Hope in Miniature: The First Case of Implantation of a “Tiny Pacemaker” in Italy as a Successful Treatment for Congenital Atrioventricular Block in a Low Birth Weight Child

Congenital complete atrioventricular block (CAVB) is a rare cardiac condition occurring in approximately one in 15,000 to one in 22,000 live births. Maternal autoimmune diseases, with anti‐ssA (Ro) and anti‐ssB (La) antibodies implicated in 56%–90% of cases, are primary causes. We present a case of a 31‐year‐old primigravid woman referred at 29 weeks of gestation for fetal high‐grade AVB, initially diagnosed as 2:1 AVB with a ventricular rate of 45 bpm. Maternal corticosteroid therapy was initiated for suspected immune‐mediated etiology, pending autoantibody test results. Upon transfer, a 3:1 AVB was detected, with fetal heart failure signs. Genetic and autoimmune evaluations ruled out primary electrical heart diseases and infections. Prompt intervention was necessitated due to fetal cardiac decompensation. Sympathomimetic drugs via placental circulation were ineffective. Cesarean section was scheduled at 30 weeks and 1 day. The neonate, weighing 1280 g, had an APGAR score of 7 and a heart rate of 40 bpm. Initial resuscitation and isoproterenol infusion resulted in a moderate heart rate increase. Temporary pacing wires were surgically placed. As permanent pacemaker implantation became necessary, traditional venous access was impractical. A “tiny pacemaker” made with modification of a Medtronic Micra MC1VR01 generator connected to an epicardial lead ensured hemodynamic stability. Approval of this off‐label device from the Italian Ministry of Health was swiftly obtained. Diagnosis of CAVB typically involves fetal echocardiography and fetal magnetocardiography for precise arrhythmia diagnosis. Treatment varies, with fluorinated steroids reducing block severity in autoimmune cases. Miniaturized pacemakers offer a promising solution for neonates, addressing challenges of conventional devices. Further research is needed to evaluate their long‐term efficacy and safety, potentially benefiting patients with venous and cardiac abnormalities.