New insight into left ventricular function in tricuspid atresia after total cavopulmonary connection: a three-dimensional echocardiographic study

Background In patients with tricuspid atresia palliated by construction of a total cavopulmonary connection, both pulmonary and systemic circulations depend on the performance of the dominant left ventricle. When estimating the volume of such ventricles using cross-sectional echocardiography, it is necessary to make assumptions concerning the geometry of the ventricular shape. This is avoided by three-dimensional echocardiography, which provides direct volumetric data. Our purpose was to apply this new method to quantify left ventricular volumes and function in patients with tricuspid atresia after construction of a total cavopulmonary connection. Methods: We studied ten patients (median age: 8 years) with tricuspid atresia who had undergone a total cavopulmonary connection, comparing them with 10 normal children matched for age, sex and size. The three-dimensional echocardiography was performed with electrocardiographic and respiratory gating. A new transthoracic integrated probe designed for small children was used with a rotational scanning increment of 3 degrees. The 60 slices obtained from the ventricular cavity were stored and formatted in a commercial system (TomTec(R)). End-diastolic and end-systolic volumes, stroke volume and ejection fraction were calculated after manual tracing of the endocardial surfaces. The volumes were indexed to the body surface area. Results: As seen in the reconstructions, the dominant left ventricle in tricuspid atresia had a spherical shape, whereas the normal left ventricle is oblong. The left ventricular volumes and function in tricuspid atresia were 54+/-4 ml/m(2) (end-diastolic volume), 28+/-3 ml/m(2) (end-systolic volume), 26+/-7 ml/m(2) (stroke volume) and 48+/-6% (ejection fraction). These volumes were nor different from those obtained in the controls (p = NS). The left ventricular stroke volume and ejection fraction in 10 patients with tricuspid atresia were lower than those calculated for the controls d(p < 0.05). Conclusions: Three-dimensional echocardiography provides a quantitative insight into the pathophysiologic function of the dominant left ventricle in tricuspid atresia after construction of a total cavopulmonary connection.