Discussion

Severe tricuspid regurgitation in the neonatal period can be caused by various anatomical anomalies of the tricuspid valve,1 ,6 but it can also be secondary to severe pulmonary hypertension or obstruction of the right ventricular outflow tract.7 Isolated transient tricuspid regurgitation without an obvious anatomical and haemodynamic basis has also been described.8 Antenatal events that cause increased pressure in the right ventricle may explain this clinical entity. It has been shown that fetal closure of the ductus arteriosus causes increased pulmonary arterial pressure, right ventricular enlargement, and tricuspid valve regurgitation. This mostly improves and even resolves during the first weeks of life.4 ,5

Our patient presented during the neonatal period with the clinical picture of functional pulmonary atresia caused by massive tricuspid regurgitation and “normal” high perinatal pulmonary vascular resistance. We previously reported her case as an example of “transient tricuspid regurgitation”.1 Other than a slightly thickened tricuspid valve, neonatal Doppler echocardiographies excluded gross anomalies of the tricuspid valve such as Ebstein's anomaly or severe dysplasia of the tricuspid valve. Over a period of several weeks, as the pulmonary vascular resistance decreased and the right ventricle recuperated, her haemodynamic condition improved progressively, and at the ages of 3 and 6 months she had normal clinical and Doppler echocardiographic examinations. At the age of 14 years our patient once more presented with severe tricuspid regurgitation and massive dilatation of the right heart.

Echocardiographically the tricuspid valve leaflets appeared slightly thickened and the chordae tendineae seemed remarkably shortened. This is an unusual evolution after transient tricuspid regurgitation. Various hypotheses can be put forward to explain this observation. It is possible that with time the tricuspid valve started to leak again because of progressive right ventricular dysfunction long after an initial perinatal insult. Sustained perinatal right ventricular overload could have caused subendocardial myocardial damage involving the papillary muscles.9 When right ventricular afterload decreased postnatally, ventricular function initially improved resulting in decreased tricuspid regurgitation. The “scarred” ventricle continued to function relatively normally but progressively became dysfunctional after many years. This resulted in recurrence of tricuspid regurgitation, which further caused ventricular dysfunction. A second possibility is that the growth of the tricuspid valve was disturbed. A striking finding on echocardiography was the short chordae tendineae, which seemed to have grown inadequately over the preceding years. It is, however, difficult to assess the adequacy of the length of the chordae in the context of a severely dilated right ventricle. Another, less probable, explanation is that our patient did have mild Ebstein's disease. Although the single most diagnostic feature—namely, downward displacement of the septal leaflet—was absent, the surgeon reported some features suggestive of Ebstein's anomaly: a severely dilated annulus, “Ebstein-like” adhesion of the septal leaflet, and a thin anterior leaflet with multiple fenestrations.10 Anatomical and functional severity in Ebstein's anomaly are not necessarily related and newborns with isolated Ebstein's anomaly often show spontaneous improvement as the pulmonary vascular resistance decreases.10

From this case we conclude that patients with transient neonatal tricuspid regurgitation, without an obvious anatomical and haemodynamic basis, should be followed up during growth for the possible development of late tricuspid regurgitation.