[An accurate formula for assessing the volume of the right ventricular outflow tract]

Practical application of formulae for separate assessment of the volumes of inlet and outlet sections of the right ventricle derived previously by the authors has shown that the formula for right ventricular outlet section determining it as a curved truncated cone with nonparallel bases does not take into account a narrowing in the middle third of the outlet portion during the right ventricular systole and/or supraventricular crest hypertrophy. In the specified formula right ventricular outlet portion volume is determined as a sum of the volumes of two truncated cones with a borderline in the middle of the outlet portion long axis. The most reliable difference from the main formula was obtained in the control group where the borderline of outlet portion division coincided with the area of the maximal stenosis of outlet portion stenosis in the systole. In other groups (patients with some congenital heart diseases) the maximal stenosis zone is located lower. Hence, the specified formula helps reduce the overvaluing of the right ventricular outlet portion volume; to make the estimation more accurate, the borderline between the cones should be carried out at the site of this portion maximal stenosis.