The valve of the foramen ovale in interatrial right-to-left shunt: echocardiographic cineangiocardiographic and hemodynamic observations.

In postpartum persistent right-to-left shunt at the atrial level, the valve of the foramen ovale fails to close. As a thin valve-flap the septum primum is pushed to the left during the phases of right atrial pressure predominance and closes to the septum secundum, when left atrial pressure exceeds right atrial pressure. Thus, it performs a marked movement during the cardiac cycle, reflecting the interatrial pressure-flow dynamics. With use of M-mode echocardiography, this movement pattern was studied in 24 patients: 13 with cyanotic heart disease (age 2 days to 21 years) and 11 newborns with persistent transatrial right-to-left shunt due to noncardiac disease. Cardiac defects were confirmed by cardiac catheterization and cineangiocardiography. Interatrial right-to-left shunts were proved by M-mode and 2-dimensional contrast echocardiography. The comparison of the M-mode echocardiographic findings in our patient groups with normal atrial septal movement studied in 20 healthy infants and children revealed considerable differences. The characteristic movement of the valve of the foramen ovale also was compared with results obtained by cineangiography and 2-dimensional echocardiography. Analysis of interatrial blood pressure difference provided a pathophysiologic explanation of the septum primum movement in transatrial right-to-left shunt.