From the Carl Zeiss Corp., Oberkochen, Germany. Address reprint requests to P. H. Grassmann, PhD, Carl Zeiss Corp., 73446 Oberkochen, Germany. Acad Radio11996;3:$129-$130 9 1996, Association of University Radiologists C oronary diseases are the most frequent (30%) cause of death in industrialized nations. Although balloon angioplasty provides a less traumatic method of treating coronary arteriosclerosis, the number of bypass interventions has not changed. In 1992, about 500,000 bypass operations were done in about 2,000 heart centers worldwide. Open-heart surgery is extremely stressful, both physically (opening of the thorax, use of a heartlung machine, and artificial heart arrest) and psychologically. A 10-day hospital s tay (average cost -= DM30,000 [approximately 817,000 as of March 1996]) is followed by a rehabilitation phase of several weeks. Complications from the thoracic incision include chronic pain when breathing. Increased interest in minimally invasive surgery (particularly laparoscopic removal of the gallbladder) has led to consideration of endoscot~ic methods for bypass operations, which would not only minimize the strain on the patient but also reduce the length of hospitalization. Advances in the design of endoscopes, which now provide full stereoscopic vision, and their combination with surgical microscopes have made it possible to develop a new surgical technique that is now being used on patients for the first time. The bypass procedure as such is not substantially different from the conventional bypass operation (anesthesia, use of a heart-lung machine, and heart arrest). The similarity ends there, however, because in the new procedure, both lobes of tile left lung are collapsed, and trocars with instruments (e.g., optical systems, forceps, scissors, needles) are introduced throug h five to seven punctures between the ribs. First, a section of the mammary artery is exposed and separated temporarily from the blood flow by means of clips. The pericardium is opened, and the heart is turned so that the stenosed artery is clearly visible and can be freed from the heart and resected lengthwise. The longitudinal incision thus produced is then used to connect the coronary artery with the end of the mammary artery that is located in the direction of the blood flow. This is the most difficult phase of the surgery. Because the clips that can be used for laparoscopy cannot be used with coronary arteries, the anastomosis nmst be sutured. The temporary clips are then removed as are the trocars, the patient is taken off bypass, and the heart is reactivated.