Abstract Permanent pacemaker implantation in small infants can be challenging because of patient size and expected somatic growth. In our case, we used the retrosternal space as a generator pocket for an extremely low-birth-weight premature baby with autoantibody-associated congenital heart block born to a systemic lupus erythematosus mother. Pacemaker, Congenital complete atrioventricular block, Infant, Retrosternal space INTRODUCTION Autoantibody-associated congenital complete atrioventricular block has high morbidity and mortality among infants, with more than 60% of patients requiring permanent pacemaker therapy in their first year of life . However, increasing clinical experience and follow-up data indicate a favourable effect on prognosis and better cardiovascular performance in paediatric patients with atrioventricular block treated by pacemaker implantation . CASE A 590-g premature baby was born at the gestational age of 29 weeks to a mother with systemic lupus erythematosus, and the newborn had persistent bradycardia. Congenital complete atrioventricular block and atrial septal defect (ASD) were confirmed using foetal echocardiography 2 months before birth. After birth, he was admitted to the neonatal intensive care unit due to acute respiratory failure with bradycardia. Because the baby’s heart rate was less than 60 bpm, intravenous isoproterenol was administered. Because the patient had a persistent bradycardia, we decided to perform permanent pacemaker implantation when the patient was 4-months old and had reached a weight of 2.3 kg. A unipolar steroid-eluting lead was implanted in the right ventricular apex with ventricular on-demand mode (Adapta ADSR01, Medtronic, Inc., Minneapolis, MN, USA). The patient’s low body weight (2.3 kg) was a concern with regard to the location of the generator and the type of pacing. Although bichamber pacing is more effective for atrioventricular synchrony than unichamber pacing, bichamber pacing’s large generator was not suitable for this small patient. Although the rectus sheath is usually preferred as a generator pocket, we decided to place the generator in the retrosternal space because the patient’s rectus sheath and peritoneum were too thin, and the epigastric space was not large enough for the generator. We were also worried about the possibility of peritoneal perforation, migration and infection. Under the full sternotomy, we performed left total thymectomy and right partial thymectomy to make space for the generator. Phrenic nerves were preserved. The generator was fixed to the sternum (Figs 1 and 2). Removing the thymus created enough space for the generator’s placement. In this location, the generator did not interfere with any other organs, including the heart and major vessels. Two months after the pacemaker implantation, he underwent repair of ASD via redo sternotomy. We located the generator in the retrosternal space again because the patient’s body weight was still only 3 kg, and the rectus sheath and peritoneum were still too weak to serve as a generator pocket. Figure 1: View largeDownload slide Chest X-ray (anteroposterior view): 3 months after pacemaker implantation. Figure 1: View largeDownload slide Chest X-ray (anteroposterior view): 3 months after pacemaker implantation. Figure 2: View largeDownload slide Chest X-ray (left lateral view): 3 months after pacemaker implantation. Figure 2: View largeDownload slide Chest X-ray (left lateral view): 3 months after pacemaker implantation. COMMENT Implanting pacemakers in infants is very difficult because there is very little space for leads and to make a generator pocket. Especially for patients with low body weight, making the generator pocket in the epigastric area, the most common area for the generator pocket, is a challenging procedure because their rectus muscle sheath and peritoneal membrane are too thin to support the generator. Therefore, we struggled to overcome the shortcomings of a rectus sheath pocket which is preferred . In the past, a small generator, Microny II SR (St. Jude Medical, Inc., Sylmar, CA, USA) was used for the small infants or neonates, but it had been discontinued. We were aware of other approaches, such as extrapleural intrathoracic or retroperitoneal positions, but we did not choose either of these because they require an extra incision, and the patient’s soft tissue layer was extremely fragile. Because the patient did not show definitive signs of heart failure or pulmonary hypertension at the time of implantation, we planned to repair ASD later. However, 2 months after implantation, heart failure had progressed and weight gain was unsatisfactory. At that point, we decided that it was necessary to close the ASD earlier than planned. With a retrosternal approach for generator placement, we could obtain sufficient space for the generator without other structure compression and could avoid additional dissection of the rectus sheath and extension of the incision. It will be necessary to reopen the sternum when the battery requires changing, but redo sternotomy should not be difficult because the generator is placed on the anterior surface of the heart, which should protect the heart during re-entry. We must also avoid damage to the generator and leads. The location of the generator pocket may be changed to the epigastric area, and the pacing type may be changed to a transvenous type as the patient matures. Although we cannot assert that our approach can be applied in all neonatal cases, it deserves to be considered as one good option for placement of pacemaker generators in neonates, especially those with a very low body weight. Conflict of interest: none declared. REFERENCES 1 Buyon JP, Hiebert R, Copel J, Craft J, Friedman D, Katholi M. Autoimmune-associated congenital heart block: mortality, morbidity, and recurrence rates obtained from a national neonatal lupus registry. J Am Coll Cardiol 1998; 31: 1658– 66. Google Scholar CrossRef Search ADS PubMed 2 Kwak JG, Kim SJ, Song YJ, Choi EY, Lee SY, Shim WS et al. Permanent epicardial pacing in pediatric patients: 12-year experience at a single center. Ann Thorac Surg 2012; 93: 634– 40. Google Scholar CrossRef Search ADS PubMed 3 Haydin S, Ozturk E, Ergul Y, Tuzcu V. Intrathoracic implantation of a dual-chamber pacemaker in a preterm infant with congenital AV block. J Card Surg 2013; 28: 196– 8. Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Interactive CardioVascular and Thoracic Surgery – Oxford University Press
Published: Mar 29, 2018
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