A new computer-assisted navigation system, developed by an interdisciplinary team of researchers and doctors at the University of Ulm over the last three years, makes bypass surgery safer and more precise.
The new method, used in open-heart bypass surgery, has been successfully used on eleven patients. The new method enables intrasurgical navigation, both on beating hearts as well as on hearts that have been temporarily stopped. The heart surgeon Reinhard Friedl, who carried out the 11 interventions, envisages that the new technology will become standard once CT technology is widely available.
According to the project leader, Klaus Dietmayer, negotiations are underway with the medical engineering industry in order to further develop the navigation system. “The innovation potential of the project is beyond doubt,” said the director of the Institute for Measurement, Control and Microtechnology at the University of Ulm, who developed the concept in close cooperation with Reinhard Friedl, the radiologist Martin Hoffmann and the physicists Claudia Gnahm and Christine Hartung.
The novelty of the new method is that it combines novel surgical planning, which is made possible by high resolution 3D computer tomography (CT) images, and image-assisted navigation during surgical intervention. “The 3D-CT model enables the planning of the bypass site prior to the operation,” added Dietmayer. “The method also simplifies diagnosis and the exact localisation of stenosis and is less invasive for patients because they do not require a cardiac catheter,” said Friedl who now works at the University Hospital of Lübeck.On average, the surgeons placed three bypasses per patient all of which, with one exception, could be placed at the predetermined site,” said the heart specialist. “Computer tomography is very helpful when planning surgeries, because it also displays plaque structures,” said the radiologist Hoffmann, who is assistant medical director of the Department of Radiology at the Children’s Hospital at Ulm University.
An instrument known as a cardio-pointer plays a major role in open-heart surgery. The instrument is equipped with reflecting markers, which, in connection with an optical tracking system, continuously indicates the exact three-dimensional position in the surgical field. A stereo camera system continuously delivers pictures and three-dimensional surface information of the heart. The system continuously compares new data with previously stored data and enables the surgeon to navigate to the place that was determined in the 3D model prior to the operation.
“With the previous system it was impossible to measure accuracy,” said Reinhard Friedl, “the surgeon’s intuition and experience were of key importance.” “Therefore, the new navigation system is also a relevant factor for guaranteeing medical quality,” said Klaus Dietmayer.