Reduction of right atrial peak systolic velocity in growth-restricted discordant twins.

Abstract

The objective of this study was to measure blood flow velocity changes through the tricuspid valve in intrauterine growth-restricted twins. Discordant twins were evaluated by measurement of tricuspid valve flow velocities. Twin pairs with one intrauterine growth-restricted fetus caused by uteroplacental insufficiency and one appropriately grown fetus were included in the analysis. Fetuses with chromosomal or structural abnormalities and confirmed twin-twin transfusion syndrome were excluded. Eighteen pairs met these criteria. Student's t test was used for comparison of flow velocities. Peak ventricular diastolic flow velocities through the tricuspid valve in the twin with intrauterine growth restriction and the appropriately grown twin were 35.8 +/- 4.43 cm/sec and 34.0 +/- 6.7 cm/sec, respectively (p = 0.35). The atrial peak systolic flow velocity values were 42.1 +/- 1.2 and 50.3 +/- 1.2, respectively (p = 0.049). The velocity of blood flow through the tricuspid valve during atrial systole is lower in growth-restricted twins than in appropriately grown cotwins when growth restriction is caused by uteroplacental insufficiency. Its potential in differentiating discordancy from the other causes remains to be explored.