Beating Atrial Septal Defect Closure Monitored by Epicardial Real-Time Three-Dimensional Echocardiography Without Cardiopulmonary Bypass

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Abstract
Background— We assessed the feasibility of beating atrial septal defect (ASD) closure monitored by real-time 3D echocardiography (RT3DE). Methods and Results— RT3DE was developed with prototype ultrasound equipment consisting of a high-speed 3D rendering unit with a frame rate of 5 to 10 frames/s. We also developed a prototype semiautomatic suture device and suture cutting system. In the experiment, 12 mongrel dogs were anesthetized, and after median sternotomy, the echo probe was applied directly to the surface of the right atrium. Three surgical maneuvers (balloon atrial septectomy, enlargement of the ASD, and ASD closure) were performed through the atrial port inserted into the right atrial appendage. The heart was then excised, and the area of the ASD measured by RT3DE was compared with its area measured directly. The ASD was successfully closed in all experimental animals except the first 2. Examination of the excised heart showed that none of the sutures were loose. The mean area of the ASD was 82.5±38.6 mm 2 when measured by RT3DE and 81.6±38.2 mm 2 when measured directly, and there was a significant correlation between the areas measured by RT3DE and those measured directly (echo measurements=1.007×direct measurements+0.337; P 2 upper and −6.024 mm 2 lower limit of agreement). Conclusions— Introduction of RT3DE, a semiautomatic suture device, and a suture cutting system made beating ASD closure without cardiopulmonary bypass possible.