Real-time three dimensional echo-guided closure of atrial septal defect: an experimental model.

Real-time 3D echo may open the way to off-pump closure of an atrial septal defect with a robotic surgery technique without remnant of closure device. We report the preliminary results of 3D echo-guided closure of defect in an experimental model. A sheet with an oval defect immersed in water was visualized with 3D echo as well as surgical instruments. The defect was closed under echo guidance. Visualization of objects and instruments, and feasibility and problems of this technique were examined. The defect was visualized like an endoscopic view. Changing the view point without moving the transducer was a unique advantage. Visualization of instruments was acceptable with the lowest gain level. Acoustic shadow was helpful for comprehending the spatial relationship among the objects. Position of needle entry could be confirmed by the movement of the sheet. As the defect was sutured, fold convergence appeared on the sheet. Difficulties were encountered in passing the needle between instruments because of echo dropout. The string was poorly visualized. 3D echo-guided suturing was feasible with adequate image quality. However, an improvement of the surface of instruments and a wider scanning area is necessary for achieving surgical procedures with more safety and reliability.