We compared 2-dimensional and Doppler echocardiographic indices of RV size and function , neo-aortic and tricuspid valve annulus dimensions and function , and aortic size and patency at 14.1 1.2 months and 33.6 9.6 months in subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt ( MBTS ) or right ventricle to pulmonary artery shunt ( RVPAS ) .