日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

Multifocal atrial tachycardia (MAT) is generally diagnosed in infants under one year of age; a few of these infants may also present with arrhythmia-induced cardiomyopathy. We report the case of 4-month-old boy diagnosed with cardiogenic shock secondary to MAT who responded to antiarrhythmic medications. The child was delivered by caesarean section at gestational age of 36 weeks due to fetal distress; his birth weight was 2,362 g. He was referred to our hospital at four months of age with chief complaints of poor feeding and tachyarrhythmias detected during a previous examination. A 12-lead electrocardiogram (ECG) revealed a narrow QRS complex and irregular tachycardia at a rate of 200–240 beats per minute, leading to the diagnosis of MAT. Echocardiography revealed severe functional decline, including an 11％ shortening fraction (SF) and a dilated left ventricle. Amiodarone (5 mg/kg injection) was administered in an attempt to normalize the atrial tachycardia; this resulted in a substantial drop in blood pressure. The patient was intubated and provided with inotropic support, including dopamine and milrinone. Landiolol (10 µg/kg/min by continuous infusion) and oral aprindine (1.5 mg/kg/day) were initiated on hospital day 8. The frequency of tachycardia decreased and cardiac function gradually recovered over a period of 2–3 weeks. The patient was discharged on hospital day 43 with improved cardiac function and a SF of 30％. Results from a follow-up visit revealed the cardiac function had returned to near-normal with no recurrence of MAT. We conclude that it is critical to control MAT in pediatric patients with arrhythmia-induced cardiomyopathy.