An one-year old girl presented a persistent tachycardia during a routine visit at the local pediatrician and was immediately transferred to KUNO university hospital. There had been a benign febrile infection 1 week prior to admission. Personal and family history was non-contributory to the tachycardia. Six months before, the previous check at the pediatrician had been uneventful. On admission she had mild signs of heart failure with delayed capillary refill time (3 s) and an enlarged liver. She had a tachycardia with 240 beats/min. Echocardiography showed structural normal anatomy with moderately reduced contractility while tachycardia. Laboratory studies including blood count, inflammatory biomarkers and cardiac troponin were normal but NT-proBNP was significantly elevated (maximum 2,685 pg/ml, lab reference <130 pg/ml).\nThe initial 12-lead electrocardiogram (ECG) showed a regular, sustained small-QRS-complex-tachycardia (mean heart-rate 240 beats/min). The tachycardia demonstrated a 1:1 atrio-ventricular conduction (P-P cycle length 250 ms) with a monomorphic P-wave configuration characterized by a superior axis (P-vector of −60°) and sinus tachycardia was therefore not possible. RP interval was significantly longer than PR—interval (i.e., long-RP-tachycardia) and we thought about a permanent orthodromic supraventricular tachycardia first (such as permanent junctional reciprocating tachycardia) () and gave Adenosine intravenously. This did not stop atrial tachycardia and ruled out a reentry-tachycardia dependent on the AV-node. We therefore hypothesized a focal ectopic atrial tachycardia. Infusion of Flecainide (1 mg/kg/30 min) did not affect the atrial rate or atrioventricular conduction. Synchronized electric cardioversion with 0.5 and 1 J/kg was performed due to signs of hemodynamic instability but this just interrupted the tachycardia for seconds. Medical cardioversion and rate control were attempted starting Amiodarone with a bolus. After 30 min the girl developed a second-degree AV-block (type Wenckebach) with ongoing QRS-amplitude alternans, eventually resulting in a bradycardia with 70 beats/min. Amiodarone infusion was stopped and the AV-block resolved. While persisting EAT, Esmolol infusion was started and slowly increased to a maximum rate of 75 mcg/kg/min. This lowered the atrial tachycardia rate to 160 beats/min without affecting the blood pressure. Ivabradine was started with a dose of 0.25 mg (0.025 mg/kg) every 12 h and increased to 0.5 mg (0.05 mg/kg) per dose on the second day. This led to a persistent heart rate reduction to a physiologic level (80–100 beats/min at rest) with alternating periods of restored sinus rhythm and ectopic atrial rhythm. Subsequent ECG recordings showed sinus rhythms with regular AV conduction and no abnormalities of de- or repolarization (). No adverse effects attributable to Ivabradine were registered. After stabilization Esmolol infusion was discontinued and the beta-blocker therapy was switched to Metoprolol administered orally (1 mg/kg/d). Holter evaluation before discharge (1 week after admission) showed sinus rhythm with short times of ectopic atrial rhythm and a regular diurnal pattern and heart rate.\nIn the follow up visits 2 and 10 weeks later echocardiography showed normal left-ventricular function and dimension. The 12-lead-ECG and Holter evaluation showed alternating ectopic atrial and sinus rhythm with a physiologic diurnal heart rate spectrum and a regular response to physical activity (). Combination of Metoprolol and Ivabradine did not cause bradycardia and no other side effects attributable to medication were noticed.
A 2-year-6-month-old girl was transferred to our hospital from a primary care center for the management of tachyarrhythmia. Eight months prior to her presentation, she was found to have an increased heart rate (HR) of around 200 bpm on routine physical examination. At that time she was asymptomatic and her echocardiography was normal. Nevertheless, a week prior to her presentation to our center, an increased HR of 190 bpm was noted again on routine exam. Repeat echocardiography revealed LV dilatation along with a reduced LV systolic ejection fraction of 35%. ECG showed supraventricular tachycardia (SVT), namely atrial tachycardia. She failed a trial of adenosine and responded weakly to metoprolol. The patient was discharged on metoprolol 25 mg/day divided into two doses. She presented 2 days later to the same hospital. She had a HR of 250 bpm. She received two doses of adenosine, one dose of amiodarone and several doses of flecainide during her admission. However, no improvement was noted after 5 days of treatment, and also after direct current cardioversion. She was then transferred to our center for adequate rate control and appropriate investigation.\nUpon admission to our PICU, HR was 190 bpm. On examination, she was pale, tachypneic and hypoactive, but responsive to verbal stimulation. A third heart sound was noted on cardiac auscultation. Additionally, she had cool extremities and palpable hepatomegaly. Echocardiography was repeated, it showed worsened LV dilatation and severe LV systolic dysfunction (EF was around 20%), and moderate mitral regurgitation (see ). ECG revealed an atrial tachycardic rhythm. Patient was given adenosine. She received a second higher dose of adenosine and an infusion of amiodarone. She failed to respond adequately to these medications. Consequently, the patient was started on ivabradine at 0.15 mg/kg/day. An adequate response was noted few hours after the first dose of ivabradine. HR decreased to 90 bpm and she reverted to sinus rhythm. shows the patient's ECG pre- and post-ivabradine. The dose of ivabradine was adjusted to 0.033 mg/kg thrice daily. Adequate response was noted and the patient was discharged on ivabradine.\nOne month after the discharge, she presented to our clinic and was found to have a normocardic sinus rhythm on ECG, and an improved cardiac function on echocardiography (EF of 50%). In short, this is a case of SVT-induced DCM managed appropriately with ivabradine.