Development of an endocardioscope for repair of an atrial septal defect in the beating heart.

The purpose of this study was to evaluate the possibility of surgical treatment of an atrial septal defect in the beating heart without cardiopulmonary bypass. The first step was to develop an endocardioscope that permitted observation of the inside of the beating heart. To visualize the inside of the beating heart, the tip of the endoscope was covered with a glass adapter. The endocardioscope was inserted through the right atrial appendage in eight beagles. The atrial septum, foramen ovale, coronary sinus, tricuspid valve, and chordae tendineae were identified without hemodynamic derangement. The second step was to attempt to close the foramen ovale with clips or staplers. We were able to close the foramen ovale with these devices, but a safer, easier device is needed. The endocardioscope we developed should prove to be a useful tool for minimally invasive surgical treatment of heart diseases, such as atrial septal defect.