A 60-day-old male weighing 5 kg was referred for cardiac evaluation in view of suspicion of dilated cardiomyopathy. Physical examination revealed tachycardia and tachypnea with decreased pulses and peripheral perfusion. Chest radiograph showed a cardiothoracic ratio of 70%. The 12-lead electrocardiogram (ECG) showed a regular narrow QRS tachycardia with a rapid ventricular rate of 250 bpm with a long RP interval and abnormal peaked P-wave morphology. Differential diagnosis of ectopic atrial tachycardia (EAT) and permanent junctional reciprocating tachycardia were considered. The P waves were negative in V1 and aVR and positive in leads II, III, and aVF suggestive of EAT of superolateral crista terminalis origin []. Echocardiography showed severe left ventricular (LV) dysfunction with an ejection fraction (EF) of 17% with significant LV dilatation (LVIDd 3.58 cm [Z score + 5.60]).The coronary artery origins and aortic arch were normal. Serum electrolytes and renal function were normal. Severe acute respiratory syndrome coronavirus 2 polymerase chain reaction was negative and antibodies levels were normal. All serum inflammatory/cardiac markers were normal (C-reactive protein, ferritin, troponin I, and CK MB). The NT pro-BNP level was grossly elevated (31,500 pg/ml [normal <125]). Adenosine given during the tachycardia resulted in transient slowing of the heart rate from 250 to 187 bpm followed by reappearance of the tachycardia [Figure and ]. The tachycardia persisted despite giving three doses of bolus intravenous metoprolol and metoprolol infusion. The infant was hemodynamically unstable with poor perfusion, decreased urine output, and low blood pressure (mean 20 mmHg). Hence, synchronized cardioversion with 5J was given with no benefit. Intravenous digoxin 15 μg/kg given over 30 min resulted in decrease in heart rate (107 bpm) followed by severe bradycardia (65 bpm) and cardiac arrest. ECG during the time of bradycardia showed multiple P waves with periods of flat isoelectric line confirming EAT []. After cardiopulmonary resuscitation (0.4 ml of 1 in 10,000 dilution adrenaline single dose) and mechanical ventilation, heart rate picked up and tachyarrhythmia persisted. Furosemide (1 mg/kg/day), milrinone (0.5 mcg/kg/min), and amiodarone infusion (25 mcg/kg/min for 4 h followed by 15 mcg/kg/min for 24 h) were started in view of severe LV dysfunction and persistent tachyarrhythmia. There was no improvement in the hemodynamics and tachycardia persisted even after continuous metoprolol and amiodarone infusion for 2 h. Hence, enteral sotalol (1 mg/kg) was started. Despite all the above pharmacological interventions for 10 h since admission, the tachyarrhythmia persisted and the mean blood pressure was persistently low with poor urine output. Repeat synchronized cardioversion with 5J resulted in conversion of the rhythm to ventricular fibrillation. Unsynchronized cardioversion 10J thrice resulted in termination of VF and the EAT restarted. The child remained with a poor urine output (<0.3 ml/kg/hr) and hypotension, with mean blood pressure <25 mmHg for >6 h.\nConsidering the hemodynamic instability and persistence of tachyarrhythmia despite using most of the conventional antiarrhythmic drugs, we administered enteral ivabradine. Within 45 min of the initiation of ivabradine (0.15 mg/kg), the heart rate slowed down to 190 bpm with significant improvement in the hemodynamics and perfusion (mean BP 40 mmHg). Metoprolol infusion was stopped and amiodarone infusion was continued for 24 h and then stopped. The heart rhythm became sinus after 12 h of enteral ivabradine and digoxin []. The LVEF improved from 17% to 33% after 24 h of ivabradine. The LVIDd started decreasing (LVIDd Z score + 4.26). He was extubated after 48 h of ventilation and put on high flow nasal cannula in view of respiratory distress and moderate LV dysfunction. He had one transient episode of tachyarrhythmia (250 bpm) which lasted for 2 min and terminated by itself. Hence, oral propranolol was added. Milrinone infusion was tapered and stopped with subsequent addition of enalapril. The LV function and LVIDd recovered completely (EF 58%; LVIDd 2 cm (Z score-0.22) after 7 days of achievement of sinus rhythm. The timeline of events which happened during the first 24 h was shown in . He was discharged after 10 days of hospitalization on oral ivabradine (0.15 mg/kg twice a day), digoxin (5 μg/kg twice a day), and propranolol (0.5 mg/kg twice a day). The efficacy of the treatment was monitored by patch ambulatory ECG (aECG) recorder for 7 days after discharge. The aECG recordings were predominant in sinus rhythm with short episodes of ectopic atrial rhythm. The average heart rate was 132 bpm (58–163). At follow-up after 3 months, ECG was in sinus rhythm and the LV function (EF 70%) is normal. The developmental milestones are appropriate for the age.
A 30 day old boy weighing 3 kg was referred to our pediatric intensive care unit in view of significant respiratory distress and cardiogenic shock. Physical examination revealed tachycardia (200bpm), and tachypnoea with decreased pulses and poor peripheral perfusion. Blood gas showed severe metabolic acidosis (pH 6.9; HCO3 3.6 mol/L; PCO2 15mmHg). The baby was resuscitated with intravenous fluid and sodium bicarbonate correction.The 12-lead electrocardiogram (ECG) showed a regular narrow QRS tachycardia with a rapid ventricular rate of 187 bpm with long RP interval and abnormal peaked P wave morphology.The P waves were biphasic in V1 and positive in leads II, III and aVF suggestive of EAT []. Chest radiograph showed a cardiothoracic ratio of 75%. Echocardiography showed severe left ventricular (LV) dysfunction [ejection fraction (EF) 19%] with significant LV dilatation [LVIDd 2.5cm (Z score +3.18)]. SARS-CoV-2 PCR was negative and antibodies levels were normal. Adenosine given during the tachycardia, resulted in transient termination of the tachyarrhythmia followed by reappearance []. Enteral ivabradine (0.15mg/kg) was given resulting in gradual reduction of heart rate one hour after initiation and the rhythm became sinus after 4 hours. Enteral digoxin (10mcg/kg/day) was added one hour after ivabradine. There was significant improvement in the hemodynamics and perfusion (mean BP 25 mmHg). Blood gas after stabilization revealed improvement in the metabolic acidosis (pH 7.49; HCO3 16.6 mol/L; PCO2 22mmHg). However the respiratory distress and LV dysfunction persisted. Supportive care including bubble continuous positive airway pressure, milrinone and furosemide infusion were provided for the LV dysfunction. He symptomatically improved with supportive care and it was weaned off after 24 hours. LV dimension [LVIDd 1.6cm (Z score -1.29)] and function (EF 55%) improved significantly after 72 hours. He was discharged after 5 days of hospitalization on oral ivabradine (0.15mg/kg twice a day), and digoxin (5mcg/kg twice a day). The timeline of events which happened during the first 72 hours isshown in the .