SOPHAGEAL PACING can provide a reliable method for controlling heart rate, but transesophageal ventricular pacing is often unsuccessful in children. The authors achieved transesophageal ventricular pacing in 2 infants without difficulty, and transesophageal atrial pacing in 1 child by using the transesophageal echocardiography (TEE) probe as a guide. CASE REPORTS Case 1 A 3-day-old newborn boy (weight 1,838 g) underwent emergency implantation of a permanent pacemaker. Immediately after the patient was delivered by cesarean section because of fetal bradycardia, he was intubated and mechanically ventilated. An electrocardiogram (ECG) showed complete atrioventricular block with a heart rate (HR) of 44 beats/min. Echocardiography showed aortic regurgitation, tricuspid regurgitation, pulmonary hypertension, and a left ventricular ejection fraction of 49%. Continuous intravenous infusions of dopamine, 5 g/kg/min, and isoproterenol, 0.06 g/kg/min, were administered. When the patient arrived at the operating room, his HR was about 50 beats/min. Anesthesia was induced and maintained with intravenous fentanyl, and muscle relaxation was obtained with intravenous vecuronium. A quadruplet pacing lead with an interelectrode distance of 10 mm and an electrode diameter of 3 mm (TOEC-P; MEDICO, Rubano, Italy) was inserted orally into the esophagus and positioned at a distance of 15 cm from the inferior alveolar ridge. The pacing lead was connected to a pulse generator (TECS II, MEDICO). Bipolar pacing was initiated at a rate of 100 beats/min, and the 4 electrodes were used alternately as cathodes or anodes. Ventricular pacing was easily established with a threshold current of 20 mA at a pulse duration of 20 milliseconds using the distal electrode as the cathode and the second electrode as the anode. HR increased from 52 to 100 beats/min, and arterial blood pressure increased slightly from 96/54 mmHg to 100/62 (Fig 1). Transesophageal ventricular pacing was continued until the permanent pacemaker was implanted. Case 2 A 5-day-old neonate boy (weight 2,410 g) was scheduled for urgent implantation of a permanent pacemaker. Because of his mother’s extremely low level of amniotic fluid, the patient was delivered by cesarean section at 36 weeks and 4 days gestation. Immediately after delivery, the patient was intubated and mechanically ventilated. An ECG showed complete atrioventricular block and an HR of about 45 beats/min. Echocardiography revealed pulmonary hypertension and an LV ejection fraction of 27%. Intravenous dopamine, 3 g/kg/min, and isoproterenol, 0.1 g/kg/min, were continuously administered, and his HR increased to about 65 beats/min. When the patient arrived in the operating room, his HR was about 55 beats/min. Anesthesia was induced with sevoflurane, air, and oxygen (FIO2 0.5) and maintained with sevoflurane and intravenous fentanyl. Muscle relaxation was obtained with intravenous vecuronium. A quadruplet pacing lead (TOEC-P) was inserted orally into the esophagus and positioned at a distance of 13 cm from the inferior alveolar ridge. The pacing lead was connected to a pulse generator (TECS II) and was adjusted to achieve ventricular capture as confirmed by ECG and central venous pressure waveforms. Ventricular pacing at 100 beats/min was established with a threshold current of 32 mA at a pulse duration of 20 milliseconds; the distal electrode served as the cathode and the second electrode as the anode. HR increased from 73 to 100 beats/min, and arterial blood pressure decreased from 107/64 to 101/66 mmHg. Transesophageal ventricular pacing was maintained until the permanent pacemaker was implanted. Case 3 A 6-year-old girl (height 117 cm, weight 20 kg) with sick sinus syndrome was scheduled for permanent pacemaker implantation and ventricular septal defect (VSD) closure. A fetal heart murmur was identified, and she was diagnosed with tetralogy of Fallot after birth. When she was 2 years and 3 months old, she underwent VSD closure and repair of the right ventricular outflow tract; however, a residual shunt was revealed by postoperative echocardiography. At the age of 4 years, she was diagnosed with atrial fibrillation (AF), and Stokes Adams syndrome occurred. Medication was started, but the conditions could not be controlled. Even after 3 catheter ablations, the patient experienced several episodes of bradycardia or AF so she was scheduled for pacemaker implantation and further VSD repair. The ECG showed an incomplete right bundle-branch block and sinoatrial block. Preoperative medication included propranolol, 15 mg/d, and digoxin, 0.1 mg/d; when she had an episode of AF, a bolus of verapamil, 3 mg, was administered intravenously. The patient was premedicated with atropine, 0.2 mg, and midazolam, 2 mg, intramuscularly, 30 minutes before induction of anesthesia. Anesthesia was induced with sevoflurane, nitrous oxide, and oxygen (FIO2 0.33). Muscle relaxation was obtained with intravenous vecuronium. A quadrapolar pacing lead (TOEC-P) was fixed anteriorly to the pediatric biplane TEE probe (21366A; Philips Medical Systems, Andover, MA) with silk thread (Fig 2). The distal electrode was placed 20 mm from the TEE probe tip, and a pacing lead was connected to a pulse generator (TECS II). The biplane TEE probe was inserted atraumatically into the esophagus. After the start of surgery, HR decreased gradually to about 60 beats/min. The TEE probe was positioned to obtain a long-axis 3-chamber view. At first, the authors planned ventricular pacing and started pacing with a 20-millisecond pulse duration at a rate of 120 beats/min. Atrial pacing was unexpectedly established with a threshold current of 11 mA. HR increased from 69 to 118 beats/min, arterial blood pressure increased from 80/44 to 85/55 mmHg (Fig 3), and central venous pressure was unchanged. Transesophageal atrial pacing was maintained for 2 hours until the initiation of cardiopulmonary bypass.