A Tiny Pacemaker for a Tiny Baby: An Interdisciplinary Approach

All articles of this category (opens in new window) Background: Congenital heart block is very rare. In bradycardia, the most effective treatment is myocardial stimulation. However, in smaller babies and especially in preterm newborns with low birth weight, primary pacemaker implantation is not possible due to the large size of available devices. We report the implantation of a modified tiny pacemaker for the first time in Germany. Methods: Case presentation of a preterm with the fetal diagnosis of congenital heart block. Results: For the first time, a gynecologist detected a low heart rate at gestational week (GW) 25. Fetal echocardiography confirmed findings; 2 weeks later, hemodynamics and ventricular contractility remained stable. Therefore, we planned weekly follow-up controls and an elective caesarean section for GW 37. Simultaneously, we asked for a novel, specially modified tiny pacemaker (modified Micra pediatric implantable pulse generator [IPG] sized 27 mm × 15 mm × 8 mm), and after positive feedback, we applied for special approval. After release authorization for the modified pacemaker, we received the device a few days later. Due to deteriorating bradycardia with ventricular dilation and reduced contractility, we preponed delivery. After caesarean section on GW 35, careful evaluation of findings and neonatal treatment, including endotracheal intubation, followed. Immediately thereafter, we transferred the newborn (2,200 g birth-weight) to the prepared pediatric heart surgery operating room for implantation of the modified tiny pacemaker via subxiphoid approach. We fixed the two electrodes of the bipolar ventricular epicardial lead to the apical and lateral area of the left ventricle. The stimulation threshold was 0.9 V at 0.5 ms pulse duration, sensing amplitude 12 mV, and impedance 950 Ω. Then, we connected the lead to the device and placed the tiny pacemaker left subcostal and dorsal to the rectus abdominis muscle. We initially programmed pacing with 80 beats per minute. Postoperative treatment in the pediatric intensive care unit was uneventful, and 2 weeks later, we transferred her to the neonatal ward. Conclusion: Management of congenital heart block is challenging. The novel, specially modified tiny pacemaker is an excellent option in smaller neonates and infants, including low birth-weight preterm babies. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany