Epicardial ultrasound in coronary artery bypass surgery

Chapter 1 Coronary artery bypass surgery (CABG) is traditionally performed via a median sternotomy approach on cardiopulmonary bypass (arrested heart). Since the mid 1990ties, beating heart, minimally invasive and even totally endoscopic CABG are (re)explored. In all approaches to CABG, the surgeon may face several intraoperative difficulties: 1. Localization of the target coronary artery for bypass grafting. 2. Selection of the optimal anastomotic site on the target coronary artery. 3. Assessment of the quality of the constructed anastomosis. An epicardial ultrasound mini-transducer was evaluated to aid in all the intraoperative difficulties described above. Chapter 2 Three devices: 1) a sternum lift for the creation of additional workspace; 2) an EndoStarfish for closed chest exposure of the posterior side of the heart, and; 3) an EndoOctopus for closed chest stabilization of the coronary artery, were employed for closed-chest multivessel robot-assisted beating heart CABG in a porcine model. Chapter 3&4 The epicardial ultrasound mini-transducer was used in the model described in chapter 2, in order to endoscopically locate and assess the major target coronary arteries for bypass grafting and assessment of coronary anastomoses. The mini-transducer was introduced through a port and manipulated over the heart using robot-assisted instruments. The ultrasound image was displayed picture-in-picture on the master console of the tele-manipulation system. Robot-assisted scanning enabled endoscopic identification and assessment of the major coronary branches and anastomoses. Chapter 5&6 In pressure perfused porcine and human hearts, we investigated the epicardial ultrasound presentation and geometry alteration of specific construction errors in coronary artery anastomoses. Also, the sensitivity and specificity of epicardial ultrasound for the detection of coronary anastomosis construction errors was determined and compared to the gold standard angiography. Using ultrasound construction errors were detected with a sensitivity of 0.98 and specificity of 1.00 which is significantly higher than by angiography (0.75 and 0.81, respectively). Chapter 7 During application of the S2AS distal coronary bypass connector in porcine beating heart CABG, we employed the mini-transducer to evaluate quantitative calliper measurements for vessel size matching and assess the quality of the anastomosis. The external calliper measurements provided a reliable quantitative estimate of vessel diameter for size matching. Epicardial ultrasound enabled intraoperative assessment of the S²AS coronary connector anastomosis in considerable detail. Chapter 8&9 The successful initial results of the application of the mini-transducer, on all sides of the arrested heart, in patients undergoing CABG surgery is described. Epicardial scanning resulted in changes of the selected anastomotic site, the number of constructed anastomoses and prevented grafting of the wrong vessel. Subesequently, a study protocol was set-up that will evaluate the relation between intraoperative epicardial ultrasound, pre- and postoperative coronary angiography and postoperative multislice CT scanning, in CABG patients. Chapter 10 The mini-transducer described this thesis, can be used on all sides of the heart, in all approaches currently used for CABG. Epicardial ultrasound helps in (1) locating the target coronary artery, (2) selecting the optimal anastomotic site, (3) assessing the quality of the constructed anastomosis, (4) selecting the optimal site for aortic clamping and cannulation