24 hours he became anuric and peritoneal dialysis was started. Regular oral amiodarone was given at Case report a dose of 350 mg/m2/day (loading dose) and A male infant was born to a 26 year old white the infant remained stable over the following mother. Pregnancy was uncomplicated until 10 days. Renal function recovered and after on September 28, 2021 by guest. Protected copyright. 29 weeks' gestation when an irregular fetal seven days the amiodarone concentration was heart rhythm was noted. A fetal echocardio- 1 gg/l. However, after 10 days of amiodarone gram showed a structurally normal heart with treatment a rapid wide complex tachycardia an irregular rhythm diagnosed as atrial developed (fig 2). This was interpreted as extrasystoles, but no other abnormalities were preexcited atrial flutter. The atrial flutter rate identified. A repeat scan performed at 32 had slowed and was conducted in a 1:1 fash- weeks again confirmed an irregular fetal car- ion. Amiodarone was stopped and an elective diac rhythm but no evidence of sustained was performed, restoring or fetal hydrops. Spontaneous rhythm. The infant slowly recovered and oral labour started at 37 weeks' gestation and on propranolol was introduced. No further admission of the mother to the labour ward attacks of supraventricular tachycardia have Department of the fetal heart rate was noted to be high and been noted. Paediatrics, National sustained. An emergency caesarean section Heart and Lung was therefore performed and a grossly Institute, London hydropic live infant was delivered. The infant Discussion J A Till was bradycardic with a low cardiac output When atrial flutter and occur Department of Paediatrics, Royal and immediate resuscitation was required in the Wolff-Parkinson-White syndrome a Postgraduate Medical with intubation, ventilation, and external car- rapid ventricular response to such an atrial School, Hammersmith diac massage. The infant's condition was sta- arrhythmia has been associated with haemo- Hospital, London unit and sudden death.12 The M Baxendall bilised and transfer to a cardiac dynamic collapse A Benetar arranged. An echocardiogram confirmed a ventricular response to an atrial arrhythmia is Correspondence to: structurally normal heart but with consider- determined by several factors including the Dr J A Till, able dilatation of the right and ventri- characteristics of both the accessory connec- Department of Pacing and Electrophysiology, Royal cle with poor systolic function. There were tion and the , the atrial Brompton, National Heart bilateral pleural effusions, a small pericardial and ventricular refractory periods, and the and Lung Hospital, Sydney Street, London SW3 6NP. effusion, and ascites and the infant required degree of adrenergic stimulation.7 Assessment Acceleration of the ventricular response to atrialflutter by amiodarone in an infant with Wolff-Parkinson-White syndrome 85

Figure 1 (A) Electrocardiogram from A B leads Vl, II, and V5 showing overt preexcitation during sinus rhythm. vi Vlj (B) Leads Vl, II and V5, during atrialflutter with Br Heart J: first published as 10.1136/hrt.70.1.84 on 1 July 1993. Downloaded from 2:1 . V19 V1~~~~~~~~~~~~~~~~~~~I The atrial rate is 375 beats per minute. Paper speed 25 mmls.

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i , ;V1 V1 V1 of the anterograde effective refractory period mean or minimum RR interval seen in either of the accessory connection has been suggest- induced or spontaneously occurring atrial ed to be of value in predicting those patients fibrillation.7 at risk. This value correlates well with the Drugs such as digoxin and verapamil can http://heart.bmj.com/ Figure 2 A 12 lead 1- III aVR-aVF V1-3 electrocardiogram showing V4-6 preexcited atrialflutter with a ventricular rate of 210 beats per minute. Paper speed 25 mmls. on September 28, 2021 by guest. Protected copyright. A I A-

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v* 86 Til, Baxendall, Benetar

have an adverse effect in the presence of an Atrioventricular reentry tachycardia is the atrial arrhythmia in that the ventricular commonest supraventricular tachycardia response may quicken. In a patient with encountered in the newborn infant and can Wolff-Parkinson-White syndrome intraven- result in cardiovascular collapse or death in

ous verapamil or digoxin can cause such a this age group.'2 Management of an arrhyth- Br Heart J: first published as 10.1136/hrt.70.1.84 on 1 July 1993. Downloaded from rapid ventricular response that ventricular mia in the newborn hydropic infant with poor fibrillation follows.36 Sudden death after oral ventricular function is difficult. Such manage- administration of digoxin or verapamil in ment problems are aggravated if the infant is patients with Wolff-Parkinson-White syn- preterm, and it has therefore been recom- drome is well recognised.4 The predominant mended that a trial of inutero therapy for a effect of the drugs has been suggested to be a fetal arrhythmia may be better than early direct action on the accessory connection delivery.'314 Unfortunately in our patient sus- causing a shortening of the anterograde tained supraventricular tachycardia was not effective refractory period. Other mechanisms detected by two antenatal scans. An irregular may play a part in that both drugs have a pro- fetal heart rhythm due to atrial or ventricular found effect on atrioventricular nodal con- extrasystoles is common and is generally dis- duction and slowing of atrioventricular nodal missed as a benign funding unconnected with conduction may restrict the number of structural abnormality.'7 Allan stated that impulses reaching the ventricular end of the though some have suggested that an irregular accessory connection in patients who would rhythm may precede a tachyarrhythmia, this normally conduct atrial fibrillatory impulses was not the case in her series of nearly 100 in part by their atrioventricular node and in cases.'5 An irregular rhythm from such a part by their accessory connection. The num- cause usually disappears spontaneously to- ber of impulses limiting anterograde conduc- wards term or soon after birth.'5-'7 Hydrops tion would therefore be less. In addition, the was not detected in this infant despite a peripheral vasodilatation that follows vera- repeat scan, and spontaneous onset of labour pamil treatment may cause a reflex increase at 37 weeks led to the delivery of an infant in in adrenergic tone, which in turn may further poor condition. shorten the anterograde refractory period of The use of digoxin in this age group is con- the accessory connection or make the ventric- troversial. Some physicians continue to use ular myocytes more susceptible to fibrillation. digoxin in the presence of preexcitation Antiarrhythmic drugs which lengthen the because the incidence of atrial fibrillation in anterograde effective refractory period have infancy is rare. In a study by Deal et al four of been suggested to be of value in the treatment the 85 children presenting with supraventric- of patients with Wolff-Parkinson-White syn- ular tachycardia before 4 months of age died of 6 5 All four drome who have had or who are judged to be over a mean period years.'8 http://heart.bmj.com/ at risk of ventricular fibrillation. Such drugs children were taking digoxin. Two had struc- include the class 1 agents disopyramide, fle- tural congenital heart disease in addition to cainide, and propafenone and amiodarone.r'0 Wolff-Parkinson-White syndrome but two In trials to assess the effect of drugs on an died after a sudden . Because accessory connection amiodarone was the digoxin can cause ventricular fibrillation in most consistent in lengthening the antero- the presence of preexcitation even in small grade effective refractory period." Such an children we avoided digoxin in this infant and effect was greatest in those patients with instead chose amiodarone. A class 1 drug or on September 28, 2021 by guest. Protected copyright. accessory connections with a long refractory propranolol was not used because of the very period-that is, longer than 270 ms. Most poor contractile function of the heart. In drugs achieved only minimal effects in those addition the hepatobiliary mode of excretion patients with very short refractory periods. of amiodarone was thought to be an advan- However, of all the drugs tested amiodarone tage in this sick infant with acute tubular was the most effective in those patients with a necrosis. The subsequent development of refractory period less than 270 ms. preexcited atrial flutter with an increase in Several mechanisms may have contributed ventricular response was not predicted. Such to the onset of preexcited atrial flutter in the an increase in ventricular response to an atrial infant we report. The major electrophysiolog- arrhythmia in a patient with Wolff-Parkinson- ical actions of amiodarone are to increase the White syndrome as a result of amiodarone refractory period of atrial and ventricular tis- has been reported in an adult.'9 In this sue and slow conduction in the His-Purkinje patient, as with our case, the arrhythmia was system. In our case amiodarone slowed the promptly recognised and treated appropriate- flutter rate and in doing so allowed conduc- ly. Such a response is likely to be unusual but tion in a 1:1 fashion through the accessory it is important that physicians treating such connection where it had not been possible at patients are aware of its occurrence. the higher rate. Restriction of atrial impulses There are two interesting aspects of this reaching the ventricular end of the accessory case; the first is the unusual but potentially connection through the atrioventricular node life-threatening complication of amiodarone because of His-Purkinje slowing may have in the Wolff-Parkinson-White syndrome; the contributed by further limiting any concealed second is the development of near fatal fetal entrance to the ventricular end of the acces- hydrops as a result of supraventricular tachy- sory connection. The direct effect of amio- cardia in a fetus previously scanned but darone on the effective refractory period of untreated because atrial extra were the accessory connection cannot be assessed. perceived as benign. Acceleration of the ventricular response to atrialflutter by amiodarone in an infant with Wolff-Parkinson-White syndrome 87

We thank Dr Neena Modi for her help and advise in the care Wolff-Parkinson-White syndrome. Am Jf Cardiol 1976; of this patient. 38:189-94. 10 Kim SS, Smith P, Ruffy R.. Treatment of atrial tachy- and pre-excitation syndrome with flecainde acetate. Am J Cardiol 1988;62:29-34. 11 Wellens HJJ, Bar FW, Dassen WRM, Brugada P, Vanagt 1 Dreifus LS, Haiat R, Watanabe Y, Arriaga J, Reitman N. EJ, Farre J. Effect of drugs in the Wolff-Parkinson- Ventricular fibrillation: a possible mechanism of sudden White syndrome. Importance of initial length of effec- Br Heart J: first published as 10.1136/hrt.70.1.84 on 1 July 1993. Downloaded from death in patients with Wolff-Parkinson-White syn- tive refractory period of the accessory pathway. Am J drome. Circulation 1971;43:520-7. Cardiol 1980;46:665-9. 2 Klein GJ, Bashore TM, Sellers TD, et al. Ventricular fib- 12 Gikonyo BM, Dunnigan A, Benson WD. Cardiovascular rillation in the Wolff-Parkinson-White syndrome. N Eng collapse in infants: association with paroxysmal atrial Jf Med 1979;301:1080-5. tachycardia. Pediatrics 1985;76:922-6. 3 Wellens HJ, Durrer D. Effect of digitalis on atrioventricu- 13 Allan LD, Anderson RH, Sullivan ID, Campbell S, Holt lar conduction and circus-movement in DW, Tynan M. Evaluation of fetal arrhythmias by patients with Wolff-Parkinson-White syndrome. echocardiography. Br HeartJ 1983;50:240-5. Circulation 1973;47: 1229-33. 14 Maxwell DJ, Crawford DC, Curry PVM, Tynan MJ, 4 Gulamhusein M, Ko P, Klein G. Ventricular fibrillation Allan LD. Obstetric importance, diagnosis, and following verapamil in the Wolff-Parkinson-White syn- management of fetal tachycardias. BMJ 1988;297: drome. Am HeartJ 1983;106:145-147. 107-10. 5 Gulamhusein SKP, Carruthers G, Klein G. Acceleration 15 Allan LD. Manual of fetal echocardiography. Lancaster of the ventricular response during atrial fibrillation in MTP Press, 1986. the Wolff-Parkinson-White syndrome after verapamil. 16 Komaromy B, Gaal J, Lampe L. Fetal arrhythmias during Circulation 1982;65:348-53. pregnancy and labour. Br Jf Obstet Gynaecol 1977; 6 Schwartz JB. Verapamil in atrial fibrillation: the expected, 43:719-21. the unexpected, and the unknown. Am Heart J 1983; 17 Southall DP, Richards J, Hardwick RA, et al. Prospective 106:173-5. study of fetal heart rate and rhythm patterns. Arch Dis 7 Wellens HJ, Durrer D. Wolff-Parkinson-White syndrome Child 1980;55:506-11. and atrial fibrillation: relation between refractory period 18 Deal B, Keane JF, Gillette PC, Garson A. Wolff- of accessory pathway and ventricular rate during atrial Parkinson-White syndrome and supraventricular tachy- fibrillation. Am Jf Cardiol 1974;34:777-82. cardia during infancy; management and follow-up. JAm 8 Bennett DH. Disopyramide in patients with the Wolff- Coll Cardiol 1985;5:130-5. Parkinson-White syndrome and atrial fibrillation. Chest 19 Sheinman BD, Evans T. Acceleration of ventricular rate 1978;74:624-8. by amiodarone in atrial fibrillation associated with the 9 Wellens HJJ, Lie KI, Bar FW, Wesdorp JC, Dohmen HJ, Wolff-Parkinson-White syndrome. BMJ 1982;285 Duren DR, Durrer D. Effect of amiodarone in the 999-1000. http://heart.bmj.com/ on September 28, 2021 by guest. Protected copyright.