Functional characteristics of the single ventricle were studied by means of biplane angiocardiography in 34 patients. Group 1 consisted of 14 patients with normal or increased pulmonary vascular marking on chest film and no pulmonary stenosis. Group 2 included 20 patients with severe angiographic pulmonary stenosis and decreased pulmonary vascular marking. Ventricular volume parameters were calculated according to Simpson's rule and were compared with normal values. The sum of the normal left and right ventricular volumes was assumed to be 100%.
In group 1, ventricular end-diastolic volumes averaged 143 ± 11% and were significantly (p < 0.001) larger than end-diastolic volumes in group 2 (81 4%). The presence or absence of severe pulmonary stenosis affecting pulmonary blood flow was a main factor regulating the ventricular chamber size in single ventricle. In both groups, the ejection fraction of a single ventricle was significantly lower than that of a normal left or right ventricle. Ventricular size and function in patients with a single ventricle should be carefully assessed before ventricular septation surgery.