An innovative design for semi-automatic suture in mini-invasive surgery

Partner: Fraunhofer IPA (Stuttgart, D.)

Since 2008 CEA LIST has been collaborating with Fraunhofer IPA (Institute for production and automation technology) as a partner in the MISS project (Minimally Invasive Smart Suture), initiated as part of the call for Inter Carnot Fraunhofer projects. The goal of MISS is to develop innovative suture devices for mini-invasive surgery. The target application is coronary bypass surgery, which aims to circumvent an obstructed section of coronary artery by connecting a graft, one end on the aorta and the other on the affected artery downstream from the stenosis (vessel diameter: 3 mm). The surgical objective is to make the connection procedure (anastomosis) as rapid as possible, in a mini-invasive way and with the heart beating, in order to reduce the patient’s rehabilitation period from several months, as required for a conventional operation, to several days.
Researchers at LIST have developed a design for a semi-automatic suture instrument, for which the movements are manually controlled by the surgeon. The challenge consisted of firstly gaining mini-invasive access to the operating area, which required passage of the instrument along very small diameter trocars and/or natural pathways (such as the arteries), and then, secondly, performing the suture with surgical thread (and not clips or fasteners), thus improving the reliability, scarification and behaviour at the time of anastomosis.

To address the major issue of obstruction, and also to remove the electronic difficulties related to use of actuators inside the body, it was decided to use a hydraulic circuit to provide the power for control of the suture by the surgeon. This approach could use a physiological serum, hence guaranteeing biocompatibility in the event of accidental leaks. The device that was designed consists of two units, one containing the needles and the other the hooks. Two lines of needles pierce through the walls of the artery and the graft and form loops of thread. Under these passes a second thread carried by the hooks. A cutting system makes it possible to restore blood flow between the graft and the artery. A prototype with manual actuation, constructed on a scale of 8:1, was able to validate the concept of a semi-automatic thread-suture, rapidly and using conventional means, (tested in-vitro). The next step involved reduction to design scale (1:1 scale), implementation of the hydraulic actuation of the system and in-vivo testing of the new prototype on a porcine model (with heart beating).

This patented, innovative design will be presented to European surgical equipment companies at the Medical Physics and Biomedical Engineering World Congress 2009 exhibition, which will take place in Munich in September 2009.