Device and delivery system
The closure device and delivery system used in this study was a domestic
concentric occluder (Shanghai Shape Memory Alloy Co., Ltd., Shanghai,
China, and Shanghai Push Medical Device Technology Co., Ltd., Shanghai,
China). The minimum size of the occluder was 4 mm. Both disks of the
concentric occluder have a diameter of 2 mm larger than that of the
waist (Fig. 1). The waist is 3.5-4.5 mm in height. The entire delivery
system consisted of a trocar, a guidewire, a delivery cable, a short
loading sheath, a long delivery sheath and a dilator.
Before using, the selected concentric occluder must be immersed in
heparin saline, and the delivery system must be washed with heparin
saline. The selected occluder was screwed onto the delivery cable which
had been inserted into the loading sheath. Then, the procedure of smooth
release and withdrawn of the device must be examined prior to the
surgery via the device being pushed forward out the sheath and pulled
back into the sheath. In order to improve the safety of this closure
technique, a device protective suture of 3–0 polypropylene was passed
through the mesh of the right disk near the middle of every device. It
has to be emphasized that the suture cannot entwine the delivery cable
as it was pulled out of the sheath.