Case presentation A 9-day-old full-term girl with a temperature of 38.3°C arrived at the ER with tachycardia (210 beats/min), tachypnea (62 breaths/min ), and a history of nasal congestion. Her blood pressure was 87/63 mmHg , and her oxygen saturation was 97% at the time of admission. Investigations The 12-lead ECG revealed consistent tachycardia at 215 beats/min . With a 1:1 ventricular-atrial (VA) connection, a putative retrograde p-wave inscription was seen 140 ms after the beginning of QRS.
In lead I, the maximum QRS duration was 108 ms (typical for babies is 28 ms–75 ms). A bipolar atrial electrogram was created by connecting the anode to the right arm lead and the cathode to the left arm lead. The standard ECG amplitude, speed, and filtering (0.1 mV/mm, 25 mm/s) were used. With a tachycardia cycle length of 275 ms and a VA interval of 140 ms , the atrial electrogram confirmed…
