Despite the remaining debate regarding the optimal pacing site, traditional right ventricular (RV) pacing has been used successfully for bradyarrhythmia management for decades. The harmful effects of long-term RV apical pacing (ventricular dyssynchrony) are well known. These effects caused interest in approaches that provided more physiological stimulation, specifically, His bundle pacing (HBP). His bundle pacing brings hope as an attractive model to achieve physiological pacing. We present a case of a 12-year-old boy with symptomatic sinus arrest who underwent successful permanent HBP implantation. He complained of episodes of syncope and was examined by a neurologist. Electroencephalography with an ECG tracer demonstrated sinus bradycardia with a heart rate as low as 45 beats per minute and then, a transition to sinus arrest lasting 7.5 seconds with a syncopal attack during the day (Figure 1 Panel A). In this regard, he was referred to a cardiologist. On physical examination, his height was 153 cm, his weight was 36 kg, and his body surface area was 1.26 m2. On the ECG, sinus rhythm with an incomplete right-bundle branch block pattern, and a QRS duration of 120 msec was seen (Figure 1 PAnel B). On transthoracic echocardiography, the left ventricular ejection fraction was 60% without any structural abnormalities. We decided to implant a permanent pacemaker using HBP. The subfascial pocket was created by the blunt method. Two punctures through the axillary vein were performed. First, a 7F peelaway introducer was advanced through the guidewire, and a specialized delivery catheter instructed for HBP (SelectSite™ C315HIS, Medtronic) was advanced through the sheath and located around the superior aspect of the tricuspid annulus in the right anterior oblique projection. A 69-cm, 4.1F active fixation, lumenless electrode (SelectSecure™ MRI SureScan™ Model 3830) was introduced up to the tip of the sheath. With finetuning of the catheter using both clockwise and counterclockwise rotations, His bundle potential was searched on the pace-sense analyzer, and when the His potential was observed with small atrial and large ventricular potentials demonstrating distal His bundle location, a unipolar capture test was initiated. At the high output of 5V@1ms, a non-selective His capture was observed with a selective His capture threshold of 1.5V@1ms and loss of capture at 0.5V@1ms. The identical 12-lead surface ECG compared to the baseline ECG was obtained during capture tests (Figure 2 Panel A). Enough atrial slack was left, taking into account the growth of the child. Then, a standard atrial electrode was conventionally implanted in the right atrial appendage. A standard, dual-chamber pacemaker was connected to the electrodes and positioned in the pocket (Figure 2 Panel B). All electrical parameters and the left ventricular ejection fraction were stable, and no acute or late procedure-related complications were observed during the 16 months follow-up.

No syncopal episodes were also detected during the follow-up. A summary of the device and echocardiography parameters with laboratory markers was presented in the Table. Our case shows that HBP is implementable even in young children with syncope due to sinus arrest. With the help of HBP, we have physiological stimulation and stable electrical parameters at >12 months. In addition, a stable left ventricular function without dyssynchrony criteria was realized on echocardiography.