Ann Thorac Surg 2006;81:2310-2312
© 2006 The Society of Thoracic Surgeons
Case report
Anterior Mitral Leaflet Reconstruction With Pericardium in a 1.9 kg Infant With Endocarditis
David G. Healy, MRCSI
*
,
Alfred E. Wood, FRCSI
Professor Eoin O'Malley National Centre for Cardiothoracic Surgery, Mater Misericordiae University Hospital, Dublin, Ireland
Accepted for publication July 20, 2005.
* Address correspondence to Dr Healy, Professor Eoin O'Malley National Centre for Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St, Dublin, 7 Ireland (Email: cardiothoracic{at}eircom.net).
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Abstract
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A premature twin of 1.9 kg had mitral valve endocarditis develop during neonatal intensive care. Vegetation involving the entire anterior mitral valve leaflet was identified. Reconstruction was achieved by near complete resection of the anterior mitral valve leaflet and retention of the peripheral margin of coaptation including primary and secondary chordae. The body of the anterior mitral valve leaflet was reconstructed using fresh autologous pericardium, a technique not previously reported in an infant of this size. Three and a half years later, the child is well and has required no further intervention.
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Introduction
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The incidence of neonatal endocarditis has increased with the establishment of neonatal intensive care but it remains rare occurring in only 0.07% [1]. Although more common on the tricuspid valve, mitral valve endocarditis is reported, and when associated with significant valve destruction, surgical intervention must be considered [1]. We present a case of successful mitral repair in a 3-month old infant with excision of the damaged anterior mitral valve leaflet and reconstruction with autologous pericardium.
The child was twin number 1 of a set of monochorionic diamniotic female twins. Discordant growth was noted at 24 weeks. At 30 weeks a decision to deliver by caesarean section was made. The 1-minute and 5-minute Apgar scores for twin number 1 were 8 and 8, respectively, with a delivery weight of 1,500 g. The baby had respiratory distress syndrome develop, which required assisted ventilation. She also had thrombocytopenia and anemia requiring transfusion. Total parenteral nutrition was commenced on day 4 and was continued to day 18. Fifteen days after delivery her respiratory performance acutely deteriorated. A septic screen performed in response included blood cultures, which was positive for methicillin-resistant S. aureus. At this time a murmur was first noted, which was initially believed to represent a patent ductus arteriosus. On day 18, a transthoracic echocardiogram identified a thrombus or vegetation on the anterior mitral valve leaflet (AML). The methicillin-resistant S. aureus sepsis and endocarditis was treated with vancomycin, gentamicin, and rifampin. On day 31 a repeat transthoracic echocardiogram found that the vegetation had become larger and that it was prolapsing across the mitral valve. On day 39 she had a thromboembolic event to her left lower limb, and a transthoracic echocardiogram showed that the mitral leaflet vegetation had become smaller. The left lower limb was managed successfully with intravenous heparin and dextran, and antibiotic treatment was continued. However by day 71 her respiratory effort was increasing and there was evidence of left ventricular hypertrophy and pulmonary congestion on chest roentgenogram. An echocardiogram showed the thrombus had increased in size, there was severe mitral regurgitation, and a large left atrium and pulmonary veins suggesting pulmonary hypertension. She was transferred to the pediatric cardiothoracic center at which time she required frusemide (1 mg/kg) twice daily, spironolactone (1 mg/kg) once daily and captopril (0.5 mg) 3 times daily.
The baby underwent surgical repair at 76 days. At that time she weighted 1.9 kg and had a body surface area of 0.15 m2. Surgical repair was performed under cardiopulmonary bypass (85 min) with aorto-bi-caval cannulation. Bi-caval cannulation was utilized to minimize the arrest time, as the cardiopulmonary bypass and rewarming could be re-commenced while the surgeon continued with tasks such as closing the atrium. Blood cardioplegia was used with an aortic cross-clamp time of 36 minutes. Circulatory arrest with profound hypothermia at 16°C was utilized for a duration of 22 minutes. A left atrial approach was used, and on inspection, the AML had a large vegetation covering almost the entire atrial surface with perforations and gross mitral incompetence. In addition the ductus arteriosus was patent and there was a small patent foramen ovale atrial septal defect. Mitral reconstruction was achieved by excising the AML but leaving the chordal leaflet margin (Fig 1). The AML was replaced with autologous fresh pericardium (20 x 16 mm) and sutured in place with 6-0 polypropylene. There was no indication for an additional annuloplasty. The atrial septal defect was also closed, and the patent ductus arteriosus was ligated. Intraoperative left atrial pressure studies were performed prior to closure. She was ventilated in intensive care for 3 days. Transthoracic echocardiography was performed immediately postoperatively and the intravenous antibiotic regime continued to discharge 13 days after surgery. Histologic analysis of the vegetation identified a large organized fibrinous deposit, but no proliferative organisms were seen. Her first postoperative transthoracic echocardiogram showed no mitral incompetence. At clinical examination and transthoracic echocardiogram follow-up, 31/2 years after surgery the patient was found to be a normally active child without restriction, who was on captopril (1 mg 3 times daily) and had mild mitral regurgitation.
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Fig 1. This line drawing indicates the line of excision on the anterior mitral valve leaflet (AML) and replacement with autologous pericardial tissue.
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Comment
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Neonatal and infant endocarditis is most commonly treated with antibiotics alone, a regime with a reported 87.5% survival rate [1]. Surgical intervention is generally used as a last resort, although early intervention has been advocated when thromboembolism is believed to be likely [2, 3]. When surgery is utilized, an operative mortality of 0% to 25% is reported [2]. The principles of treating endocarditis are complete excision of the infective and necrotic material and restoration of function. We endeavored to avoid replacement in this case, despite significant damage to the native valve leaflet. The disease had damaged the AML, but left the posterior leaflet complex intact. The AML repair with bovine and autologous pericardium has been reported in adults and in a 3-year-old with successful outcome [4, 5]. However reconstruction of the AML with autologous pericardium for destruction related to infective endocarditis has not been previously reported in a child less than 1 year of age. Resection of the damaged leaflet with retention of the leaflet margin allows conservation of the chordal insertion margin, which is particularly important. In contrast with valve replacement, this conserves the subvalvular apparatus and ventricular geometry, preserving left ventricular function and resulting in long-term survival benefits. An alternative strategy would have been to use artificial chordae; however, in this case we were able to satisfactorily remove the vegetation while retaining the leaflet margin. Mitral repair also reduces the risk of thromboembolism and avoids the need for anticoagulation, which is particularly difficult to manage in the pediatric population. An incidence of serious hemorrhage of 9%, and a 12% incidence of thromboembolic events, is reported in a review of children who were anticoagulated with warfarin after cardiac valve replacement [6]. Mitral repair is particularly advantageous in endocarditis, as the risk of prosthetic valve endocarditis is avoided. Data from adult series report very low recurrent endocarditis rates with repair of mitral valves. Mechanical valve usage in young children is significantly challenged by patient-prosthesis size mismatch and these very small children will quickly outgrow the prosthetic valve, requiring reoperation. In children under 1 year undergoing mitral replacement, reoperation within 6 years is required in 36% [7]. Excellent results in children under 1 year of age have been reported with mitral valve repair, with a 7-year survival rate of 94% [8].
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References
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- Jones J, Sarsam M. Partial mitral valve replacement for acute endocarditis Ann Thorac Surg 2001;72:255-257.[Abstract/Free Full Text]
- Frank M, Mavroudis C, Backer C, Rocchini A. Repair of mitral valve and subaortic mycotic aneurysm in a child with endocarditis Ann Thorac Surg 1998;65:1788-1790.[Abstract/Free Full Text]
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Abstract
Introduction
