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Marc R. de Leval, M.D.
Tricuspid Valve
Thus far, congenital malformations of the tricuspid valve requiring treatment have remained in the surgeon's territory.
Tricuspid valve stenosis
Isolated tricuspid valve stenosis is an extremely rare lesion. When caused by a fusion of the leaflets, the stenosis can be relieved by tricuspid valve commissurotomy. Most commonly, tricuspid valve stenosis is associated with right ventricular cavity hypoplasia and pulmonary valve stenosis or atresia. Depending on the degree of hypoplasia, these patients can be candidates for a biventricular repair, a one-and-a-half ventricular repair, or right ventricular exclusion (Fontan procedure).
Tricuspid valve regurgitation
Isolated tricuspid valve regurgitation is also a very rare condition. Most commonly, tricuspid valve regurgitation is secondary to right ventricular dilatation and/or iatrogenic lesions following repair of lesions such as ventricular septal defect, tetralogy of Fallot, transposition of the great arteries/ventricular septal defect and pulmonary stenosis, truncus arteriosus, etc. Tricuspid valve annuloplasty is the most commonly performed procedure. Tricuspid valve ring annuloplasty or tricuspid valve replacement are rarely indicated in the paediatric practice.
Ebstein's anomaly is a rare, complex malformation of the right heart structures including the tricuspid valve, the right atrium and the right ventricle. The detailed surgical management of this condition goes beyond the brief of this meeting. Various techniques of repair have been recommended. The most commonly used technique was proposed by Carpentier and consists of freeing the sail-like anterior leaflet, which is used as a monocusp with longitudinal plication of the atrialised portion of the right ventricle.
Pulmonary Valve
Pulmonary valve stenosis
Isolated pulmonary valve stenosis or atresia is treated nowadays by interventional catheterisation. Pulmonary valve stenosis that is part of tetralogy of Fallot or associated with a ventricular septal defect is often only a component of diffuse right ventricular outflow tract obstructions at valvar, subvalvar and sometimes supravalvar levels. In those cases the valvar stenosis is managed by surgical valvotomy. If the pulmonary annulus is more than two or three standard deviations below normal, a transannular patch is indicated.
Extracardiac valved conduit
In cases of absent pulmonary valve (pulmonary atresia, truncus arteriosus) or severe pulmonary stenosis associated with complex malformations such as transposition of the great arteries and some double outlet right ventricles, the surgical repair includes interposition of a valved conduit between the right ventricle and the pulmonary artery. Bioprosthese (homografts or heterografts) are used for that purpose. When implanted in young infants and children, they need to be replaced as a result of outgrowth of the conduit. In addition, all extracardiac conduits available at present have a propensity to become stenotic because of calcification, deformation, anastomotic fibrosis, progressive right ventricular hypertrophy, and/or external compression. Until recently, surgical conduit replacement was the only therapeutic option for stenotic conduits. Percutaneous pulmonary valve implantation following dilatation is emerging as an appealing alternative in selected cases.
Pulmonary valve regurgitation
Isolated pulmonary valve regurgitation is an extremely rare malformation. The most common naturally occurring pulmonary valve regurgitation is the absent pulmonary valve syndrome, which is a variant of tetralogy of Fallot.
Pulmonary valve regurgitation following repair of tetralogy of Fallot has become one of the most common indications for interventional procedures in adults with congenital heart diseases. Chronic pulmonary valve incompetence can lead to right ventricular dilatation, overt heart failure, atrial and ventricular arrhythmias, and sudden death. The degree of pulmonary valve incompetence depends on the integrity of the valve structures, the right ventricular diastolic function, the afterload on the right ventricle and the mechano-electric interactions. Cardiac magnetic resonance imaging is currently the gold standard imaging tool to evaluate patients with pulmonary valve regurgitation and to refine indications and timing for intervention. Percutaneous pulmonary valve implantation is emerging as a promising technique of orthotopic pulmonary valve replacement. The current indications, however, remain limited because most of those patients have dilated or even aneurysmal right ventricular outflow tracts. Ongoing research on outflow tract reducers may, in the near future, overcome these contraindications. The most controversial issue, however, is the growing evidence that pulmonary valve replacement in patients with longstanding pulmonary valve regurgitation may not result in significant improvement of right ventricular function or even improvement in symptoms. As well as pulmonary valve replacement, those patients may need additional procedures such as resection of aneurysmal patches, resection of scarred anterior right ventricular wall, right ventricular remodelling, tricuspid valve annuloplasty, arrhythmic procedures, AICD, etc, and will therefore remain candidates for surgical rather than catheter intervention.
