Case 2: Wide-Complex Tachycardia in a Newborn

Twelve hours after birth, an otherwise healthy newborn infant is noted to have an irregular pulse during routine examination in the well-child unit. The infant was born at term after an uncomplicated pregnancy and vaginal delivery. An electrocardiogram (ECG) reveals frequent single premature wide complexes corresponding to the pulse irregularity. The infant has good perfusion, easily palpable pulses in all 4 limbs, and no murmur. He is afebrile and has been feeding and voiding normally. He is transferred to the intensive care unit for monitoring and further evaluation. In the following hours, the infant exhibits frequent wide-complex couplets, progressing to runs of wide-complex beats lasting up to 45 seconds at a time (Figure). Periods of wide-complex arrhythmia are unrelated to activity level, and the infant continues to demonstrate good perfusion. An arterial line is placed and reveals that while in sinus rhythm at a heart rate of 146 beats per minute, the blood pressure is 75/40 mm Hg. The heart rate is 161 beats per minute and the blood pressure is 65/35 mm Hg during the wide-complex rhythm. Figure. Electrocardiogram of an infant 21 hours after birth, which shows a run of monomorphic wide-complex tachycardia. Further analysis of the patient’s ECG during periods of sinus …