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Ann Thorac Surg 2001;72:251-253
© 2001 The Society of Thoracic Surgeons

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Case report

Emergency pulmonary autograft mitral valve replacement in a child

Accepted for publication May 24, 2000.

Address reprint requests to Dr Mitchell, Cardiac Care Center, The Children’s Hospital, 1056 19th Ave, B200, Denver, CO 80218
e-mail: mitchell.max{at}tchden.org

	Abstract

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Mitral valve replacement in small children imposes significant clinical difficulties because of the relatively small mechanical prosthetic valves required and the need for lifelong anticoagulation therapy. A child weighing 10.4 kg presented with thrombosis of her 19-mm mechanical mitral prosthesis 4 weeks after implantation despite appropriate oral anticoagulation therapy. An emergency mitral valve replacement with a pulmonary autograft was successfully performed with encouraging short-term results.

	Introduction

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Occasionally, mitral valve replacement is the only option for small children with congenital or acquired mitral valve disease. Bioprosthetic valves fail quickly in children and are not available in very small sizes. Mechanical valves have been the only suitable option available for small children. We present a case in which an emergent pulmonary autograft mitral valve replacement was performed in a small child with acute thrombosis of a mechanical valve.

A 36-month-old developmentally delayed girl presented with fever and poorly compensated congestive heart failure. Six weeks previously, she had undergone a tooth extraction. She weighed 10.4 kg (1st percentile) at presentation. A 4/6 systolic murmur was heard at the left sternal border, and diffuse rales were heard bilaterally. Severe mitral regurgitation and large vegetations on both leaflets were demonstrated by echocardiogram. Anemia (hemoglobin 6.8 g/dL) due to hemolysis was present. Blood cultures grew Enterococcus. After bloodstream sterilization with intravenous antibiotics, a 19-mm St. Jude HP mechanical valve (St. Jude Medical, Minneapolis, MN) was implanted, as valve repair was not possible. Intravenous heparin was administered until adequate oral anticoagulant intake was achieved. The patient was discharged home 14 days postoperatively on continued intravenous antibiotics and warfarin ( International Normalized Ratio [INR] 3.0 on discharge).

Three weeks later the patient returned in cardiogenic shock with a loud systolic murmur and absent valve click on auscultation. Echocardiogram demonstrated a mechanical valve leaflet fixed in the closed position, impaired movement of the other leaflet, and an estimated mitral gradient of 33 mm Hg. An INR drawn 6 days before readmission was 3.1, and the INR on readmission was 5.4. Given her precarious hemodynamic condition and recent surgery, thrombolytic therapy was not considered. Emergency reoperation revealed thrombus impeding the hinges of both leaflets. There was no evidence of prosthetic valve endocarditis. The pulmonary annulus, measured using a Hegar dilator (V. Meuller, Deerfield, IL), was 19 mm at surgery. The autograft was harvested and mounted within an 18-mm polytetrafluoroethylene (PTFE) tube graft (Fig 1a) using 5-0 monofilament suture at both the inflow and outflow portions, as previously described [1]. We slightly downsized the PTFE graft in order to maximize autograft competence, because the pulmonary valve had been subjected to significant hypertension both before the original procedure and currently, resulting in some dilation. A skirt of 0.6-mm PTFE patch with a central 18-mm hole was attached to the inflow portion of the autograft/PTFE tube complex (Fig 1b) using a continuous 5-0 monofilament suture. During preparation of the autograft, the St. Jude prosthesis was explanted, and multiple simple interrupted 4-0 braided sutures were placed in the mitral annulus. These sutures were then placed in the outflow portion of the autograft, which was seated and tied into position (Fig 1c). The previously constructed PTFE skirt was trimmed and sutured to the left atrial wall, excluding the left atrial appendage, maintaining unobstructed drainage of all pulmonary veins (Fig 1d). The left atrium was closed, and the right ventricular outflow tract was reconstructed with a 19-mm pulmonary homograft. Myocardial ischemia time was 128 minutes. Intraoperative transesophageal echocardiography demonstrated trivial autograft regurgitation and no gradient. The patient recovered without adverse sequelae. Her surgery was 8 months ago, and she remains well with trivial autograft insufficiency assessed by transthoracic echocardiography (Fig 2).

View larger version (41K): [in this window] [in a new window]   Fig 1. (a–d) Surgical technique for construction and insertion of the pulmonary autograft/prosthetic conduit complex in the mitral position.

View larger version (51K): [in this window] [in a new window]   Fig 2. Follow-up transthoracic echocardiographic apical four-chamber view of the pulmonary autograft with polytetrafluoroethylene conduit in the mitral position.

	Comment

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Ensuring autograft competence in the mitral position requires fixation of the autograft within a prosthetic conduit. Therefore, autograft growth cannot occur. Consequently, the potential for late mitral stenosis with patient growth is a major concern when using this procedure in small children. Adult patients with significant mitral stenosis usually have mitral valve areas of less than 1.5 cm² [6]. If the supporting conduit is not downsized, the minimum pulmonary annulus diameter required to achieve a valve area of 2.0 cm² is 16 mm, whereas an 18-mm annulus would allow a valve area of 2.5 cm². In our case, the maximum expected autograft valve area is 1.5 cm², allowing for a 2-mm autograft wall thickness mounted within an 18-mm PTFE tube. Our patient has severe growth retardation not attributable to her heart; therefore, this procedure could conceivably provide a lifelong solution to her mitral disease. Reoperation for pulmonary allograft replacement is inevitable in our patient, a reasonable trade-off in this case. However, this procedure may eventually result in the conversion of single-valve disease to double-valve disease.

Pulmonary autograft mitral valve replacement using the top hat technique was an effective solution in this child with early prosthetic valve failure. Extensive follow-up is essential before this procedure can be recommended for children.

	References

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1. Kabbani S.S., Ross D.N., Jamil H., et al. Mitral valve replacement with a pulmonary autograft: initial experience. J Heart Valve Dis 1999;8:359-367.[Abstract]
2. Ross D.N. Replacement of the aortic and mitral valves with a pulmonary autograft. Lancet 1967;2:956-958.[Medline]
3. Yacoub M.H., Kittle C.F. A new technique for replacement of the mitral valve by a semilunar valve homograft. J Thorac Cardiovasc Surg 1969;58:859-869.[Medline]
4. Yacoub M.H., Towers M., Somerville W. Results of mitral valve replacement using unstented fresh semilunar valve homografts. Circulation 1972;14(Suppl I):I44-I50.
5. Ross D.N., Kabbani S. Mitral valve replacement with a pulmonary autograft: the mitral top hat. J Heart Valve Dis 1997;6:542-545.[Medline]
6. Gaasch W.H., O’Rourke R.A., Cohn L.H., Rackley C.E. Mitral valve disease. In: Schlant R.C., Alexander R.W., O’Rourke R.A., Roberts R., Sonnenblick E.H., eds. Hurst’s the heart, 8th ed. New York: McGraw-Hill, 1994:1484.

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Max B. Mitchell Gyaandeo S. Maharajh Mark R. Bielefeld David R. Clarke Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mitchell, M. B. Articles by Clarke, D. R. Search for Related Content PubMed PubMed Citation Articles by Mitchell, M. B. Articles by Clarke, D. R. Related Collections Congenital - acyanotic