Robot-assisted 13 MHz epicardial ultrasound for endoscopic quality assessment of coronary anastomoses

In totally endoscopic coronary artery bypass surgery, intra-operative assessment of anastomotic quality is needed. We evaluated the endoscopic application of epicardial ultrasound to visualize the coronary anastomosis and detect a construction error. In 8 pigs (71-78kg), 16 internal mammary artery to left anterior descending coronary artery anastomoses were constructed conventionally, either correctly (n=8) or incorrectly with a suture cross-over construction error (n=8). A 13MHz mini-transducer (15x9x6mm) was introduced through a port and manipulated by the 'da Vinci' system. The chest was re-opened and scanning repeated manually. Postoperatively, macroscopic inspection served as reference and the intra-operative ultrasound images were scored as 'correct' or 'construction error' by two blinded observers. All anastomoses were scored accurately by both observers. One anastomosis constructed to be correct was scored as construction error, due to narrowing of the outflow corner and anastomotic orifice. Ultrasound images corresponded with macroscopic inspection. Closed-chest scan time was about 1.5 times longer than open-chest scan time, 176s (88-464) (median, range) versus 125s (75-314) (P=0.01), respectively. Closed-chest epicardial 13MHz ultrasound scanning required a median of 3min and enabled discrimination between correctly and incorrectly constructed coronary anastomoses.