Atrial septal defect closure using percutaneous techniques has become a standard practice in symptomatic infants(l). The incidence of arrhythmia, following the device closure is rare in those without a pre-existing one(2). More so, atrial flutter is uncommnn in infancy(3). We report a case of atrial flutter in a child following device closure which was successfully ablated.

A four-month-old baby (weight 5.5 kg; length 60 cm; head circumference 39 cm) presented with failure to thrive and congestive cardiac failure associated with an episode of lower respiratory tract infection. The child’s birth weight was 3030 g and he had perinatal asphyxia and hypoxia induced encephalopathy (stage II) requiring phenytoin.

He appeared lethargic and had subcostal retraction with a sinus tachycardia rate of 140 bpm. There was a widely split second heart sound accompanied by grade 3/6 systolic murmur in the pulmonary area. The liver was palpable 6 cm below the right costal margin associated with mild splenomegaly. Echocardiography revealed a large ostium secundum atrial septal defect (ASD) measuring 18 mm. He underwent percutaneous ASD closure at four months of age under general anesthesia. A 20 mm ASD occluder (Blockaid- Shanghai Shape Memory Alloy Company Ltd, China) was deployed. The post-procedure period was uneventful.

One month after the device deployment the child developed typical atrial flutter with a ventricular rate of 140 bpm. There was no residual shunt on echocardiogram He was initiated on rate control drugs which included propranolol and digoxin. Despite this the ventricular rate remained 140 bpm over the next several months.

At two years of age, due to persistent atrial flutter associated with fast ventricular rate, an electrophysiological study with view to ablation was performed. The right femoral vein could not be cannulated and thus a single radiofrequency (RF) ablation catheter (6F, 4 mm tip. Biosense-Webster) was introduced via the left femoral vein. Since the ECG was consistent with typical counterclockwise atrial flutter it was decided to "empirically" attempt an isthmus cavo-tricuspid isthmus line. Ablation was performed in the temperature-controlled mode with a preset maximum temperature of 55ºC. An intermediate line was attempted starting from the ventricular aspect of the tricuspid annulus and using a dragging technique extended to the inferior vena cava. At each spot RF energy was applied for a minimum of 20 seconds. Surprisingly, there seemed to be a large isthmus. Totally nine RF energies were required to reach from the tricuspid annulus to the IVC. During the 8th energy the atrial flutter terminated (Fig. 1.). Following flutter termination, vigorous stimulation using programmed extra-stimuli. burst pacing and isoproterenol could not induce any tachycardia. The child has remained in sinus rhythm after 18 months of follow-up.

Fig. 1. 12 lead ECG showing termination of atrial flutter during radiofrequency ablation.

Atrial tachyarrhythmia (AT) is known in patients following surgical closure of atrial septal defect(4) Silversides et al(2) studied the immediate and long term complications associated with trans-catheter closure of the defect and found AT was common (13%) in the immediate follow up period, only in patients with past history of the arrhythmia(2) However, in this child, atrial flutter occurred only after trans-catheter closure of atrial septal defect. It is possible that persistent RA dilatation and fibrosis consequent to congestive cardiac failure pre-disposed to the development of this arrhythmia. Rosenblueth and Ramos(5) have demonstrated atrial flutter in a canine model, with mechanical obstacles; it is now known that for perpetuation of the re-entranl rhythm, areas of slow conduction are required. Therefore, its manifestation after the deployment of the device cannot exclude the possibility of the device altering the geometry of the atrium so as to change its conduction property Moreover, this is a rare arrhythmia in infancy. It is uncommon even in infants with atrial septal defects which would lead us to speculate that the mechanical obstacle produced by early closure of the defect with the device would have triggered the arrhythmia in this child(3).