Case report
An 11-year-old female presented with a 4-week history of fever and fatigue. She had a background history of Down syndrome, non-verbal autism, atrioventricular septal defect repair, and a transvenous pacemaker. Eight years prior, she had a group A streptococcal sepsis with infection of an epicardial pacemaker, which was replaced with a transvenous system. At presentation to hospital, there was a new soft, systolic murmur at the left sternal border. There were no other clinical features of infective endocarditis. Her heart rate was at her paced rate of 74 beats per minute, and her blood pressure was 103/60 mmHg. Laboratory tests showed a C-reactive protein of 255 mg/L with normal serum electrolytes and hepatic function. The haemoglobin level was 11.3 g/dl, and her total white blood cell count was 13.2 109/L. Intravenous ceftriaxone, vancomycin, and gentamycin were instituted as empiric therapy.
Following transfer to a tertiary-level cardiac centre, echocardiography identified a large vegetation on the right atrioventricular valve, which extended over the transvenous pacemaker lead. Peripheral blood cultures were subsequently positive for a penicillin-sensitive group B streptococcus, serotype III, after 9 hours of incubation. Therapy was converted to intravenous benzylpenicillin and gentamicin and continued for 9 days. Once blood culture clearance was proven, a peripherally inserted central catheter was inserted for intravenous antimicrobial delivery.
CT pulmonary angiography demonstrated mild atelectasis of the lung parenchyma, without evidence of septic emboli. It reported hypoattenuation adjacent to the right atrioventricular valve. It was not possible to assess the pacemaker wires secondary to metallic streak artefact.
Transoesophageal echocardiography revealed a 2 cm vegetation, which was adhered to the pacing lead (Figure 1). It demonstrated a pedunculated origin of the vegetation from the septal leaflet of the right atrioventricular valve to the pacemaker lead. There was mild regurgitation of the right atrioventricular valve (peak gradient of 24 mmHg).
Transoesophageal echocardiography demonstrating a large vegetation adhered to the transvenous pacing lead and to the tricuspid valve annulus.
After 28 days of intravenous antibiotic therapy, she underwent a right atrioventricular valve leaflet repair using an autologous pericardial patch with excision of the vegetation on the anterior right atrioventricular valve leaflet.
The transvenous pacemaker system was removed, and a permanent pericardial pacemaker was placed in the posterior rectus sheath. The patient was commenced on a six-week course of intravenous ceftriaxone following the procedure. She made an uneventful recovery and was discharged ten days postoperatively.
Discussion
Children with Down syndrome have a significantly elevated risk of infective endocarditis due to the higher prevalence of CHD (approximately 50%) and frequent exposure to invasive cardiac procedures. Reference Delany, Gaydos and Romeo1 In addition, immune dysfunction, recurrent respiratory infections and suboptimal dental hygiene all increase the susceptibility to bacteraemia and infective endocarditis. The associated immunological deficiencies include T and B cell lymphopenia, decreased numbers of naïve lymphocytes, reduced antibody responses to vaccination, and defects of neutrophil chemotaxis. Reference Ram and Chinen2–Reference Bloemers, Broers, Bont, Weijerman, Gemke and van Furth3
Infective endocarditis involving the right atrioventricular valve is uncommon compared to left-sided infective endocarditis. Right-sided infective endocarditis accounts for approximately 5–10% of all cases, and 90% of these involve the tricuspid valve. Reference Hussain, Witten, Shrestha, Blackstone and Pettersson4 Two recent studies demonstrated that 25% of patients who require surgery during an episode of infective endocarditis had a history of CHD and previous cardiac surgery. Reference Shamszad, Khan, Rossano and Fraser5–Reference Murakami, Niwa, Yoshinaga and Nakazawa6 The placement of a transvenous pacemaker system elevates this risk further through bacterial colonisation and biofilm formation on the intracardiac lead. Staphylococcal and streptococcal species are the most commonly associated pathogens in device-related endocarditis and infective endocarditis requiring surgery. Reference Russell, Johnson, Wurlitzer and Backer7
The clinical presentation of infective endocarditis may be non-specific, where fever and fatigue are the primary symptoms. This is particularly evident in children with developmental delays. Diagnosis in these patients often relies on blood culture testing and echocardiography. Though transoesophageal echocardiography is reported to have a higher sensitivity for infective endocarditis when compared to transthoracic echocardiography in the adult population, they are comparable in paediatric patients with (93–97%). Reference Vicent, Luna and Martínez-Sellés8–Reference Penk, Webb, Shulman and Anderson10
The treatment of infective endocarditis involves a prolonged course of intravenous antibiotic therapy, which typically requires central intravenous access for optimal delivery. In most cases, removal of the pacemaker system is indicated, as eradication without extraction is rare. As demonstrated in this case, reimplantation is deferred until bacteraemia clearance has been proven. Placement of an epicardial device is preferred in paediatric patients in order to minimise infection.
Early recognition and specialist input are essential in the care of children with CHD. In Down syndrome, heightened vigilance for infection is warranted, particularly in cases where there is an indwelling cardiac device, due to their vulnerability and potential for atypical presentation.
Acknowledgements
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