Cobra Anastomotic Tool

		Fig.1: Cobra Tool Fig.2: Redesigned Cobra that improves tool placement

The increasing age of patients being subjected to coronary bypass surgery requires increasing attention that must be paid to the adverse effects of the heart lung machine and the effect of coexisting diseases on the overall outcome. Today's standard cardiac operations are still considerably invasive. Recently it has been shown that cardiac operations are possible with much smaller incisions, using robotic systems, and that the cardio-pulmonary bypass-pump might be avoided. Existing robotic systems, however, are still very large, which implicates that the surgeon is kept away from the operation field and has no fast access to the patient in case of emergency.

The goal of the project is to develop semi-automatic small robotic devices to support surgeons performing anastomosis in coronary bypass surgery on the beating heart. Such a device could ease the time-consuming suturing process while simultaneously ensuring a reproducible anastomotic quality. In addition, these anastomotic devices enable minimally invasive cardiac operations through small incisions that results in reduced mortality and higher quality of life for the patients.

The basic idea is to connect two vessels in an end-to-side arrangement with a helical needle using the conventional suturing technique which is seen as the gold standard in cardiac surgery. The developed anastomotic device (Figure 1) provides constant distances between the stitches, thus allowing reproducible high quality anastomosis on a beating heart to all cardiac surgeons. For this purpose a mechanical intima-intima fixation of the coronary artery and the bypass graft was developed. The use of small hooks to hold the vessels in place reduces the possibility of vessel spasm and guarantees uniform, bio-compatible, continuous suturing. A prototype of the anastomotic device has been realized (Figure 1) enabling successful anastomosis (Figure 1 main page) in the laboratory on explanted pig hearts. The subsequent tests on freshly explanted animal heart, however, revealed some fields of improvement. Predominantly, they concern the placement of the tool that still takes to much time. With a major redesign (Figure 2) that aimed at preserving the advantages of the original design, whilst providing better controllability during tool placement in the coronary artery we could achieve substantial improved handling.

The development of the Cobra and helical needle based suturing marks the next evolutionary step of the time tested hand based suturing of hollow human structures (in our case blood vessels). The potential advantages, it is likely to provide, can be broadly grouped into two distinct areas: 1) Increased speed of high quality suturing and 2) ease of performing the anastomosis. In the future, this technique could be applied in other emerging fields such as the treatment of aortic aneurysms.