Introduction Mitral valve repair in congenital heart disease has variable long-term results depending on the morphology of the valve. In the context of patients with variations of hypoplastic left heart syndrome, the outcomes are particularly disappointing. An 11-year-old boy, who had undergone repair of double outlet right ventricle with an aortic arch reconstruction as an infant, followed by mitral commissurotomy and resection of a supra-mitral membrane at 15 months of age developed progressive mitral stenosis leading to a further failed repair, then replacement of the valve with a 21 mm St. Jude mechanical prosthesis. He represented 3 weeks later in extremis with pulmonary oedema, a high velocity mitral inflow gradient, evidence of prosthetic leaflet fixation and signs of acute dysfunction of the mechanical valve on echocardiography.
Method The recently placed mechanical valve was explanted via a left atriotomy and exploration revealed an organised clot completely fixing one leaflet and severely restricting the other (despite therapeutic anticoagulation (Warfarin) since implantation). Due to this early thrombosis of the mechanical valve and limited options for a standard biological prosthesis at this age, an Edwards’ Sapien 3 valve was implanted via a hybrid approach. A flexible 28 mm MEMO 3D (Sorin Group, Milan Italy) annuloplasty ring was secured above the left atrial appendage as an anchor for the prosthesis. The valve was prepared, crimped and mounted in the standard manner and deployed using the proprietary delivery system. An additional 2mls was added to the suggested volume for a 23mm valve implant to ensure tight apposition and to ensure that the annuloplasty ring (D shaped in its native state) adopted a circular conformation to maximise the valve performance. The skirt of the valve was sewn to the annuloplasty ring with interrupted sutures for additional stability.
Results The patient separated from bypass with ease and trans-oesophageal echo showed a minimal inflow gradient through the valve with no regurgitation and no paravalvar leak. After an unremarkable post-operative recovery the patient was discharged home. The tricuspid regurgitation jet diminished and at follow-up (>6months) there has been no evidence of elevated pulmonary artery or left atrial pressures. Warfarin was continued for an arbitrary period of 6 months and aspirin indefinitely.
Conclusion The options for mitral valve replacement in neonates and infants are poor and also challenging in children with an underdeveloped annulus. Mechanical mitral valve prostheses are only available at 23mm and above. It is therefore common to use smaller aortic prosthesis upside-down in the mitral position. The width of the sewing ring of all prosthetic valves further limits the effective orifice. The result is that that the flow dynamics for these valves in the low velocity mitral position is poor, resulting in valve dysfunction such as described in our case. The Edwards Sapien valve chosen in this case effectively has no sewing ring and relatively short stent length, decreasing the risk of the valve support system causing significant left ventricular outflow tract obstruction. Mounting the valve using a supra-annular annuloplasty device, provides an anchor point and further decreases the risk of the valve protruding into the left ventricular outflow tract. Combining these technologies allows maximisation of the effective orifice. This technique has been used in a limited number of adult patients and to our knowledge is its first application in paediatric or congenital heart disease, representing a further step in the progress of hybrid techniques to improve treatment options in such difficult cases.
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