Serial changes of mitral and tricuspid valve diameter after the Norwood procedure in patients with aortic atresia.

BACKGROUND

In hypoplastic left heart syndrome with aortic atresia, the non-functional left ventricle may influence right ventricular performance. We evaluated serial changes in tricuspid and mitral valve diameters after the Norwood procedure and their relationship to right ventricular function.

METHODS

Of 150 patients who underwent the Norwood procedure (2001-2020), 47 died before total cavopulmonary connection. Of the 103 survivors, 76 with sufficient serial echocardiographic data were analysed (1,399 examinations). Tricuspid and mitral valve diameters were measured, and right ventricular function was assessed. Right ventricular dysfunction was defined as any degree of impairment. Mixed-effects models were used to account for repeated measures.

RESULTS

Median follow-up was 4.6 years (IQR 2.4-11.8). Right ventricular dysfunction was observed in 15.9% of examinations. Patients with right ventricular dysfunction had significantly larger tricuspid valve diameters than those with normal function (24.3 mm vs 23.4 mm, p = 0.006), whereas mitral valve diameters showed no significant difference (7.6 mm vs 7.1 mm, p = 0.120). The mitral/tricuspid ratio was similar between groups (0.320 versus 0.324, p = 0.340). Mixed-effects modelling showed that the tricuspid valve diameter remained 0.618 mm larger in the dysfunction group after adjusting for growth over time (p = 0.029). Tricuspid valve diameter differences emerged at the bidirectional cavopulmonary shunt stage and accelerated through Fontan completion (p < 0.001).

CONCLUSIONS

In hypoplastic left heart syndrome with aortic atresia, right ventricular dysfunction is associated with progressive tricuspid valve enlargement but not with changes in the mitral/tricuspid ratio. While the stable ratio suggests proportional annular growth, a comprehensive volumetric assessment is needed to clarify ventricular-ventricular interactions.