Case report

An 8-month-old male infant weighing 6.4 kilograms was admitted because of tachypnea due to congestive heart failure. A diagnosis of Marfan's syndrome had been suspected after birth because of the chest deformity, arachnodactyly, scoliosis, narrowly arched palate, congenital flexion contracture, inguinal hernia, and mild mitral insufficiency. On admission, the heart rate was 142 beats per minute and regular, and a grade 3 out of 6 ejection systolic murmur was audible. The rate of respiration was 54 breaths per minute. The edge of the liver was palpable 3 fingerbreadths below the right costal margin. A chest X-ray showed cardiac enlargement. Echocardiography showed marked hypertrophy and prolapse of the mitral leaflets (Fig. 1a). Cardiac catheterization confirmed severe mitral insufficiency. When the patient was aged nine months, we planned plasty of the mitral valve to treat the recurrent heart failure. At the operation, cardiopulmonary bypass was established through a median sternotomy. The mitral valve was exposed through an incision in the right-side wall of the left atrium along the interatrial groove under cardioplegic cardiac arrest. The mitral valve had two leaflets, but both leaflets were remarkably hypertrophic, with markedly elongated and adherent tendinous cords (Fig. 1b). A cleft was seen in the aortic leaflet. We noted three papillary muscles, to which the cords were irregularly attached. We chose to shorten five of the cords, combining this with an annuloplasty that was performed at the inferomedial ends of the solitary zone of apposition between the two major leaflets performed as suggested by Reed et al.,⁴ and inserting a 25-millimetre Duran flexible annuloplasty ring (Medtronic, Incorporation, Minneapolis, Minnesota). Subsequent to these procedures, the water leak test showed poor ballooning of the leaflets. Thus, we took down the plasty and replaced the valve using an inversed mechanical aortic valve of 19 millimetres (ATS Medical Incorporation, Minneapolis, Minnesota). The period of extracorporeal circulation lasted 325 minutes, and the aortic cross-clamping time was 181 minutes. Paroxysmal supraventricular tachycardia was seen in the early postoperative period. postoperative respiratory management was difficult because of intractable pneumonia. Anticoagulation therapy included aspirin and ticlopidine hydrochloride. Histological examination showed a reaction to the periodic acid-Schiff stain, and toluidine blue positive mucinous deposits, in the mitral valve. The stromal cells had vacuolated cytoplasm (Fig. 2). Two weeks after the operation, cytoplasmic vacuoles were found in the lymphocytes by microscopic blood cell assessment, and further studies indicated I-cell disease. One month after the operation, echocardiographic assessment indicated normal cardiac function, and the patient was referred for transplantation of bone marrow for treatment of the I-cell disease.

Figure 1. (a) Preoperative echocardiography showing marked thickening of both leaflets of the mitral valve (arrow). LA: left atrium; LV: left ventricle. (b) Resected mitral valve showing thickening of both leaflets and adhesion of tendinous cords. AML: aortic mitral leaflet MML: mural mitral leaflet.

Figure 2. Photomicrograph of degenerative mitral valve showing mucinous deposits with swollen mononuclear cells. Hematoxylin and eosin. ×20.

Discussion

I-cell disease is an inherited, congenital, and slowly progressive disorder, and has a fatal outcome during early childhood. Its clinical manifestations are psychomotor retardation, growth failure, hypotonia, frequent respiratory infections, dysostosis multiplex, stiffness of joints and Hurler-like appearance.^{3, 5–7} The activity of serum lysosomal enzymes is high, although urinary excretion of acid mucopolysaccharides is normal. Cardiac manifestations have been reported including cardiomegaly and valvar disease.^{3, 6} I-cell disease is difficult to diagnose, since its manifestations resemble other disorders which also include skeletal deformity. At first, we treated the patient for Marfan's syndrome, because his physical characteristics were consistent with the diagnostic criterions. Thus, careful examination is necessary to identify I-cell disease.

To reduce the postoperative complications related to insertion of prosthetic valves, plasty is the preferred method of treatment for young patients, and early surgical results can be good.⁸ In our patient, we hoped to perform plasty, but it was difficult because of the marked deformities of the leaflets and tendinous cords. Specific valvar manifestations in this disease remain unknown. Valvar thickening and prolapse, nonetheless, are often seen in metabolic storage disorders.^{2, 3} We believe that the surgery was effective in our patient for the treatment of congestive heart failure. Thus, if heart failure is caused by valvar insufficiency, aggressive heart surgery can reduce mortality in early childhood, and thus allow for further treatment of other complicating processes, such as I-cell disease.