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Ann Thorac Surg 1995;60:90-95
© 1995 The Society of Thoracic Surgeons
Victorian Paediatric Cardiac Surgery Unit and Department of Cardiology, Royal Children's Hospital, Melbourne, Australia
| Abstract |
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Methods. Retrospective review of 98 patients treated for infective endocarditis during the past 13 years at the Royal Children's Hospital, including medically and surgically treated patients.
Results. Thirty of 98 patients had surgical intervention with 6.7% hospital mortality, and 76% survival probability at 45 months. The remaining patients were treated medically, with 10% hospital mortality and 52% 5-year survival probability. The incidence of structural heart disease, congestive heart failure, and spectrum of organisms was similar in the two groups.
Conclusions. Despite advances in antibiotic therapy, early surgical intervention is required in a significant subset. Concurrent intracardiac repair may be appropriate.
| Introduction |
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| Material and Methods |
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| Results |
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Surgical Patients
Thirty-three surgical interventions were required in 30 patients. Median age at operation was 22.5 months (range, 1 month to 15 years). Twenty-two of the surgical patients had underlying structural congenital heart disease, of whom 9 had undergone palliative and 6 had undergone corrective procedures (Table 2
). One patient had an acquired cardiomyopathy. Staphylococcus aureus was the organism most commonly isolated in the surgical group (Table 3
). The indications for surgical intervention and the procedures performed are presented in Table 6
. Common indications included left-sided vegetations (in 1 patient with evidence of embolic phenomena), evidence of persisting infection (despite antibiotic therapy), and significant hemodynamic compromise (usually related to valvular dysfunction). Infection related to artificial tissue was an indication in 3 patients with pulmonary artery bands (leading to band erosion) and in 2 patients with systemic-to-pulmonary artery shunts. Although removal of a vegetation was often the only procedure performed, some patients required extensive debridements, associated with either valve repair or replacement, exclusion of an abscess, closure of a false aneurysm, or removal of prosthetic material (Table 6
). Operative specimens were cultured in all patients. Evidence of recurring infection developed in 4 patients, and 3 of them required a second operation. Recurrent infection developed in 2 of 6 (33%) patients with positive tissue cultures (obtained at operation) and 2 of 24 (8%) patients with negative cultures. These differences did not reach statistical significance.
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| Comment |
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The close association between structural heart disease and endocarditis seen in other series [24] is supported by our data. Underlying structural heart disease was seen in 79 of our 98 patients. There is little agreement in the published literature with regard to the relative risk of endocarditis with different cardiac lesions. In our experience, as in that of Van Hare and co-workers [2], left-to-right shunting through a ventricular or atrioventricular septal defect forms the underlying substrate for infective endocarditis in a significant proportion of patients. However, although some series suggest that the risk of endocarditis in patients with right-to-left shunts may be low [2], our data do not support this impression. Of the 79 patients with congenital heart disease in our patient group, 10 had tetralogy of Fallot, with or without pulmonary atresia.
It may not be possible to make statistically valid statements regarding the relative risk of endocarditis for different congenital heart lesions by comparing our patient group with the published population-based series for congenital heart disease. Nonetheless, in Table 2
we present the proportional distribution of some of the more common lesions seen in our endocarditis patients. Also shown are data from some of the larger population-based series, which assessed the distribution for the same lesions in all live-born infants with congenital heart disease [711]. These data suggest that the relative risk of endocarditis for lesions such as atrial septal defect, pulmonary stenosis, and coarctation of the aorta is low, whereas tetralogy of Fallot appears to be overrepresented in our series.
As in other centers, the most common organisms isolated in our patients were Staphylococcus and Streptococcus [2, 12, 13]. The proportion of patients with staphylococcal infection was similar in those with and without congenital heart disease. Although it has been suggested that staphylococcal infection associated with left-sided vegetations may be a prima facie indication for operation [14], we operated on only 4 of 11 patients with this clinical picture. Six patients were cured with antibiotic treatment alone. Indeed, in our experience, unlike that of others [13], staphylococcal endocarditis was not associated with a greater likelihood of surgical intervention. Embolization occurred with similar frequency in patients with Staphylococcus compared with those with other organisms. There were four early deaths in the 32 patients with staphylococcal infection compared with 5 of the 66 patients with other types of endocarditis, although the differences did not reach statistical significance.
Our experience regarding the clinical presentation of patients with Staphylococcus aureus infection is similar to that of others [15]. Many of these patients present with an acute septic crisis, rather than with the classic syndrome of ``subacute'' endocarditis. Our series includes children who progressed from being vaguely unwell, without any cardiovascular signs, to septic shock, severe cardiac failure, and valve destruction within less than 24 hours.
In our institution, the medical management of patients with endocarditis is based on extensive microbiological investigations before the institution of antibiotics, the use of combinations of synergistic bactericidal agents, and measurement of their minimal bactericidal concentrations. Although we recognize that there has been much recent interest in the potential for short antibiotic courses [16], or predominantly oral therapy, we continue to recommend the proven 4- to 6-week course of intravenous antibiotics. All patients with endocarditis undergo regular echocardiograms during treatment, principally for the detection of valvular dysfunction, abscess formation, and deteriorating ventricular function. It is our impression, however, that serial echocardiographic estimations of vegetation size are of little value for the most part, because of variations in technique and interpretation, and because a vegetation may show no significant reduction in size despite adequate antibiotic therapy [17]. Nonetheless, we would consider that continued growth of a vegetation, in the presence of continuing bacteremia, may indicate treatment failure and precipitate surgical intervention.
Data from adult patients have suggested that the identification of a vegetation identifies a group of patients who are at high risk of life-threatening complications [14, 18]. In our patients, although the presence of a vegetation was associated with an increased risk of embolism, the risk of death and congestive heart failure was similar in patients with and without vegetations. It is likely, however, that this may reflect, in part, that most of our patients who did not have identifiable vegetations had underlying structural heart disease.
The likelihood of surgical intervention for infective endocarditis increased over the period of this study. Patients in the most recent decade were twice as likely to have an operation during the course of treatment (p < 0.0001). This may relate more closely to the increased availability and quality of pediatric open heart surgery in Melbourne during this time course, rather than a specific change in the virulence of the disease. The latter possibility cannot be discounted completely, however, as the growing population of survivors of corrective or palliative operations for congenital heart disease may have been more difficult to cure with antibiotics alone than their unoperated counterparts.
The surgical procedures used during this study period constitute a wide technical spectrum, but with uniform goals. Removal of as much infected tissue as is reasonably possible and restoration of a favorable hemodynamic state were the priorities. When possible, concurrent complete repair of congenital cardiac defects was considered highly desirable.
The technical details of operation for infective endocarditis have been well described, and are outside the scope of the present discussion. Improvements in aortic valvuloplasty techniques may preclude the need for valve or root replacement in many cases of antibiotic failure. When required, however, homograft rather than prosthetic replacement has been considered preferable. It is likely, however, that the pulmonary autograft will prove to be the best option in suitable patients.
Infective endocarditis after a palliative operation may present the surgeon with a difficult decision regarding surgical options. We have encountered this situation with infected polytetrafluoroethylene modified Blalock shunts (2 children) and pulmonary arteryAu: OK for PA? (PA) bands (3 children). In 2 patients we were able to perform a complete repair, and although implantation of further prosthetic material was required, antibiotic therapy resulted in a cure. In 3 patients with infection at PA band sites, loss of banding effect was encountered when the band eroded the wall of the main PA. One of these patients had been banded in preparation for conversion from Senning to arterial switch operation for late right ventricular failure [19]. Because left ventricular ``retraining'' was still in an early stage, left ventricular-to-pulmonary artery continuity was restored using a homograft tube tailored to an hourglass configuration. The patient was cured with antibiotic therapy and later had successful switch conversion.
Indications for operation in infective endocarditis remain debatable and challengeable in children, and each patient must be considered on its own merits. This is especially true when dealing with the aortic root. Abnormalities, such as cavity and sinus tract formation and leaflet abnormalities, may or may not constitute indications for immediate operation. The key issues are control of systemic sepsis and hemodynamic status. Patients who are satisfactory in both regards can usually wait. Although many will eventually require operation, it is vastly preferable to complete antibiotic therapy beforehand. This is especially true in lesions of the aortic root, in which a radical reconstruction will often be required.
In our series, 3 patients with essentially untreated infective endocarditisAu: OK? who were operated on for acute hemodynamic deterioration or multiple emboli required postoperative extracorporeal support. Two were supported with a left ventricular assist device and one with extracorporeal membrane oxygenation [20, 21]. All 3 patients survived and were cured of infection after antibiotic therapy. These cases illustrate that severe sepsis is not an absolute contraindication to extracorporeal life support in postoperative patients.
In conclusion, infective endocarditis remains a complex and virulent disease in children. Staphylococcus aureus is the most common organism isolated, commonly leading to an acute septic crisis, rather than the classic syndrome of subacute bacterial endocarditis. Despite advances in antibiotic therapy, early surgical intervention is necessary in a subgroup of patients. All children with infective endocarditis should be treated during the acute phase of the infection in a cardiac surgical center, where close surveillance is possible. Despite advances in antibiotic therapy, a significant proportion of patients will need early surgical intervention. Complete repair of the congenital defect may be appropriate as part of the treatment of endocarditis in selected patients. Postoperative extracorporeal life support, which may be a useful adjunct, is not absolutely contraindicated in patients with severe sepsis.
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| Footnotes |
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Address reprint requests to Dr Karl, Victorian Paediatric Cardiac Surgery Unit, Royal Children's Hospital, Flemington Rd, Parkville, Victoria 3052, Australia.
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