May 2025
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European Heart Journal Supplements
A 31–year–old woman (G3P2) was referred to our specialized center during her 29th week of gestation, for fetal high–grade atrioventricular block. Fetal ultrasound revealed persistent high–grade atrioventricular block, with an average heart rate of 35 bpm, to a nadir of 20 bpm; both ventricles appeared hypokinetic; vasodilatation of middle cerebral artery was also noted. Genetic evaluation was negative. We attempted to infuse sympathomimetic drugs: ritodrine with no or very limited effect on heart rate; isoproterenol, exerted no effect on atrioventricular conduction, but increased only maternal heart rate and fetal atrial heart rate. It became necessary to schedule a cesarean section, which was programmed with the presence of a cardiothoracic surgeon expert in congenital heart disease stand–by. The delivery was carried out at 30 weeks and 1 day of gestation, with the neonate weighting 1280 g and measuring 39 cm. The newborn was treated with isoprenaline and adrenaline in the very first hours of his life. Surgical placement of two pairs of temporary pacing wires was performed, and an external pacemaker was programmed in VVI mode at a rate of 120 beats per minute. Epicardial stimulation using a tunneled bipolar lead placed in the abdomen emerged as the preferred treatment. However, in infants weighing less than 2.5 kg, the generator‘s size incongruity may cause adverse local effects such as wound dehiscence and skin erosion. Therefore, a decision was made to utilize a novel technology, such as the prototype “tiny pacemaker“ where a Medtronic Micra generator was incorporated into a polymer header to enable connection with the CapSure Epi™ model 4968 bipolar IS–1 epicardial lead (Medtronic, Inc.), specifically designed for this unique neonatal population. The device was programmed in VVI mode at 100 bpm, effectively maintaining hemodynamic stability. During the following weeks cardiac function assessed by echocardiogram improved to an ejection fraction of left ventricle of more than 55%. At the time of discharge, growth was satisfactory (2892 g, 43 cm), along with hemodynamic parameters and pacemaker function. The subsequent follow–up revealed estimated lifespan of approximately 3.6 years allowing for relative growth of the little patient (Figure 1). In our case idiopathic congenital high–grade atrioventricular block was effectively managed by implanting a prototype of “tiny pacemaker”, a promising technology for an orphan, rare disease.Figure 1
