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BACKGROUND AND AIM OF THE STUDY: Right ventricular dilatation observed after tetralogy of Fallot repair regresses after pulmonary valve implantation, unless the dilation is too severe. The presence of an akinetic patch in the right ventricular outflow tract (RVOT), a known factor promoting right ventricular dilatation, may prevent right ventricular recovery after valve implantation. The exclusion of a large akinetic RVOT area during reoperation of patients presenting with severe post-repair right ventricular dilatation was investigated. METHODS: Eight patients underwent a pulmonary infundibuloplasty between May 2000 and October 2002. Their mean preoperative cardothoracic index was 0.66 +/- 0.08, and preoperative NYHA class II (n = 4), III (n = 3) or IV (n = 1). Three patients were offered heart transplantation but refused. All had severe pulmonary regurgitation and underwent a RVOT valve implantation except one patient who had a previous homograft pulmonary valve insertion. Concomitant procedures were tricuspid ring implantation (n = 3), atrial septal defect closure (n = 2), mitral valve repair (n = 1) and modified right atrial Maze (n = 1). RESULTS: Median follow up time was 13 months (range: 6 -29 months). One patient suffered a fatal ventricular fibrillation at home. All patients but one were in NYHA class I. After a mean of 5 +/- 3 months, their mean workload capacity rose from 115 +/- 19 W to 155 +/- 62 W, and mean VO2max rose from 16.5 +/- 2 to 18.3 +/- 2 ml/min/kg. CONCLUSION: Pulmonary infundibuloplasty may be a useful adjunct in reoperation of tetralogy of Fallot patients presenting with severe right ventricular dilatation and large akinetic area of the RVOT.

Repair of tetralogy of Fallot gives excellent results in terms of survival, but many of these patients suffer from late right ventricular dilatation. This phenomenon has been attributed to the chronic volume overload related to the pulmonary insufficiency caused by transannular patching. In chapter 1, we showed that valvulation of the outflow tract of these patients led to their functional recovery and to the regression of their ventricular dilatation. In chapter 2, we displayed the 25 years follow-up of a longitudinal cohort of 191 patients operated in our institution. This study, instead of proving the causal relationship between pulmonary regurgitation and right ventricular enlargement, showed that pulmonary regurgitation might not be the only factor leading to ventricular dilatation. The suspicion raised that perioperative damage to the right ventricular outflow tract may also play an important role. In order to ascertain this hypothesis, we conducted in chapter 3 a comparative clinical study. of two groups of patients who both suffered from long-term pulmonary insufficiency. One who had right ventricular outflow tract damage, the Fallot patients who had a transventricular repair and one who had no damage to the outflow tract, patients operated for isolated pulmonary commissurotomy. The fate of these two group of patients was so different, that it confirmed our suspicion that the pulmonary infundibulum may not be the passive conduit everybody thought it was. In chapter 4, we decided to investigate the anatomy and function of the pulmonary infundibulum with MRI investigations of our operated Fallot patients. This study proved our hypothesis, and delineated the exact role of the pulmonary infundibulum. The pulmonary valve is anatomically and functionally different from the other cardiac valves. It is not supported by any fibrous tissue, but exclusively by a muscular cylinder. The pulmonary infundibulum participates to the pulmonary valve function because it remain, Bien que la réparation chirurgicale de la tétralogie de Fallot donne d'excellents résultats en terme de survie, la dilatation ventriculaire droite tardive reste un problème majeur chez ces patients. Depuis toujours, cette dilatation a été attribuée à l'insuffisance valvulaire pulmonaire liée à la réparation transannulaire effectuée chez ces patients. Dans le chapitre 1, nous démontrons que la mise en place d'une homogreffe pulmonaire chez les patients souffrant de dilatation ventriculaire droite tardive permet la régression de cette dilatation et leur récupération fonctionnelle. Dans le chapitre 2, est présentée l'étude d'une cohorte longitudinale de patients suive pendant 25 ans. Cette étude au lieu de prouver la relation causale entre l'insuffisance valvulaire pulmonaire et la dilatation ventriculaire droite tend à démontrer que l'insuffisance n'est pas le seul facteur causal et que le traumatisme peropératoire de l'infundibulum pulmonaire pourrait jouer un rôle important dans la genèse de cette dilatation. Afin de confirmer cette hypothèse, nous avons dans le chapitre 3 réalisé une étude clinique comparative de deux groupes de patients souffrant d'insuffisance pulmonaire au long terme : les patients ayant bénéficié d'une réparation transventriculaire d'une tétralogie de Fallot et les patients opérés d'une commissurotomie pulmonaire isolée, indemnes de tout dommage infundibulaire. Le sort de ces patients était tellement différent qu'il tend à confirmer le rôle primordial de l'infundibulum pulmonaire dans la protection contre la dilatation ventriculaire tardive chez les Fallots opérés. Dans le chapitre 4, nous présentons l'étude en RMN de nos Fallots opérés. Ces investigations démontrent l'exactitude de notre hypothèse et précisent le rôle exact de l'infundibulum pulmonaire. La valve pulmonaire est fonctionnellement distincte des autres valves cardiaques. C'est la seule valve qui n'est pas supportée par du tissu fibreux, mais exclusivement par du tissu musculaire., Thèse de doctorat en sciences médicales (MED 3) -- UCL, 2003