Two-dimensional echocardiographic evaluation of right ventricular size and function in newborns with severe right ventricular outflow tract obstruction

Critical pulmonary stenosis or atresia with intact ventricular septum represents a congenital cardiac lesion for which the long-term prognosis appears to depend partly on the size of the right ventricle. Thus, the capability of noninvasive assessment of right ventricular size to predict operative outcome was examined in 15 infants (aged 1 to 30 days, mean 5.6) with severe right ventricular outflow tract obstruction (either critical pulmonary stenosis [7 patients] or pulmonary atresia with intact ventricular septum [8 patients]). Using echocardiography in two orthogonal subxiphoid views, right ventricular volume, wall thickness, area change fraction, ejection fraction and tricuspid anulus dimension were measured.All patients with a normalized right ventricular enddiastolic volume of less than 5 ml/m2and a normalized tricuspid anulus dimension of less than 1.0 cm/m2/3required a shunt operation. Only one patient with a volume of more than 6 ml/m2and a normalized tricuspid anulus dimension of more than 1.4 cm/m2/3required more than relief of right ventricular outflow tract obstruction. In this patient, residual severe pulmonary stenosis necessitated the shunt procedure. One patient with a volume of more than 6 ml/m2had an anulus diameter of less than 1.4 cm/m2/3and one patient with an anulus diameter of more than 1.4 cm/m2/3had a volume of less than 6 ml/m2; both required shunt procedures. It therefore appears that if either the ventricular volume or tricuspid anulus size is excessively small, a shunt procedure is necessary. Wall thickness, area change fraction and ejection fraction measurements were not significantly correlated with right ventricular volume or postoperative outcome.The noninvasive (echocardiographic) assessment of right ventricular volume and tricuspid valve anulus dimension permits excellent prediction of postoperative outcome. In patients with severe right ventricular hypoplasia, the need for alternative surgical therapy may thereby be recognized before initial intervention