To check a possible mechanism for residual patency of arterial ducts closed with umbrellas, we studied retrospectively all 25 implantations of the Rashkind device carried out in our institution. In all instances, the smaller umbrella had been used. Residual patency occurred in 40%. There was a significant correlation (p<0.001) between the way the umbrella was rotated and the rate of residual patency. In the larger subgroup, the residual patency was 75% when two arms were pointing towards the aortic blood stream. In contrast, when only one arm pointed upwards, there was only one patient (8.3%) with residual shunt. This potential precipitating mechanism should be considered when implanting the Rashkind devices in future.
